8_6_sphere

Code 8.9, 8.10, Figure 8.9:

8_6_sphere.frag

#version 300 es precision highp float; precision highp int; out vec4 fragColor; uniform float u_time; uniform vec2 u_resolution; float sphereSDF(vec3 p){ return length(p) - 1.0; } float sceneSDF(vec3 p){ return sphereSDF(p); } vec3 gradSDF(vec3 p){ float eps = 0.001; return normalize(vec3( sceneSDF(p + vec3(eps, 0.0, 0.0)) - sceneSDF(p - vec3(eps, 0.0, 0.0)), sceneSDF(p + vec3(0.0, eps, 0.0)) - sceneSDF(p - vec3(0.0, eps, 0.0)), sceneSDF(p + vec3(0.0, 0.0, eps)) - sceneSDF(p - vec3(0.0, 0.0, eps)) )); } void main(){ vec2 p = (gl_FragCoord.xy * 2.0 - u_resolution) / min(u_resolution.x, u_resolution.y); vec3 cPos = vec3(0.0, 0.0, 2.0); vec3 cDir = vec3(0.0, 0.0, - 1.0); vec3 cUp = vec3(0.0, 1.0, 0.0); vec3 cSide = cross(cDir, cUp); float targetDepth = 1.0; vec3 lPos = vec3(2.0); vec3 ray = cSide * p.x + cUp * p.y + cDir * targetDepth; vec3 rPos = ray + cPos; ray = normalize(ray); fragColor.rgb = vec3(0.0); for(int i = 0; i < 50; i ++ ){ if (sceneSDF(rPos) > 0.001){ rPos += sceneSDF(rPos) * ray; } else { float amb = 0.1; float diff = 0.9 * max(dot(normalize(lPos - rPos), gradSDF(rPos)), 0.0); vec3 col = vec3(0.0, 1.0, 1.0); col *= diff + amb; fragColor.rgb = col; break; } } fragColor.a = 1.0; }

#version 300 es
precision highp float;
precision highp int;
out vec4 fragColor;
uniform float u_time;
uniform vec2 u_resolution;

float sphereSDF(vec3 p){
  return length(p) - 1.0;
}

float sceneSDF(vec3 p){
  return sphereSDF(p);
}

vec3 gradSDF(vec3 p){
  float eps = 0.001;
  return normalize(vec3(
    sceneSDF(p + vec3(eps, 0.0, 0.0)) - sceneSDF(p - vec3(eps, 0.0, 0.0)),
    sceneSDF(p + vec3(0.0, eps, 0.0)) - sceneSDF(p - vec3(0.0, eps, 0.0)),
    sceneSDF(p + vec3(0.0, 0.0, eps)) - sceneSDF(p - vec3(0.0, 0.0, eps))
  ));
}

void main(){
  vec2 p = (gl_FragCoord.xy * 2.0 - u_resolution) / min(u_resolution.x, u_resolution.y);
  
  vec3 cPos = vec3(0.0, 0.0, 2.0);
  vec3 cDir = vec3(0.0, 0.0, - 1.0);
  vec3 cUp = vec3(0.0, 1.0, 0.0);
  vec3 cSide = cross(cDir, cUp);
  
  float targetDepth = 1.0;
  
  vec3 lPos = vec3(2.0);
  
  vec3 ray = cSide * p.x + cUp * p.y + cDir * targetDepth;
  vec3 rPos = ray + cPos;
  ray = normalize(ray);
  
  fragColor.rgb = vec3(0.0);
  for(int i = 0; i < 50; i ++ ){
    if (sceneSDF(rPos) > 0.001){
      rPos += sceneSDF(rPos) * ray;
    } else {
      float amb = 0.1;
      float diff = 0.9 * max(dot(normalize(lPos - rPos), gradSDF(rPos)), 0.0);
      vec3 col = vec3(0.0, 1.0, 1.0);
      col *= diff + amb;
      fragColor.rgb = col;
      break;
    }
  }
  fragColor.a = 1.0;
}