use a Gaussian-like random distribution for random subsampling

diff --git a/tools/quake3/q3map2/light_ydnar.c b/tools/quake3/q3map2/light_ydnar.c
index 4d3254522642c7dd4992d2f19bfa9b97c32ef2c7..393548bcf5426677c7f9437fb56a26c6798c1474 100644 (file)
--- a/tools/quake3/q3map2/light_ydnar.c
+++ b/tools/quake3/q3map2/light_ydnar.c
@@ -1889,12 +1889,27 @@ static void SubsampleRawLuxel_r( rawLightmap_t *lm, trace_t *trace, vec3_t sampl
                }
        }
 }
+
+/* A mostly Gaussian-like bounded random distribution (sigma is expected standard deviation) */
+static void GaussLikeRandom(float sigma, float *x, float *y)
+{
+       float r;
+       r = Random() * 2 * Q_PI;
+       *x = sigma * 2.73861278752581783822 * cos(r);
+       *y = sigma * 2.73861278752581783822 * sin(r);
+       r = Random();
+       r = 1 - sqrt(r);
+       r = 1 - sqrt(r);
+       *x *= r;
+       *y *= r;
+}
 static void RandomSubsampleRawLuxel( rawLightmap_t *lm, trace_t *trace, vec3_t sampleOrigin, int x, int y, float bias, float *lightLuxel, float *lightDeluxel )
 {
        int                     b, mapped;
        int                     cluster;
        vec3_t          origin, normal;
        vec3_t          total, totaldirection;
+       float           dx, dy;
        
        VectorClear( total );
        mapped = 0;
@@ -1902,9 +1917,14 @@ static void RandomSubsampleRawLuxel( rawLightmap_t *lm, trace_t *trace, vec3_t s
        {
                /* set origin */
                VectorCopy( sampleOrigin, origin );
-               
+               GaussLikeRandom(bias, &dx, &dy);
+               if(dx > 1) dx = 1;
+               if(dy > 1) dy = 1;
+               if(dx < -1) dx = -1;
+               if(dy < -1) dy = -1;
+
                /* calculate position */
-               if( !SubmapRawLuxel( lm, x, y, (bias * (2 * Random() - 1)), (bias * (2 * Random() - 1)), &cluster, origin, normal ) )
+               if( !SubmapRawLuxel( lm, x, y, dx, dy, &cluster, origin, normal ) )
                {
                        cluster = -1;
                        continue;