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$XMCOPY
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.TH "TRANSFORM POINT" 3P "29 February 1991"
.SH NAME
TRANSFORM POINT  \- apply a \s-2\&2D\s+2 transformation matrix to a specified \s-2\&2D\s+2 point
.SH SYNOPSIS
.SS C Syntax
.ft B
.ta 1.5i 3i
.nf
void
ptran_point ( p, m, error_ind, r)
Ppoint	*p;	\fIpoint\fP
Pmatrix	m;	\fItransformation matrix\fP
Pint	*error_ind;	\fIOUT error indicator\fP
Ppoint	*r;	\fIOUT transformed point\fP
.fi
.ft R
.SS Required PHIGS Operating States
(PHOP, *, *, *)
.SH DESCRIPTION
.SS Purpose
Use \s-2TRANSFORM POINT\s+2 to calculate the transformed coordinates of a
\s-2\&2D\s+2 point.
.SS C Input Parameters
.IP \fIp\fP
A pointer to a Ppoint data structure containing the coordinates of the
point to be transformed.
Ppoint is defined in phigs.h as follows:
.sp .4
.ta .5i +\w'Pfloat     'u +\w'x;     'u
.nf
typedef struct  {
.sp .2
	Pfloat	x;	/* x coordinate */
	Pfloat	y;	/* y coordinate */
.sp .2
} Ppoint;
.fi
.IP \fIm\fP
The 3\ \(mu\ 3 homogeneous transformation matrix to apply to \fIp\fP.
Pmatrix is defined in phigs.h as follows:
.IP
typedef  Pfloat  Pmatrix[3][3];
.SS C Output Parameters
.IP \fIerror_ind\fP
A pointer to the location to store the error number of any error detected
by this function.
.IP \fIr\fP
A pointer to a Ppoint structure in which to store the coordinates of the
transformed point.
.SS Execution
\s-2TRANSFORM POINT\s+2 applies the 3\ \(mu\ 3 homogeneous
\fItransformation matrix\fP
to the \s-2\&2D\s+2 \fIpoint\fP, and returns the coordinates of the resulting point:
.sp
	\fItransformed point\fP = \fImatrix\fP \s-2X\s+2 \fIpoint\fP
.SH ERRORS
.IP 002
Ignoring function, function requires state (\s-2PHOP, *, *, *\s+2)
.SH SEE ALSO
.nf
.IP
.ta 0.5i
.SM "SET LOCAL TRANSFORMATION 3 (3P)"
.SM "ROTATE (3P)"
.SM "SCALE (3P)"
.SM "TRANSLATE (3P)"
.SM "BUILD TRANSFORMATION MATRIX (3P)"
.SM "COMPOSE TRANSFORMATION MATRIX (3P)"
.SM "COMPOSE MATRIX (3P)"
.SM "TRANSFORM POINT 3 (3P)"
.fi