#define PI 3.141592653589793

vec3 world_space_location(vec2 uv, float depth)
{
    //converts from normalized range to -1.0..1.0
    vec4 clip_space = vec4(1.0);
    clip_space.xy = uv*2.0-1.0;
    clip_space.z = depth;

    mat4 p = projection_data.p;
    p[0][3] = 0.0;
    p[1][3] = 0.0;
    p[2][3] = -1.0;
    vec4 homogenous = inverse(p)*clip_space;
    homogenous /= homogenous.w;
    
    vec4 world_space = inverse(projection_data.mv) * homogenous;
    return world_space.xyz;
}

vec3 get_view_pos()
{
    vec3 pos;
    pos.x = projection_data.p[0][3];
    pos.y = projection_data.p[1][3];
    pos.z = projection_data.p[2][3];
    return pos;
}

void swap(inout float a, inout float b)
{
    float t = a;
    a = b;
    b = t;
}