From 43a7e54067b62a3fe783b37670c1a3329c14a7c5 Mon Sep 17 00:00:00 2001
From: Rubidium <rubidium@openttd.org>
Date: Mon, 10 Apr 2023 19:02:31 +0200
Subject: [PATCH] Add: unit test functionality using catch2

---
 .github/workflows/ci-build.yml          |   2 +-
 .github/workflows/codeql.yml            |   1 +
 CMakeLists.txt                          |   6 +
 cmake/SourceList.cmake                  |  23 +
 src/landscape.cpp                       |  17 +-
 src/tests/CMakeLists.txt                |   6 +-
 src/tests/landscape_partial_pixel_z.cpp | 642 ++++++++++++++++++++++++
 src/tests/landscape_partial_pixel_z.h   | 552 --------------------
 src/tests/math_func.cpp                 |  77 +++
 src/tests/test_main.cpp                 |  14 +
 10 files changed, 769 insertions(+), 571 deletions(-)
 create mode 100644 src/tests/landscape_partial_pixel_z.cpp
 delete mode 100644 src/tests/landscape_partial_pixel_z.h
 create mode 100644 src/tests/math_func.cpp
 create mode 100644 src/tests/test_main.cpp

diff --git a/.github/workflows/ci-build.yml b/.github/workflows/ci-build.yml
index a9c868242e..4567a5833b 100644
--- a/.github/workflows/ci-build.yml
+++ b/.github/workflows/ci-build.yml
@@ -65,7 +65,7 @@ jobs:
 
         echo "::group::Build"
         echo "Running on $(nproc) cores"
-        cmake --build . -j $(nproc)
+        cmake --build . -j $(nproc) -t openttd
         echo "::endgroup::"
 
   linux:
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 936c4c92d7..912223e500 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -74,6 +74,7 @@ jobs:
           +**/*.*
           -**/table/*.*
           -**/generated/**/*.*
+          -**/tests/*.*
         input: sarif-results/cpp.sarif
         output: sarif-results/cpp.sarif
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e911625cfa..655f4c144f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -215,6 +215,7 @@ if(OPTION_PACKAGE_DEPENDENCIES)
     set(CMAKE_BUILD_WITH_INSTALL_RPATH ON)
 endif()
 
+include(CTest)
 include(SourceList)
 
 # Needed by rev.cpp
@@ -226,6 +227,7 @@ include(MSVCFilters)
 
 add_library(openttd_lib OBJECT ${GENERATED_SOURCE_FILES})
 add_executable(openttd WIN32)
+add_executable(openttd_test)
 set_target_properties(openttd PROPERTIES OUTPUT_NAME "${BINARY_NAME}")
 # All other files are added via target_sources()
 
@@ -254,6 +256,10 @@ target_link_libraries(openttd
     openttd::basesets
 )
 
+target_link_libraries(openttd_test PRIVATE openttd_lib)
+include(Catch)
+catch_discover_tests(openttd_test)
+
 if(HAIKU)
     target_link_libraries(openttd_lib "be" "network" "midi")
 endif()
diff --git a/cmake/SourceList.cmake b/cmake/SourceList.cmake
index b576e20a02..af87c09e82 100644
--- a/cmake/SourceList.cmake
+++ b/cmake/SourceList.cmake
@@ -21,6 +21,29 @@ function(add_files)
     endforeach()
 endfunction()
 
+# Add a test file to be compiled.
+#
+# add_test_files([file1 ...] CONDITION condition [condition ...])
+#
+# CONDITION is a complete statement that can be evaluated with if().
+# If it evaluates true, the source files will be added; otherwise not.
