第 5 课：Light Attenuation

实现

uniform sampler2D iChannel0;

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

void main() {
  vec3 viewPos = vec3(0.0, 0.0, 2.5);
  float Kc = 1.0;
  float Kl = 0.0;
  float Kq = 0.1;

  vec3 objectColor = texture2D(iChannel0, vUv).rgb;
  vec3 fragNormal = normalize(vNormal);
  vec3 fragPos = vPos;

  vec3 lightColor = vec3(1.0, 1.0, 0.75) * 3.0;
  vec3 lightPos = vec3(-1.0, 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 specular = max(dot(viewDir, reflectDir), 0.0);
  specular = pow(specular, 32.0);

  float Distance = distance(vPos, lightPos);
  float Attenuation = 1.0 / (Kc + Kl * Distance + Kq * Distance * Distance);


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

  gl_FragColor = vec4(result, 1.0);
}