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SGI Developer Toolbox 6.1
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SGI Developer Toolbox 6.1 - Disc 1.iso
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toolbox
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src
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exampleCode
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opengl
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motif
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ostencil.c
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1996-11-11
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/*
* Copyright (c) 1993-94, Silicon Graphics, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software and
* its documentation for any purpose is hereby granted without fee, provided
* that the name of Silicon Graphics may not be used in any advertising or
* publicity relating to the software without the specific, prior written
* permission of Silicon Graphics.
*
* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
*
* IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
* RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF THE
* POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* OpenGL(TM) is a trademark of Silicon Graphics, Inc.
*/
/*----------------------------------------------------------------------------
*
* ostencil.c : openGL (motif) example showing how to use stencils
*
* Author : Yusuf Attarwala
* SGI - Applications
* Date : Mar 93
*
* note : the main intent of this program is to demo the stencil
* plane functionality, hence the rendering is kept
* simple (wireframe).
*
* press left button for animation
* press middle button to turn OFF stenciling
* press right button to turn ON stenciling
*
*---------------------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <Xm/Xm.h>
#include <Xm/Frame.h> /* for frame widgets */
#include <Xm/Form.h> /* for frame widgets */
#include <X11/keysym.h> /* keyboard translations */
#include <X11/StringDefs.h>
#include <GL/gl.h> /* gl includes */
#include <GL/glu.h> /* utility library includes */
#include <GL/GLwMDrawA.h> /* include for the drawing area widget */
static int stencilOn = 1;
/* function declarations */
void
createToplevel(void),
drawScene(void),
setMatrix(void),
setEtchingArea(void),
initLightAndMaterial(void),
animation(void),
exposeCB(Widget,XtPointer,XtPointer),
resizeCB(Widget,XtPointer,XtPointer),
initCB(Widget,XtPointer,XtPointer),
inputCB(Widget,XtPointer,XtPointer);
/* global variables */
Display *display; /* current display */
XtAppContext appContext; /* X application context */
float ax,ay,az; /* angles for animation */
GLUquadricObj *quadObj; /* used in drawscene */
Widget toplevel, /* toplevel shell */
glw; /* current widget */
GLXContext glxc; /* current glx context */
Arg args[20];
int acnt;
void
main(int argc, char** argv)
{
XtToolkitInitialize();
appContext = XtCreateApplicationContext();
display = XtOpenDisplay(appContext, NULL, "Ostencil","ostencil",NULL,0,
&argc,argv);
if (!display) {
printf("%s : Unable to open display\n",argv[0]);
exit(0);
}
printf("\n---------------------------------------------\n");
printf("OpenGL stencil example \n\n");
printf("Press: left button for animation\n\
middle button to turn OFF stenciling\n\
right button to turn ON stenciling (default)\n");
quadObj = gluNewQuadric (); /* this will be used in drawScene */
createToplevel(); /* create widget hierarchy */
XtAppMainLoop(appContext); /* loop forever */
}
void
createToplevel(void)
{
Widget frame;
acnt = 0;
XtSetArg(args[acnt],XmNminHeight, 300);acnt++;
XtSetArg(args[acnt],XmNminWidth, 300);acnt++;
XtSetArg(args[acnt],XmNminAspectX, 1);acnt++;
XtSetArg(args[acnt],XmNminAspectY, 1);acnt++;
XtSetArg(args[acnt],XmNmaxAspectX, 1);acnt++;
XtSetArg(args[acnt],XmNmaxAspectY, 1);acnt++;
toplevel = XtAppCreateShell("openGL stencil","ostencil",
applicationShellWidgetClass,
display,args,acnt);
/* create a frame to hold glx widget */
frame = XtVaCreateManagedWidget("frame",
xmFrameWidgetClass, toplevel,
NULL);
/* create a double buffer widget, in rgb mode and manage it */
acnt = 0;
