NAME

mapw - maps a point on the screen into a line in 3D 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: Screencoord;
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 modelling commands.  A correct mapping from screen to world space requires that the viewing object contain the projection and viewing transformations that mapped the displayed object from world to screen coordinates.  The world space line that is computed from (sx, sy) and vobj is returned as two points and stored in the locations addressed by wx1, wy1, wz1 and wx2, wy2, wz2. 

SEE ALSO

mapw2

NOTE

This command can be used only in immediate mode. 

Version 2.4  —  May 08, 1986