Show HN: Tectonic Game Engine

A modern, feature-rich 3D game engine written in pure C, inspired by classic FPS engines.

An overview of the core technologies and rendering capabilities of the Tectonic Engine.

• Physically-Based Rendering (PBR) Pipeline: Core rendering is built on a deferred PBR model using a metallic/roughness workflow, enabling realistic material interactions with light.

• Normal Mapping: Supported on both world geometry (brushes) and models for high-frequency surface detail.

• Relief Mapping: Height maps can be used to create the illusion of depth and self-shadowing on surfaces, providing a more convincing 3D effect than standard normal mapping.

• Light Styles & Presets: Lights can utilize preset animation styles for effects such as flickering, strobing, and pulsing.

• Light Cookies: Spotlights support projected textures (cookies) for gobo and patterned lighting effects.

• Shadow Mapping: Real-time dynamic shadows are supported for all light types.

• Omnidirectional Shadows: Point lights use cubemap shadow maps for 360-degree shadow coverage.

• Projected Shadows: Spotlights and the sun use standard 2D shadow maps for efficient directional shadowing.

• Percentage-Closer Filtering (PCF): Implemented for soft shadow edges.

• Global Illumination via Virtual Point Lights (VPLs): The engine supports real-time, one-bounce global illumination by generating hundreds of virtual point lights from surfaces hit by direct light, providing realistic color bleeding and indirect lighting.

• High-Dynamic Range (HDR) Lighting: The entire lighting pipeline operates in HDR.

• Auto-Exposure: The final image exposure is automatically adjusted based on scene luminance, simulating the human eye's adaptation to light and dark areas.

• Bloom: Bright areas of the scene realistically "bloom" into neighboring areas, enhancing the HDR effect.

• Screen-Space Ambient Occlusion (SSAO): Adds contact shadows and depth to scenes by darkening creases, corners, and ambiently lit areas.

• Volumetric Lighting: Supports "god rays" and light shafts from the sun and other dynamic lights, rendering visible beams of light through the environment.

• Water Rendering: Features environmental reflections using cubemaps, Fresnel effects for angle-dependent reflectivity, and flowmapping for a dynamic appearance.

• Glass & Refraction: Supports translucent glass surfaces that refract the scene behind them, creating a realistic distortion effect.

• Reflection Probes: Static cubemaps can be baked from any point in the world and applied to nearby geometry for accurate, parallax-corrected local reflections on PBR materials and water.

• Procedural Skybox: A dynamic skybox system with procedural atmospheric scattering (Rayleigh & Mie) and animated clouds, removing the need for static 2D skybox images.

• Includes a suite of configurable effects such as Film Grain, Chromatic Aberration, CRT screen curvature, Vignette, Sharpening, Black and White and Depth of Field.

• Brush-Based World Construction: World geometry is built using classic CSG (Constructive Solid Geometry) brush techniques, allowing for rapid and robust level design.

• Advanced Particle System: Capable of emitting sprites with configurable properties like gravity, velocity, color-over-life, and size-over-life, loaded from simple .par definition files.

• Physics Integration: Utilizes the Bullet Physics library for a robust simulation environment.

• Collision Primitives: Supports player capsules, static triangle meshes, dynamic and static convex hulls.

• Dynamic Objects: Brushes and models can be configured with mass to become fully dynamic physics objects.

• Input/Output (I/O) Logic System: A powerful, trigger-based system inspired by Source's entity I/O allows for complex scripting and level interactivity without writing code. Entities can fire outputs (e.g., OnTrigger, OnTimer) which connect to the inputs of other entities (TurnOn, PlaySound).

• Hierarchical Undo/Redo System: The integrated editor features a robust, multi-level undo/redo stack for all entity creation, deletion, and modification actions.

• Cross-Platform Support: The engine and its tooling are built with modern CMake for compilation on Windows (32/64-bit, MSVC) and Linux (GCC).

• In-Engine Editor: A comprehensive, real-time "Hammer-style" editor is built directly into the engine.

• Multi-Viewport Editing: Features classic 3D perspective, top, side, and front 2D orthographic views.

• CSG Tools: Includes tools for brush creation, clipping, and vertex manipulation.

• Vertex Painting & Sculpting: Terrain and complex brushes can be directly painted with vertex colors for texture blending or sculpted for organic shapes.

• Developer Console & CVars: A Quake-style dropdown console provides direct access to engine commands and tunable "CVars" for runtime configuration.

Only the following folders are under the main project license (MIT):

• engine/
• launcher/
• Batchmodelimporter/
• docs/

All other folders are third-party dependencies and fall under their respective open-source licenses.