How do I integrate Lightmapper into my existing OpenGL game engine?

Include lightmapper.h with LIGHTMAPPER_IMPLEMENTATION defined, set up geometry with lmSetGeometry, and render scenes within lmBegin/lmEnd loops as shown in the example usage. You'll need to handle UV atlas generation separately using external tools.

Lightmapper vs Blender's baking tools – which should I use?

Lightmapper is better for integrated, programmatic baking in C/C++ OpenGL projects, while Blender offers a full GUI and supports various renderers but requires export/import cycles. Choose based on whether you need in-engine control or a visual workflow.

What settings improve lightmap quality in Lightmapper?

Increase the hemicube resolution, adjust the interpolation threshold to avoid missing variations, and use the alpha channel technique for closed meshes as detailed in the quality improvement section of the README.

Can Lightmapper handle emissive materials for global illumination?

Yes, any light shapes drawn with emissive colors are supported, allowing for flexible light source definitions directly in your rendering code for multi-bounce calculations.

How does selective hierarchical interpolation work in Lightmapper?

It renders only a subset of texels in initial passes and interpolates others based on a threshold, speeding up baking by 3-10x as explained with the debug image in the README, but requires careful tuning to avoid artifacts.

What post-processing functions does Lightmapper include?

It provides lmImageDilate for filling gaps, lmImagePower for gamma correction, and lmImageSaveTGAf for saving lightmaps, all usable after baking passes to refine and export results.

Open-Awesome

Light Mapper

A C/C++ single-file library for drop-in lightmap baking using your existing OpenGL renderer.

GitHub

1.5k stars138 forks0 contributors

What is Light Mapper?

Lightmapper is a C/C++ single-file library that enables developers to bake lightmaps for static scene geometry using their existing OpenGL renderer. It solves the problem of adding precomputed global illumination and ambient occlusion to games or applications without requiring external baking tools or complex integrations.

Target Audience

Graphics programmers and game developers working with C/C++ and OpenGL who need to integrate lightmap baking directly into their rendering pipeline.

Value Proposition

Developers choose Lightmapper for its simplicity and drop-in design—it leverages their existing OpenGL code, supports multi-bounce global illumination, and includes performance optimizations like selective hierarchical interpolation, all in a single-file library.

Overview

A C/C++ single-file library for drop-in lightmap baking. Just use your existing OpenGL renderer to bounce light!

Use Cases

Best For

Adding ambient occlusion to static game environments
Baking global illumination for pre-rendered scenes in OpenGL applications
Integrating lightmap baking into custom game engines
Learning lightmap baking techniques in C/C++
Prototyping lighting effects without external tools
Optimizing lightmap generation with selective interpolation

Not Ideal For

Projects using rendering APIs other than OpenGL, such as DirectX or Vulkan
Games with fully dynamic environments requiring real-time lighting updates
Developers who prefer all-in-one GUI tools over code-based baking solutions

Pros & Cons

Pros

Single-File Integration

As a header-only library, Lightmapper can be dropped into any C/C++ project with minimal dependencies, requiring only the inclusion of lightmapper.h.

OpenGL Pipeline Leverage

It uses your existing OpenGL renderer to compute light bounces, eliminating the need for separate rendering systems and simplifying integration.

Multi-Bounce Global Illumination

Supports multiple light bounces for realistic indirect lighting, as demonstrated in the example for ambient occlusion and beyond.

Performance Optimization

Selective hierarchical interpolation accelerates baking by up to 10x on large lightmaps, as described in the README with debug images.

Cons

External UV Atlas Dependency

The README explicitly recommends using tools like thekla_atlas or xatlas for geometry preparation, adding an extra step and dependency to the workflow.

Manual Quality Configuration

Improving quality requires disabling backface culling and using alpha channel markers, which demands additional graphics programming knowledge and tweaking.

Static Geometry Limitation

Designed only for precomputed lighting on static scenes, making it unsuitable for applications with moving or deformable objects.

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