DX12 WCSPH (EOS-SPH) Attempt — Archived

A repository exploring WCSPH (EOS-SPH) fluid simulation based on DirectX 12 Compute Shaders.
This project is currently Archived. The plan is to maintain the existing DX12 compute pipeline while re-implementing the physics solver using PBF/XPBD approaches.

Detailed Postmortem & Decisions: POSTMORTEM.md

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What’s inside (Implemented / WIP)

• DX12 Particle Pipeline: Compute shader-based spawn/update loop integrated with the graphics rendering pipeline.
• 2D Boundary Collision: Basic boundary handling with debug visualization.
• Neighbor Search (Uniform Grid): Spatial Hashing implementation.
  • Hashing → Grouping → Scan/Prefix-sum (WIP)
• Physics Solver: Preliminary implementation of Density/Pressure (EOS) calculation and Force application steps.

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Requirements

• Windows 10+ (DirectX 12)
• Visual Studio 2019 or later
• C++17 Standard
• vcpkg
• Windows SDK 10.0.18362.0+ (HLSL 2021)

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Build & Run (Quick Start)

1) Install vcpkg

git clone [https://github.com/microsoft/vcpkg.git](https://github.com/microsoft/vcpkg.git)
cd vcpkg
bootstrap-vcpkg.bat
vcpkg integrate install

2) Enable vcpkg manifest mode (Visual Studio)

Go to: Project Properties -> vcpkg -> Use Vcpkg Manifest = Yes

Dependencies will be automatically installed based on vcpkg.json.

3) Build & Run

Open Solution -> Select x64 / Debug (or Release) -> Run

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Assets / Third-Party Content

This repository uses an HDRI environment map originally from ambientCG:

• Asset: IndoorEnvironmentHDRI013 (converted to cubemap)
• Source: ambientCG.com
• License: Creative Commons CC0 1.0 Universal

Created using IndoorEnvironmentHDRI013 from ambientCG.com, licensed under CC0 1.0 Universal.

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Debug Shader PDB

• In Debug builds, shader PDB files are generated under ./PDB/.
• It is recommended to configure the ./PDB/ folder to be generated at runtime (excluded from version control).

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Repository Notes

• Key Fluid Simulation Code:
• Core/SphSimulator.cpp
• Shaders/SphCS.hlsl

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Controls

• Space : Start / Pause simulation
• F : Toggle camera lock
• T : Toggle particle init mode (Dam Break / Emitter)
• R : Reset particle positions
• W/A/S/D : Move camera

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License

• Code: MIT License (see LICENSE)
• Third-party assets: Subject to their respective licenses (e.g., ambientCG HDRI is CC0 1.0).

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Technical Notes (High-level)

• GPU Neighbor Search: Implemented using Spatial Hashing + Grouping + Prefix-sum (Cell ranges).
• Sorting: Bitonic sort (Initially naive implementation → Attempted optimization → Reverted for stability).
• Data Layout: Tested both AoS and SoA; SoA (Structure of Arrays) demonstrated better performance in this compute pipeline.
• Debugging: Validated using PIX (GPU buffer inspection) and UAV barriers between compute passes.
• Scale: Tested up to ~100k particles (50×40×50 grid), with a compute group size of 512.