8_5_raymarching

Figure 8.8:

8_5_raymarching.frag

#version 300 es precision highp float; precision highp int; out vec4 fragColor; uniform float u_time; uniform vec2 u_resolution; uniform vec2 u_mouse; float circleSDF(vec2 p, vec2 c, float r){ return length(p - c) - r; } float contour(float v){ return step(abs(v), 0.002); } float point(vec2 p, vec2 c){ return step(length(p-c), 0.01); } float line(vec2 p, vec2 c, vec2 d){ return step(abs(dot(p - c, vec2(-d.y, d.x))), 0.002); } void main(){ vec2 pos = (2.0 * gl_FragCoord.xy -u_resolution.xy)/ u_resolution.yy; vec2 cPos = vec2(-0.5, 0.0); //camera position vec2 oPos = vec2(1.0, 0.0); //object position vec2 ray = oPos - cPos; ray.y += 2.0 * u_mouse.y / u_resolution.y - 1.0; ray = normalize(ray); float rad = 0.8; vec2 rPos = cPos; fragColor.rgb = contour(circleSDF(pos, oPos, rad)) * vec3(1); //draw circle of object fragColor.rgb += line(pos, cPos, ray) * vec3(0,0,1); //draw line for (int i = 0; i < 50; i++){ fragColor.rgb += point(pos, rPos) * vec3(1.0, 0.0, 0.0); //plot ray position float dist = circleSDF(rPos, oPos, rad); if (dist < 0.01){ break; } fragColor.rgb += contour(circleSDF(pos, rPos, dist)) * vec3(0.5, 0.5, 0.0); //draw circle with radius of SDF value rPos += dist * ray; if (rPos.x > oPos.x + rad){ 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;
uniform vec2 u_mouse;

float circleSDF(vec2 p, vec2 c, float r){
  return length(p - c) - r;
}

float contour(float v){
  return step(abs(v), 0.002);
}

float point(vec2 p, vec2 c){
  return step(length(p-c), 0.01);
}

float line(vec2 p, vec2 c, vec2 d){
  return step(abs(dot(p - c, vec2(-d.y, d.x))), 0.002);
}

void main(){
  vec2 pos = (2.0 * gl_FragCoord.xy -u_resolution.xy)/ u_resolution.yy;
  vec2 cPos = vec2(-0.5, 0.0);  //camera position
  vec2 oPos = vec2(1.0, 0.0); //object position
  vec2 ray = oPos - cPos;
  ray.y +=  2.0 * u_mouse.y / u_resolution.y - 1.0;
  ray = normalize(ray);
  float rad = 0.8;
  vec2 rPos = cPos;
  fragColor.rgb = contour(circleSDF(pos, oPos, rad)) * vec3(1);  //draw circle of object
  fragColor.rgb += line(pos, cPos, ray) * vec3(0,0,1);  //draw line
  for (int i = 0; i < 50; i++){
    fragColor.rgb += point(pos, rPos) * vec3(1.0, 0.0, 0.0);  //plot ray position
    float dist = circleSDF(rPos, oPos, rad);
    if (dist < 0.01){
      break;
    }
    fragColor.rgb += contour(circleSDF(pos, rPos, dist)) * vec3(0.5, 0.5, 0.0);   //draw circle with radius of SDF value
    rPos += dist * ray;
    if (rPos.x > oPos.x + rad){
      break;
    }
  }
  fragColor.a = 1.0;
}