Why Isn't My Normal Mapping Working Correctly?

Normal Mapping Gone Awry

Normal mapping, a technique for simulating additional detail on a surface without increasing the model's geometry, has unfortunately not worked as expected in your implementation. Let's delve into the code and identify the potential issues.

Vertex Shader

Your vertex shader appears to be mostly correct. However, one minor point to address is using attribute instead of in for vertex attributes, as it is the preferred syntax in newer GLSL versions.

Fragment Shader

Upon reviewing the fragment shader, several critical issues emerge:

• Multiple Color Assignments: You seem to be setting the output color multiple times within the fragment shader. Typically, you only set the final color once at the end.
• Incorrect Color Addition: Instead of performing color addition, you are adding intensities in the fragment shader. The correct formulation should be:

color.rgb *= light.ambient + diffuse + specular;

• Overwriting Color: The base color is set twice, overwriting any subsequent color calculations. Remove the initial:

color = vec4(brownColor * (texture(diffuseMap, fsCoords).rgb + 0.25), 1.0);

Normal Vector Calculation

The code for calculating the tangent and bitangent vectors (commonly referred to as binormals) in your function seems sound. However, it's recommended to normalize both vectors to ensure their unit length for proper TBN calculations.

Tangent Space Matrix (TBNMatrix)

You are using the TBN matrix to transform light and surface vectors into tangent space. However, it's essential to remember that the TBN matrix is a transpose of the tangent space basis matrix (TBN). The correct way to build the TBN matrix is as follows:

mat3 TBNMatrix = mat3(normalize(tangent), normalize(bitangent), normalize(normal));

Debugging Tips

To effectively debug normal mapping issues, consider the following steps:

• Check Shader Logs: Review the compilation and link logs for both the vertex and fragment shaders. Errors or warnings can provide valuable insights.
• Inspect TBN Vectors: Manually verify the TBN vectors at different points on the mesh to ensure they correctly represent the surface curvature.
• Start Simpler: Begin with a simpler scenario, such as a flat surface with a single light, and gradually add complexity as you gain confidence in the process.

Remember, meticulous attention to detail and thorough testing are crucial for troubleshooting normal mapping issues.

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