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What is the standardmaterial.lightmapTexture for?


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Hi there,

I found there are both 'ambientTexture' and 'lightmapTexture' properties on StandardMaterial in the doc, and I think I got a little confused with them.

Firstly, if I'm not mistaken, a lightmap is an image with not only the shadow data but also include some environment colors on it. It's not the same thing as the Ambient Occlusion(AO) map, which is just a black and white image with only shadow data, right? If so, my questions are:

1. I used to think the 'ambientTexture' means the AO map, until I read this: 'Unleash the StandardMaterial for your babylon.js game'. It says the 'ambientTexture' on StandardMaterial is for the lightmap, if so, what is the StandardMaterial.lightmapTexture for??

2. About the AO map, so the StandardMaterial doesn't support it, right? 

3. Does the PBRMaterial.ambientTexture means the AO map? Because I found it says 'AKA Occlusion Texture in other nomenclature' in the doc.



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1. ambientTexture is used to add a value to the lighting computation: (check the baseAmbientColor here: https://github.com/BabylonJS/Babylon.js/blob/master/src/Shaders/default.fragment.fx#L375)

2. if you are looking for a multiplicative value, then this is the goal of lightmapTexture: https://github.com/BabylonJS/Babylon.js/blob/master/src/Shaders/default.fragment.fx#L384

3. I leave this one to @Sebavan

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8 hours ago, V!nc3r said:

When we put lightmap in lightmap channel, and then set useLightmapAsShadowmap to true, is it the same process that put lightmap in ambient channel ?

Actually no. See the shader code which Deltakosh mentioned (The first reply). The ambientColor only effects on the diffuse color, it has no effects on the other colors (specular, reflection, or emissive...). But the lightmapColor (with 'useLightmapAsShadowmap' to true) effects on the final output color.

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