public void setBlurScale(float f) {
        this.blurScale = f;
        if (material != null) {
            material.setFloat("XScale", blurScale * xScale);
            material.setFloat("YScale", blurScale * yScale);
        }
    }
Sets the blur amount by scaling the convolution filter up or
 down.  A value of 1 (the default) performs a sparse 5x5 evenly
 distributed convolution at pixel level accuracy.  Higher values skip
 more pixels, and so on until you are no longer blurring the image
 but simply hashing it.

 The sparse convolution is as follows:
%MINIFYHTMLc3d0cd9fab65de6875a381fd3f83e1b338%*
 Where 'x' is the texel being modified.  Setting blur scale higher
 than 1 spaces the samples out.

@param f the desired filter scale (default=1)
jme3-effects/src/main/java/com/jme3/post/filters/DepthOfFieldFilter.java