Programmer Guide/Command Reference/EVAL/pgtrans: Difference between revisions

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:;<var>DX, DY</var>: shift values for x and y (default=0, no shift)
:;<var>DX, DY</var>: shift values for x and y (default=0, no shift)
::* shift the center point <code><xc,yc></code> of ''X<sub>IX</sub>''
::* shift the center point <code><xc,yc></code> of ''X<sub>IX</sub>''
:::<code><x[i] , y[i]> -> <x[i]+''DX'' , y[i]+''DY''></code>
:::<code><x[i] , y[i]> -> <x[i]+<var>DX</var> , y[i]+<var>DY</var>></code>
:;<var>KX, KY</var>: scaling factors; both factors must be greater than zero (default=1, no scaling)
:;<var>KX, KY</var>: scaling factors; both factors must be greater than zero (default=1, no scaling)
::* scale the distances of corners of ''X<sub>IX</sub>'' to the center point
::* scale the distances of corners of ''X<sub>IX</sub>'' to the center point
:::<code><x[i] , y[i]> -> <(x[i]-xc)*''KX''+xc , (y[i]-yc)*''KY''+yc></code>
:::<code><x[i] , y[i]> -> <(x[i]-xc)*<var>KX</var>+xc , (y[i]-yc)*<var>KY</var>'+yc></code>
:;<var>A</var>: rotation angle in degree (default=0, no rotation); a scaling factors (default=1)
:;<var>A</var>: rotation angle in degree (default=0, no rotation); a scaling factors (default=1)
::*rotate the polygon around the center point
::*rotate the polygon around the center point

Revision as of 10:15, 20 April 2011

Shift, scale and/or rotate a polygon.

Usage
pgtrans(X, IX {, DX, DY), KX, KY, A})
X
a closed point-list or a polygon-stream defining one or more polygons.
IX
The index of the polygon of X to be tested; 0 <= IX < pgget(X)
DX, DY
shift values for x and y (default=0, no shift)
  • shift the center point <xc,yc> of XIX
<x[i] , y[i]> -> <x[i]+DX , y[i]+DY>
KX, KY
scaling factors; both factors must be greater than zero (default=1, no scaling)
  • scale the distances of corners of XIX to the center point
<x[i] , y[i]> -> <(x[i]-xc)*KX+xc , (y[i]-yc)*KY'+yc>
A
rotation angle in degree (default=0, no rotation); a scaling factors (default=1)
  • rotate the polygon around the center point
Result
The result r is a polygon-stream containing the transformed XIX.
See also
pginit, pgget, pgitest, pgxgrid, pgsplit, pgtrans, pghull

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