/* 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 * Unpublished-- rights reserved under the copyright laws of the * United States.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. */ /* * pickdepth.c * Picking is demonstrated in this program. In * rendering mode, three overlapping rectangles are * drawn. When the left mouse button is pressed, * selection mode is entered with the picking matrix. * Rectangles which are drawn under the cursor position * are "picked." Pay special attention to the depth * value range, which is returned. */ #include <stdlib.h> #include <stdio.h> #include <GL/glut.h> void myinit(void) { glClearColor(0.0, 0.0, 0.0, 0.0); glDepthFunc(GL_LESS); glEnable(GL_DEPTH_TEST); glShadeModel(GL_FLAT); glDepthRange(0.0, 1.0); /* The default z mapping */ } /* The three rectangles are drawn. In selection mode, * each rectangle is given the same name. Note that * each rectangle is drawn with a different z value. */ void drawRects(GLenum mode) { if (mode == GL_SELECT) glLoadName(1); glBegin(GL_QUADS); glColor3f(1.0, 1.0, 0.0); glVertex3i(2, 0, 0); glVertex3i(2, 6, 0); glVertex3i(6, 6, 0); glVertex3i(6, 0, 0); glEnd(); if (mode == GL_SELECT) glLoadName(2); glBegin(GL_QUADS); glColor3f(0.0, 1.0, 1.0); glVertex3i(3, 2, -1); glVertex3i(3, 8, -1); glVertex3i(8, 8, -1); glVertex3i(8, 2, -1); glEnd(); if (mode == GL_SELECT) glLoadName(3); glBegin(GL_QUADS); glColor3f(1.0, 0.0, 1.0); glVertex3i(0, 2, -2); glVertex3i(0, 7, -2); glVertex3i(5, 7, -2); glVertex3i(5, 2, -2); glEnd(); } /* processHits() prints out the contents of the * selection array. */ void processHits(GLint hits, GLuint buffer[]) { GLint i; GLuint j, 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/0xffffffff); ptr++; printf(" z2 is %g\n", (float) *ptr/0xffffffff); ptr++; printf(" the name is "); for (j = 0; j < names; j++) { /* for each name */ printf("%d ", *ptr); ptr++; } printf("\n"); } } /* pickRects() sets up selection mode, name stack, * and projection matrix for picking. Then the objects * are drawn. */ #define BUFSIZE 512 void pickRects(int button, int state, int x, int y) { GLuint selectBuf[BUFSIZE]; GLint hits; GLint viewport[4]; if (button != GLUT_LEFT_BUTTON || state != GLUT_DOWN) return; glGetIntegerv(GL_VIEWPORT, viewport); glSelectBuffer(BUFSIZE, selectBuf); (void) glRenderMode(GL_SELECT); glInitNames(); glPushName(-1); glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity(); /* create 5x5 pixel picking region near cursor location */ gluPickMatrix((GLdouble) x, (GLdouble) (viewport[3] - y), 5.0, 5.0, viewport); glOrtho(0.0, 8.0, 0.0, 8.0, -0.5, 2.5); drawRects(GL_SELECT); glPopMatrix(); glFlush(); hits = glRenderMode(GL_RENDER); processHits(hits, selectBuf); } void display(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); drawRects(GL_RENDER); glutSwapBuffers(); } void myReshape(int w, int h) { glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0.0, 8.0, 0.0, 8.0, -0.5, 2.5); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } 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, depth buffer, and handle input events. */ int main(int argc, char **argv) { glutInitWindowSize(200, 200); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInit(&argc, argv); glutCreateWindow(argv[0]); myinit(); glutMouseFunc(pickRects); glutReshapeFunc(myReshape); glutDisplayFunc(display); glutKeyboardFunc(key); glutMainLoop(); return 0; /* ANSI C requires main to return int. */ }