Raindrops

My attempt at converting https://www.shadertoy.com/view/ldfyzl

See the link for animation.

To use, place the shader on a shaderMaterial on a colorRect.

Import the sample background texture or use your own.

Please enjoy

I learned to convert glsl shaders to godot shaders using these resources. You can learn it too!

https://docs.godotengine.org/en/3.4/tutorials/shaders/converting_glsl_to_godot_shaders.html

https://www.youtube.com/watch?v=Kn49zhCwg-0

Shader code

shader_type canvas_item;

uniform sampler2D backgroundTexture;

// Maximum number of cells a ripple can cross.
uniform float MAX_RADIUS = 2.0;

// Hash functions shamefully stolen from:
// https://www.shadertoy.com/view/4djSRW
uniform float HASHSCALE1 = 0.1031;
uniform vec3 HASHSCALE3 = vec3(0.1031, 0.1030, 0.0973);

float hash12(vec2 p)
{
	vec3 p3  = fract(vec3(p.xyx) * HASHSCALE1);
	p3 += dot(p3, p3.yzx + 19.19);
	return fract((p3.x + p3.y) * p3.z);
}

vec2 hash22(vec2 p)
{
	vec3 p3 = fract(vec3(p.xyx) * HASHSCALE3);
	p3 += dot(p3, p3.yzx+19.19);
	return fract((p3.xx+p3.yz)*p3.zy);
}

void fragment()
{
	float resolution = 10.0 * exp2(-3.0 / (1.0 / TEXTURE_PIXEL_SIZE).x);
	vec2 uv = UV.xy / (1.0 / TEXTURE_PIXEL_SIZE).y * resolution;
	vec2 p0 = floor(uv);

	vec2 circles = vec2(0.0);
	for (float j = -MAX_RADIUS; j <= MAX_RADIUS; ++j)
	{
		for (float i = -MAX_RADIUS; i <= MAX_RADIUS; ++i)
		{
			vec2 pi = p0 + vec2(i, j);
			
			vec2 hsh = hash22(pi);
			
			vec2 p = pi + hash22(hsh);
			
			float t = fract(0.3 * TIME + hash12(hsh));
			vec2 v = p - uv;
			float d = length(v) - (float(MAX_RADIUS) + 1.)*t;
			
			float h = 1e-3;
			float d1 = d - h;
			float d2 = d + h;
			float p1 = sin(31.*d1) * smoothstep(-0.6, -0.3, d1) * smoothstep(0., -0.3, d1);
			float p2 = sin(31.*d2) * smoothstep(-0.6, -0.3, d2) * smoothstep(0., -0.3, d2);
			circles += 0.5 * normalize(v) * ((p2 - p1) / (2. * h) * (1. - t) * (1. - t));
		}
	}
	
	circles /= float((MAX_RADIUS * 2.0 + 1.0) * (MAX_RADIUS * 2.0 + 1.0));
	
	float intensity = mix(0.01, 0.15, smoothstep(0.1, 0.6, abs(fract(0.05 * TIME + 0.5) * 2.0 -1.0)));
	vec3 n = vec3(circles, sqrt(1.0 - dot(circles, circles)));
	vec3 color = texture(backgroundTexture, uv/resolution - intensity * n.xy).rgb + 5.0 * pow(clamp(dot(n, normalize(vec3(1.0, 0.7, 0.5))), 0.0, 1.0), 6.0);
	COLOR = vec4(color, 1.0);
}

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