Reflactor Unit

#version 300 es

precision highp float;

precision highp int;

​

#define norm normalize

#define len length

#define count(i,n) for(int i=0;i<n;i++)

const float ETA= .1234321e-8;

#define nozero(v) (v+ETA)

#define minv(v) min(v.x,min(v.y,v.z))

​

vec3 axis(vec3 n){

  //certain theres better way

  n-= sign(n)*minv(abs(n));

  n-= sign(n)*minv(abs(n));

  return norm(n);

}

​

uniform mat3 u_m;

uniform vec2 u_mouse;

uniform int N;

uniform int MODE;

in vec3 v_p;

in vec3 v_v;

out vec4 color_out;

void main() {

  vec3 p= v_p;

  vec3 v= norm(v_v);

  vec3 c= vec3(0.);

  vec3 n;

  float T= 1.;

  count(i,N){

    //novel cube marcher shadertoy.com/view/Wld3R4

    //mod to use single cube instead of voxel field

    vec3 dp= sign(v)-p;//delta position to next-edges

    vec3 edt= dp/nozero(v);//time to each

    float dt= minv(edt);//time to soonest

    //dt= max(0.,dt);//no negative time //nevermind negative time is fine

    if(dt<0.) T*=.02;

    dp= v/dt;   

    p+= dp;

    if(MODE==0)

      n= axis(p);

    else

      n= norm(p*abs(p));

    v= reflect(v,-n);

    T*= .5;

    c+= abs(n)*T * tan(abs(v.z*1.5));

    c.xyz= c.zxy;

    //allow the normals to sing

  }

  //c/= float(N);

  //c= abs(n);

  c*= 3.20; //exposure

  c= 1.-1./(.7+c); //tonemap

  c= pow(c,vec3(3.2));//gamma

  color_out= vec4(c,1.);

}