Misaki
f940569ca3
Added: - AOV support for normals, albedo, and depth marked as completed. - New function `normal_unpack` in `BSDF.h`. - New field `esp` in `ray_t` structure in `RayIntersection.h`. Changed: - Updated `normal_ts_to_ws` to accept an additional parameter. - Refactored `weight_nee_light` for clarity. - Modified `RAY_EPSILON` for improved precision. - Updated `path_output` structure to include a `normal` field. - Normalized unpacked normal vector in `normal_unpack` function. - Updated `path_trace` to use closest hit ray intersection. - Updated `render_aov` to utilize closest hit logic. - Modified `ray_create` to initialize `esp` based on ray origin. - Improved accuracy in `offset_ray_origin` calculations. - Updated ray intersection logic in `ray_intersect_triangle` and `ray_intersect_aabb` to include epsilon checks. - Updated `evaluate_bsdf_directional` and `evaluate_bsdf_const_sky` for shadow rays. - Adjusted `sample_bsdf_simple_lit` for incoming light direction calculations. - Enhanced `render_pixel` to manage AOV flags effectively. - Changed camera rotation and light intensity in `scene_setup`. - Simplified texture loading by removing unnecessary sRGB conversion. Modified: - Several binary image files have been updated.
77 lines
3.1 KiB
Markdown
77 lines
3.1 KiB
Markdown
# Simple Ray Tracer - A physical-based path tracing in C
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A high-performance Monte Carlo path tracer written from scratch in pure C, featuring BVH acceleration, multiple importance sampling (MIS), Sobol sequences, and energy-conserving BSDFs.
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## ✨ Features
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- **Pure C implementation** — zero external dependencies beyond Assimp for mesh loading and cglm for math
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- **BVH Acceleration** — SAH-optimized binary tree with per-ray traversal stats
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- **Multiple Importance Sampling** — combines BSDF and light sampling using the balance heuristic
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- **Next-Event Estimation** — direct lighting with directional lights and sky
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- **HDR Environment Lighting** — MIS-enabled sampling of HDR sky using precomputed CDFs.
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- **Sobol Quasi-Random Sampling** — fast convergence and low-discrepancy stratification
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- **Recursive Path Integration** — with Russian Roulette termination for energy conservation
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- **OBJ Support** — via Assimp for mesh import and material parsing (OpenPBR-compatible)
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## 📸 Example Render
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Sponza rendered with 64 spp:
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Sponza rendered with 64 spp and hdri sky only:
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## 🔧 Build Instructions
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### Requirements
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- C compiler (GCC, Clang, MSVC)
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- OpenMP
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- CMake
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### Build
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You can use the provided CMakeLists.txt to build the project. Just run the following commands in the root directory of the project:
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```bash
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cmake -S . -B build
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```
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If you have powershell installed, you can run the build.ps1 script in project root directory.
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## 🧠 Technical Breakdown
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### BVH Acceleration
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- Built with Surface Area Heuristic (SAH) to reduce average traversal cost.
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- Debug counters log how many BVH nodes each ray touches, for profiling scene structure.
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### Multiple Importance Sampling (MIS)
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- Balance heuristic weights BSDF and light sampling PDFs.
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- Supports both directional lights and sky light via next-event estimation. Produce noise-free renders with low sample counts.
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### HDR Sky Lighting
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- Supports importance sampling of environment maps using a hierarchical CDF over solid angles.
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- Combined with MIS and BSDF sampling for noise-free global illumination, even with strong dynamic ranges.
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### Sobol Sampling
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- 32D low-discrepancy sequences for camera rays, light sampling, and Russian roulette.
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- Faster convergence and lower variance than pure RNG at 64 spp.
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### Materials (BSDFs)
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- Lambertian, and specular supported.
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- Designed to align with the OpenPBR material model.
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### Path Tracing
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- Recursive, physically-based integration with energy conservation checks.
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- Russian Roulette applied adaptively after second bounce.
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## 🚧 Roadmap
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- [x] AOV support (e.g. normals, albedo, depth)
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- [ ] Support for more complex materials (e.g. glass)
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- [ ] Standardize light unit
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- [ ] General speed improvements
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- [ ] Add GPU backend with CUDA
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- [ ] Support for glossy microfacet models (GGX)
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- [ ] Support for better diffuse models (Oren-Nayar)
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- [ ] Support for volumetric scattering (homogeneous media)
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- [ ] Light hierarchy for large emitter sets
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- [ ] Better multithreaded rendering
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- [ ] GUI frontend with real-time control
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