+# For example: ADD_IF SDL_FOUND AND Allegro_FOUND
+#
+function(add_test_files)
+    cmake_parse_arguments(PARAM "" "" "CONDITION" ${ARGN})
+    set(PARAM_FILES "${PARAM_UNPARSED_ARGUMENTS}")
+
+    if(PARAM_CONDITION)
+        if(NOT (${PARAM_CONDITION}))
+            return()
+        endif()
+    endif()
+
+    foreach(FILE IN LISTS PARAM_FILES)
+        target_sources(openttd_test PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/${FILE})
+    endforeach()
+endfunction()
+
 # This function works around an 'issue' with CMake, where
 # set_source_files_properties() only works in the scope of the file. We want
 # to set properties for the source file on a more global level. To solve this,
diff --git a/src/landscape.cpp b/src/landscape.cpp
index aeacf65ba7..bfff296294 100644
--- a/src/landscape.cpp
+++ b/src/landscape.cpp
@@ -221,7 +221,7 @@ uint ApplyFoundationToSlope(Foundation f, Slope *s)
  * @param corners slope to examine
  * @return height of given point of given slope
  */
-static constexpr uint InternalGetPartialPixelZ(int x, int y, Slope corners)
+uint GetPartialPixelZ(int x, int y, Slope corners)
 {
 	if (IsHalftileSlope(corners)) {
 		/* A foundation is placed on half the tile at a specific corner. This means that,
@@ -285,21 +285,6 @@ static constexpr uint InternalGetPartialPixelZ(int x, int y, Slope corners)
 	}
 }
 
-#include "tests/landscape_partial_pixel_z.h"
-
-/**
- * Determines height at given coordinate of a slope.
- * See #InternalGetPartialPixelZ.
- * @param x x coordinate (value from 0 to 15)
- * @param y y coordinate (value from 0 to 15)
- * @param corners slope to examine
- * @return height of given point of given slope
- */
-uint GetPartialPixelZ(int x, int y, Slope corners)
-{
-	return InternalGetPartialPixelZ(x, y, corners);
-}
-
 /**
  * Return world \c Z coordinate of a given point of a tile. Normally this is the
  * Z of the ground/foundation at the given location, but in some cases the
diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index d028125ae9..b920fd6fdb 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -1,3 +1,5 @@
-add_files(
-    landscape_partial_pixel_z.h
+add_test_files(
+    landscape_partial_pixel_z.cpp
+    math_func.cpp
+    test_main.cpp
 )
diff --git a/src/tests/landscape_partial_pixel_z.cpp b/src/tests/landscape_partial_pixel_z.cpp
new file mode 100644
index 0000000000..f5c22786f7
--- /dev/null
+++ b/src/tests/landscape_partial_pixel_z.cpp
@@ -0,0 +1,642 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file landscape_partial_pixel_z.cpp Tests for consistency/validity of the results of GetPartialPixelZ. */
+
+#include "../stdafx.h"
+
+#include "../3rdparty/catch2/catch.hpp"
+
+#include "../landscape.h"
+#include "../slope_func.h"
+#include <array>
+
+/**
+ * Check whether the addition of two slope's GetPartialPixelZ values results in
+ * the GetPartialPixelZ values of the expected slope.
+ * This iterates over all sub-pixel locations within a single tile.
+ * @param slope_expected The slope that is expected.
+ * @param slope_a The first slope of the addition.
+ * @param slope_b The second slope of the addition.
+ * @return True iff at all GetPartialPixelZ results are the same for each sub-tile position.
+ */
+bool CheckPartialPixelZSlopeAddition(Slope slope_expected, Slope slope_a, Slope slope_b)
+{
+	for (uint x = 0; x < TILE_SIZE; x++) {
+		for (uint y = 0; y < TILE_SIZE; y++) {
+			int z_a = GetPartialPixelZ(x, y, slope_a);
+			int z_b = GetPartialPixelZ(x, y, slope_b);
+			int z_result = GetPartialPixelZ(x, y, slope_expected);
+			if (z_result != z_a + z_b) return false;
+		}
+	}
+	return true;
+}
+
+TEST_CASE("PartialPixelSlopeAdditionTest - A one corner slope, plus the opposite three corner slope results in a flat but elevated slope")
+{
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_N, SLOPE_WSE));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_E, SLOPE_NWS));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_S, SLOPE_ENW));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_W, SLOPE_SEN));
+}
+
+TEST_CASE("PartialPixelSlopeAdditionTest - Diagonal slopes with their opposite slope result in a flat but elevated slope")
+{
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_NW, SLOPE_SE));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_SW, SLOPE_NE));
+}
+
+TEST_CASE("PartialPixelSlopeAdditionTest - Half tile slopes with their opposite half tile slope result in a flat but elevated slope")
+{
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, HalftileSlope(SLOPE_N, CORNER_N), HalftileSlope(SLOPE_S, CORNER_S)));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, HalftileSlope(SLOPE_E, CORNER_E), HalftileSlope(SLOPE_W, CORNER_W)));
+}
+
+TEST_CASE("PartialPixelSlopeAdditionTest - Two opposite one corner slopes result in the two corner slope with opposite corners")
+{
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_NS, SLOPE_N, SLOPE_S));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_EW, SLOPE_E, SLOPE_W));
+}
+
+TEST_CASE("PartialPixelSlopeAdditionTest - A steep slope is a one corner slope on top of a three corner slope")
+{
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_STEEP_N, SLOPE_N, SLOPE_ENW));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_STEEP_E, SLOPE_E, SLOPE_SEN));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_STEEP_S, SLOPE_S, SLOPE_WSE));
+	CHECK(CheckPartialPixelZSlopeAddition(SLOPE_STEEP_W, SLOPE_W, SLOPE_NWS));
+}
+
+TEST_CASE("PartialPixelSlopeAdditionTest - A half tile steep slope is a one corner half tile on top of a three corner slope")
+{
+	CHECK(CheckPartialPixelZSlopeAddition(HalftileSlope(SLOPE_STEEP_N, CORNER_N), HalftileSlope(SLOPE_N, CORNER_N), SLOPE_ENW));
+	CHECK(CheckPartialPixelZSlopeAddition(HalftileSlope(SLOPE_STEEP_E, CORNER_E), HalftileSlope(SLOPE_E, CORNER_E), SLOPE_SEN));
+	CHECK(CheckPartialPixelZSlopeAddition(HalftileSlope(SLOPE_STEEP_S, CORNER_S), HalftileSlope(SLOPE_S, CORNER_S), SLOPE_WSE));
+	CHECK(CheckPartialPixelZSlopeAddition(HalftileSlope(SLOPE_STEEP_W, CORNER_W), HalftileSlope(SLOPE_W, CORNER_W), SLOPE_NWS));
+}
+
+/**
+ * Check whether the partial pixel Z values are the expected values. The arrays
+ * are as if the map is rotated 45 degrees counterclockwise.
