text: // varying: vPosition, vNormal, vColor
  export default `\
  #define SHADER_NAME direction-layer-fragment-shader
  
  varying vec4 vPosition;
  varying vec4 vNormal;
  varying vec4 vColor;
  
  void main(void) {
    if (vColor.a == 0.) {
      discard;
    }
    float lightWeight = getLightWeight(vPosition.xyz, vNormal.xyz);
    // gl_FragColor = vec4(vColor.xyz * lightWeight, 1);
    gl_FragColor = vColor;
  }
  `
  