text: #import "GPUImageFilter.h"
  
  extern NSString *const kGPUImageTwoInputTextureVertexShaderString;
  
  /**
   * 两个InputFilter,两个input 的纹理，同一个GPU处理方法
   * 注意和其他的几种filter的区别
   */
  @interface GPUImageTwoInputFilter : GPUImageFilter
  {
      GPUImageFramebuffer *secondInputFramebuffer;
  
      GLint filterSecondTextureCoordinateAttribute;
      GLint filterInputTextureUniform2;
      GPUImageRotationMode inputRotation2;
      CMTime firstFrameTime, secondFrameTime;
      
      BOOL hasSetFirstTexture, hasReceivedFirstFrame, hasReceivedSecondFrame, firstFrameWasVideo, secondFrameWasVideo;
      BOOL firstFrameCheckDisabled, secondFrameCheckDisabled;
  }
  
  - (void)disableFirstFrameCheck;
  - (void)disableSecondFrameCheck;
  
  @end
  