how the axial shading is preserve in pdf

Hi, Sasi -

The Matrix maps coordinates in your shading dictionary into User Space. That is, the Matrix entry in the Pattern dictionary specifies a coordinate transformation that will be applied to coordinates specified in the shading dictionary.

To take your example, you have an axial shading extending from (rounding off) 109,69 to 109,0.  Your Pattern dictionary specifies the Matrix

[ 1  0  0  1  54  53 ]

This transformation matrix corresponds to a scale of 1,1 (that is, no change in scale) and a translation of 54,53. Thus, the actual endpoints for the axial shading will be the User Space positions 163,122 and 163,53 (assuming I’ve added correctly).

As to what values to use for your Matrix, it depends on how you’ve set up your Shading dictionary. If the coordinates you’ve specified are actually where you want the gradient to go, then just use an identity matrix

[ 1  0  0  1  0  0 ]

By the way, are you sure that the Pattern dictionary includes a Matrix entry? I seem to remember (it's been a while since I've looked at Patterns) that the matrix is supplied as an argument to the makepattern operator:

<<patternDict>> [ 1 0 0 1 0 0 ] makepattern

Hope that helps.

- John Deubert

  Acumen Training

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