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+
+/* 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+ * Unpublished-- rights reserved under the copyright laws of the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[])
+{
+ 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/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();
+}
+
+/* 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);
+ glutMainLoop();
+ return 0; /* ANSI C requires main to return int. */
+}