uniform sampler2D uTexGarbage;

in vec4 aColour;
in vec2 aUv;
in vec3 aNorm;
in vec3 aCo;
in vec3 aWorldCo;

// Spooky!
const vec3 uCamera = vec3(0.0);

#include "light_clearskies_stddef.glsl"
#include "common_world.glsl"
#include "motion_vectors_fs.glsl"

float stars1( vec3 rd, float rr, float size ){
   vec3 co = rd * rr;

   float a = atan(co.y, length(co.xz)) + 4.0 * PI;

   float spaces = 1.0 / rr;
   size = (rr * 0.0015) * fwidth(a) * 1000.0 * size;
   a -= mod(a, spaces) - spaces * 0.5;

   float count = floor(sqrt(pow(rr, 2.0) * (1.0 - pow(sin(a), 2.0))) * 3.0);
   
   float plane = atan(co.z, co.x) + 4.0 * PI;
   plane = plane - mod(plane, PI / count);

   vec2 delta = rand33(vec3(plane, a, 0.0)).xy;

   float level = sin(a + spaces * (delta.y - 0.5) * (1.0 - size)) * rr;
   float ydist = sqrt(rr * rr - level * level);
   float angle = plane + (PI * (delta.x * (1.0-size) + size * 0.5) / count);
   vec3 center = vec3(cos(angle) * ydist, level, sin(angle) * ydist);
   float star = smoothstep(size, 0.0, distance(center, co));
   return star;
}

void main(){
   compute_motion_vectors();

   vec3 rd = -normalize(aNorm);

   float star = 0.0;
   for( float j = 1.0; j <= 4.1; j += 1.0 ){
      float m = mix(0.6, 0.9, smoothstep(1.0, 2.0, j));
      star += stars( rd, 1.94 * pow( 1.64, j ), m ) * (1.0 / pow(4.0, j));
   }

   oColour = vec4( vec3(star*20.0), 1.0);
}