Cascaded Shadow Maps

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Implement Cascaded Shadow Mapping technique for shadowing.

Resources:

• OpenGL Cascaded Shadow Maps
• https://ahbejarano.gitbook.io/lwjglgamedev/chapter26
• Nvidia Cascaded Shadow Maps Presentation
• OGLDev Cascaded Shadow Maps

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Algorithm:

1. Partition the frustum into subfrusta.
2. Compute an orthographic projection for each subfrustum.
3. Render a shadow map for each subfrustum.
4. Render the scene.
5. Bind the shadow maps and render.
   • The vertex shader does the following:
     • Computes texture coordinates for each light subfrustum (unless the needed texture coordinate is calculated in the pixel shader).
     • Transforms and lights the vertex, and so on.
   • The pixel shader does the following:
     • Determines the proper shadow map.
     • Transforms the texture coordinates if necessary.
     • Samples the cascade.
     • Lights the pixel.