forge-normal-maps

To add normal mapping in SDL GPU, you extend your vertex layout with a vec4 tangent, reconstruct the TBN basis in the vertex shader, and apply a TBN transform to a sampled normal map texture in the fragment shader to modulate lighting.

Tangent-space normal mapping provides per-texel surface detail without increasing geometry by decoding a normal map texture relative to the mesh surface. You need it when your 3D pipeline requires enhanced surface lighting detail on low-poly models.

Yes, you can compute tangents for models lacking precomputed data using Lengyel's method. This approach calculates the tangent, bitangent, and handedness data to reconstruct a robust TBN basis directly within your rendering workflow.

You need a working 3D pipeline, a shader pipeline supporting TBN transforms, and a vertex structure extended with a vec4 tangent. Tangent computation capabilities are also required if your models lack precomputed tangent data.

The TBN basis transforms the decoded tangent-space normal map values into world space for lighting calculations. The vertex shader reconstructs the tangent, bitangent, and normal vectors, which the fragment shader uses to modulate per-pixel lighting.

Normal maps often fail when the vertex shader lacks the correct TBN basis reconstruction from the vec4 tangent data, or if the fragment shader does not properly decode the normal map texture and apply the TBN transform for lighting modulation.