text: #import "XDGPUImageFilter.h"
  
  /** Performs a vignetting effect, fading out the image at the edges
   */
  @interface  XDGPUImageVignetteFilter :  XDGPUImageFilter 
  {
      GLint vignetteCenterUniform, vignetteColorUniform, vignetteStartUniform, vignetteEndUniform;
  }
  
  // the center for the vignette in tex coords (defaults to 0.5, 0.5)
  @property (nonatomic, readwrite) CGPoint vignetteCenter;
  
  // The color to use for the Vignette (defaults to black)
  @property (nonatomic, readwrite) GPUVector3 vignetteColor;
  
  // The normalized distance from the center where the vignette effect starts. Default of 0.5.
  @property (nonatomic, readwrite) CGFloat vignetteStart;
  
  // The normalized distance from the center where the vignette effect ends. Default of 0.75.
  @property (nonatomic, readwrite) CGFloat vignetteEnd;
  
  @end
  