Using Baked Lightmap in Stride

[ArieLeo]

Current Implementation

Currently if we want to use baked lightmap from 3d software (In this case blender) is not quite straight forward and there's several issue due stride doesn't support shading from external lightmap.

Issue 1 The issue that we get is we have to multiply diffuse texture with lightmap manually.

This is not ideal, because it make the diffuse shading darker and the lightmap are incorrectly blended with the diffuse shading. And making the material setup bit cumbersome.
Ideally Lightmap Setup should have it's own texture slot similar to Cel Shading Diffuse Model. In proper setup when we use Lightmap Diffuse Model there's should be additional slot for the Lightmap Texture under Diffuse Model just like the Ramp Function Input in the Cel Shading.

Another requirement is the Intensity slider for the lightmap, as we are baking the lightmap from external software there's a chance that the exposure that we want are missmatched. Example of the intensity slider is similar to the specular map input.

in Summary for the Lightmap Input setup, an additional Lightmap Diffuse Model, when this is selected it enable additonal texture input for Lightmap along with the Intensity Slider for the Lightmap input.

Issue 2 Another issue is double lighting. This is caused by Diffuse texture are multiplied by lightmap and then multiplied again with environment diffuse lighting (skybox/lightprobe).

This is also the cause why the lighting looks darker, and the lightmap display incorrectly.
This is how it should be if we used baked lightmap. Any mesh that used baked lightmap should be excluded from environment light contribution.

Update : Shader and code updated, it should fixed the Issue 1
Still not quite convinced with the blending between the lightmap and realtime light, i'll might tweak the shader again.
But for now it's should give you a better workflow if you want to use lightmap, just place these into your project
LightMapDiffuseModel.zip

[ArieLeo]

Indirect Lightmap Baking

This is the process that is use to bake indirect lightmap in blender.

1. First and main requirement if you use HDR in the world lighting you need this setup. Pay attention to the Indirect World Switch. That's an important parameter in the process
   

2. Create to output target texture for the EnvironmentLight and IndirectLight
   

3.Baking Environment Light.

• Set the Bake Type to Diffuse, and Disable Color on the Contribution (I and II)
• Set the Indirect World Switch to Zero (III)
• Select the EnvironmentLight Texture as the Target Texture (IV)
• After you bake it should give diffused environment light only (V)

4. Baking IndirectLight
   

• Bake setting as similar the only difference are we only need the Indirect Contribution (I)
• Set the Indirect World Switch to One (II)
• Select the IndirectLight Texture as Target (III)
• When you bake the texture it should give you a directional Indirect light (IV). Notice the black spots, we gonna fixed that on the next step.

5. Combine the Texture.
   

• Move to Compositor Tab.
• Mixed both output Texture with Mix node set the mode to Add
• You might notice the texture become to bright, add another Mix node, set to Multiply. Multiply it with grey color (pure white set the value to 0.5).
• Don't forget to denoise.

[ArieLeo]

Currently the lightmap texture that i used are using BC6H DDS, that i exported using Blender DDS addon, not sure if this is ideal we might need RGBM Encoding/Decoding in stride to for HDR Texture