// Copyright (c) 2017-2020 Xiamen Yaji Software Co., Ltd.
CCEffect %{
  editor:
    hide: true
  techniques:
  - name: transparent
    passes:
    - vert: terrain-brush-vs:vert
      frag: terrain-brush-fs:frag
      depthStencilState:
        depthTest: true
        depthWrite: false
      blendState:
        targets:
        - blend: true
          blendSrc: src_alpha
          blendDst: one_minus_src_alpha
          blendDstAlpha: one_minus_src_alpha
      properties:
        BrushPos:         { value: [0, 0, 0, 1] }
        BrushParams:      { value: [2.5, 2.5, 0, 0] }
        BrushImage:       { value: grey         }
        BrushDepthOffset: { value: 0.05 }
}%

CCProgram terrain-brush-vs %{
  precision mediump float;
  #include <builtin/uniforms/cc-global>
  #include <builtin/uniforms/cc-local>

  in vec3 a_position;

  out vec4 wposition;

  uniform Constant {
      float BrushDepthOffset;
  };

  vec4 vert () {
    vec3 worldPos;
    worldPos.x = cc_matWorld[3][0] + a_position.x;
    worldPos.y = cc_matWorld[3][1] + a_position.y;
    worldPos.z = cc_matWorld[3][2] + a_position.z;
    worldPos.y += BrushDepthOffset; // depth increment for terrain brushes

    vec4 pos = vec4(worldPos, 1);
    pos = cc_matViewProj * pos;

    wposition = vec4(worldPos, 1);

    return pos;
  }
}%

CCProgram terrain-brush-fs %{
  precision mediump float;
  #include <legacy/output>

  in vec4 wposition;

  uniform TexCoords {
    vec4 BrushPos;
    vec4 BrushParams;
  };

  uniform sampler2D BrushImage;

  vec4 frag () {
    float Radius = BrushParams.x;
    float Falloff = BrushParams.y;
    float Rotation = BrushParams.z;
    float DeltaU = BrushPos.x - wposition.x;
    float DeltaV = BrushPos.z - wposition.z;

    if (Rotation != 0.0) {
      float sine = sin(Rotation);
      float cosine = cos(Rotation);
      float _11 = cosine, _21 = sine;
      float _12 = -sine, _22 = cosine;
      float tmpx = DeltaU * _11 + DeltaV * _21;
      float tmpz = DeltaU * _12 + DeltaV * _22;
      DeltaU = tmpx;
      DeltaV = tmpz;
    }

    float k = 0.0;
    if (abs(DeltaU) < Radius && abs(DeltaV) < Radius) {
      float u = DeltaU / Radius * 0.5 + 0.5;
      float v = DeltaV / Radius * 0.5 + 0.5;

      k = texture(BrushImage, vec2(u, v)).r;
    }

    vec4 color = vec4(0, 0, 0, 0);
    color.rgb = vec3(100, 100, 135) / 255.0;
    color.a = 0.85 * k;

    return CCFragOutput(color);
  }
}%