我根据THREE.BlendShader和AlteredQualia JupiterShader制作了以下BlendShader。我正在努力为这个着色器添加Directional Light到材质。我已阅读this教程，但它仍然会渲染完全亮起的对象，而不考虑定向光。在定义gl_FragColor时，我可能在最后一行做错了，但无法弄清楚它是什么。请帮忙。谢谢。
FragmentShader：
"#if NUM_DIR_LIGHTS > 0",
"uniform vec3 directionalLightColor[NUM_DIR_LIGHTS];",
"uniform vec3 directionalLightDirection[NUM_DIR_LIGHTS];",
"#endif",
"uniform float opacity;",
"uniform float mixRatio;",
"uniform float staticRatio;",
"uniform sampler2D tDiffuse1;",
"uniform sampler2D tDiffuse2;",
"uniform sampler2D tDiffuse3;",
"varying vec2 vUv;", // = uv
// vNormal is worldNormal calculated in vertex shader as follows:
// "vec3 worldNormal = mat3( modelMatrix[0].xyz, modelMatrix[1].xyz, modelMatrix[2].xyz ) * normal ;",
// "vNormal = normalize( worldNormal );",
"varying vec3 vNormal;",
"void main() {",
"vec4 texel1 = texture2D( tDiffuse1, vUv );", // frame i
"vec4 texel2 = texture2D( tDiffuse2, vUv );", // frame i + 1
"vec4 texel3 = texture2D( tDiffuse3, vUv );", //static texture
"texel1.xyz = pow( texel1.xyz, vec3( 1.7 ) );", // gamma correction
"texel2.xyz = pow( texel2.xyz, vec3( 1.7 ) );", // gamma correction
"float m = 1.0;",
"float m1 = smoothstep( 0.23, 0.3, vUv.y );", //
"float m2 = 1.0 - smoothstep( 0.75, 0.82, vUv.y );",
"m = m1 * m2;",
"vec4 dynamic = mix( texel1, texel2, mixRatio );", // mixing two frames
//directional light
"vec4 sumDirLights = vec4(0.0, 0.0, 0.0, 1.0);",
"#if NUM_DIR_LIGHTS > 0",
"for( int i = 0; i < NUM_DIR_LIGHTS; i++ ) {",
"vec3 dir = directionalLightDirection[i];",
"sumDirLights.rgb += clamp( dot( -dir, vNormal ), 0.0, 1.0 ) * directionalLightColor[i];",
"}",
"#endif",
"gl_FragColor = vec4( 1.0, 1.0, 1.0, 1.0 ) * sumDirLights + ( opacity * mix( texel3, dynamic, staticRatio * m ) ) ;",
"}"