I think I'm close to inserting and using the TBN correctly.

data/shaders/geometry.glsl

@@ -2,6 +2,8 @@
 layout (triangles) in;
 layout (triangle_strip) out;
 
+uniform mat4 Model;
+
 in vec2 gtexCoord[];
 in vec3 gnormCoord[];
 in vec3 gWorldPos[];
@@ -10,8 +12,48 @@ out vec2 texCoord;
 out vec3 normCoord;
 out vec3 WorldPos;
 
-void main()
+out mat3 TBN;
+
+void main(void)
 {
+   // Calculate Normal Map stuff
+
+   // Real space triangle
+   vec3 p1 = gl_in[0].gl_Position.xyz;
+   vec3 p2 = gl_in[1].gl_Position.xyz;
+   vec3 p3 = gl_in[2].gl_Position.xyz;
+
+   // Normal texture space triangle
+   vec2 uv1 = gtexCoord[0];
+   vec2 uv2 = gtexCoord[1];
+   vec2 uv3 = gtexCoord[2];
+
+   // Calculate edge translation vectors duv stands for delta uv
+   vec3 edge1 = p2 - p1;
+   vec3 edge2 = p3 - p1;
+   vec2 duv1 = uv2 - uv1;
+   vec2 duv2 = uv3 - uv1;
+
+   // Calculation of tangents and bi tangents
+   // [ddTxBxTyByTzBz]=1ΔU1ΔV2−ΔU2ΔV1[ΔV2−ΔU2−ΔV1ΔU1][E1xE2xE1yE2yE1zE2z]
+   // https://learnopengl.com/Advanced-Lighting/Normal-Mapping
+
+   float f = 1.0 / (duv1.x * duv2.y - duv2.x * duv1.y);
+
+   float tx = f * (duv2.y * edge1.x - duv1.y * edge2.x);
+   float ty = f * (duv2.y * edge1.y - duv1.y * edge2.y);
+   float tz = f * (duv2.y * edge1.z - duv1.y * edge2.z);
+
+   vec3 tangent = vec3(tx, ty, tz);
+
+   //Calculate TBN
+   vec3 T = normalize(vec3(Model * vec4(tangent, 0.0)));
+   vec3 N = normalize(vec3(Model * vec4(gnormCoord[0], 0.0)));
+   vec3 B = cross(N, T);
+
+   TBN = mat3(T, B, N);
+
+   // send data to Fragment Shader
    gl_Position = gl_in[0].gl_Position;
    texCoord = gtexCoord[0];
    normCoord = gnormCoord[0];

data/shaders/pbrFragment.glsl

@@ -4,7 +4,7 @@ out vec4 FragColor;
 in vec2 texCoord;
 in vec3 normCoord;
 in vec3 WorldPos;
-//in mat4 TBN;
+in mat3 TBN;
 
 // TODO: make temporary hard coded world/camera pos dynamic
 //uniform vec3 WorldPos ;
@@ -73,12 +73,8 @@ float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness)
 
 vec3 normal(){
    // load and invert normal
-   vec3 normal = normalize(texture(texture_normal1, texCoord).rgb * 2.0 - 1.0);
-
-   //normal = (TBN * vec4(normal, 1.0)).xyz;
-
-   //TODO: Make the normal vector match the matrix of the rest of the model by
-   //actually calculating the TBN
+   vec3 normal = texture(texture_normal1, texCoord).rgb * 2.0 - 1.0;
+   normal = normalize(TBN * normal);
 
    return normal;
 }
@@ -94,8 +90,8 @@ vec3 PBR(vec3 albedo, float roughness, float metallic, float ao)
 
    vec3 N = normalize(normCoord);
    vec3 V = normalize(CameraPos - WorldPos);
-   N = (N + normal()) / 2;
-   //N = normal(); For seeing if normal map tracks with light.
+   //N = (N + normal()) / 2;
+   //N = normal(); //For seeing if normal map tracks with light.
 
    vec3 F0 = vec3(0.04);
    F0 = mix(F0, albedo, metallic);
@@ -143,5 +139,6 @@ void main()
    float metallic = texture(texture_rma1, texCoord).g;
    float ao = texture(texture_rma1, texCoord).b;
 
-   FragColor = vec4(PBR(albedo, roughness, metallic, ao), 1.0);
+   //FragColor = vec4(PBR(albedo, roughness, metallic, ao), 1.0);
+   FragColor = vec4(normal(), 1.0);
 }

data/shaders/pbrVertex.glsl

@@ -12,8 +12,6 @@ out vec3 gnormCoord;
 //Pbr
 out vec3 gWorldPos;
 
-//Normals
-
 void main()
 {
    gl_Position = MVP * Model * vec4(aPos, 1.0);