fisheye.shader

uniform int center_x_percent = 50;
uniform int center_y_percent = 50;
uniform float power = 1.75;

float4 mainImage(VertData v_in) : TARGET
{
    float2 center_pos = float2(center_x_percent * .01, center_y_percent * .01);
    float2 uv = v_in.uv;
    if (power >= 0.0001){
        float b = sqrt(dot(center_pos, center_pos));
        uv = center_pos  + normalize(v_in.uv - center_pos) * tan(distance(center_pos, v_in.uv) * power) * b / tan( b * power);
    } else if(power <= -0.0001){
        float b;
        if (uv_pixel_interval.x < uv_pixel_interval.y){
            b = center_pos.x;
        } else {
            b = center_pos.y;
        }
        uv = center_pos  + normalize(v_in.uv - center_pos) * atan(distance(center_pos, v_in.uv) * -power * 10.0) * b / atan(-power * b * 10.0);
    }
    return image.Sample(textureSampler, uv);
}