out vec4 FragColor;
uniform sampler2D uTexMain;
uniform sampler2D uTexMotion;
uniform float uBlurStrength;
uniform vec2 uOverrideDir;
uniform float uTime;
uniform float uGlitchStrength;
uniform vec2 uClampUv;

in vec2 aUv;

vec2 rand_hash22( vec2 p ){
   vec3 p3 = fract(vec3(p.xyx) * 213.8976123);
   p3 += dot(p3, p3.yzx+19.19);
   return fract(vec2((p3.x + p3.y)*p3.z, (p3.x+p3.z)*p3.y));
}

const int NOISE_LOOP = 3;
vec3 digital_noise( uvec3 iuv ){
   iuv *=uvec3(8,2524,7552);
   for( int i=0; i<NOISE_LOOP; i++ )
      iuv += (iuv.yzx<<2) ^ (iuv.yxz)+iuv.z;
   return vec3(iuv)*(1.0/float(0xffffffffU));
}

void main(){
   vec2 vuv = aUv; 

   //if( uGlitchStrength > 0.0 ){
   //   uvec3 p = uvec3( gl_FragCoord.xy, uint(uTime*30.0) );
   //   vec2 g = digital_noise(p).xy;
   //   vuv = aUv + g.xy*uGlitchStrength - uGlitchStrength*0.5;
   //}

   vec2 vrand = rand_hash22( vuv ) * 2.0 - vec2(1.0);
   vec2 vrand1 = rand_hash22( vrand ) * 2.0 - vec2(1.0);
   
   vec2 vdir = texture( uTexMotion, vuv ).xy * uBlurStrength + uOverrideDir;

   vec4 vcolour0 = texture( uTexMain, min(vuv + vdir*vrand.x,uClampUv) );
   vec4 vcolour1 = texture( uTexMain, min(vuv + vdir*vrand.y,uClampUv) );
   vec4 vcolour2 = texture( uTexMain, min(vuv + vdir*vrand1.x,uClampUv) );
   vec4 vcolour3 = texture( uTexMain, min(vuv + vdir*vrand1.y,uClampUv) );

   FragColor = ( vcolour0 + vcolour1 + vcolour2 + vcolour3 ) * 0.25;
}