XtSetArg(args[acnt], GLwNrgba, TRUE); acnt++;
XtSetArg(args[acnt], GLwNdoublebuffer, TRUE); acnt++;
XtSetArg(args[acnt], GLwNstencilSize, 1); acnt++;
XtSetArg(args[acnt], GLwNallocateBackground, TRUE); acnt++;
glw = GLwCreateMDrawingArea(frame, "glw", args, acnt);
XtManageChild(glw);
/* register callbacks */
XtAddCallback(glw, GLwNginitCallback, initCB, NULL);
/* realize widget hierarchy */
XtRealizeWidget(toplevel);
/*
initLightAndMaterial();
*/
/* additional callbacks */
XtAddCallback(glw, GLwNexposeCallback, exposeCB, NULL);
XtAddCallback(glw, GLwNresizeCallback, resizeCB, NULL);
XtAddCallback(glw, GLwNinputCallback, inputCB, NULL);
}
static float p0[] = {-5.0,-5.0,0.0};
static float p1[] = {5.0,-5.0,0.0};
static float p2[] = {5.0,5.0,0.0};
static float p3[] = {-5.0,5.0,0.0};
void
setEtchingArea()
{
/* create a rectangle in the center where the stencil
bits are set */
glColorMask(GL_FALSE,GL_FALSE,GL_FALSE,GL_FALSE);
glClearStencil(0);
glClear(GL_STENCIL_BUFFER_BIT);
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_ALWAYS,1,1);
glStencilOp(GL_REPLACE,GL_REPLACE,GL_REPLACE);
glBegin(GL_POLYGON);
glVertex3fv(p0);
glVertex3fv(p1);
glVertex3fv(p2);
glVertex3fv(p3);
glEnd();
glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_TRUE);
glDisable(GL_STENCIL_TEST);
}
void
drawScene(void)
{
glClearColor(0.3, 0.3, 0.3, 0.0);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
/* draw the etched area in a different color for visual clue */
/* note that the stencil test is disabled at this point */
glColor3f (0.0, 0.0, 0.0);
glBegin(GL_POLYGON);
glVertex3fv(p0);
glVertex3fv(p1);
glVertex3fv(p2);
glVertex3fv(p3);
glEnd();
if (stencilOn) glEnable(GL_STENCIL_TEST);
glPushMatrix();
gluQuadricDrawStyle (quadObj, GLU_LINE);
glRotatef (ax,1.0,0.0,0.0);
glRotatef (-ay,0.0, 1.0, 0.0);
/* draw a cone where the stencil is not set to 1 */
glStencilOp(GL_KEEP,GL_KEEP,GL_KEEP);
glStencilFunc(GL_NOTEQUAL,1,1);
glColor3f (1.0, 1.0, 0.0);
gluCylinder (quadObj, 2.0,5.0,10.0,20,8); /* draw a cone */
/* draw a cone (in different color) where the stencil is set to 1 */
glStencilOp(GL_KEEP,GL_KEEP,GL_KEEP);
glStencilFunc(GL_EQUAL,1,1);
glColor3f (0.0, 1.0, 1.0);
gluCylinder (quadObj, 2.0,5.0,10.0,20,8); /* draw a cone */
glPopMatrix();
if (stencilOn) glDisable(GL_STENCIL_TEST);
glFlush();
glXSwapBuffers(XtDisplay(glw), XtWindow(glw));
}
void
setMatrix(void)
{
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-12.0,12.0,-12.0,12.0,-12.0,12.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void
animation(void)
{
register int i;
/* animate the cone */
for (i=0;i<60;i++) {
ax += 5.0;
ay -= 2.0;
az += 5.0;
if (ax >= 360) ax = 0.0;
if (ay <= -360) ay = 0.0;
if (az >= 360) az = 0.0;
drawScene();
}
}
void
inputCB(Widget w, XtPointer client_data, XtPointer call)
{
char string[31];
XComposeStatus composeStatus;
KeySym keysym;
GLwDrawingAreaCallbackStruct *call_data;
call_data = (GLwDrawingAreaCallbackStruct *) call;
switch(call_data->event->type) {
case ButtonPress:
switch (call_data->event->xbutton.button) {
case Button1:
animation();
break;
case Button2 :
stencilOn = 0;
drawScene();
break;
case Button3 :
stencilOn = 1;
drawScene();
break;
}
break;
case KeyPress :
XLookupString((XKeyEvent *)call_data->event,string,
30,&keysym,&composeStatus);
switch(keysym) {
case XK_Escape :
exit(0);
break;
}
break;
default:
break;
}
}
void
resizeCB(Widget w, XtPointer client_data, XtPointer call)
{
GLwDrawingAreaCallbackStruct *call_data;
call_data = (GLwDrawingAreaCallbackStruct *) call;
GLwDrawingAreaMakeCurrent(w, glxc);
glViewport(0, 0, call_data->width, call_data->height);
setMatrix();
setEtchingArea(); /* using stencils */
drawScene();
}
void
exposeCB(Widget w, XtPointer client_data, XtPointer call)
{
GLwDrawingAreaCallbackStruct *call_data;
call_data = (GLwDrawingAreaCallbackStruct *) call;
GLwDrawingAreaMakeCurrent(w, glxc);
glViewport(0, 0, call_data->width, call_data->height);
drawScene();
}
void
initCB(Widget w, XtPointer client_data, XtPointer call)
{
XVisualInfo *vi;
XtSetArg(args[0], GLwNvisualInfo, &vi);
XtGetValues(w, args, 1);
glxc = glXCreateContext(XtDisplay(w), vi, 0, GL_TRUE);
ax = 10.0;
ay = -10.0;
az = 0.0;
}