#type vertex
#version 410 core

// Vertex attributes
layout(location = 0) in vec3 v_position;
layout(location = 1) in vec3 v_normal;
layout(location = 2) in vec2 v_UV;

// Outputs to fragment shader
out vec3 normalWS;
out vec3 normalVS;
out vec3 positionVS;

// Uniforms
uniform mat4 u_worldMatrix;
uniform mat4 u_viewMatrix;

void main()
{
    gl_Position = u_viewMatrix * u_worldMatrix * vec4(v_position, 1.0);
    positionVS = gl_Position.xyz;

    mat3 normalMatrix = transpose(inverse(mat3(u_worldMatrix)));
    normalWS = normalize(normalMatrix * v_normal);

    mat3 normalMatrixView = transpose(inverse(mat3(u_viewMatrix * u_worldMatrix)));
    normalVS = normalize(normalMatrixView * v_normal);

}

#type fragment
#version 410 core

// Fragment outputs
layout(location = 0) out vec4 fragColor;
layout(location = 1) out int objectID;

// Inputs from vertex shader
in vec3 normalWS;
in vec3 normalVS;
in vec3 positionVS;

// Uniforms
uniform int u_objectID;

void main()
{
    // Directional light
    vec3 lightDir = normalize(vec3(1.0, 7.0, 3.0));

    // Base light intensity
    float light = clamp(dot(normalWS, lightDir) * 0.8 + 0.2, 0.0, 1.0);

    // Gradient from purple (dark) to cyan (lit)
    vec3 gradientColor = mix(
        vec3(0.1137, 0.0471, 0.0112),
        vec3(0.7255, 0.9725, 0.5),
        light
    );

    // Rim/fresnel effect
    float rim = 0.5 - dot(normalWS, normalize(lightDir)) * 0.5;
    float rimValue = rim * rim * rim * rim * clamp(dot(lightDir, normalWS), 0, 1);
    vec3 rimColor = vec3(1.0, 0.8, 0.5) * rimValue;

    vec3 mixedColor = mix(
        gradientColor,
        vec3(1, 1, 1) ,
        rimValue
    );

    //float fresnel = dot(, vec3(0, 0, -1));
    //fresnel = fresnel * fresnel;

    float fresnel = 1 + dot(normalize(positionVS), normalize(normalVS));
    fresnel = fresnel * fresnel * fresnel * fresnel * clamp(dot(lightDir, normalWS), 0, 1);

    // Combine everything
    fragColor = vec4(gradientColor + vec3(fresnel, fresnel, fresnel), 1.0);

    // Object ID output
    objectID = u_objectID;
}