GetShearQuad

Computes vertex coordinates of the quadrangle, to which the source ROI rectangle is mapped by the shearing transform.

Syntax

IppStatus ippiGetShearQuad(IppiRect srcRoi, double quad[4][2], double xShear, double yShear, double xShift, double yShift);

Parameters

srcRoi	Region of interest in the source image (of the IppiRect type).
quad	Output array. Contains vertex coordinates of the quadrangle, to which the source ROI is mapped by the shearing transform function.
xShear, yShear	Shearing transform coefficients.
xShift, yShift	Additional shift values along the horizontal and vertical axes.

Description

The function ippiGetShearQuad is declared in the ippi.h file. It operates with ROI (see ROI Processing in Geometric Transforms).

This function is used as a support function for ippiShear. It computes vertex coordinates of the quadrangle, to which the source rectangular ROI is mapped by the shearing transform function ippiShear using coefficients xShear, yShear and shift values xShift, yShift.

The first dimension [4] of the array quad[4][2] is equal to the number of vertices, and the second dimension [2] means x and y coordinates of the vertex. Quadrangle vertices have the following meaning:

quad[0] corresponds to the transformed top-left corner of the source ROI,

quad[1] corresponds to the transformed top-right corner of the source ROI,

quad[2] corresponds to the transformed bottom-right corner of the source ROI,

quad[3] corresponds to the transformed bottom-left corner of the source ROI.

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error.
ippStsCoeffErr	Indicates an error condition if xShear*yShear = 1.
ippStsSizeErr	Indicates an error condition if srcRoi has a size field with zero or negative value.