Inside Macintosh: QuickTime /

Chapter 2 - Movie Toolbox / Movie Toolbox Reference

Matrix Functions /

SkewMatrix

The SkewMatrix function allows your application to modify the contents of a matrix so that it defines a skew transformation. A skew operation alters the display of an element along one dimension--for example, converting a rectangle into a parallelogram is a skew operation.

pascal void SkewMatrix (MatrixRecord *m, Fixed skewX, Fixed skewY, 
                           Fixed aboutX, Fixed aboutY);

m

Contains a pointer to the matrix for this operation. The SkewMatrix function updates the contents of this matrix so that it defines a skew operation--that is, it concatenates the respective transformations onto whatever was initially in the matrix structure. You specify the magnitude and direction of the skew operation with the skewX and skewY parameters. You specify an anchor point with the aboutX and aboutY parameters.

skewX

Specifies the skew value to be applied to x coordinates.

skewY

Specifies the skew value to be applied to y coordinates.

aboutX

Specifies the x coordinate of the anchor point.

aboutY

Specifies the y coordinate of the anchor point.