+ * @param slope The slope that is to be checked.
+ * @param expected The expect partial pixels Z values.
+ * @return True iff at all GetPartialPixelZ results are the same as the expected Z-coordinates.
+ */
+bool CheckPartialPixelZ(Slope slope, std::array<int, TILE_SIZE * TILE_SIZE> expected)
+{
+	for (uint i = 0; i < expected.size(); i++) {
+		int actual = GetPartialPixelZ(GB(i, 4, 4), GB(i, 0, 4), slope);
+		if (actual != expected[i]) return false;
+	}
+	return true;
+}
+
+TEST_CASE("PartialPixelTest - One corner up slopes - SLOPE_N")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_N, {
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0,
+		7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0,
+		6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0,
+		6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0,
+		5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0,
+		5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0,
+		4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
+		4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
+}
+
+TEST_CASE("PartialPixelTest - One corner up slopes - SLOPE_E")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_E, {
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7,
+		0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7,
+		0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
+		0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
+		0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5,
+		0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
+		0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
+}
+
+TEST_CASE("PartialPixelTest - One corner up slopes - SLOPE_S")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_S, {
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4,
+		0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4,
+		0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
+		0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5,
+		0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
+		0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
+		0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7,
+		0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7}));
+}
+
+TEST_CASE("PartialPixelTest - One corner up slopes - SLOPE_W")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_W, {
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
+		5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0,
+		5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0,
+		6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0,
+		6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0,
+		7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0,
+		7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0}));
+}
+
+TEST_CASE("PartialPixelTest - Two corner up, diagonal slopes - SLOPE_NE")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_NE, {
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+		7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+		6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+		6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+		5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+		5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+		4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+		4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+		3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+		3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+		2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+		2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+		1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
+}
+
+TEST_CASE("PartialPixelTest - Two corner up, diagonal slopes - SLOPE_SE")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_SE, {
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8}));
+}
+
+TEST_CASE("PartialPixelTest - Two corner up, diagonal slopes - SLOPE_SW")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_SW, {
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+		2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+		2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+		3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+		3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+		4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+		4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+		5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+		5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+		6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+		6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
+		7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+		7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}));
+}
+
+TEST_CASE("PartialPixelTest - Two corner up, diagonal slopes - SLOPE_NW")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_NW, {
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0}));
+}
+
+TEST_CASE("PartialPixelTest - Two opposite corner up slopes - SLOPE_NS")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_NS, {
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0,
+		7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1,
+		6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1,
+		6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2,
+		5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2,
+		5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3,
+		4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3,
+		4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4,
+		3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4,
+		3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
+		2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5,
+		2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
+		1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
+		1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7,
+		0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7}));
+}
+
+TEST_CASE("PartialPixelTest - Two opposite corner up slopes - SLOPE_EW")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_EW, {
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7,
+		1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7,
+		1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
+		2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
