mirror of
https://github.com/JGRennison/OpenTTD-patches.git
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90 lines
3.6 KiB
C++
90 lines
3.6 KiB
C++
/*
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* This file is part of OpenTTD.
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* 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.
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* 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.
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* 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/>.
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*/
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/** @file landscape_ppz.cpp Functions related to landscape partial pixel z. */
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#include "stdafx.h"
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#include "slope_func.h"
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#include "safeguards.h"
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/**
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* Determines height at given coordinate of a slope.
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*
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* At the northern corner (0, 0) the result is always a multiple of TILE_HEIGHT.
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* When the height is a fractional Z, then the height is rounded down. For example,
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* when at the height is 0 at x = 0 and the height is 8 at x = 16 (actually x = 0
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* of the next tile), then height is 0 at x = 1, 1 at x = 2, and 7 at x = 15.
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* @param x x coordinate (value from 0 to 15)
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* @param y y coordinate (value from 0 to 15)
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* @param corners slope to examine
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* @return height of given point of given slope
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*/
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uint GetPartialPixelZ(int x, int y, Slope corners)
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{
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if (IsHalftileSlope(corners)) {
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/* A foundation is placed on half the tile at a specific corner. This means that,
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* depending on the corner, that one half of the tile is at the maximum height. */
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switch (GetHalftileSlopeCorner(corners)) {
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case CORNER_W:
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if (x > y) return GetSlopeMaxPixelZ(corners);
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break;
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case CORNER_S:
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if (x + y >= (int)TILE_SIZE) return GetSlopeMaxPixelZ(corners);
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break;
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case CORNER_E:
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if (x <= y) return GetSlopeMaxPixelZ(corners);
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break;
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case CORNER_N:
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if (x + y < (int)TILE_SIZE) return GetSlopeMaxPixelZ(corners);
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break;
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default: NOT_REACHED();
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}
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}
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switch (RemoveHalftileSlope(corners)) {
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case SLOPE_FLAT: return 0;
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/* One corner is up.*/
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case SLOPE_N: return x + y <= (int)TILE_SIZE ? (TILE_SIZE - x - y) >> 1 : 0;
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case SLOPE_E: return y >= x ? (1 + y - x) >> 1 : 0;
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case SLOPE_S: return x + y >= (int)TILE_SIZE ? (1 + x + y - TILE_SIZE) >> 1 : 0;
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case SLOPE_W: return x >= y ? (x - y) >> 1 : 0;
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/* Two corners next to eachother are up. */
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case SLOPE_NE: return (TILE_SIZE - x) >> 1;
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case SLOPE_SE: return (y + 1) >> 1;
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case SLOPE_SW: return (x + 1) >> 1;
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case SLOPE_NW: return (TILE_SIZE - y) >> 1;
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/* Three corners are up on the same level. */
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case SLOPE_ENW: return x + y >= (int)TILE_SIZE ? TILE_HEIGHT - ((1 + x + y - TILE_SIZE) >> 1) : TILE_HEIGHT;
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case SLOPE_SEN: return y < x ? TILE_HEIGHT - ((x - y) >> 1) : TILE_HEIGHT;
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case SLOPE_WSE: return x + y <= (int)TILE_SIZE ? TILE_HEIGHT - ((TILE_SIZE - x - y) >> 1) : TILE_HEIGHT;
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case SLOPE_NWS: return x < y ? TILE_HEIGHT - ((1 + y - x) >> 1) : TILE_HEIGHT;
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/* Two corners at opposite sides are up. */
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case SLOPE_NS: return x + y < (int)TILE_SIZE ? (TILE_SIZE - x - y) >> 1 : (1 + x + y - TILE_SIZE) >> 1;
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case SLOPE_EW: return x >= y ? (x - y) >> 1 : (1 + y - x) >> 1;
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/* Very special cases. */
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case SLOPE_ELEVATED: return TILE_HEIGHT;
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/* Steep slopes. The top is at 2 * TILE_HEIGHT. */
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case SLOPE_STEEP_N: return (TILE_SIZE - x + TILE_SIZE - y) >> 1;
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case SLOPE_STEEP_E: return (TILE_SIZE + 1 + y - x) >> 1;
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case SLOPE_STEEP_S: return (1 + x + y) >> 1;
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case SLOPE_STEEP_W: return (TILE_SIZE + x - y) >> 1;
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default: NOT_REACHED();
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}
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}
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