Why is My Normal Mapping Rendering Incorrectly?

Normal Mapping Gone Horribly Wrong

In your normal mapping implementation, you may have overlooked several crucial aspects:

Fragment Shader

Color Mixing:

• You are setting the output color multiple times, which can lead to undefined behavior.
• Consider removing the extra assignments and setting the color in one step.

Ambient and Specular:

• You are adding these components to the color instead of multiplying them.
• The correct approach is to add ambient and multiply specular by the diffuse value.

TBN Matrix Creation

Function:

• Ensure the getTangent() function correctly calculates the tangents and bitangents. You may want to refer to reliable sources for the proper equations.
• Some graphics drivers tend to optimize unused shader variables, potentially removing the normal map data and leading to incorrect rendering. Check for this possibility.

Improved Fragment Shader

#version 430

uniform sampler2D diffuseMap;
uniform sampler2D normalMap;
uniform mat4 ModelMatrix;
uniform vec3 CameraPosition;

uniform struct Light {
    float ambient;
    vec3 position;
} light;
uniform float shininess;

in vec2 fsCoords;
in vec3 fsVertex;
in mat3 TBNMatrix;

out vec4 color;

void main()
{
    // Base color
    vec3 brownColor = vec3(153.0 / 255.0, 102.0 / 255.0, 51.0 / 255.0);
    vec3 baseColor = brownColor + 0.25; // Add a fixed base color
    
    // Normal
    vec3 normal = texture(normalMap, fsCoords).rgb * 2.0 - 1.0;
    
    // Surface position and lighting
    vec3 surfacePos = vec3(ModelMatrix * vec4(fsVertex, 1.0));
    vec3 surfaceToLight = normalize(TBNMatrix * (light.position - surfacePos)); // Unit vector
    vec3 eyePos = TBNMatrix * CameraPosition;
    
    // Diffuse
    float diffuse = max(0.0, dot(normal, surfaceToLight));
    
    // Specular
    float specular;
    vec3 incidentVector = -surfaceToLight; // Unit
    vec3 reflectionVector = reflect(incidentVector, normal); // Unit vector
    vec3 surfaceToCamera = normalize(eyePos - surfacePos); // Unit vector
    float cosAngle = max(0.0, dot(surfaceToCamera, reflectionVector));
    if (diffuse > 0.0)
        specular = pow(cosAngle, shininess);
    
    // Lighting
    vec3 finalColor = baseColor * light.ambient;
    finalColor += (diffuse + specular) * light.position;
    
    // Output color
    color = vec4(finalColor, 1.0);
}

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