Water Caustic

Shader code

shader_type canvas_item;
//Origin code from https://www.shadertoy.com/view/MdlXz8
//Ported by haruyou27

const float TAU = 6.28318530718;

uniform int iteration_times = 5;
uniform float speed = 1;
uniform vec4 color :hint_color = vec4(0.0, .35, .5, 1.0);
uniform float intensity = .005;

void fragment() 
{
    lowp vec2 p = mod(UV*TAU, TAU)-250.0;
	lowp vec2 i = vec2(p);
	lowp float c = 1.0;
	lowp float t = TIME * speed;

	for (int n = 0; n < iteration_times; n++) 
	{
		i = p + vec2(cos(t - i.x) + sin(t + i.y), sin(t - i.y) + cos(t + i.x));
		c += 1.0/length(vec2(p.x / (sin(i.x+t)/intensity),p.y / (cos(i.y+t)/intensity)));
	}
	c /= float(iteration_times);
	c = 1.17-pow(c, 1.4);
	vec4 colour = vec4(pow(abs(c), 8.0));
    colour = clamp(colour + color, 0.0, 1.0);
    
	COLOR = colour;
}

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