readme.md

May 14, 2026 · View on GitHub

One engineer. Ten years. A bindless, GPU-driven engine with real-time path-traced global illumination.

A personal R&D engine, not a commercial product. No roadmap promises, no support queue, no compromises on the vision.

The Engine

Spartan started as a university project. Ten years of nights and weekends later, its rendering technology runs in Godot Engine and S.T.A.L.K.E.R. Anomaly, ships in a published programming book, and anchors a community of 600+ engineers on Discord.

It is built around one philosophy: favor real-time over baked, dynamic over static, modern over safe. Every system here exists to serve that.

There is a destination that gives all this tech a purpose. Curious? Read the plan →

The Trailer

Worlds

Launch the engine and choose from a selection of default worlds. Each is physics-enabled—walk around, pick up objects with your mouse, or take a car for a spin.

Forest

The most demanding world: 256 million procedurally generated grass blades (inspired by Ghost of Tsushima), spanning 64.1 km² covered with thousands of trees and rocks.

More Worlds

Sponza 4K	Basic
Classic Dubrovnik building—ideal for path tracing	Contains some render test objects

Liminal Space	Showroom
Reality shifts to a nearby frequency	Clean showcase—no experimental tech

The Plan
A neon-soaked city, built to push the engine toward real-time path-traced driving through rain-slicked streets at 60fps, that's the plan.

Rendering

The renderer is built around one principle: the GPU owns the data. Every resource (geometry, materials, textures, lights, transforms, AABBs) lives in persistent, globally accessible buffers. No per-draw descriptor updates, no per-draw resource binding, no CPU-side draw loops.

Architecture

Zero-binding draw path, all per-draw data lives in a single bindless storage buffer, push constants carry only an index
Single global vertex and index buffer for all geometry (inspired by id Tech), with vertex pulling that bypasses the Input Assembler and is shared by rasterization and ray tracing
GPU-driven indirect rendering with per-meshlet frustum, Hi-Z occlusion, and backface cone culling, the CPU issues a single DrawIndexedIndirectCount per pass
Meshlet clustering via meshoptimizer, no mesh shader dependency
Bindless everything: materials, lights, samplers, uber shaders, minimal PSO permutations
Universal HLSL compiled for both Vulkan (SPIR-V) and DirectX 12
GPU-side asset processing: mip generation (FidelityFX SPD) and texture compression (Compressonator) at load time, not baked offline
Unified deferred rendering, opaque and transparent surfaces share the same BSDF and render path
Async compute for SSAO, screen-space shadows, and cloud shadows, parallel with shadow rasterization

Lighting and Global Illumination

Clustered deferred shading with a GPU-built logarithmic-Z grid and cone-vs-AABB culling for spots, scales to many local lights at near-constant per-pixel cost
ReSTIR path tracing with spatiotemporal reservoir resampling for real-time multi-bounce global illumination
Hardware ray-traced reflections and shadows via ray queries
Atmospheric scattering and image-based lighting with bent normals
Volumetric fog and clouds with temporal reprojection and shadow casting
Screen-space shadows (inspired by Days Gone) and XeGTAO ambient occlusion
Shadow map atlas with fast filtering and penumbra estimation

Performance and Upscaling

Variable rate shading and dynamic resolution scaling
TAAU, temporal anti-aliasing with built-in upsampling, Halton-jittered with variance-clip history reprojection
Intel XeSS 2 upscaling
FXAA
Custom breadcrumbs for GPU crash tracing and post-mortem debugging

Camera and Post-Processing

Physically based camera with auto-exposure and physical light units (lumens and kelvin)
Tonemappers: ACES, AgX, Gran Turismo 7 (default)
HDR10 output
Bloom, motion blur, depth of field, chromatic aberration, film grain, sharpening (CAS)

Car Simulation — 200Hz

A full vehicle dynamics simulation running inside the PhysX fixed-timestep loop.

System	Details
Tires	Pacejka MF 5.2 with combined slip, thermal model, pressure, wear, multiple surfaces
Suspension	Convex hull sweep contact, spring-damper, anti-roll bars, bump stops, bump steer, camber/toe
Weight transfer	Geometric + elastic lateral split via roll center heights and roll stiffness
Drivetrain	Engine torque curve, turbo, 7-speed gearbox, rev-match, open/locked/LSD differentials, RWD/FWD/AWD
Brakes	Thermal model with fade, front/rear bias, slip-threshold ABS
Aerodynamics	Drag, front/rear downforce, ground effect, DRS, rolling resistance
Steering	Ackermann geometry, high-speed reduction, self-aligning torque
Assists	ABS, traction control, handbrake
Integration	Semi-implicit Euler with consolidated net-torque per wheel
Input	Controllers and steering wheels with haptic feedback
Camera	GT7-inspired chase camera with speed-based dynamics

Engine Systems

System	Details
Particles	GPU-driven with compute emission and simulation, depth-buffer collision, soft blending
Animation	Skeletal hierarchies with keyframed clips and four-bone vertex skinning
Physics	PhysX with rigid bodies, character kinematics, and vehicle dynamics
Scripting	Lua 5.4 via Sol2 with full engine API and lifecycle callbacks
Audio	3D positional audio, streaming, reverb, procedural synthesis via SDL3
Input	Keyboard, mouse, controllers, and steering wheels with haptic feedback
Entity system	Component-based with transform hierarchies, prefabs, and XML serialization
Threading	Hardware-aware thread pool with parallel loops and nested parallelism detection
VR (WIP)	OpenXR with Vulkan multiview single-pass stereo across the full pipeline
Profiling	Nsight/RGP-style timeline with separate graphics and async compute lanes, RenderDoc integration
Asset import	40+ model formats (Assimp), 30+ image formats (FreeImage), 10+ font formats (FreeType)
Editor	ImGui-based with hierarchy, asset browser, inspector, script and shader editors, gizmos, profiler

Getting Started

Building

One-click project generation—see the Building Guide for details.

Learning the Engine

Start with Game.cpp, it shows how default worlds are loaded and is the best entry point for understanding the engine's structure. For gameplay scripting, check out the Lua Scripting Guide, it covers the full API, lifecycle callbacks, and examples.

Project	Description
Godot Engine	Integrates Spartan's TAA (view source)
S.T.A.L.K.E.R. Anomaly	Rendering addon using Spartan's source (ModDB)
Programming Book	Jesse Guerrero's beginner programming book features Spartan's code and community
University Thesis	Originally created as a portfolio piece while studying at the University of Thessaly with Professor Fotis Kokkoras

Using code from Spartan? Reach out, I'd love to showcase your project!

License

MIT License, free to use with attribution.