#include <flutter/runtime_effect.glsl>
uniform vec2 uCenter;
uniform vec3 uColor;
uniform float uProgress; // 0.0 to 1.0
uniform float uRadius;
out vec4 fragColor;
void main() {
vec2 pos = FlutterFragCoord().xy;
float dist = distance(pos, uCenter);
// Create a expanding ring
float innerR = uRadius * uProgress;
float width = 30.0;
// Smooth pulse ring
// 1.0 when dist is in [innerR, innerR + width]
float ring = smoothstep(innerR, innerR + 10.0, dist) * (1.0 - smoothstep(innerR + width - 10.0, innerR + width, dist));
// Fade out as it expands
float alpha = ring * (1.0 - uProgress) * 0.8;
fragColor = vec4(uColor * alpha, alpha);
}
