NAME

TRANSFORM POINT  − apply a 2D transformation matrix to a specified 2D point

SYNOPSIS

C Syntax

void
ptran_point ( p, m, error_ind, r)
Ppoint∗p;point
Pmatrixm;transformation matrix
Pint∗error_ind;OUT error indicator
Ppoint∗r;OUT transformed point

Required PHIGS Operating States

(PHOP, ∗, ∗, ∗)

DESCRIPTION

Purpose

Use TRANSFORM POINT to calculate the transformed coordinates of a 2D point. 

C Input Parameters

pA pointer to a Ppoint data structure containing the coordinates of the point to be transformed.  Ppoint is defined in phigs.h as follows:

typedef struct  {
Pfloatx;/∗ x coordinate ∗/
Pfloaty;/∗ y coordinate ∗/
} Ppoint;

mThe 3 × 3 homogeneous transformation matrix to apply to p.  Pmatrix is defined in phigs.h as follows:

typedef  Pfloat  Pmatrix[3][3];

C Output Parameters

error_ind
A pointer to the location to store the error number of any error detected by this function.

rA pointer to a Ppoint structure in which to store the coordinates of the transformed point. 

Execution

TRANSFORM POINT applies the 3 × 3 homogeneous transformation matrix to the 2D point, and returns the coordinates of the resulting point: transformed point = matrix X point

ERRORS

002Ignoring function, function requires state (PHOP, ∗, ∗, ∗)

SEE ALSO

SET LOCAL TRANSFORMATION 3 (3P)
ROTATE (3P)
SCALE (3P)
TRANSLATE (3P)
BUILD TRANSFORMATION MATRIX (3P)
COMPOSE TRANSFORMATION MATRIX (3P)
COMPOSE MATRIX (3P)
TRANSFORM POINT 3 (3P)

September 02, 1992