+		2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5,
+		3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
+		3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4,
+		4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4,
+		4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3,
+		5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3,
+		5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2,
+		6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2,
+		6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1,
+		7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1,
+		7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0}));
+}
+
+TEST_CASE("PartialPixelTest - Three corner up slopes - SLOPE_ENW")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_ENW, {
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4,
+		8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4,
+		8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3,
+		8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3,
+		8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2,
+		8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2,
+		8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1,
+		8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1}));
+}
+
+TEST_CASE("PartialPixelTest - Three corner up slopes - SLOPE_SEN")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_SEN, {
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8,
+		3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8,
+		3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8,
+		2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8,
+		2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8,
+		1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8,
+		1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8}));
+}
+
+TEST_CASE("PartialPixelTest - Three corner up slopes - SLOPE_WSE")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_WSE, {
+		0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
+		1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
+		1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8,
+		2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8,
+		2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8,
+		3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8,
+		3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8,
+		4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8,
+		4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}));
+}
+
+TEST_CASE("PartialPixelTest - Three corner up slopes - SLOPE_NWS")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_NWS, {
+		8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
+		8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1,
+		8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1,
+		8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2,
+		8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2,
+		8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3,
+		8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3,
+		8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}));
+}
+
+TEST_CASE("PartialPixelTest - Normal half tile slopes - SLOPE/CORNER_N")
+{
+	CHECK(CheckPartialPixelZ(HalftileSlope(SLOPE_N, CORNER_N), {
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
+}
+
+TEST_CASE("PartialPixelTest - Normal half tile slopes - SLOPE/CORNER_E")
+{
+	CHECK(CheckPartialPixelZ(HalftileSlope(SLOPE_E, CORNER_E), {
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8}));
+}
+
+TEST_CASE("PartialPixelTest - Normal half tile slopes - SLOPE/CORNER_S")
+{
+	CHECK(CheckPartialPixelZ(HalftileSlope(SLOPE_S, CORNER_S), {
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+		0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}));
+}
+
+TEST_CASE("PartialPixelTest - Normal half tile slopes - SLOPE/CORNER_W")
+{
+	CHECK(CheckPartialPixelZ(HalftileSlope(SLOPE_W, CORNER_W), {
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0,
+		8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0}));
+}
+
+TEST_CASE("PartialPixelTest - Steep slopes - SLOPE_STEEP_N")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_STEEP_N, {
+		16, 15, 15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,
+		15, 15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,
+		15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,
+		14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,
+		14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,
+		13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,
+		13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,
+		12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,
+		12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,
+		11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,
+		11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,
+		10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,
+		10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,
+		 9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,
+		 9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,
+		 8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1}));
+}
+
+TEST_CASE("PartialPixelTest - Steep slopes - SLOPE_STEEP_E")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_STEEP_E, {
+		 8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16,
+		 8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15,
+		 7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15,
+		 7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14,
+		 6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14,
+		 6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13,
+		 5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13,
+		 5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12,
+		 4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12,
+		 4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11,
+		 3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11,
+		 3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10,
+		 2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10,
+		 2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9,
+		 1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,
+		 1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8}));
