ref: 968ea5f2c3b96b5bd413534ed11789ef9026c47e
dir: /d_alpha.c/
#include "quakedef.h" pixel_t blendadditive(pixel_t ca, pixel_t cb, int alpha) { int a, b, c; if(ca == 0 || (ca >> 24) != 0){ alpha = alpha*(ca >> 24) + 0x80; alpha = ((alpha>>8) + alpha) >> 8; } ca = mulalpha(ca, alpha); a = ((ca>> 0)&0xff) + ((cb>> 0)&0xff); b = ((ca>> 8)&0xff) + ((cb>> 8)&0xff); c = ((ca>>16)&0xff) + ((cb>>16)&0xff); return (cb & 0xff000000) | min(a, 255) | min(b, 255)<<8 | min(c, 255)<<16; } pixel_t blendalpha(pixel_t ca, pixel_t cb, int alpha) { if(ca == 0 || (ca >> 24) != 0){ alpha = alpha*(ca >> 24) + 0x80; alpha = ((alpha>>8) + alpha) >> 8; } return mulalpha(ca, alpha) + mulalpha(cb, 255-alpha); } 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; }