CustomShader with procedural normals missing #define HAS_NORMALS

[ptrgags]

While working on a sandcastle for #10180, I had tried making procedural normals for a torus. the lighting wasn't showing up and it took my a while to realize, the HAS_NORMALS define is only applied if the original model had normals. the lightingModel: LightingModel.PBR option does not add this define.

excerpt from this sandcastle (requires the feature-id-labels branch from #10180):

  // This is a bug, I shouldn't have to add this define in custom shaders...
  #define HAS_NORMALS

  void fragmentMain(FragmentInput fsInput, inout czm_modelMaterial material) {
    // See https://en.wikipedia.org/wiki/Toroidal_and_poloidal_coordinates
    float toroidal = 2.0 * czm_pi * (float(fsInput.featureIds.featureId_0) / 29.0);
    float poloidal = 2.0 * czm_pi * (float(fsInput.featureIds.featureId_1) / 19.0);
    mat3 rotate = mat3(
      cos(toroidal), sin(toroidal), 0.0,
      -sin(toroidal), cos(toroidal), 0.0,
      0.0, 0.0, 1.0
    );

    // normal when toroidal = 0;
    vec3 normal0 = vec3(cos(poloidal), 0.0, sin(poloidal));
    vec3 normalMC = rotate * normal0;
    
    // unfortunately this requires using private API, czm_normal
    material.normalEC = czm_normal * normalMC;
    material.specular = vec3(0.98, 0.90, 0.59);
    material.roughness = 0.3;
  }

Not sure the cleanest place to handle this in the code. Maybe in CustomShaderPipelineStage? or should it be handled later in LightingPipelineStage regardless of what set the PBR mode? And should ShaderBuilder have a way to add a define if it doesn't already exist so we don't add repeated code?

Regardless, this is low priority since procedural normals computed in the shader is likely not a very common use case.

[magixmin]

fsInput.featureIds.featureId_0 ，this value not exit .