Blinn-Phong Shading

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////////////////////VERTEX SHADER////////////////////
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#version 330

layout(location = 0) in vec3 inPosition;
layout(location = 1) in vec3 inNormal;
layout(location = 2) in vec2 inTexCoord;
layout(location = 3) in vec3 inTangent;
layout(location = 4) in vec3 inBitangent;

out vec2 texCoord;
out vec3 camDir;
out vec3 lightDir;
out float attenuation;

uniform mat4 viewMatrix;
uniform mat4 modelMatrix;
uniform mat4 projectionMatrix;
uniform mat3 normalMatrix;
uniform vec3 camPosIn;
uniform vec3 lightPosIn;

void main()
{
    vec3 N = normalize(normalMatrix * inNormal);
    vec3 T = normalize(normalMatrix * inTangent);
         T = normalize(T - (dot(N, T) * N));
    vec3 B = normalize(normalMatrix * inBitangent);

    if (dot(cross(N, T), B) < 0.0)
        T = T * -1.0;

    mat3 TBNMatrix = transpose(mat3(T, B, N));

    vec3 position = vec3((viewMatrix * modelMatrix) * vec4(inPosition, 1.0)); //Vector is a position so W = 1.0. If it were a direction w = 0.0.
    camDir = TBNMatrix * (normalize(camPosIn - position));
    lightDir = TBNMatrix * (normalize(lightPosIn - position));
    texCoord = inTexCoord;

    float radius = 50.0;
    float dist = length(vec3((viewMatrix * modelMatrix) * vec4(lightPosIn, 1.0)) - position);
    attenuation = 1.0 / (1.0 + ((2.0 / radius) * dist) + ((1.0 / (radius * radius)) * (dist * dist)));

    gl_Position = (projectionMatrix * (viewMatrix * modelMatrix)) * vec4(inPosition, 1.0);
}

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////////////////////FRAGMENT SHADER////////////////////
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#version 330
precision mediump float;

in vec2 texCoord;
in vec3 camDir;
in vec3 lightDir;
in float attenuation;

layout (location = 0) out vec4 FragColour;

uniform sampler2D textureMap;
uniform sampler2D normalMap;
uniform sampler2D AOMap;
uniform sampler2D specMap;
uniform sampler2D roughMap;
uniform vec3 lightColour;

void main() //Blinn-Phong = (Ka * Ia) + (Kd * (Il * (N.L))) + (Ks * (Il * ((N.H)^Ns)))
{
    vec3 albedo = texture(textureMap, texCoord).rgb;
    vec3 normals = normalize(2.0 * texture(normalMap, texCoord).rgb - 1.0);
    float roughness = texture(roughMap, texCoord).r;
    float spec = texture(specMap, texCoord).r;
    float AO = texture(AOMap, texCoord).r;

    vec3 diffuse = vec3(0.0);
    vec3 specular = vec3(0.0);
    vec3 ambientColour = vec3(0.0);

    for (int i = 0; i < 1; i++)
    {
        vec3 halfAngle = normalize(camDir + lightDir);
        float NdotL = clamp(dot(normals, lightDir), 0.0, 1.0);
        float NdotH = clamp(dot(normals, halfAngle), 0.0, 1.0);

        float specularHighlight = pow(NdotH, 1.0 - roughness);
        vec3 S = spec * (lightColour * specularHighlight);
        vec3 D = (1.0 - roughness) * (lightColour * NdotL);

        diffuse += D * attenuation;
        specular += S * attenuation;
        ambientColour += lightColour * attenuation;
    }
    vec3 ambience = (0.01 * ambientColour) * AO;

    vec3 BlinnPhong = ambience + diffuse + specular;
    vec3 final = albedo * BlinnPhong;
    final = pow(final, vec3(1.0 / 2.2));
    FragColour = vec4(final, 1.0);
}