Untitled Shader · ShaderBox

#ifdef GL_ES
precision mediump float;
#endif

#define PI 3.1415926538

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

float scale(float v, vec2 scale_in, vec2 scale_out) {
  return scale_out.x 
    + ( scale_out.y - scale_out.x ) 
    * ( 
      ( v - scale_in.x ) 
      / (scale_in.y - scale_in.x) 
    );
}

float circle(vec2 uv, float r, float f, float a, float k) {
  // Compute angle and distance from center
  float angle = atan(uv.y, uv.x);
  float radius = length(uv);

// Time-dependent base radius
  float baseRadius = scale(sin(PI), vec2(-1.,1.), vec2(0.1, r));

// Add sinusoidal wave to the circle contour
  float waveFreq = f;
  float waveAmp = a;
  float wave = sin(angle * waveFreq + u_time * k) * waveAmp;

// Final radius with wave applied
  float finalRadius = baseRadius + wave;

// Smooth edge for anti-aliasing (optional)
  float edgeThickness = 0.005;
  return step(finalRadius - edgeThickness, radius) 
    - step(finalRadius, radius)
    ;
}

void main() {
  // Normalize and center UV coordinates
  vec2 uv = (gl_FragCoord.xy - u_resolution.xy * 0.5) / u_resolution.y;

float alpha = 
    circle(uv, 0.4, 5.0, 0.02, 3.0)
    + circle(uv, 0.4, 4.0, 0.02, -1.0)
  ;
  
  gl_FragColor = vec4(vec3(alpha), 1.0);
}