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Merge pull request #619 from adamharrison/fix-alpha-rendering 

Changed font rendering computation to take into account alpha blending.
This commit is contained in:
Adam 2021-10-20 11:00:01 -04:00 committed by GitHub
parent 3e2b0f28c8 3092dca919
commit c973b9306b
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 4 additions and 20 deletions
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24
src/renderer.c
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@ -10,8 +10,6 @@
#include "renderer.h"
#include "renwindow.h"
#define DIVIDE_BY_255_SIGNED(x, sign_val) (((x) + (sign_val) + ((x)>>8)) >> 8)
#define DIVIDE_BY_255(x) DIVIDE_BY_255_SIGNED(x, 1)
#define MAX_GLYPHSET 256
#define SUBPIXEL_BITMAPS_CACHED 3
@ -154,7 +152,6 @@ RenFont* ren_font_load(const char* path, float size, bool subpixel, unsigned cha
FT_Face face;
if (FT_New_Face( library, path, 0, &face))
return NULL;
const int surface_scale = renwin_surface_scale(&window_renderer);
if (FT_Set_Pixel_Sizes(face, 0, (int)(size*surface_scale)))
goto failure;
@ -261,23 +258,10 @@ float ren_draw_text(RenFont *font, const char *text, float x, int y, RenColor co
for (int x = glyph_start; x < glyph_end; ++x) {
unsigned int destination_color = *destination_pixel;
SDL_Color dst = { (destination_color >> 16) & 0xFF, (destination_color >> 8) & 0xFF, (destination_color >> 0) & 0xFF, (destination_color >> 24) & 0xFF };
if (font->subpixel) {
SDL_Color src = { *source_pixel++, *source_pixel++, *source_pixel++ };
r = color.r * src.r + dst.r * (255 - src.r) + 127;
r = DIVIDE_BY_255(r);
g = color.g * src.g + dst.g * (255 - src.g) + 127;
g = DIVIDE_BY_255(g);
b = color.b * src.b + dst.b * (255 - src.b) + 127;
b = DIVIDE_BY_255(b);
} else {
unsigned char intensity = *source_pixel++;
r = color.r * intensity + dst.r * (255 - intensity) + 127;
r = DIVIDE_BY_255(r);
g = color.g * intensity + dst.g * (255 - intensity) + 127;
g = DIVIDE_BY_255(g);
b = color.b * intensity + dst.b * (255 - intensity) + 127;
b = DIVIDE_BY_255(b);
}
SDL_Color src = { *(font->subpixel ? source_pixel++ : source_pixel), *(font->subpixel ? source_pixel++ : source_pixel), *source_pixel++ };
r = (color.r * src.r * color.a + dst.r * (65025 - src.r * color.a) + 32767) / 65025;
g = (color.g * src.g * color.a + dst.g * (65025 - src.g * color.a) + 32767) / 65025;
b = (color.b * src.b * color.a + dst.b * (65025 - src.b * color.a) + 32767) / 65025;
*destination_pixel++ = dst.a << 24 | r << 16 | g << 8 | b;
}
}