+}
+
+TEST_CASE("PartialPixelTest - Steep slopes - SLOPE_STEEP_S")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_STEEP_S, {
+		 0,  1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,
+		 1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,
+		 1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,
+		 2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9,
+		 2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10,
+		 3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10,
+		 3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11,
+		 4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11,
+		 4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12,
+		 5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12,
+		 5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13,
+		 6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13,
+		 6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14,
+		 7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14,
+		 7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15,
+		 8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15}));
+}
+
+TEST_CASE("PartialPixelTest - Steep slopes - SLOPE_STEEP_W")
+{
+	CHECK(CheckPartialPixelZ(SLOPE_STEEP_W, {
+		 8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1,  0,
+		 8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1,
+		 9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,
+		 9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,
+		10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,
+		10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,
+		11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,
+		11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,
+		12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,
+		12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,
+		13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,
+		13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,
+		14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,
+		14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,
+		15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,
+		15, 15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8}));
+}
+
+TEST_CASE("PartialPixelTest - Half tile on top of steep slopes - SLOPE_STEEP/CORNER_N")
+{
+	CHECK(CheckPartialPixelZ(HalftileSlope(SLOPE_STEEP_N, CORNER_N), {
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,
+		16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,
+		16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,
+		16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,
+		16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,
+		16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,
+		16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,
+		16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,
+		16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,
+		16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1}));
+}
+
+TEST_CASE("PartialPixelTest - Half tile on top of steep slopes - SLOPE_STEEP/CORNER_E")
+{
+	CHECK(CheckPartialPixelZ(HalftileSlope(SLOPE_STEEP_E, CORNER_E), {
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16,
+		 4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16,
+		 3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16,
+		 3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16,
+		 2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16,
+		 2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16,
+		 1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16,
+		 1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16}));
+}
+
+TEST_CASE("PartialPixelTest - Half tile on top of steep slopes - SLOPE_STEEP/CORNER_S")
+{
+	CHECK(CheckPartialPixelZ(HalftileSlope(SLOPE_STEEP_S, CORNER_S), {
+		 0,  1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,
+		 1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16,
+		 1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16,
+		 2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16,
+		 2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16,
+		 3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16,
+		 3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16,
+		 4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16,
+		 4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16,
+		 5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
+		 8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16}));
+}
+
+TEST_CASE("PartialPixelTest - Half tile on top of steep slopes - SLOPE_STEEP/CORNER_W")
+{
+	CHECK(CheckPartialPixelZ(HalftileSlope(SLOPE_STEEP_W, CORNER_W), {
+		 8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1,  0,
+		16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1,
+		16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,
+		16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,
+		16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,
+		16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,
+		16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,
+		16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,
+		16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,
+		16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,
+		16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8}));
+}
diff --git a/src/tests/landscape_partial_pixel_z.h b/src/tests/landscape_partial_pixel_z.h
deleted file mode 100644
index a825709392..0000000000
--- a/src/tests/landscape_partial_pixel_z.h
+++ /dev/null
@@ -1,552 +0,0 @@
-/*
- * This file is part of OpenTTD.
- * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
- * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
- */
-
-/** @file landscape_partial_pixel_z.h Tests for consistency/validity of the results of GetPartialPixelZ. */
-
-/**
- * Check whether the addition of two slope's GetPartialPixelZ values results in
- * the GetPartialPixelZ values of the expected slope.
- * This iterates over all sub-pixel locations within a single tile.
- * @param slope_expected The slope that is expected.
- * @param slope_a The first slope of the addition.
- * @param slope_b The second slope of the addition.
- * @return True iff at all GetPartialPixelZ results are the same for each sub-tile position.
