Archives/OpenTTD-patches
2
0
Fork 0
mirror of https://github.com/JGRennison/OpenTTD-patches.git synced 2024-11-17 21:25:40 +00:00
Code Issues Packages Projects Releases Wiki Activity

Blitter: Adjust line-drawing algorithm to reduce wasted off-screen work

Browse Source
This commit is contained in:
Jonathan G Rennison 2018-01-17 02:52:40 +00:00
parent 2534c2a162
commit 83e6cf50a0
1 changed files with 66 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
src/blitter/base.hpp
View File

@ -16,6 +16,8 @@
#include "../spriteloader/spriteloader.hpp"
#include "../core/math_func.hpp"
#include <utility>
/** The modes of blitting we can do. */
enum BlitterMode {
BM_NORMAL, ///< Perform the simple blitting.
@ -279,23 +281,50 @@ void Blitter::DrawLineGeneric(int x, int y, int x2, int y2, int screen_width, in
if (dash == 0) dash = 1;
int dash_count = 0;
if (dx > dy) {
if (stepx < 0) {
std::swap(x, x2);
std::swap(y, y2);
stepy = -stepy;
}
if (x2 < 0 || x >= screen_width) return;
int y_low = y;
int y_high = y;
int frac_low = dy - frac_diff / 2;
int frac_high = dy + frac_diff / 2;
while (frac_low + dx / 2 < 0) {
while (frac_low < -(dx / 2)) {
frac_low += dx;
y_low -= stepy;
}
while (frac_high - dx / 2 >= 0) {
while (frac_high >= dx / 2) {
frac_high -= dx;
y_high += stepy;
}
x2 += stepx;
if (x < 0) {
dash_count = (-x) % (dash + gap);
auto adjust_frac = [&](int64 frac, int &y_bound) -> int {
frac -= ((int64) dy) * ((int64) x);
if (frac >= 0) {
int quotient = frac / dx;
int remainder = frac % dx;
y_bound += (1 + quotient) * stepy;
frac = remainder - dx;
}
return frac;
};
frac_low = adjust_frac(frac_low, y_low);
frac_high = adjust_frac(frac_high, y_high);
x = 0;
}
x2++;
if (x2 > screen_width) {
x2 = screen_width;
}
while (x != x2) {
if (dash_count < dash && x >= 0 && x < screen_width) {
if (dash_count < dash) {
for (int y = y_low; y != y_high; y += stepy) {
if (y >= 0 && y < screen_height) set_pixel(x, y);
}
@ -308,29 +337,56 @@ void Blitter::DrawLineGeneric(int x, int y, int x2, int y2, int screen_width, in
y_high += stepy;
frac_high -= dx;
}
x += stepx;
x++;
frac_low += dy;
frac_high += dy;
if (++dash_count >= dash + gap) dash_count = 0;
}
} else {
if (stepy < 0) {
std::swap(x, x2);
std::swap(y, y2);
stepx = -stepx;
}
if (y2 < 0 || y >= screen_height) return;
int x_low = x;
int x_high = x;
int frac_low = dx - frac_diff / 2;
int frac_high = dx + frac_diff / 2;
while (frac_low + dy / 2 < 0) {
while (frac_low < -(dy / 2)) {
frac_low += dy;
x_low -= stepx;
}
while (frac_high - dy / 2 >= 0) {
while (frac_high >= dy / 2) {
frac_high -= dy;
x_high += stepx;
}
y2 += stepy;
if (y < 0) {
dash_count = (-y) % (dash + gap);
auto adjust_frac = [&](int64 frac, int &x_bound) -> int {
frac -= ((int64) dx) * ((int64) y);
if (frac >= 0) {
int quotient = frac / dy;
int remainder = frac % dy;
x_bound += (1 + quotient) * stepx;
frac = remainder - dy;
}
return frac;
};
frac_low = adjust_frac(frac_low, x_low);
frac_high = adjust_frac(frac_high, x_high);
y = 0;
}
y2++;
if (y2 > screen_height) {
y2 = screen_height;
}
while (y != y2) {
if (dash_count < dash && y >= 0 && y < screen_height) {
if (dash_count < dash) {
for (int x = x_low; x != x_high; x += stepx) {
if (x >= 0 && x < screen_width) set_pixel(x, y);
}
@ -343,7 +399,7 @@ void Blitter::DrawLineGeneric(int x, int y, int x2, int y2, int screen_width, in
x_high += stepx;
frac_high -= dy;
}
y += stepy;
y++;
frac_low += dx;
frac_high += dx;
if (++dash_count >= dash + gap) dash_count = 0;