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even cooler starfield... simulate gravity between stars

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This commit is contained in:
Rudolf Polzer 2010-10-14 15:53:18 +02:00
parent 84f1a31821
commit e9ad7b8a9f
1 changed files with 51 additions and 14 deletions
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65
misc/tools/spherefunc2skybox.c
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@ -147,17 +147,32 @@ struct
double darkness;
double power;
double density;
int g;
double gpower;
double gfactor;
double gdpower;
}
color_starfield_parms;
typedef struct
{
double x, y, z, e;
double R, G, B, A;
} starfield_t;
starfield_t *starfield = NULL;
int starfield_cmp(const void *a_, const void *b_)
{
const starfield_t *a = a_;
const starfield_t *b = b_;
if(a->z < b->z)
return -1;
if(a->z > b->z)
return +1;
return 0;
}
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;
double f;
int i, j, k;
double f, mindot, d;
if(!starfield)
{
@ -176,12 +191,6 @@ void color_starfield(double x, double y, double z, double *r, double *g, double
+ 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 = color_starfield_parms.density * pow(rnd(), -color_starfield_parms.power);
starfield[i].R = rnd();
starfield[i].G = rnd();
@ -191,15 +200,39 @@ void color_starfield(double x, double y, double z, double *r, double *g, double
starfield[i].G /= f;
starfield[i].B /= f;
starfield[i].A = rnd();
starfield[i].e = color_starfield_parms.density * pow(rnd(), -color_starfield_parms.power);
}
fprintf(stderr, "Gravitating starfield...\n");
for(k = 0; k < color_starfield_parms.g; ++k)
{
i = rand() % color_starfield_parms.n;
j = rand() % color_starfield_parms.n;
f = pow(rnd(), color_starfield_parms.gpower);
f = f * color_starfield_parms.gfactor;
d = pow(starfield[j].x - starfield[i].x, 2)
+ pow(starfield[j].y - starfield[i].y, 2)
+ pow(starfield[j].z - starfield[i].z, 2);
f *= pow(1 / (1 + d), color_starfield_parms.gdpower);
starfield[i].x += f * (starfield[j].x - starfield[i].x);
starfield[i].y += f * (starfield[j].y - starfield[i].y);
starfield[i].z += f * (starfield[j].z - starfield[i].z);
double r = starfield[i].x * starfield[i].x + starfield[i].y * starfield[i].y + starfield[i].z * starfield[i].z;
r = sqrt(r);
starfield[i].x /= r;
starfield[i].y /= r;
starfield[i].z /= r;
}
fprintf(stderr, "Sorting starfield...\n");
qsort(starfield, sizeof(*starfield), color_starfield_parms.n, starfield_cmp);
fprintf(stderr, "Done.\n");
}
*r = *g = *b = 0;
mindot = pow(1/256.0, 1.0/color_starfield_parms.density);
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)
if(dot <= mindot)
continue;
double f = pow(dot, starfield[i].e) * starfield[i].A;
*r += starfield[i].R * f;
@ -355,6 +388,10 @@ int main(int argc, char **argv)
color_starfield_parms.darkness = argc<= 5 ? 0.4 : atof(argv[5]);
color_starfield_parms.power = argc<= 6 ? 2.5 : atof(argv[6]);
color_starfield_parms.density = argc<= 7 ? 60000 : atof(argv[7]);
color_starfield_parms.g = argc<= 8 ? 10000000 : atoi(argv[8]);
color_starfield_parms.gpower = argc<= 9 ? 3 : atoi(argv[9]);
color_starfield_parms.gfactor = argc<= 10 ? 0.9 : atof(argv[10]);
color_starfield_parms.gdpower = argc<= 11 ? 15 : atof(argv[11]);
}
else
{