- */
-constexpr bool CheckPartialPixelZSlopeAddition(Slope slope_expected, Slope slope_a, Slope slope_b)
-{
-	for (uint x = 0; x < TILE_SIZE; x++) {
-		for (uint y = 0; y < TILE_SIZE; y++) {
-			int z_a = InternalGetPartialPixelZ(x, y, slope_a);
-			int z_b = InternalGetPartialPixelZ(x, y, slope_b);
-			int z_result = InternalGetPartialPixelZ(x, y, slope_expected);
-			if (z_result != z_a + z_b) return false;
-		}
-	}
-	return true;
-}
-
-/* A one corner slope, plus the opposite three corner slope results in a flat but elevated slope. */
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_N, SLOPE_WSE));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_E, SLOPE_NWS));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_S, SLOPE_ENW));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_W, SLOPE_SEN));
-
-/* Diagonal slopes with their opposite slope result in a flat but elevated slope. */
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_NW, SLOPE_SE));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, SLOPE_SW, SLOPE_NE));
-
-/* Half tile slopes with their opposite half tile slope result in a flat but elevated slope. */
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, HalftileSlope(SLOPE_N, CORNER_N), HalftileSlope(SLOPE_S, CORNER_S)));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_ELEVATED, HalftileSlope(SLOPE_E, CORNER_E), HalftileSlope(SLOPE_W, CORNER_W)));
-
-/* Two opposite one corner slopes result in the two corner slope with opposite corners. */
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_NS, SLOPE_N, SLOPE_S));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_EW, SLOPE_E, SLOPE_W));
-
-/* A steep slope is a one corner slope on top of a three corner slope. */
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_STEEP_N, SLOPE_N, SLOPE_ENW));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_STEEP_E, SLOPE_E, SLOPE_SEN));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_STEEP_S, SLOPE_S, SLOPE_WSE));
-static_assert(CheckPartialPixelZSlopeAddition(SLOPE_STEEP_W, SLOPE_W, SLOPE_NWS));
-
-/* A half tile steep slope is a one corner half tile on top of a three corner slope. */
-static_assert(CheckPartialPixelZSlopeAddition(HalftileSlope(SLOPE_STEEP_N, CORNER_N), HalftileSlope(SLOPE_N, CORNER_N), SLOPE_ENW));
-static_assert(CheckPartialPixelZSlopeAddition(HalftileSlope(SLOPE_STEEP_E, CORNER_E), HalftileSlope(SLOPE_E, CORNER_E), SLOPE_SEN));
-static_assert(CheckPartialPixelZSlopeAddition(HalftileSlope(SLOPE_STEEP_S, CORNER_S), HalftileSlope(SLOPE_S, CORNER_S), SLOPE_WSE));
-static_assert(CheckPartialPixelZSlopeAddition(HalftileSlope(SLOPE_STEEP_W, CORNER_W), HalftileSlope(SLOPE_W, CORNER_W), SLOPE_NWS));
-
-
-/**
- * Check whether the partial pixel Z values are the expected values. The arrays
- * are as if the map is rotated 45 degrees counterclockwise.
- * @param slope The slope that is to be checked.
- * @param expected The expect partial pixels Z values.
- * @return True iff at all GetPartialPixelZ results are the same as the expected Z-coordinates.
- */
-constexpr bool CheckPartialPixelZ(Slope slope, std::array<int, TILE_SIZE * TILE_SIZE> expected)
-{
-	for (uint i = 0; i < expected.size(); i++) {
-		int actual = InternalGetPartialPixelZ(GB(i, 4, 4), GB(i, 0, 4), slope);
-		if (actual != expected[i]) return false;
-	}
-	return true;
-}
-
-/* One corner up slopes. */
-static_assert(CheckPartialPixelZ(SLOPE_N, {
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0,
-	7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0,
-	6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0,
-	6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0,
-	5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0,
-	5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0,
-	4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
-	4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
-
-static_assert(CheckPartialPixelZ(SLOPE_E, {
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7,
-	0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7,
-	0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
-	0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
-	0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5,
-	0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
-	0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
-
-static_assert(CheckPartialPixelZ(SLOPE_S, {
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4,
-	0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4,
-	0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
-	0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5,
-	0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
-	0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
-	0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7,
-	0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7}));
-
-static_assert(CheckPartialPixelZ(SLOPE_W, {
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
-	5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0,
-	5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0,
-	6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0, 0,
-	6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0, 0,
-	7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 0,
-	7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0}));
-
-/* Two corner up, diagonal slopes. */
-static_assert(CheckPartialPixelZ(SLOPE_NE, {
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-	5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
-
-static_assert(CheckPartialPixelZ(SLOPE_SE, {
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8}));
-
-static_assert(CheckPartialPixelZ(SLOPE_SW, {
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
-	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
-	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
-	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
-	5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-	5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
-	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}));
-
-static_assert(CheckPartialPixelZ(SLOPE_NW, {
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0}));
-
-/* Two opposite corner up slopes. */
-static_assert(CheckPartialPixelZ(SLOPE_NS, {
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0,
-	7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1,
-	6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1,
-	6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2,
-	5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2,
-	5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3,
-	4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3,
-	4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4,
-	3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4,
-	3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
-	2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5,
-	2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
-	1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
-	1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7,
