PostFx Glow Effect

Multi-pass glow/bloom post-processing effect using Gaussian blur. Downsamples the glow buffer, applies vertical and horizontal blur passes, then composites back with additive blending.

Overview

Declarative setup script (no M module). Registers a 4-stage glow pipeline:

1. Downsample - Passthrough shader copies #glowbuffer at 50% scale
2. Vertical Blur - Gaussian blur in Y direction
3. Horizontal Blur - Gaussian blur in X direction
4. Upsample & Combine - Additive blend back to $backBuffer

Scene Objects

Pipeline

#glowbuffer → Downsample (50%) → Blur Y → Blur X → Additive Combine → $backBuffer

Shader Configuration

-- Vertical blur direction
pfxGlowBlurVertShader:setField("defines", 0, "BLUR_DIR=float2(0.0,1.0)")

-- Horizontal blur direction (inherits from vertical)
pfxGlowBlurHorzShader:setField("defines", 0, "BLUR_DIR=float2(1.0,0.0)")

Combine State Block

The final composite uses additive blending with alpha test:

pfxGlowCombineStateBlock.blendEnable = true
pfxGlowCombineStateBlock:setField("blendSrc", 0, "GFXBlendOne")
pfxGlowCombineStateBlock:setField("blendDest", 0, "GFXBlendOne")
pfxGlowCombineStateBlock.alphaTestEnable = true
pfxGlowCombineStateBlock.alphaTestRef = 1

Notes

• Renders after GlowBin to process glow-tagged geometry
• Reflection passes excluded (allowReflectPass = false)
• The downsample to 50% reduces blur cost while maintaining visual quality
• Child PostEffects are added via gammaPostFX:add() to form the chain

See Also

• PostFx Light Ray - Volumetric light rays
• PostFx SSAO - Screen-space ambient occlusion