HDR Pipeline

Shows how to compose the individual post processing effects (ExtractEffect, DownsampleEffect, UpsampleEffect, CombineEffect, TonemapEffect) into a full bloom + tonemap pipeline:

1. Scene - the HDR source texture is drawn into a floating point render target.
2. Extract - bright pixels above a threshold are cut out (the "glow").
3. Downsample / Upsample - the extracted glow is repeatedly downsampled, then upsampled back up again, blending each step additively. This dual filtering approach produces a cheap, wide blur.
4. Combine - the blurred glow is added back onto the original scene.
5. Tonemap - the combined HDR result is mapped down to displayable LDR output.

The output dropdown lets you inspect the texture at each stage. Every stage writes into its own render target - more than a real pipeline would need - purely so the intermediate buffers can be selected and viewed here.