ref: 49a810aeb5cb996bf9a6d4e3c38fc4d17fb77610
dir: /d_alpha.c/
#include "quakedef.h"
pixel_t
blendalpha(pixel_t ca, pixel_t cb, int alpha)
{
int a, b, c;
if(ca == 0 || (ca >> 24) != 0)
alpha = (ca >> 24)*alpha >> 8;
if(currententity != nil && currententity->effects & EF_ADDITIVE){
a = (alpha*((ca>> 0)&0xff) + 255*((cb>> 0)&0xff))>> 8;
b = (alpha*((ca>> 8)&0xff) + 255*((cb>> 8)&0xff))>> 8;
c = (alpha*((ca>>16)&0xff) + 255*((cb>>16)&0xff))>> 8;
return (cb & 0xff000000) | min(a, 255) | min(b, 255)<<8 | min(c, 255)<<16;
}
return
(cb & 0xff000000) |
((alpha*((ca>> 0)&0xff) + (255-alpha)*((cb>> 0)&0xff))>> 8) << 0 |
((alpha*((ca>> 8)&0xff) + (255-alpha)*((cb>> 8)&0xff))>> 8) << 8 |
((alpha*((ca>>16)&0xff) + (255-alpha)*((cb>>16)&0xff))>> 8) << 16;
}
float
alphafor(int flags)
{
if(flags & (SURF_TELE|SURF_FENCE))
return 1.0;
if(flags & SURF_LAVA)
return r_lavaalpha.value;
if(flags & SURF_SLIME)
return r_slimealpha.value;
return r_wateralpha.value;
}