IrisTech Game Engine

IrisTech is a custom 3D game engine written in C++ and developed from scratch.

The project focuses on real-time rendering, engine architecture, scene management, graphics programming, animation, deformation, and game development technologies. It also powers Pedal to the Medal, an arcade-driving game used to test IrisTech on Windows and Android.

This repository serves as a public technical showcase of the project.

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Features

Engine features include:

• 3D rendering with bgfx and DirectX 11
• Custom vertex and fragment shader pipeline
• Material and texture systems
• Directional lighting and multiple point lights
• Dynamic shadows and shadow mapping
• Point-light shadow cubemaps
• Configurable lighting and shadow settings
• Entity Component System based on EnTT
• Hierarchical scene graph, groups, and child entities
• Scene and project serialization
• Frustum culling and shadow visibility optimizations
• Experimental occlusion culling and portal culling
• Camera system and model loading
• ImGui-based scene editor with docking panels
• Hierarchy, Inspector, and transform manipulation tools
• Play Mode with a separate runtime scene state
• Skeletal animation and animation editing tools
• Lua scripting integration
• miniaudio-based audio system
• Tetrahedral Cage deformation system
• Spatial grid acceleration and experimental GPU deformation
• Debug counters and large-scene stress testing
• Windows game player and Android native game runtime
• Android touch input and on-screen game controls
• Project-based Windows and Android game build workflows
• Experimental Jolt Physics integration
• Atmospheric fog, automatic LOD, and model-streaming experiments
• CMake-based build system and Windows build packaging

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Tech Stack

Core engine technologies:

• C++
• bgfx, bx, and bimg
• DirectX 11 (current Windows rendering backend)
• SDL3
• EnTT
• Dear ImGui (docking-enabled build)
• GLM
• Lua 5.5
• Jolt Physics
• miniaudio
• nlohmann/json

Development and build tools:

• CMake and CMake Presets
• vcpkg
• Visual Studio 2022, MSVC, and MSBuild
• Windows SDK
• Android SDK, NDK, and Gradle
• PowerShell shader build scripts
• Git and GitHub Actions
• bgfx shader tools

The vcpkg dependency and graphics toolchain also includes cgltf, meshoptimizer, glslang, SPIRV-Cross, SPIRV-Tools, SPIRV-Headers, stb, tinyexr, miniz, and supporting libraries. Some are transitive dependencies or build tools, not separate engine subsystems.

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Game Showcase — Pedal to the Medal

Pedal to the Medal is an arcade-driving game built with IrisTech. It is an end-to-end test project for the engine's rendering, scene assets, game logic, input, and Android runtime. The project revisits a driving-game remake originally developed with Unity in 2021–2022.

The Android gameplay build demonstrates:

• A 3D road environment with traffic vehicles and roadside scenery
• Nighttime lighting, atmospheric effects, and rainy weather
• On-screen steering, accelerator, brake, and pause controls
• A gameplay HUD with speed, score, high score, collected coins, and a multiplier
• Bonuses for close passes through traffic, objectives, boosts, and vehicle-condition feedback
• A run-summary screen with results, retry, and main-menu controls
• Game content running through the IrisTech mobile runtime

Android Gameplay Gallery

Click a screenshot to view it at full resolution.

Rainy night drive	Daytime highway	Traffic streak	Hillside roads
Urban district	Rainy downhill	Rain & pickups	Run summary

Pedal to the Medal on Android — daytime and rainy conditions, hilly and urban roads, traffic overtakes, collectibles, touch controls, and the run-summary UI.

The game serves as a practical integration test for a standalone project that runs on the engine without requiring game-specific changes to its core.

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Screenshots

Dark Castle — Lighting & Shadows

A large dark-fantasy castle scene demonstrating textured models, multiple lights, real-time shadows, atmospheric rendering, and editor tools.

Scene Editor — Hierarchy & Play Mode

Editor interface with hierarchical scene objects, model and transform tools, rendering controls, and Play Mode.

