ZombieBattle/assets/res/effects/bgScroll.effect

CCEffect %{
  techniques:
  - passes:
    - vert: vs
      frag: fs
      blendState:
        targets:
        - blend: true
      rasterizerState:
        cullMode: none
      properties:
        texture: { value: white }
        alphaThreshold: { value: 0.5 }
        time: {value: 0.0 }
        speed: {value: 1.0 }   // time 和speed 共同决定采样的偏移量.
}%


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>

  in vec4 v_color;

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

  uniform Param {
    float time;
    float speed;
  };

  void main () {
    vec4 o = vec4(1, 1, 1, 1);

    float offset = fract( time* speed + v_uv0.y);

    o *= texture(texture, vec2(v_uv0.x, offset));
    
    o *= v_color;

    ALPHA_TEST(o);

    gl_FragColor = o;
  }
}%