cocos-awesome/assets/Scene/Metaball/Metaball.effect

// Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.

CCEffect %{
  techniques:
  - passes:
    - vert: vs
      frag: fs
      blendState:
        targets:
        - blend: true
      rasterizerState:
        cullMode: none
      properties:
        texture: { value: white }
        u_point: { value: [ 0.5, 0.5 ] }
        u_radius: {  value: 0.1 }

}%


CCProgram vs %{
  precision highp float;

  #include <cc-global>
  #include <cc-local>

  in vec3 a_position;
  in vec4 a_color;
  out vec4 v_color;

  #if USE_TEXTURE
  in vec2 a_uv0;
  out vec2 v_uv0;
  #endif

  void main () {
    vec4 pos = vec4(a_position, 1);

    #if CC_USE_MODEL
    pos = cc_matViewProj * cc_matWorld * pos;
    #else
    pos = cc_matViewProj * pos;
    #endif

    #if USE_TEXTURE
    v_uv0 = a_uv0;
    #endif

    v_color = a_color;

    gl_Position = pos;
  }
}%


CCProgram fs %{
  precision highp float;

  #include <alpha-test>
  #include <cc-global>

  in vec4 v_color;

  #if USE_TEXTURE
  in vec2 v_uv0;
  uniform sampler2D texture;
  #endif

  uniform ARGS {
    vec2 u_point;
    float u_radius;
  };

  float energy(float r, vec2 point1, vec2 point2) {
    return (r * r) / ((point1.x - point2.x) * (point1.x - point2.x) + (point1.y - point2.y) * (point1.y - point2.y));
  }

  void main(){
    vec4 color = texture(texture, v_uv0);

    float fragEnergy = energy(u_radius + 0.1, v_uv0.xy, vec2(0.5)) + energy(u_radius, v_uv0.xy, u_point);
    color.a = smoothstep(0.95, 1.0, fragEnergy);
    gl_FragColor = color;
  }
}%