第 4 课：Specular Lighting

实现

uniform sampler2D iChannel0;

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

void main() {
  vec3 objectColor = texture2D(iChannel0, vUv).rgb;
  vec3 fragNormal = normalize(vNormal);
  vec3 viewDir = normalize(vec3(0.0, 0.0, 2.5) - vPos);

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

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

  vec3 reflectDir = lightDir - 2.0 * dot(lightDir, fragNormal) * fragNormal;
  float specular = pow(max(dot(reflectDir, -viewDir), 0.0),32.0);

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

  gl_FragColor = vec4(result, 1.0);
}