// https://godotshaders.com/shader/rotation-displacement-vertex-shader/
shader_type canvas_item;

// Set this to your polygon's center in local space.
uniform vec2 center = vec2(25., 25.);
uniform float amplitude : hint_range(0.0, 1.0) = 0.15;
uniform float frequency = 1.5;

void vertex() {
    // Translate vertex position so the center is at (0, 0).
    vec2 pos = VERTEX - center;
    // Compute the angle of the vertex relative to the center.
    // This angle will be used to offset the sine wave phase.
    float angle = atan(pos.y, pos.x);
    // Create a sine wave where each vertex is offset by its angle.
    // You can adjust the formula as desired.
    float wave = sin(TIME * frequency - angle);
    // Use the wave value to scale the vertex's distance from the center.
    pos *= 1.0 + amplitude * wave;
    // Move the vertex back to the original coordinate space.
    VERTEX = pos + center;
}