NAME

mapw − maps a point on the screen into a line in three-dimensional world coordinates

SPECIFICATION

C
mapw(vobj, sx, sy, wx1, wy1, wz1, wx2, wy2, wz2)
Object vobj;
Screencoord sx, sy;
Coord *wx1, *wy1, *wz1, *wx2, *wy2, *wz2;

FORTRAN
subroutine mapw(vobj, sx, sy, wx1, wy1, wz1, wx2, wy2, wz2)
integer*4 vobj, sx, sy
real wx1, wy1, wz1, wx2, wy2, wz2

Pascal
procedure mapw(vobj: Object; sx, sy: longint;
var wx1, wy1, wz1, wx2, wy2, wz2: Coord);

DESCRIPTION

mapw takes a pair of 2D screen coordinates and maps them into 3D world space.  Since the z coordinate is missing from screen space, the point becomes a line in world space.  mapw computes the inverse mapping from vobj, a viewing object. 

A viewing object is a graphical object that contains only  viewport, projection, viewing transformation, and modeling routines.  A correct mapping from screen space to world space requires the viewing object contain the projection and viewing transformations that mapped the displayed object from world to screen coordinates.  The IRIS returns a world space line, which is computed from (sx, sy) and vobj, as two points and stores them in the locations addressed by wx1, wy1, wz1 and wx2, wy2, wz2. 

SEE ALSO

mapw2 IRIS Graphics Programming, Section 9.1, Mapping the Screen to World Space

NOTE

This routine is available only in immediate mode. 

Version 2.5  —  April 22, 1987