dynamic_displacement_shader.frag

// Shader ported from : https://x.com/dankuntz/status/1813283813881225625
// all rights go back to him
#version 460 core
precision mediump float;

#include <flutter/runtime_effect.glsl>

uniform vec2 u_position;
uniform vec2 u_velocity;
uniform vec2 u_resolution;
uniform sampler2D u_layerTexture;

out vec4 fragColor;

void main() {
    vec2 fragCoord = FlutterFragCoord().xy;
    vec2 uv = fragCoord / u_resolution.xy;
    vec2 p = fragCoord;
    vec2 l = u_position;

    vec2 displacement = -u_velocity * pow(clamp(1.0 - length(l - p) / 190.0, 0.0, 1.0), 2.0) * 1.5;
    vec3 color = vec3(0.0);

    for (float i = 0.0; i < 10.0; i++) {
        float s = 0.175 + 0.005 * i;
        color += vec3(
        texture(u_layerTexture, (p + s * displacement) / u_resolution).r,
        texture(u_layerTexture, (p + (s + 0.025) * displacement) / u_resolution).g,
        texture(u_layerTexture, (p + (s + 0.05) * displacement) / u_resolution).b
        );
    }

    fragColor = vec4(color / 10.0, 1.0);
}