#version 450
#extension GL_ARB_separate_shader_objects : enable

layout(location = 0) in vec2 position;

layout(binding = 0) uniform Camera {
    mat4 viewProjection;
} camera;

layout(push_constant) uniform Model {
    mat4 model;
} model;

struct Province {
    uint regionId;
    uint color;
};
layout(std430, binding = 1) readonly buffer Data {
    Province provinces[];
};

layout(location = 0) out vec3 fragColor;

const float PI = 3.141592653589793;

vec3 unpackColor(uint c) {
    return vec3(
    c & 0xFFu,
    (c >> 8) & 0xFFu,
    (c >> 16) & 0xFFu
    ) / 255.0;
}

vec2 toUV(vec2 pos)
{
    vec2 uv = pos / vec2(5632.0, 2048.0);

    uv.y = 1.0 - uv.y;

    return uv; //TODO: Provide map size
}

vec3 mercatorToSphere(vec2 uv)
{
    float lon = uv.x * 2.0 * PI - PI;
    lon += PI;
    float lat = PI * 0.5 - uv.y * PI;

    float cosLat = cos(lat);

    return vec3(
    cosLat * cos(lon),
    sin(lat),
    cosLat * sin(lon)
    );
}

void main() {
    vec2 uv = toUV(position);
    vec3 spherePos = mercatorToSphere(uv);
    gl_Position = camera.viewProjection
                    * vec4(spherePos, 1.0);

    //gl_Position = camera.viewProjection * vec4(position, 0.0, 1.0);
    //fragColor = unpackColor(provinces[gl_InstanceIndex].color);
    fragColor = unpackColor(provinces[gl_InstanceIndex].regionId);
}