Files
kichikuou_xsystem35-sdl2/modules/lib/graph_blend_amap.c
T
2025-06-11 09:23:42 +09:00

59 lines
1.7 KiB
C

// 転送元 alpha map を参照して、転送元ピクセルと転送先ピクセルをブレンドし、
// 転送先ピクセルに描画
#include <stdio.h>
#include "portab.h"
#include "system.h"
#include "graph_blend_amap.h"
#include "ags.h"
static void gre_BlendUseAMap(surface_t *dst, int dx, int dy, surface_t *src, int sx, int sy, int width, int height) {
uint8_t *sp = GETOFFSET_PIXEL(src, sx, sy);
uint8_t *dp = GETOFFSET_PIXEL(dst, dx, dy);
uint8_t *ap = GETOFFSET_ALPHA(src, sx, sy);
switch (dst->sdl_surface->format->BitsPerPixel) {
case 16:
for (int y = 0; y < height; y++) {
uint16_t *yls = (uint16_t *)(sp + y * src->sdl_surface->pitch);
uint16_t *yld = (uint16_t *)(dp + y * dst->sdl_surface->pitch);
uint8_t *yla = (uint8_t *)(ap + y * src->width);
for (int x = 0; x < width; x++) {
*yld = ALPHABLEND16(*yls, *yld, *yla);
yls++; yld++; yla++;
}
}
break;
case 24:
case 32:
for (int y = 0; y < height; y++) {
uint32_t *yls = (uint32_t *)(sp + y * src->sdl_surface->pitch);
uint32_t *yld = (uint32_t *)(dp + y * dst->sdl_surface->pitch);
uint8_t *yla = (uint8_t *)(ap + y * src->width);
for (int x = 0; x < width; x++) {
*yld = ALPHABLEND24(*yls, *yld, *yla);
yls++; yld++; yla++;
}
}
break;
}
}
void gr_blend_alpha_map(surface_t *dst, int dx, int dy, surface_t *src, int sx, int sy, int sw, int sh) {
if (src == NULL || dst == NULL) return;
SDL_Rect src_window = { 0, 0, src->width, src->height };
SDL_Rect dst_window = { 0, 0, dst->width, dst->height };
if (!ags_clipCopyRect(&src_window, &dst_window, &sx, &sy, &dx, &dy, &sw, &sh)) return;
if (src->alpha == NULL) {
WARNING("src alpha NULL");
return;
}
gre_BlendUseAMap(dst, dx, dy, src, sx, sy, sw, sh);
}