ObsidianGL

Real-time SIMD-optimized CPU software renderer with a modern API, alongside OnyxEngine (a small engine layer on top) and a demo game (Minecraft clone).

A complete rewrite of AmberGL from scratch, originally designed to provide an immediate-mode API capable of rendering Minecraft Classic 0.30 (OpenGL 1.1), for science. It has since grown into a full engine with multiple rendering backends.

• ObsidianGL: CPU software rasterizer with multithreaded tiling and SIMD acceleration
• OnyxEngine: engine layer with an RHI backed by ObsidianGL (default) or OpenGL 4.5 via GLAD, plus pass-based rendering, scene system, and SDL3 windowing
• Game: Minecraft clone with infinite world generation

Features

• Programmable pipeline (vertex/fragment programs with varyings, uniforms, texture sampling)
• Command buffer recording (Begin/End, Submit, Present, Dispatch)
• Multithreaded tile-based rasterizer with thread pool, primitive binning, per-tile program contexts
• Tile debug overlay (grid, triangle-count heatmap, per-tile visibility toggle)
• Render targets with color/depth attachments and blit between targets
• Triangle rasterization (barycentric, subpixel-accurate with top-left fill rule, no coplanar triangle issues)
• Line and point rasterization (configurable width and size)
• AVX2 / SSE / scalar SIMD paths across rasterization, buffer clears, and texture sampling
• Texture mapping (nearest + bilinear filtering, repeat + clamp-to-edge wrapping)
• Perspective-correct interpolation (colors, texture coordinates)
• Sutherland-Hodgman frustum clipping (6 planes, Cohen-Sutherland trivial reject)
• 32-bit float depth buffer (depth test / depth write)
• Face culling (front/back, CW/CCW)
• Fill, wireframe, and point polygon modes

Getting Started

Requirements: CMake 3.20+, a C++20 compiler, x86_64 CPU (AVX2 recommended).

Windows (Visual Studio):

Scripts\GenerateVisualStudioProject.bat

Defaults to VS 2026. Pass 2022, 2024, or 2026 as an argument. Open .build/Obsidian.sln and build the Game project.

Linux / macOS:

./Scripts/GenerateMakefile.sh
cd .build && make -j

CMake options:

• OBSIDIAN_USE_AVX2 (default ON): enable AVX2 codepaths in the rasterizer
• OBSIDIAN_USE_OPENGL (default OFF): use the OpenGL 4.5 backend instead of the software rasterizer

Dependencies

• SDL3
• GLAD
• GLM
• stb_image
• FastNoiseLite (vendored single-header in the Game module)

Minimum Requirements

Component	Requirement
CPU	x86_64 (AVX2 recommended)
RAM	1 GB
GPU	OpenGL 4.5 (only when using the OpenGL backend)
OS	Windows 10+, Linux, macOS

Video and Screenshots

Minecraft 0.30 running on CPU using ObsidianGL and a Java bridge. I removed all GL11 function calls and now just blit the ObsidianGL framebuffer to OpenGL when Display is called. A lot of rendering issues remain, but at least it runs!

Recording.2026-02-25.231525.mp4

Amber preserves, Onyx structures, Obsidian cuts.