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From: dave@sgi.com (dave "who can do? ratmandu!" ratcliffe)
Newsgroups: comp.sys.sgi
Subject: Re: Problems with mapw() in GL on Personal Iris
Keywords: Silicon Graphics, 3D-Pick, GL (Graphic Language)
Message-ID: <1990Nov9.220015.27521@odin.corp.sgi.com>
Date: 9 Nov 90 22:00:15 GMT
References: <(Graphic> <Language)> <3238@zgdvda.zgdvda.uucp>
Sender: news@odin.corp.sgi.com (Net News)
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 90

In article <3238@zgdvda.zgdvda.uucp> boehmk@zgdvda.uucp writes:
>
>
>I have a problem with the 'mapw()'-Function of the GL of the Personal
>IRIS machine.
>It would also be great, if anybody could send a part of a sample Program
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>to me. I am not able to use the pick()-Function.
>
>Hope to hear anything
>Klaus

perhaps the below example will be useful:

/*
 *   mapw:
 *
 *    Bare-bones example demonstrates use of MAPW(3G) for determining a line
 *  in 3-space given a 2-D screen space point.  Note that the "line" drawn
 *  after the call to MAPW(3G) simply looks like a green point.  This is
 *  exactly as it should be--i.e. drawing a line from the first to the
 *  second point returned by mapw *should* appear to the viewer's eye as if
 *  it is simply a point in space
 *
 *                                      ratman - 1987
 */

#include <gl/gl.h>
#include <gl/device.h>

#define VOBJ 6

main()
{
    Screencoord scrx, scry;
    Coord wx1, wy1, wz1, wx2, wy2, wz2;
    short screenx, screeny, val;
    long xorig, yorig;
    Device dev;


    prefsize(512,512);
    winopen("mapw_test");
    qdevice(LEFTMOUSE);
    qdevice(ESCKEY);
    color(BLACK);
    clear();
    perspective(440,1.0,1.0,1500.0);

    makeobj(VOBJ);
        perspective(440,1.0,1.0,1500.0);
    closeobj();

    getorigin(&xorig, &yorig);

    while (TRUE) {
        dev = qread(&val);
        switch(dev) {
            case LEFTMOUSE:
                if (val) {
                    scrx = (short) getvaluator(MOUSEX) - xorig;   
                    scry = (short) getvaluator(MOUSEY) - yorig;  
                    callobj(VOBJ);
                    mapw(VOBJ,scrx,scry,&wx1,&wy1,&wz1,&wx2,&wy2,&wz2);

                    /* only get values +/- 1.0 for wz1 */
                    printf("wx1=%.2f  wy1=%.2f  wz1=%.2f  ", wx1, wy1, wz1);
                    printf("wx2=%.2f  wy2=%.2f  wz2=%.2f\n", wx2, wy2, wz2);
		    color(BLACK);
		    clear();
		    color(GREEN);
		    move(wx1, wy1, wz1);
		    draw(wx2, wy2, wz2);
                }
                break;
            case REDRAW:
                getorigin(&xorig, &yorig);
		reshapeviewport();
                callobj(VOBJ);
		color(BLACK);
		clear();
                break;
            case ESCKEY:
                gexit();
                exit(0);
                break;

        }
    }
}