Culling Pipeline
An overview of each available culling pipeline used in Flora.
Batch Renderer Group
BRG-compatible shaders generally work out of the box, but you must take steps to prevent Unity from stripping required variants in builds:
Keep BRG shader variants
Edit → Project Settings → Graphics
Set BatchRendererGroup variants to Keep all
See Unity’s BRG Getting Started Guide for more info.
Performance
BRG significantly reduces CPU overhead by minimizing state change overhead.
Particularly beneficial in scenes with many unique instance types
May provide less benefit in scenes with only a few prefab types
However, BRG scales more efficiently as project complexity increases
Lights
A major benefit of BRG is per-light shadow culling:
The legacy pipeline only determines if an instance should be rendered in any shadow pass
BRG allows Flora to cull instances per light, improving performance in scenes with multiple shadow-casting lights
Memory
The legacy pipeline is slightly more memory-efficient:
Per-instance size
48 bytes
96 bytes
With motion vectors
96 bytes
192 bytes
BRG requires inverse matrices stored in the instance buffer
The legacy pipeline reconstructs the inverse matrices in-shader, saving memory but increasing ALU instructions
Shader Compatibility
BRG supports a wide range of shaders without modification, including:
Built-in URP and HDRP shaders
ShaderGraph shaders
Third-party shaders that support DOTS Instancing (Amplify Shader Editor)
Known Limitations
Child LOD Renderer Transforms
Child renderers under an LODGroup with non-identity transforms do not render using their local transforms in BRG mode.
To resolve this:
Bake child transforms directly into the mesh. A convienient way to do this from Unity is through FBX Exporter package.
This is due to Flora treating the entire LODGroup as a single instance, whereas Unity’s default behavior treats each child renderer as separate.
Current DOTS matrix limitations prevent overriding this behavior.
Render Mesh
The legacy pipeline uses Unity’s RenderMeshIndirect API.
Requirements
To use this pipeline, shader passes must include:
#include "Packages/ma.com.flora/ShaderLibrary/Instancing.hlsl"#pragma multi_compile_instancing#pragma instancing_options procedural:SetupFloraInstancingData
Additionally, materials must have GPU Instancing enabled.
Features
Compatible with Flora’s runtime debug shaders
Supports LODGroups with child renderers that use custom local transformations
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