[카테고리:] 미분류

작성일자

Ray-Sphere 계산

수식

코드

uniform vec3 uResolution;
uniform float uTime;
uniform vec4 uMouse;

// v = a -> 0
// v = b -> 1 
// v = (a+b)/2 -> 0.5
float remap01(float a, float b, float v) {
  return (v - a) / (b - a);
}

void main() {
  vec2 uv = (gl_FragCoord.xy - .5 * uResolution.xy) / uResolution.y;

  vec3 col = vec3(0);
  vec3 Ro = vec3(0);
  vec3 Rd = normalize(vec3(uv.x, uv.y, 1.));
  vec3 S = vec3(0, 0, 3);
  float R = 1.;

  float tp = dot(S - Ro, Rd);
  vec3 Ptp = Ro + Rd * tp;
  float y = length(S - Ptp);
  
  if(y < R) {
    float x = sqrt(R*R - y*y);
    float t1 = tp - x;
    float t2 = tp + x;

    float c = remap01(S.z, S.z - R, t1);
    col = vec3(c);
  }
  
  gl_FragColor = vec4(col, 1.0);
}

결과

작성일자

code snippet (20250417,21)

  // if(p.x > .5 || p.y > .5) col.r = .8;
  if(max(p.x, p.y) > .5) col.r = .8;
  // col.r = step(.5, max(p.x, p.y));

  float a = radians(45.);
  vec2 n = vec2(sin(a), cos(a));
  float d = dot(uv, n);
  d = abs(d);
  col += smoothstep(fwidth(d), 0., d-.001);

function prepareOneFish() {
  let start = new Date().getTime();
  while (new Date().getTime() < start + 1000) {
    // preparing fish
  }
}

function setTimeoutPromise(delay) {
  return new Promise((resolve, reject) => {
    setTimeout(resolve, delay);
  });
}

function setTimeoutPromise(delay) {
  return new Promise((resolve) => setTimeout(resolve, delay));
}