an attempt at a "starfield" skybox generator. Renders something entirely different...

diff --git a/misc/tools/spherefunc2skybox.c b/misc/tools/spherefunc2skybox.c
index 3e3e7a5ad007bed931add27f01fcdee1233521d3..c45a2df730edd5c1fe637365eac04d4f772289ae 100644 (file)
--- a/misc/tools/spherefunc2skybox.c
+++ b/misc/tools/spherefunc2skybox.c
@@ -141,6 +141,65 @@ void color_mandelbrot(double x, double y, double z, double *r, double *g, double
        *b = pow(iterations, color_mandelbrot_parms[12]);
 }
 
+struct
+{
+       int n;
+}
+color_starfield_parms;
+void color_starfield(double x, double y, double z, double *r, double *g, double *b)
+{
+       static struct
+       {
+               double x, y, z, e;
+               double R, G, B, A;
+       } *starfield = NULL;
+       int i;
+
+       if(!starfield)
+       {
+               fprintf(stderr, "Initializing starfield...\n");
+               starfield = malloc(sizeof(*starfield) * color_starfield_parms.n);
+               for(i = 0; i < color_starfield_parms.n; ++i)
+               {
+                       double r;
+                       do
+                       {
+                               starfield[i].x = rnd() * 2 - 1;
+                               starfield[i].y = rnd() * 2 - 1;
+                               starfield[i].z = rnd() * 2 - 1;
+                               r = starfield[i].x * starfield[i].x
+                                 + starfield[i].y * starfield[i].y
+                                 + starfield[i].z * starfield[i].z;
+                       }
+                       while(r > 1);
+                       r = sqrt(r);
+                       starfield[i].x /= r;
+                       starfield[i].y /= r;
+                       starfield[i].z /= r;
+
+                       starfield[i].e = rnd() * 100 + 5;
+
+                       starfield[i].R = rnd();
+                       starfield[i].G = rnd();
+                       starfield[i].B = rnd();
+                       starfield[i].A = rnd();
+               }
+               fprintf(stderr, "Done.\n");
+       }
+
+       *r = *g = *b = 0;
+       for(i = 0; i < color_starfield_parms.n; ++i)
+       {
+               double dot = x * starfield[i].x + y * starfield[i].y + z * starfield[i].z;
+               if(dot <= 0)
+                       continue;
+               double f = pow(dot, starfield[i].e) * starfield[i].A;
+               *r += starfield[i].R * f;
+               *g += starfield[i].G * f;
+               *b += starfield[i].B * f;
+       }
+}
+
 void map_back(double x_in, double y_in, double *x_out, double *y_out, double *z_out)
 {
        *x_out = 2 * x_in - 1;
@@ -260,10 +319,15 @@ int main(int argc, char **argv)
                color_mandelbrot_parms[11] = argc<=15 ?   0.5   : atof(argv[15]);
                color_mandelbrot_parms[12] = argc<=16 ?   0.2   : atof(argv[16]);
        }
+       else if(!strcmp(argv[3], "starfield"))
+       {
+               f = color_starfield;
+               color_starfield_parms.n = argc<= 4 ? 1024 : atoi(argv[4]);
+       }
        else
        {
                f = color_test;
        }
-       map_all(argv[1], color_mandelbrot, res, res);
+       map_all(argv[1], f, res, res);
        return 0;
 }