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Diffstat (limited to 'progs/redbook/stencil.c')
| -rw-r--r-- | progs/redbook/stencil.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/progs/redbook/stencil.c b/progs/redbook/stencil.c new file mode 100644 index 000000000..b33e40a03 --- /dev/null +++ b/progs/redbook/stencil.c @@ -0,0 +1,193 @@ + +/* Copyright (c) Mark J. Kilgard, 1994. */ + +/* + * (c) Copyright 1993, Silicon Graphics, Inc. + * ALL RIGHTS RESERVED + * Permission to use, copy, modify, and distribute this software for + * any purpose and without fee is hereby granted, provided that the above + * copyright notice appear in all copies and that both the copyright notice + * and this permission notice appear in supporting documentation, and that + * the name of Silicon Graphics, Inc. not be used in advertising + * or publicity pertaining to distribution of the software without specific, + * written prior permission. + * + * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "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, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT, + * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY + * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, + * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF + * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN + * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON + * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE + * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE. + * + * US Government Users Restricted Rights + * Use, duplication, or disclosure by the Government is subject to + * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph + * (c)(1)(ii) of the Rights in Technical Data and Computer Software + * clause at DFARS 252.227-7013 and/or in similar or successor + * clauses in the FAR or the DOD or NASA FAR Supplement. + * Unpublished-- rights reserved under the copyright laws of the + * United States. Contractor/manufacturer is Silicon Graphics, + * Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311. + * + * OpenGL(TM) is a trademark of Silicon Graphics, Inc. + */ +/* stencil.c + * This program draws two rotated tori in a window. + * A diamond in the center of the window masks out part + * of the scene. Within this mask, a different model + * (a sphere) is drawn in a different color. + */ + +/* + * !!! NOTE !!! + * + * This demo is poorly written. The stencil buffer should be + * redrawn in display(), not in the myReshape() function. + * The reason is if the window gets "damaged" then the stencil buffer + * contents will be in an undefined state (myReshape is not called when + * a window is damaged and needs to be redrawn). If the stencil buffer + * contents are undefined, the results of display() are unpredictable. + * + * -Brian + */ + + +#include <stdlib.h> +#include <GL/glut.h> + +#define YELLOWMAT 1 +#define BLUEMAT 2 + +void myinit (void) +{ + GLfloat yellow_diffuse[] = { 0.7, 0.7, 0.0, 1.0 }; + GLfloat yellow_specular[] = { 1.0, 1.0, 1.0, 1.0 }; + + GLfloat blue_diffuse[] = { 0.1, 0.1, 0.7, 1.0 }; + GLfloat blue_specular[] = { 0.1, 1.0, 1.0, 1.0 }; + + GLfloat position_one[] = { 1.0, 1.0, 1.0, 0.0 }; + + glNewList(YELLOWMAT, GL_COMPILE); + glMaterialfv(GL_FRONT, GL_DIFFUSE, yellow_diffuse); + glMaterialfv(GL_FRONT, GL_SPECULAR, yellow_specular); + glMaterialf(GL_FRONT, GL_SHININESS, 64.0); + glEndList(); + + glNewList(BLUEMAT, GL_COMPILE); + glMaterialfv(GL_FRONT, GL_DIFFUSE, blue_diffuse); + glMaterialfv(GL_FRONT, GL_SPECULAR, blue_specular); + glMaterialf(GL_FRONT, GL_SHININESS, 45.0); + glEndList(); + + glLightfv(GL_LIGHT0, GL_POSITION, position_one); + + glEnable(GL_LIGHT0); + glEnable(GL_LIGHTING); + glDepthFunc(GL_LESS); + glEnable(GL_DEPTH_TEST); + + glClearStencil(0x0); + glEnable(GL_STENCIL_TEST); + +} + +/* Draw a sphere in a diamond-shaped section in the + * middle of a window with 2 tori. + */ +void display(void) +{ + glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); + + glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP); + +/* draw blue sphere where the stencil is 1 */ + glStencilFunc (GL_EQUAL, 0x1, 0x1); + glCallList (BLUEMAT); + glutSolidSphere (0.5, 15, 15); + +/* draw the tori where the stencil is not 1 */ + glStencilFunc (GL_NOTEQUAL, 0x1, 0x1); + glPushMatrix(); + glRotatef (45.0, 0.0, 0.0, 1.0); + glRotatef (45.0, 0.0, 1.0, 0.0); + glCallList (YELLOWMAT); + glutSolidTorus (0.275, 0.85, 15, 15); + glPushMatrix(); + glRotatef (90.0, 1.0, 0.0, 0.0); + glutSolidTorus (0.275, 0.85, 15, 15); + glPopMatrix(); + glPopMatrix(); + + glFlush(); + glutSwapBuffers(); +} + +/* Whenever the window is reshaped, redefine the + * coordinate system and redraw the stencil area. + */ +void myReshape(int w, int h) +{ + glViewport(0, 0, w, h); + + glClear(GL_STENCIL_BUFFER_BIT); +/* create a diamond shaped stencil area */ + glMatrixMode(GL_PROJECTION); + glLoadIdentity(); + glOrtho(-3.0, 3.0, -3.0, 3.0, -1.0, 1.0); + glMatrixMode(GL_MODELVIEW); + glLoadIdentity(); + + glStencilFunc (GL_ALWAYS, 0x1, 0x1); + glStencilOp (GL_REPLACE, GL_REPLACE, GL_REPLACE); + glBegin(GL_QUADS); + glVertex3f (-1.0, 0.0, 0.0); + glVertex3f (0.0, 1.0, 0.0); + glVertex3f (1.0, 0.0, 0.0); + glVertex3f (0.0, -1.0, 0.0); + glEnd(); + + glMatrixMode(GL_PROJECTION); + glLoadIdentity(); + gluPerspective(45.0, (GLfloat) w/(GLfloat) h, 3.0, 7.0); + glMatrixMode(GL_MODELVIEW); + glLoadIdentity(); + glTranslatef(0.0, 0.0, -5.0); +} + +static void +key(unsigned char k, int x, int y) +{ + switch (k) { + case 27: /* Escape */ + exit(0); + break; + default: + return; + } + glutPostRedisplay(); +} + +/* Main Loop + * Open window with initial window size, title bar, + * RGBA display mode, and handle input events. + */ +int main(int argc, char** argv) +{ + glutInit(&argc, argv); + glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH | GLUT_STENCIL); + glutInitWindowSize (400, 400); + glutCreateWindow (argv[0]); + myinit (); + glutReshapeFunc (myReshape); + glutDisplayFunc(display); + glutKeyboardFunc(key); + glutMainLoop(); + return 0; /* ANSI C requires main to return int. */ +} |