#pragma opname          fishLens
#pragma oplabel         "Fisheye Lens"

#pragma hint    x       hidden
#pragma hint    y       hidden
#pragma hint    P       hidden
#pragma hint    I       hidden
#pragma hint   valid   hidden

//CUSTOM
#pragma lable fov    "Fov"
#pragma range  fov   0 180

#include "math.h"

cvex fisheye_lens(
        /*equiangular fisheye lens shader with adjustable FOV and circular image format*/
        
        // Inputs
        float x = 0;
        float y = 0;

        // Outputs
        export vector P = 0;
        export vector I = 0;
        export int valid = 0;

        // Shader arguments
        float fov = 180.0;
        )
{
        float radius = sqrt(x*x+y*y); /*calculate distance from center of image plane*/
        /*following if statement means I is only computed inside r<=1, so that areas of image outside circular format aren't rendered*/
        if (radius <= 1){  /*using 1.0 produces blurriness(bug?), but 1.01 works fine*/
            float phi = atan2(y,x);
            float theta = radians(fov/2.0 * radius);
            I = set(sin(theta)*cos(phi),sin(theta)*sin(phi),cos(theta));
            valid = 1;

        }
}