diff options
author | jtg <jtg> | 1999-08-19 00:55:39 +0000 |
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committer | jtg <jtg> | 1999-08-19 00:55:39 +0000 |
commit | afb833d4e89c312460a4ab9ed6a7a8ca4ebbfe1c (patch) | |
tree | 59d65b4da12fb5379224cf5f6b808fde91523c7f /progs/redbook/select.c | |
parent | f2544d4920ce168bec9cd94d774b7ea5103a3d74 (diff) |
Initial revision
Diffstat (limited to 'progs/redbook/select.c')
-rw-r--r-- | progs/redbook/select.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/progs/redbook/select.c b/progs/redbook/select.c new file mode 100644 index 00000000000..4f413e73ce9 --- /dev/null +++ b/progs/redbook/select.c @@ -0,0 +1,222 @@ +/* + * Copyright (c) 1993-1997, 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 + * Unpublished-- rights reserved under the copyright laws of the + * United States.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(R) is a registered trademark of Silicon Graphics, Inc. + */ + +/* + * select.c + * This is an illustration of the selection mode and + * name stack, which detects whether objects which collide + * with a viewing volume. First, four triangles and a + * rectangular box representing a viewing volume are drawn + * (drawScene routine). The green triangle and yellow + * triangles appear to lie within the viewing volume, but + * the red triangle appears to lie outside it. Then the + * selection mode is entered (selectObjects routine). + * Drawing to the screen ceases. To see if any collisions + * occur, the four triangles are called. In this example, + * the green triangle causes one hit with the name 1, and + * the yellow triangles cause one hit with the name 3. + */ +#include <GL/glut.h> +#include <stdlib.h> +#include <stdio.h> + +/* draw a triangle with vertices at (x1, y1), (x2, y2) + * and (x3, y3) at z units away from the origin. + */ +void drawTriangle (GLfloat x1, GLfloat y1, GLfloat x2, + GLfloat y2, GLfloat x3, GLfloat y3, GLfloat z) +{ + glBegin (GL_TRIANGLES); + glVertex3f (x1, y1, z); + glVertex3f (x2, y2, z); + glVertex3f (x3, y3, z); + glEnd (); +} + +/* draw a rectangular box with these outer x, y, and z values */ +void drawViewVolume (GLfloat x1, GLfloat x2, GLfloat y1, + GLfloat y2, GLfloat z1, GLfloat z2) +{ + glColor3f (1.0, 1.0, 1.0); + glBegin (GL_LINE_LOOP); + glVertex3f (x1, y1, -z1); + glVertex3f (x2, y1, -z1); + glVertex3f (x2, y2, -z1); + glVertex3f (x1, y2, -z1); + glEnd (); + + glBegin (GL_LINE_LOOP); + glVertex3f (x1, y1, -z2); + glVertex3f (x2, y1, -z2); + glVertex3f (x2, y2, -z2); + glVertex3f (x1, y2, -z2); + glEnd (); + + glBegin (GL_LINES); /* 4 lines */ + glVertex3f (x1, y1, -z1); + glVertex3f (x1, y1, -z2); + glVertex3f (x1, y2, -z1); + glVertex3f (x1, y2, -z2); + glVertex3f (x2, y1, -z1); + glVertex3f (x2, y1, -z2); + glVertex3f (x2, y2, -z1); + glVertex3f (x2, y2, -z2); + glEnd (); +} + +/* drawScene draws 4 triangles and a wire frame + * which represents the viewing volume. + */ +void drawScene (void) +{ + glMatrixMode (GL_PROJECTION); + glLoadIdentity (); + gluPerspective (40.0, 4.0/3.0, 1.0, 100.0); + + glMatrixMode (GL_MODELVIEW); + glLoadIdentity (); + gluLookAt (7.5, 7.5, 12.5, 2.5, 2.5, -5.0, 0.0, 1.0, 0.0); + glColor3f (0.0, 1.0, 0.0); /* green triangle */ + drawTriangle (2.0, 2.0, 3.0, 2.0, 2.5, 3.0, -5.0); + glColor3f (1.0, 0.0, 0.0); /* red triangle */ + drawTriangle (2.0, 7.0, 3.0, 7.0, 2.5, 8.0, -5.0); + glColor3f (1.0, 1.0, 0.0); /* yellow triangles */ + drawTriangle (2.0, 2.0, 3.0, 2.0, 2.5, 3.0, 0.0); + drawTriangle (2.0, 2.0, 3.0, 2.0, 2.5, 3.0, -10.0); + drawViewVolume (0.0, 5.0, 0.0, 5.0, 0.0, 10.0); +} + +/* processHits prints out the contents of the selection array + */ +void processHits (GLint hits, GLuint buffer[]) +{ + unsigned int i, j; + GLuint names, *ptr; + + printf ("hits = %d\n", hits); + ptr = (GLuint *) buffer; + for (i = 0; i < hits; i++) { /* for each hit */ + names = *ptr; + printf (" number of names for hit = %d\n", names); ptr++; + printf(" z1 is %g;", (float) *ptr/0x7fffffff); ptr++; + printf(" z2 is %g\n", (float) *ptr/0x7fffffff); ptr++; + printf (" the name is "); + for (j = 0; j < names; j++) { /* for each name */ + printf ("%d ", *ptr); ptr++; + } + printf ("\n"); + } +} + +/* selectObjects "draws" the triangles in selection mode, + * assigning names for the triangles. Note that the third + * and fourth triangles share one name, so that if either + * or both triangles intersects the viewing/clipping volume, + * only one hit will be registered. + */ +#define BUFSIZE 512 + +void selectObjects(void) +{ + GLuint selectBuf[BUFSIZE]; + GLint hits; + + glSelectBuffer (BUFSIZE, selectBuf); + (void) glRenderMode (GL_SELECT); + + glInitNames(); + glPushName(0); + + glPushMatrix (); + glMatrixMode (GL_PROJECTION); + glLoadIdentity (); + glOrtho (0.0, 5.0, 0.0, 5.0, 0.0, 10.0); + glMatrixMode (GL_MODELVIEW); + glLoadIdentity (); + glLoadName(1); + drawTriangle (2.0, 2.0, 3.0, 2.0, 2.5, 3.0, -5.0); + glLoadName(2); + drawTriangle (2.0, 7.0, 3.0, 7.0, 2.5, 8.0, -5.0); + glLoadName(3); + drawTriangle (2.0, 2.0, 3.0, 2.0, 2.5, 3.0, 0.0); + drawTriangle (2.0, 2.0, 3.0, 2.0, 2.5, 3.0, -10.0); + glPopMatrix (); + glFlush (); + + hits = glRenderMode (GL_RENDER); + processHits (hits, selectBuf); +} + +void init (void) +{ + glEnable(GL_DEPTH_TEST); + glShadeModel(GL_FLAT); +} + +void display(void) +{ + glClearColor (0.0, 0.0, 0.0, 0.0); + glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); + drawScene (); + selectObjects (); + glFlush(); +} + +/* ARGSUSED1 */ +void keyboard(unsigned char key, int x, int y) +{ + switch (key) { + case 27: + exit(0); + break; + } +} + +/* Main Loop */ +int main(int argc, char** argv) +{ + glutInit(&argc, argv); + glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); + glutInitWindowSize (200, 200); + glutInitWindowPosition (100, 100); + glutCreateWindow (argv[0]); + init(); + glutDisplayFunc(display); + glutKeyboardFunc(keyboard); + glutMainLoop(); + return 0; +} |