From eeca23dc59e60def65dfefc28b69d6cfc85467ff Mon Sep 17 00:00:00 2001
From: davidovski <david@davidovski.xyz>
Date: Mon, 22 Apr 2024 14:55:24 +0100
Subject: add clouds in bg

---
 shaders/clouds.kage | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 shaders/clouds.kage

(limited to 'shaders/clouds.kage')

diff --git a/shaders/clouds.kage b/shaders/clouds.kage
new file mode 100644
index 0000000..26597e5
--- /dev/null
+++ b/shaders/clouds.kage
@@ -0,0 +1,132 @@
+//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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