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//go:build ignore
//kage:unit pixels
package main
var Time float
const cloudscale = 0.8
const speed = 0.01
const clouddark = 0.6
const cloudlight = 0.3
const cloudcover = 0.2
const cloudalpha = 8.0
const skytint = 0.5
func rand(co vec2) float {
return fract(sin(dot(co.xy, vec2(12.9898,-78.233))) * 43758.5453)
}
func hash( p vec2 ) vec2 {
p = vec2(dot(p,vec2(127.1,311.7)), dot(p,vec2(269.5,183.3)))
return -1.0 + 2.0*fract(sin(p)*43758.5453123)
}
func noise( p vec2 ) float {
const K1 = 0.366025404
const K2 = 0.211324865
i := floor(p + (p.x+p.y)*K1);
a := p - i + (i.x+i.y)*K2
var o vec2
if (a.x>a.y) {
o = vec2(1.0,0.0)
} else {
o = vec2(0.0,1.0)
}
b := a - o + K2
c := a - 1.0 + 2.0*K2
h := max(0.5-vec3(dot(a,a), dot(b,b), dot(c,c) ), 0.0)
n := h*h*h*h*vec3( dot(a,hash(i+0.0)), dot(b,hash(i+o)), dot(c,hash(i+1.0)))
return dot(n, vec3(70.0))
}
func fbm(n vec2) float {
v := n
total := 0.0
amplitude := 0.1
for i := 0; i < 7; i++ {
total += noise(v) * amplitude
v = mat2(1.6, 1.2, -1.2, 1.6) * v
amplitude *= 0.4
}
return total
}
func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
m := mat2(1.6, 1.2, -1.2, 1.6)
skycolour1 := vec3(0.45, 0.57, 0.66)
skycolour2 := vec3(0.55, 0.77, 0.86)
p := srcPos.xy / imageSrc0Size().xy;
uv := p*vec2(imageSrc0Size().x/imageSrc0Size().y,1.0);
time := Time * speed
q := fbm(uv * cloudscale * 0.5)
//ridged noise shape
r := 0.0
uv *= cloudscale
uv.x -= q - time
weight := 0.8
for i:=0; i<8; i++{
r += abs(weight*noise( uv ))
uv = m*uv + time
weight *= 0.7
}
//noise shape
f := 0.0
uv = p*vec2(imageSrc0Size().x/imageSrc0Size().y,1.0);
uv *= cloudscale
uv.x -= q - time
weight = 0.7
for i:=0;i<8;i++{
f += weight*noise( uv )
uv = m*uv + time
weight *= 0.6
}
f *= r + f
//noise colour
c := 0.0
time = Time * speed * 2.0
uv = p*vec2(imageSrc0Size().x/imageSrc0Size().y,1.0)
uv *= cloudscale*2.0
uv.x -= q - time
weight = 0.4
for i:=0;i<7;i++{
c += weight*noise( uv )
uv = m*uv + time
weight *= 0.6
}
//noise ridge colour
c1 := 0.0
time = Time * speed * 3.0
uv = p*vec2(imageSrc0Size().x/imageSrc0Size().y,1.0)
uv *= cloudscale*3.0
uv.x -= q - time
weight = 0.4
for i:=0; i<7; i++{
c1 += abs(weight*noise( uv ))
uv = m*uv + time
weight *= 0.6
}
c += c1
skycolour := mix(skycolour2, skycolour1, p.y);
cloudcolour := vec3(1.1, 1.1, 0.9) * clamp((clouddark + cloudlight*c), 0.0, 1.0);
f = cloudcover + cloudalpha*f*r;
result := mix(skycolour, clamp(skytint * skycolour + cloudcolour, 0.0, 1.0), clamp(f + c, 0.0, 1.0));
return vec4( result, 1.0 );
}
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