-	0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7}));
-
-static_assert(CheckPartialPixelZ(SLOPE_EW, {
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7,
-	1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7,
-	1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
-	2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
-	2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5,
-	3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
-	3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4,
-	4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4,
-	4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3,
-	5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 3,
-	5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2,
-	6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 2,
-	6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1,
-	7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1,
-	7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0}));
-
-/* Three corner up slopes. */
-static_assert(CheckPartialPixelZ(SLOPE_ENW, {
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4,
-	8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4,
-	8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3,
-	8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3,
-	8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2,
-	8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2,
-	8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1,
-	8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1}));
-
-static_assert(CheckPartialPixelZ(SLOPE_SEN, {
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8,
-	3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8,
-	3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8,
-	2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8,
-	2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8,
-	1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8,
-	1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8}));
-
-static_assert(CheckPartialPixelZ(SLOPE_WSE, {
-	0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
-	1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
-	1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8,
-	2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8,
-	2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8,
-	3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8,
-	3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8,
-	4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8,
-	4, 5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	5, 5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	5, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	6, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}));
-
-static_assert(CheckPartialPixelZ(SLOPE_NWS, {
-	8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0,
-	8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1,
-	8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1,
-	8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2,
-	8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2,
-	8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3,
-	8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3,
-	8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5, 4,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5, 5,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6, 5,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6, 6,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7, 6,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 7,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}));
-
-/* Normal half tile slopes. */
-static_assert(CheckPartialPixelZ(HalftileSlope(SLOPE_N, CORNER_N), {
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}));
-
-static_assert(CheckPartialPixelZ(HalftileSlope(SLOPE_E, CORNER_E), {
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8}));
-
-static_assert(CheckPartialPixelZ(HalftileSlope(SLOPE_S, CORNER_S), {
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
-	0, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}));
-
-static_assert(CheckPartialPixelZ(HalftileSlope(SLOPE_W, CORNER_W), {
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0, 0,
-	8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 0}));
-
-/* Steep slopes. */
-static_assert(CheckPartialPixelZ(SLOPE_STEEP_N, {
-	16, 15, 15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,
-	15, 15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,
-	15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,
-	14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,
-	14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,
-	13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,
-	13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,
-	12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,
-	12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,
-	11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,
-	11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,
-	10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,
-	10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,
-	 9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,
-	 9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,
-	 8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1}));
-
-static_assert(CheckPartialPixelZ(SLOPE_STEEP_E, {
-	 8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16,
-	 8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15,
-	 7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15,
-	 7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14,
-	 6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14,
-	 6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13,
-	 5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13,
-	 5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12,
-	 4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12,
-	 4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11,
-	 3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11,
-	 3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10,
-	 2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10,
-	 2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9,
-	 1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,
-	 1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8}));
-
-static_assert(CheckPartialPixelZ(SLOPE_STEEP_S, {
-	 0,  1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,
-	 1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,
-	 1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,
-	 2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9,
-	 2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10,
-	 3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10,
-	 3,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11,
-	 4,  4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11,
-	 4,  5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12,
-	 5,  5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12,
-	 5,  6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13,
-	 6,  6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13,