Forest Scene — Vegetation & Tetrahedral Cage Tests

A dense forest environment used for vegetation-related Tetrahedral Cage experiments, as well as rendering stress tests and shadow visibility analysis.

Forest Debug Visualization — Cage Experiments

Development-time geometry and debug overlays from the forest vegetation tests, used to inspect scene structure and deformation-related geometry.

Earlier Rendering Experiments

Earlier tests of scene editing, materials, lighting, and shadow mapping.

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Rendering

The rendering system provides real-time 3D graphics, lighting, and scene visualization.

Rendering features include:

• 3D mesh rendering
• Material and texture parameters
• Custom vertex and fragment shaders
• Directional and point lights
• Dynamic shadow maps
• Point-light shadow cubemaps
• Camera-based scene rendering
• Frustum culling
• Experimental occlusion and portal culling
• Render targets
• Debug rendering and performance counters

The renderer currently uses bgfx with the DirectX 11 backend on Windows.

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Lighting & Shadows

IrisTech supports configurable directional lighting and multiple point lights.

Lighting functionality includes:

• Light direction, position, color, and intensity
• Point-light radius and attenuation
• Ambient lighting
• Directional shadow maps
• Point-light cubemap shadows
• Shadow quality controls
• Frustum-based shadow rendering optimizations

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Entity Component System

IrisTech uses EnTT as the foundation of its Entity Component System.

Scene entities can contain independent components such as:

• Transform
• Mesh Renderer
• Materials
• Lights
• Camera-related data
• Animation and script-related data

The scene graph supports parent-child relationships, object groups, and nested objects.

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Scene System

The engine contains its own scene and project management system.

Scene functionality includes:

• Scene creation, loading, and saving
• Project files (.irisproj)
• Scene files (.irisscene)
• Entity and component serialization
• Hierarchical scene objects
• Model import and placement
• Separate editor and Play Mode scene states

Game projects can target the Windows player and the Android native runtime. The Android workflow uses project assets, a generated Gradle app, and a prebuilt mobile engine library rather than bundling private engine sources.

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Editor

IrisTech includes editor tools built with Dear ImGui.

Editor functionality includes:

• Scene viewport and camera navigation
• Hierarchy and Inspector panels
• Object selection and transform gizmos
• Group and subgroup management
• Material and lighting controls
• Model placement
• Audio controls
• Animation editing and preview tools
• Play Mode
• Debug console and rendering statistics

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Tetrahedral Cage Deformation

IrisTech includes an independently developed Tetrahedral Cage deformation system.

Current implementation includes:

• Tetrahedral mesh validation
• Cached inverse rest-pose bases
• AABB filtering and spatial grid acceleration
• Barycentric vertex binding
• Batch deformation of bound mesh vertices
• Support for multiple tetrahedra
• Dedicated regression tests for the CPU deformation pipeline
• Experimental GPU deformation work

IrisTech features a custom C++ Tetrahedral Cage deformation pipeline that binds render meshes to volumetric cages using barycentric coordinates. AABB filtering, spatial-grid acceleration, and batch processing support complex deformation workflows. The forest screenshots above document tests involving vegetation and cage-related geometry visualization.

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Animation, Scripting & Audio

Animation, scripting, and audio are integrated with the editor and game runtime.

Functionality includes:

• Skeletal animation, rigs, clips, and keyframes
• Animation preview and editing tools
• Custom .irig rig assets
• Lua script runtime and scripts associated with scene objects
• Script examples for game logic and interactions
• miniaudio playback and editor audio controls

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Performance

Rendering performance is an important part of the project.

Optimization techniques and tools include:

• Frustum culling
• Experimental occlusion culling
• Experimental portal culling
• Shadow visibility optimizations
• Spatial data structures for deformation
• Shared rendering resources
• Rendering statistics and dense stress-test scenes
• Experimental parallel preparation and GPU deformation paths

The screenshots demonstrate development scenes, not measured FPS benchmarks.

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Author & Links

Maxim Bastrykin

• Personal Website / Portfolio: mbastrykin.ru
• GitHub: github.com/mbastrykin

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