SuikaSibyl / vxpg

Real-Time Path Guiding Using Bounding Voxel Sampling

vxpg

code for SIGGRAPH 2024 paper "Real-Time Path Guiding Using Bounding Voxel Sampling".

project page: https://suikasibyl.github.io/vxpg

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Noteice: The current codebase is a bit messy,
and there could be problems to build the project.
Please contact me through [e-mail] for any questions.
I'll probably upload a clean and more easy to build version latter.

Our implementation bases on my toy renderer SIByL2023, and the code is already in the 👈 repo.

Here is a walkthrough of relevant files and codes:

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Render Graphs

The render pipelines in SIByL are defined and scheduled with Render Dependency Graph (RDG).

For simplicity, I serialize the pipeline and show them below. In the paper, we present 3 variants of vxpg pipeline:

1. vanilla vxpg [cpp]

High-Level Pipeline	Actual Pass	Description	Code
Render VBuffer	RayTraceVBuffer	render and hold V-Buffer for further reuse of 1st shading points	[cpp][slang]
Geometry Injection	PrebakeDummyPass	load prebake geometry information from external resources	[cpp]
	VXGuiderClearPass	clear relevant resources for geometry & light injection	[cpp][slang]
	VXGuiderGeometryDynamicPass	dynamic objects geometry injection	[cpp][slang]
Light Injection	VXGuider1stBounceInjection	draw 1st path sample, inject the irradiance to voxels	[cpp][slang]
	VXGuiderCompactPass	compact all populated voxels for faster manupulation later	[cpp][slang]
Superpixel Clustering	InitClusterCenterPass	set 64x64 pixel tile center as cluster center	[cpp][slang]
	FindCenterAssociationPass	use gSLICr to find nearst pixel cluster in local 3x3 field	[cpp][slang]
Supervoxel Clustering	VXInfoClearPass	clear data relevant to voxel clustering	[cpp][slang]
	RowColumnPresamplePass	randomly select 1 pixel per superpixel & 1 vertex per populated voxel	[cpp][slang]
	RowVisibilityPass	for each voxel, use the selected vertex to evaluate the mutual visibility with every representative pixels proposed in 👆 pass; then pack the visiblity as a unsigned int bitfield	[cpp][slang]
	RowKmppCenterPass	use kmpp to initialize voxel cluster center by visibility bitfield	[cpp][slang]
	RowFindCenterPass	find the nearest voxel cluster, which has most similar visibility bitfield	[cpp][slang]
Supervoxel Merging (optional)	VXTreeEncodePass	encode the voxels with cluster and position information	[cpp][slang]
	BitonicSort Subgraph	sort the voxels as tree leaves for parallel tree building	[cpp][slang]
	VXTreeIIntializePass	initialize tree leaves and nodes for parallel tree building	[cpp][slang]
	VXTreeInternalPass	and this is parallel binary tree building	[cpp][slang]
	VXTreeMergePass	merge voxel nodes along the binary tree to get cluster information (bounding box, irradiance sum)	[cpp][slang]
LightSlice Building	VXInfoRearrangePass	rearange voxel information for further visibility check	[cpp][slang]
	SPixelClearPass	clear the data structure relavent to superpixel samples	[cpp][slang]
	SPixelGatherPass	each superpixel draw some sample pixels from its domain	[cpp][slang]
	SPixelVisibilityEXPass	and we compute mutual average visibility and contributions between each pair of superpixel and supervoxel	[cpp][slang]
	VXTreeTopLevelPass	build the sampling distribution for LightSlice	[cpp][slang]
Path Tracing!!	VXGuiderGIPass	do adaptive guided sample, and MIS here	[cpp][slang]

2. ReSTIR GI + vxpg [cpp]

High-Level Pipeline	Actual Pass	Description	Code
Render VBuffer	RayTraceVBuffer	render and hold V-Buffer for further reuse of 1st shading points	[cpp][slang]
Hold GBuffer	VBuffer2GBufferPass	convert VBuffer to GBuffer for ReSTIR usage	[cpp][slang]
	GBufferHolderSource	hold and load the GBuffer from previous frame	[cpp]
VXPG	...	all passes similar to previous section, the only difference is that the guided samples are stored as proposal reservoirs	👆
ReSTIR Reuse	TemporalResampling	temporal reuse	[cpp][slang]
	SpatialResampling	spatial reuse	[cpp][slang]
Shading	FinalShading	finally shading the scene with ReSTIR samples	[cpp][slang]

3. A-SVGF + vxpg [cpp]

High-Level Pipeline	Actual Pass	Description	Code
VXPG	...	all passes similar to previous section, the only difference is that the guided samples are stored as proposal reservoirs	👆
A-SVGF	...	again lots of passes for A-SVGF, just read the code 👉	[cpp][slang]