-	 6,  7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14,
-	 7,  7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14,
-	 7,  8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15,
-	 8,  8,  9,  9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15}));
-
-static_assert(CheckPartialPixelZ(SLOPE_STEEP_W, {
-	 8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1,  0,
-	 8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1,
-	 9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,
-	 9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,
-	10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,
-	10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,
-	11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,
-	11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,  4,
-	12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,  4,
-	12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,  5,
-	13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,  5,
-	13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,  6,
-	14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,  6,
-	14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,  7,
-	15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8,  7,
-	15, 15, 14, 14, 13, 13, 12, 12, 11, 11, 10, 10,  9,  9,  8,  8}));
-
-/* Half tile on top of steep slopes. */
-static_assert(CheckPartialPixelZ(HalftileSlope(SLOPE_STEEP_N, CORNER_N), {
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,
-	16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,
-	16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,
-	16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,
-	16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,
-	16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,
-	16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,
-	16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,
-	16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,
-	16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1}));
-
-static_assert(CheckPartialPixelZ(HalftileSlope(SLOPE_STEEP_E, CORNER_E), {
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16,
-	 4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16,
-	 3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16,
-	 3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16,
-	 2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16,
-	 2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16,
-	 1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16,
-	 1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16}));
-
-static_assert(CheckPartialPixelZ(HalftileSlope(SLOPE_STEEP_S, CORNER_S), {
-	 0,  1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8,
-	 1,  1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16,
-	 1,  2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16,
-	 2,  2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16,
-	 2,  3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16,
-	 3,  3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16,
-	 3,  4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16,
-	 4,  4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16,
-	 4,  5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16,
-	 5,  5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 5,  6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 6,  6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 6,  7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 7,  7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 7,  8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
-	 8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16}));
-
-static_assert(CheckPartialPixelZ(HalftileSlope(SLOPE_STEEP_W, CORNER_W), {
-	 8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1,  0,
-	16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,  1,
-	16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,  1,
-	16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,  2,
-	16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,  2,
-	16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,  3,
-	16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,  3,
-	16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,  4,
-	16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,  4,
-	16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,  5,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,  5,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,  6,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,  6,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,  7,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8,  7,
-	16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,  8}));
diff --git a/src/tests/math_func.cpp b/src/tests/math_func.cpp
new file mode 100644
index 0000000000..0e58b79e42
--- /dev/null
+++ b/src/tests/math_func.cpp
@@ -0,0 +1,77 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file math_func_test.cpp Test functionality from core/math_func. */
+
+#include "../stdafx.h"
+
+#include "../3rdparty/catch2/catch.hpp"
+
+#include "../core/math_func.hpp"
+
+TEST_CASE("LeastCommonMultipleTest - Zero")
+{
+	CHECK(0 == LeastCommonMultiple(0, 0));
+	CHECK(0 == LeastCommonMultiple(0, 600));
+	CHECK(0 == LeastCommonMultiple(600, 0));
+}
+
+TEST_CASE("LeastCommonMultipleTest - FindLCM")
+{
+	CHECK(25 == LeastCommonMultiple(5, 25));
+	CHECK(25 == LeastCommonMultiple(25, 5));
+	CHECK(130 == LeastCommonMultiple(5, 26));
+	CHECK(130 == LeastCommonMultiple(26, 5));
+}
+
+TEST_CASE("GreatestCommonDivisorTest - Negative")
+{
+	CHECK(4 == GreatestCommonDivisor(4, -52));
+	// CHECK(3 == GreatestCommonDivisor(-27, 6)); // error - returns -3
+}
+
+TEST_CASE("GreatestCommonDivisorTest - Zero")
+{
+	CHECK(27 == GreatestCommonDivisor(0, 27));
+	CHECK(27 == GreatestCommonDivisor(27, 0));
+}
+
+TEST_CASE("GreatestCommonDivisorTest - FindGCD")
+{
+	CHECK(5 == GreatestCommonDivisor(5, 25));
+	CHECK(5 == GreatestCommonDivisor(25, 5));
+	CHECK(1 == GreatestCommonDivisor(7, 27));
+	CHECK(1 == GreatestCommonDivisor(27, 7));
+}
+
+TEST_CASE("DivideApproxTest - Negative")
+{
+	CHECK(-2 == DivideApprox(-5, 2));
+	CHECK(2 == DivideApprox(-5, -2));
+	CHECK(-1 == DivideApprox(-66, 80));
+}
+
+TEST_CASE("DivideApproxTest, Divide")
+{
+	CHECK(2 == DivideApprox(5, 2));
+	CHECK(3 == DivideApprox(80, 30));
+	CHECK(3 == DivideApprox(8, 3));
+	CHECK(0 == DivideApprox(3, 8));
+}
+
+TEST_CASE("IntSqrtTest - Zero")
+{
+	CHECK(0 == IntSqrt(0));
+}
+
+TEST_CASE("IntSqrtTest - FindSqRt")
+{
+	CHECK(5 == IntSqrt(25));
+	CHECK(10 == IntSqrt(100));
+	CHECK(9 == IntSqrt(88));
+	CHECK(1696 == IntSqrt(2876278));
+}
diff --git a/src/tests/test_main.cpp b/src/tests/test_main.cpp
new file mode 100644
index 0000000000..fbade1e6ab
--- /dev/null
+++ b/src/tests/test_main.cpp
@@ -0,0 +1,14 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file test_main.cpp Entry point for all the unit tests. */
+
+#include "../stdafx.h"
+
+#define CATCH_CONFIG_MAIN
+#define DO_NOT_USE_WMAIN
+#include "../3rdparty/catch2/catch.hpp"