static ALLEGRO_COLOR reference_implementation(
ALLEGRO_COLOR src_col, ALLEGRO_COLOR dst_col,
ALLEGRO_COLOR blend_col, int src_format, int dst_format,
int src_mode, int dst_mode, int src_alpha, int dst_alpha,
int operation)
{
float sr, sg, sb, sa;
float br, bg, bb, ba;
float dr, dg, db, da;
float r, g, b, a;
float src, dst, asrc, adst;
al_unmap_rgba_f(src_col, &sr, &sg, &sb, &sa);
al_unmap_rgba_f(blend_col, &br, &bg, &bb, &ba);
al_unmap_rgba_f(dst_col, &dr, &dg, &db, &da);
/* Do we even have source alpha? */
if (operation == 0) {
if (!has_alpha(src_format)) {
sa = 1;
}
}
r = sr * br;
g = sg * bg;
b = sb * bb;
a = sa * ba;
src = get_factor(src_mode, a);
dst = get_factor(dst_mode, a);
asrc = get_factor(src_alpha, a);
adst = get_factor(dst_alpha, a);
r = r * src + dr * dst;
g = g * src + dg * dst;
b = b * src + db * dst;
a = a * asrc + da * adst;
r = CLAMP(r);
g = CLAMP(g);
b = CLAMP(b);
a = CLAMP(a);
/* Do we even have destination alpha? */
if (!has_alpha(dst_format)) {
a = 1;
}
return al_map_rgba_f(r, g, b, a);
}
SDL_Surface* SDL_Resize(SDL_Surface *src, int new_w, int new_h, bool free, int filter)
{
SDL_Surface * dst;
bool is_alpha = has_alpha(src);
if (src->w == new_w && src->h == new_h)
{
//No change in size.
return src;
}
Uint32 rmask = 0x000000ff,
gmask = 0x0000ff00,
bmask = 0x00ff0000,
amask = 0xff000000;
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
rmask = 0xff000000;
gmask = 0x00ff0000;
bmask = 0x0000ff00;
amask = 0x000000ff;
#endif
dst = SDL_CreateRGBSurface(0, new_w, new_h, 32, rmask, gmask, bmask, amask);
SDL_Surface * temp = SDL_ConvertSurface(src,dst->format,0);
Resample(temp,dst,filter);
SDL_FreeSurface(temp);
temp = SDL_ConvertSurface(dst,src->format,0);
SDL_FreeSurface(dst);
if (is_alpha)
{
SDL_SetAlpha(temp, SDL_SRCALPHA, 0);
}
if (free)
SDL_FreeSurface(src);
return temp;
}
