#version 330

//uv coordinates from the texture
in vec2 UV;
in vec3 normal_direction;

uniform sampler2D myTextureSampler;
uniform float dim_factor = 1.0f;

uniform bool color_override = false;
uniform vec4 override_color = vec4(1.0f, 1.0f, 1.0f, 1.0f);

uniform bool text = false;
uniform vec4 text_color(1.0f, 1.0f, 1.0f, 1.0f);
uniform vec4 transparency_color(1.0f, 1.0f, 1.0f, 1.0f);

//lighting dependencies
uniform mat4 model_matrix;
uniform mat4 view_matrix;
uniform bool use_lighting = false;
vec4 light_direction(-2.0f, -1.0f, -6.0f, 1.0f);

out vec4 output_color;

void main()
{
    vec3 texture_color = texture2D( myTextureSampler, UV).rgb;

    if (text)
    {
        //check to see if color pulled from texture map matches that of the the green screen color
        vec3 transparency_delta = abs(transparency_color.rgb - texture_color);
        if (transparency_delta.x + transparency_delta.y + transparency_delta.y < .001)
            output_color = vec4(0.0f, 0.0f, 0.0f, 0.0f);

        else
        {
            float anti_alias_value = 1.0f - texture_color.y;
            output_color = vec4(text_color.x, text_color.y, text_color.z, anti_alias_value);
        }
        return;
    }

    if (!color_override)
    {
        if(use_lighting)
        {
            vec4 light_color(1.0f, 1.0f, 1.0f, 1.0f);
            vec3 worldspace_normal = vec3(model_matrix * vec4(normal_direction, 1.0f));
            worldspace_normal = glm::normalize(worldspace_normal);

            float cosTheta = clamp( dot( worldspace_normal, light_direction ), 0.0f, 1.0f );
            vec4 modified_color = light_color * cosTheta;

            output_color = modified_color;

            //vec4 diffuse_color = vec4(texture_color, 1.0f);

            //vec3 undimmed_color = texture_color;
            //output_color = vec4(undimmed_color.x * dim_factor, undimmed_color.y * dim_factor, undimmed_color.z * dim_factor, 1.0f);
        }

        else
        {
            vec3 undimmed_color = texture_color;
            output_color = vec4(undimmed_color.x * dim_factor, undimmed_color.y * dim_factor, undimmed_color.z * dim_factor, 1.0f);
        }
    }

    else output_color = override_color;
}