An example of rendering numerous instances in Unity3D using Compute shaders for culling and LOD'ing and Graphics.DrawMeshInstancedIndirect to draw.

• Tested on Metal (Mac) and D3D11.
• Quasirandom squences to place the instances
• Draw things using Graphics.DrawMeshInstancedIndirect
• GPU Sorting with Bitonic sorting
• Compute shader: Frustum and shadow caster culling
• Compute shader: Occlusion culling with HierarchicalZBuffer
• Compute shader: Detail (Screen Size) Culling
• Compute shader: LOD objects using the distance from camera to object
• Simple shadow mode: Only use one shadow mesh for each instance type to lower setpass calls

• "_Example.cs" script on the "Example" game object:
  • Creates the instance data and sends it to the Indirect Renderer class.
• "IndirectRenderer.cs" on the "MainCamera" game object:
  • Is the main class in the project. It initializes all the buffers and compute shaders and then dispatches the compute shaders and draws the objects when Unity calls the PreCull() function.
• "HiZBuffer.cs" script on the "OccluderCamera" game object:
  • Creates a hierarchial Z-Buffer texture that contains the depth texture and shadow map which are used when doing frustum and occlusion culling

• Add reprojection of last frame’s depth to the Hi-Z (See "GPU-Driven Rendering Pipelines" below)
• Improve the instance sorting:
  • On my Macbook pro (mid 2014) sorting takes approx 50% of the GPU time
  • The GPU sorting must support instance numbers that are not in the non power of two
  • Find a better performant approach for the CPU Sorting
• Create the Hi-Z Texture with compute shaders
• Try out Raster Occlusion instead of Hi-Z (See "NVidia Siggraph 2014" & "Github - nvpro-samples" below)

The Unreasonable Effectiveness of Quasirandom Sequences

Kostas Anagnostou - GPU Driven Rendering Experiments

Kostas Anagnostou - Experiments in GPU-based occlusion culling

Kostas Anagnostou - Experiments in GPU-based occlusion culling part 2

Ulrich Haar & Sebastian Aaltonen - GPU-Driven Rendering Pipelines

Sakib Saikia - Going Indirect on UE3

RasterGrid - Hierarchical-Z map based occlusion culling

StackOverflow - Hierachical Z-Buffering for occlusion culling

Daniel E - Hierarchical Z-Buffer Occlusion Culling with multiple samples

bazhenovc - GPU Driven Occlusion Culling in Life is Feudal

NVIDIA - Siggraph 2014 - Scene Rendering Techniques

Github - nvpro-samples/gl_occlusion_culling

GPU Gems 2 - Hardware Occlusion Queries Made Useful

ARM Developer Center - hiz_cull.cs

L. Spiro - Tightly Culling Shadow Casters for Directional Lights (Part 1)

L. Spiro - Tightly Culling Shadow Casters for Directional Lights (Part 2)

nonoptimalrobot - Shadow Volume Culling

Stephen Hill and Daniel Collin - Practical, Dynamic Visibility for Games

zeuxcg.org - View frustum culling optimization - Representation matters

Copyright (C) 2017-2018 Elvar Orn Unnthorsson

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