Custom Unity PCF (Poisson Sampling)

PCF (Percentage Closer Filtering) via Poisson sampling for Unity and Universal Render Pipeline.

Used to prevent aliasing, which is one of the problems of shadow mapping.

Built with Unity 2021.3.0f1 and URP v12.1.6.

Implementation

The project contains:

• A render feature to configure the poisson sampling parameters:
  • Spread
  • Mode
    • Disabled
    • Poisson Sampling
    • Poisson Sampling (Stratified)
    • Poisson Sampling (Rotated)
  • Samples Count (4 or 16)
• Lit Shader, which uses Poisson sampling to access shadow maps. Supports the following features:
  • Lambertian lighting
  • Shadow receiving/casting
  • Ambient lighting
• Editor utility to generate 3D Texture to sample rotations in the shader.
  • It can be accessed in Window/Rendering/Rotated Poisson Sampling Texture Generator.
  • The render feature uses the bundled 32x32x32 texture by default.

Examples

Shadow resolution is set to 4096 in all examples.

Hard shadows (built-in)

Soft shadows (built-in)

Poisson Sampling

• Spread: 1200
• Samples 16

Poisson Sampling

• Spread: 1500
• Samples 4

Poisson Sampling (Stratified)

• Spread: 2000
• Samples: 16

Poisson Sampling (Rotated)

• Spread: 1000
• Samples: 16

References

• http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-16-shadow-mapping/#aliasing
• https://dev.theomader.com/shadow-quality-2/