Listing 3.  Excerpts From a 3D Function Plotting Program Using the X-Specs 3D Glasses



/*----------------  INCLUDE FILES  ----------------*/

#include "/hdr/common.h"
#include "/hdr/XSpecsLib.h"


/*----------------  External Variables ---------------*/

extern struct GfxBase *GfxBase;
extern struct Library *XSpecsBase;
extern struct Window *win;
extern struct RastPort *rastport;
extern struct ViewPort *viewport;
extern AllPlotData *apd;

extern DOUBLE Evaluate(DOUBLE, DOUBLE);


/*------------------  CalcAndPlot3 Function  ----------------*/

static VOID CalcAndPlot3(DOUBLE x1, DOUBLE y1, BOOL flag)
{
   static LONG  pennum;
   static DOUBLE x2, y2, z1;

   /* Assign last 2 points to first 2 points */
   xp1 = xp4;
   xp2 = xp3;
   yp1 = yp4;
   yp2 = yp3;
   zp1 = zp4;
   zp2 = zp3;

   x2 = x1 + xspc;  /* used if flag = FALSE, plot along Y-axis */
   y2 = y1 + yspc;  /* used if flag = TRUE , plot along X-axis */

   if(flag)
      Calculate2(x1, y2, calc(x1, y2));
   else
      Calculate2(x2, y1, calc(x2, y1));

   xp3 = xp;
   yp3 = yp;
   zp3 = zp;

   z1 = calc(x1, y1);

   Calculate2(x1, y1, z1);
   xp4 = xp;
   yp4 = yp;
   zp4 = zp;

   dtoplane = zcalc(x1, y1, z1);
   pennum = (LONG)((dtoplane - dmin)/colorspread) + pennumbase;
   if (pennum > pennummax)  pennum = pennummax;
   if (pennum < pennumbase)  pennum = pennumbase;

   XSpecsSetAPen(pennum);
   XSpecsMove(xp1, yp1, zp1);
   XSpecsDraw(xp2, yp2, zp2);
   XSpecsDraw(xp3, yp3, zp3);
   XSpecsDraw(xp4, yp4, zp4);

} /* CalcAndPlot3 */


/*--------------------  DrawGraph Function  -----------------*/

VOID DrawGraph(VOID)
{
   struct IntuiMessage *message;
   DOUBLE calcspacex, calcspacey, calcincx, calcincy,
          tx, ty, tz,
          yminend, ymaxend, ybeginspc,
          xminend, xmaxend, xbeginspc,
          zradians, yradians, xradians;
   BOOL   alongxflag,
          alongyflag;

   /* Set-up code is here; not shown */

   /* PLOT THE GRAPH */

   switch(plottype) {

      case PLOTXSPECS:
         { /* block begin */
         struct MsgPort *uport;    /* user port of XSpecs windows */
         UWORD colorarray32[] = {
               0x000, 0xF00, 0xD00, 0xB00, 0x007, 0x008, 0x009, 0x00A,
               0x00B, 0x00C, 0x00D, 0x00E, 0x00F, 0x11F, 0x22F, 0x33F,
               0x44F, 0x55F, 0x66F, 0x77F, 0x88F, 0x99F, 0xAAF, 0xBBF,
               0xCCF, 0xDDF, 0xEEF, 0xFFF, 0x006, 0x005, 0x004, 0x002
         };

         if (XSpecsAllocView(NULL) != 0) goto EndDrawGraph;
         if (!(uport = (struct MsgPort *) XSpecsOn (MOUSEBUTTONS))) {
            XSpecsFreeView();    /* Free up view */
            goto EndDrawGraph;
         } /* if */
         XSpecsLoadRGB4(colorarray32,32);

         if(alongxflag) {  /* Plot along X-axis */
            yminend = apd->dd.PlotYmin;
            ymaxend = apd->dd.PlotYmax;
            /* Prevent going one yspc to far at end of plot */
            if(ybegin < yend)
               ymaxend = apd->dd.PlotYmax - yspc;
            else
               yminend = apd->dd.PlotYmin - yspc;
            for(ty = ybegin ; (ty <= ymaxend) && (ty >= yminend) ; ty += yspc) {
               /* Check for Stop Plot from user */
               if(message = (struct IntuiMessage *) GetMsg(win->UserPort)) {
                  goto EndXSpecsPlot;
               } /* if */
               /* Initialize starting plot points */
               ybeginspc = ty + yspc;
               Calculate2(xbegin, ty, calc(xbegin, ty));
               xp4 = xp;
               yp4 = yp;
               zp4 = zp;
               Calculate2(xbegin, ybeginspc, calc(xbegin, ybeginspc));
               xp3 = xp;
               yp3 = yp;
               zp3 = zp;
               /* Plot along X-axis */
               for(tx = xbegin + xspc ; (tx <= apd->dd.PlotXmax) && (tx >= apd->dd.PlotXmin) ; tx += xspc)
                  CalcAndPlot3(tx, ty, alongxflag);
            } /* for */
         } /* if */
         else {  /* Plot along Y-axis */
            xminend = apd->dd.PlotXmin;
            xmaxend = apd->dd.PlotXmax;
            /* Prevent going one xspc to far at end of plot */
            if(xbegin < xend)
               xmaxend = apd->dd.PlotXmax - xspc;
            else
               xminend = apd->dd.PlotXmin - xspc;
            for(tx = xbegin ; (tx <= xmaxend) && (tx >= xminend) ; tx += xspc) {
               /* Check for Stop Plot from user */
               if(message = (struct IntuiMessage *) GetMsg(win->UserPort)) {
                  goto EndXSpecsPlot;
               } /* if */
               /* Initialize starting plot points */
               xbeginspc = tx + xspc;
               Calculate2(tx, ybegin, calc(tx, ybegin));
               xp4 = xp;
               yp4 = yp;
               zp4 = zp;
               Calculate2(xbeginspc, ybegin, calc(xbeginspc, ybegin));
               xp3 = xp;
               yp3 = yp;
               zp3 = zp;
               /* Plot along X-axis */
               for(ty = ybegin + yspc ; (ty <= apd->dd.PlotYmax) && (ty >= apd->dd.PlotYmin) ; ty += yspc)
                  CalcAndPlot3(tx, ty, alongxflag);
            } /* for */
         } /* else */
         WaitPort(win->UserPort);     /* Wait for user mouse click */
         } /* Block end */

         EndXSpecsPlot:
            XSpecsOff();      /* Turn 'um off */
            XSpecsFreeView();    /* Free up view */
         break;

      default:
      break;
   }  /* switch */