✨ feat: lighting

[AhmedAmrNabil]

you can play around with adding lighting components in the config.jsonc and use it with a lit material

note that this pr doesn't have gltf/glb model loading yet

[Copilot]

Pull request overview

Adds initial forward-rendered lighting support by introducing a Light component, a new lit material/shader pair, and tangent generation to support normal mapping.

Changes:

• Introduce Light component + forward renderer light collection and uniform upload for lit materials.
• Add LitMaterial with support for multiple PBR-ish texture inputs (albedo/metallic/roughness/normal/AO/emissive).
• Extend mesh vertices with tangents and compute tangents when loading OBJ meshes; add new lit.vert/lit.frag shaders.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
src/common/texture/texture2d.hpp	Adds TextureUnits enum for binding multiple material textures.
src/common/systems/forward-renderer.hpp	Stores scene light render data collected per-frame.
src/common/systems/forward-renderer.cpp	Collects Light components, sets camera/model/light uniforms for LitMaterial.
src/common/mesh/vertex.hpp	Adds tangent attribute and includes it in equality/hash.
src/common/mesh/mesh.hpp	Enables vertex attribute location for tangents.
src/common/mesh/mesh-utils.cpp	Computes tangents from UVs after OBJ load.
src/common/material/material.hpp	Adds LitMaterial and factory support for "lit".
src/common/material/material.cpp	Implements LitMaterial setup, deserialization, and light uniform upload.
src/common/components/light.hpp	Introduces Light component and LightRenderData.
src/common/components/light.cpp	Implements JSON deserialization for lights.
src/common/components/component-deserializer.hpp	Registers Light in the component registry.
src/common/asset-loader.cpp	Adds AssetLoader<Light>::clear() call.
assets/shaders/lit.vert	Vertex shader with TBN output for normal mapping.
assets/shaders/lit.frag	Fragment shader implementing multi-light shading + spot/point/directional support.
config/app.jsonc	Adds lit shader and example usage of Light + lit monkey material.
CMakeLists.txt	Adds light component source to build.
flake.nix	Adds gdb to dev environment.

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[LoayAhmed304]

Tried it and it looks fine for me for now. We'll dive deeper when we have the map and real lighting source.