第 6 课：Shininess

实现

uniform float iTime;

varying vec3 vPos;
varying vec3 vNormal;
varying vec2 vUv;

float getProgress() {
  float m = mod(iTime * 0.5, 2.0);
  float t = fract(m);
  if (m > 1.0) {
    t = 1.0 - t;
  }
  return pow(2.0, 10.0 * t - 10.0);
}

void main() {
  vec3 viewPos = vec3(0.0, 0.0, 2.5);

  vec3 objectColor = vec3(0.75, 0.45, 0.45);
  vec3 fragNormal = normalize(vNormal);
  vec3 fragPos = vPos;

  vec3 lightColor = vec3(1.0, 1.0, 0.75);
  vec3 lightPos = vec3(-2.0, 2.0, 2.0);
  vec3 lightDir = normalize(lightPos - fragPos);

  float ambient = 0.2;
  float diffuse = max(dot(fragNormal, lightDir), 0.0);

  vec3 viewDir = normalize(viewPos - fragPos);
  vec3 reflectDir = reflect(-lightDir, fragNormal);
  float Shininess = mix(1.0, 256.0, getProgress());
  float specular = pow(max(dot(viewDir, reflectDir), 0.0), Shininess);

  vec3 result = lightColor * (ambient + diffuse + specular) * objectColor;

  gl_FragColor = vec4(result, 1.0);
}