Fragment Shader

struct Light {
    vec3 position;
    vec3 Iambient;
    vec3 Idiffuse;
    vec3 Ispecular;
};

uniform Light lights[LIGHTS_AMOUNT];
uniform vec3 cameraPosition;

float constant = 1.0;
float linear = 0.007;
float quadratic = 0.002;

vec3 lightning(vec3 color) {

    vec3 finalDiffuse = vec3(1.0);

    for (int i=0; i <= LIGHTS_AMOUNT; i++) {

        Light light = lights[i];

        vec3 Normal = normalize(normal);

        // Ambient
        vec3 ambient = light.Iambient;
        // Diffuse
        vec3 lightDirection = normalize(light.position - fragmentPosition);
        float diff = max(0,dot(lightDirection,Normal));
        vec3 diffuse = diff * light.Idiffuse;
        // Specular
        vec3 viewDirection = normalize(cameraPosition - fragmentPosition);
        vec3 reflectDirection = reflect(-lightDirection,Normal);
        float spec = pow(max(dot(viewDirection,reflectDirection),0),32);
        vec3 specular = spec * light.Ispecular;

        float distance = length(light.position - fragmentPosition);
        float attenuation = 1.0 / (constant + linear * distance + quadratic * (distance * distance));

        ambient *= attenuation;
        diffuse *= attenuation;
        specular *= attenuation;

        finalDiffuse += (ambient + diffuse + specular);

    }

    return color * finalDiffuse;
}

void main() {
    vec3 color = texture(textureData,uv_0).rgb;
    vec3 lightningColor = lightning(color);
    fragColor = vec4(lightningColor,1.0);
}