6_2_fdistGrad

Figure 6.8:

6_2_fdistGrad.frag

#version 300 es precision highp float; precision highp int; out vec4 fragColor; uniform float u_time; uniform vec2 u_resolution; int channel; //start hash uvec3 k = uvec3(0x456789abu, 0x6789ab45u, 0x89ab4567u); uvec3 u = uvec3(1, 2, 3); const uint UINT_MAX = 0xffffffffu; uint uhash11(uint n){ n ^= (n << u.x); n ^= (n >> u.x); n *= k.x; n ^= (n << u.x); return n * k.x; } uvec2 uhash22(uvec2 n){ n ^= (n.yx << u.xy); n ^= (n.yx >> u.xy); n *= k.xy; n ^= (n.yx << u.xy); return n * k.xy; } uvec3 uhash33(uvec3 n){ n ^= (n.yzx << u); n ^= (n.yzx >> u); n *= k; n ^= (n.yzx << u); return n * k; } float hash11(float p){ uint n = floatBitsToUint(p); return float(uhash11(n)) / float(UINT_MAX); } float hash21(vec2 p){ uvec2 n = floatBitsToUint(p); return float(uhash22(n).x) / float(UINT_MAX); } float hash31(vec3 p){ uvec3 n = floatBitsToUint(p); return float(uhash33(n).x) / float(UINT_MAX); } vec2 hash22(vec2 p){ uvec2 n = floatBitsToUint(p); return vec2(uhash22(n)) / vec2(UINT_MAX); } vec3 hash33(vec3 p){ uvec3 n = floatBitsToUint(p); return vec3(uhash33(n)) / vec3(UINT_MAX); } //end hash float fdist(vec2 p){ vec2 n = floor(p + 0.5); float dist = sqrt(2.0); for(float j = 0.0; j <= 2.0; j ++ ){ vec2 glid; glid.y = n.y + sign(mod(j, 2.0) - 0.5) * ceil(j * 0.5); if (abs(glid.y - p.y) - 0.5 > dist){ continue; } for(float i = -1.0; i <= 1.0; i ++ ){ glid.x = n.x + i; vec2 jitter = hash22(glid) - 0.5; dist = min(dist, length(glid + jitter - p)); } } return dist; } vec2 grad(vec2 p){ float eps = 0.001; return 0.5 * (vec2( fdist(p + vec2(eps, 0.0)) - fdist(p - vec2(eps, 0.0)), fdist(p + vec2(0.0, eps)) - fdist(p - vec2(0.0, eps)) )) / eps; } void main(){ vec2 pos = gl_FragCoord.xy/ min(u_resolution.x, u_resolution.y); channel = int(2.0 * gl_FragCoord.x/ u_resolution.x); pos *= 10.0; pos += u_time; fragColor = channel == 0 ? vec4(fdist(pos)) : vec4(grad(pos), 1.0, 1.0); fragColor.a = 1.0; }

#version 300 es
precision highp float;
precision highp int;
out vec4 fragColor;
uniform float u_time;
uniform vec2 u_resolution;
int channel;
//start hash
uvec3 k = uvec3(0x456789abu, 0x6789ab45u, 0x89ab4567u);
uvec3 u = uvec3(1, 2, 3);
const uint UINT_MAX = 0xffffffffu;

uint uhash11(uint n){
  n ^= (n << u.x);
  n ^= (n >> u.x);
  n *= k.x;
  n ^= (n << u.x);
  return n * k.x;
}

uvec2 uhash22(uvec2 n){
  n ^= (n.yx << u.xy);
  n ^= (n.yx >> u.xy);
  n *= k.xy;
  n ^= (n.yx << u.xy);
  return n * k.xy;
}

uvec3 uhash33(uvec3 n){
  n ^= (n.yzx << u);
  n ^= (n.yzx >> u);
  n *= k;
  n ^= (n.yzx << u);
  return n * k;
}

float hash11(float p){
  uint n = floatBitsToUint(p);
  return float(uhash11(n)) / float(UINT_MAX);
}

float hash21(vec2 p){
  uvec2 n = floatBitsToUint(p);
  return float(uhash22(n).x) / float(UINT_MAX);
}

float hash31(vec3 p){
  uvec3 n = floatBitsToUint(p);
  return float(uhash33(n).x) / float(UINT_MAX);
}

vec2 hash22(vec2 p){
  uvec2 n = floatBitsToUint(p);
  return vec2(uhash22(n)) / vec2(UINT_MAX);
}

vec3 hash33(vec3 p){
  uvec3 n = floatBitsToUint(p);
  return vec3(uhash33(n)) / vec3(UINT_MAX);
}
//end hash

float fdist(vec2 p){
  vec2 n = floor(p + 0.5);
  float dist = sqrt(2.0);
  for(float j = 0.0; j <= 2.0; j ++ ){
    vec2 glid;
    glid.y = n.y + sign(mod(j, 2.0) - 0.5) * ceil(j * 0.5);
    if (abs(glid.y - p.y) - 0.5 > dist){
      continue;
    }
    for(float i = -1.0; i <= 1.0; i ++ ){
      glid.x = n.x + i;
      vec2 jitter = hash22(glid) - 0.5;
      dist = min(dist, length(glid + jitter - p));
    }
  }
  return dist;
}

vec2 grad(vec2 p){
  float eps = 0.001;
  return 0.5 * (vec2(
      fdist(p + vec2(eps, 0.0)) - fdist(p - vec2(eps, 0.0)),
      fdist(p + vec2(0.0, eps)) - fdist(p - vec2(0.0, eps))
    )) / eps;
}

void main(){
  vec2 pos = gl_FragCoord.xy/ min(u_resolution.x, u_resolution.y);
  channel = int(2.0 * gl_FragCoord.x/ u_resolution.x); 
  pos *= 10.0;
  pos += u_time;
  fragColor = channel == 0 ? vec4(fdist(pos)) : vec4(grad(pos), 1.0, 1.0);
  fragColor.a = 1.0;
}