Syntax

[C/C++:]
void gTransformHomogPoint3D(float xs, float ys, float zs, GPOINT3 *point, float *wh);

[F90:]
subroutine gTransformHomogPoint3D(xs, ys, zs, point, wh)

real, intent(in) :: xs,ys,zs
type (GPOINT3), intent(out) :: point
real, intent(out) :: wh

Arguments

xs,ys,zs
3-D position in space coordinates

point
Transformed position in homogeneous coordinates

wh
Transformed position in homogeneous coordinates

Description

The routine gTransformHomogPoint3D() transforms the point (xs,ys,zs) into homogeneous coordinates using the current global transformation (modelling and viewing). If transforming is switched off, point is set to xs,ys,zs and wh is set to 1.0 respectively. Homogeneous coordinates are related to picture coordinates in the following way:

xp = point.x/wh;

yp = point.y/wh;

zp = point.z/wh;

If the modelling transformation contains no perspective, then by definition wh = 1.0. With perspective in the modelling transformation, the view plane corresponds to wh = 1.0 and the eye plane corresponds to wh = 0.0. All points on or behind the eye plane do not project into picture coordinates. GINO clips all graphical output which lies behind the plane wh = 0.001.

See Also

gUntransformHomogPoint3D Usage

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