//go:build ignore

//kage:unit pixels

package main

var Time float
var Ex float
var Ey float

func height(uv vec2) float {
    return imageSrc0UnsafeAt(uv).b*imageSrc0UnsafeAt((uv+vec2(0.0,Time*0.1))*imageSrc0Size()).b;
}

func normal(uv vec2) vec3 {
    NE := vec2(0.05,0.0);
    return normalize(vec3(height(uv+NE.xy)-height(uv-NE.xy),
                          0.0,
                          height(uv+NE.yx)-height(uv-NE.yx)));
}



func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
    //lightDir := normalize(vec3(10.0,15.0,5.0));
    uv := srcPos / imageSrc0Size()
    //uv.y *= imageSrc0Size().y/imageSrc0Size().x;
    
    dist := length(uv);
    angle := atan(uv.y/uv.x);
    
    ruv := uv;
    uv = vec2(cos(angle+dist*3.),dist+(Time*0.2));

    //h := height(uv);
    norm := normal(uv);
        return mix(vec4(0.), mix(
        imageSrc0UnsafeAt(uv),
                       imageSrc0UnsafeAt((norm.xz*0.5+0.5)*imageSrc0Size()),0.3),min(1.,length(ruv)*10.));
}