Confusion when reading shader source code

Zion_Huang · July 20, 2021, 8:44am

I encountered two questions while studying babylon source code(very beautiful I have to say ).

What does {X} means?

BabylonJS/Babylon.js/blob/e839b903699f99bdf6699182d9beec983f0e26d8/src/Shaders/ShadersInclude/lightUboDeclaration.fx#L1

    
      
          #ifdef LIGHT{X}

          	uniform Light{X}

          	{

          		vec4 vLightData;

          

          		vec4 vLightDiffuse;

          		vec4 vLightSpecular;

          		#ifdef SPOTLIGHT{X}

          			vec4 vLightDirection;

          			vec4 vLightFalloff;

          		#elif defined(POINTLIGHT{X})

2. Why is there “[0…maxSimultaneousLights]”(looks like array) in this “includes”?

github.com

BabylonJS/Babylon.js/blob/e839b903699f99bdf6699182d9beec983f0e26d8/src/Shaders/default.fragment.fx#L201

    
      
          	float shadow = 1.;

          

          #ifdef LIGHTMAP

          	vec4 lightmapColor = texture2D(lightmapSampler, vLightmapUV + uvOffset);

              #ifdef RGBDLIGHTMAP

                  lightmapColor.rgb = fromRGBD(lightmapColor);

              #endif

          	lightmapColor.rgb *= vLightmapInfos.y;

          #endif

          

          #include<lightFragment>[0..maxSimultaneousLights]

          

          	// Refraction

          	vec4 refractionColor = vec4(0., 0., 0., 1.);

          

          #ifdef REFRACTION

          	vec3 refractionVector = normalize(refract(-viewDirectionW, normalW, vRefractionInfos.y));

          	#ifdef REFRACTIONMAP_3D

                  #ifdef USE_LOCAL_REFRACTIONMAP_CUBIC

                      refractionVector = parallaxCorrectNormal(vPositionW, refractionVector, vRefractionSize, vRefractionPosition);

                  #endif

Evgeni_Popov · July 20, 2021, 8:57am

Those two are related:

#include<lightFragment>[0..maxSimultaneousLights]

means the lightFragment.fx file should be included maxSimultaneousLights times and for the first inclusion the {X} string will be replaced by 0, for the 2nd inclusion {X} will be replaced by 1, …, for the last inclusion {X} will be replaced by maxSimultaneousLights-1.

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Confusion when reading shader source code

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