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+/*
+ * 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+ * Unpublished-- rights reserved under the copyright laws of the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.
+ */
+
+/*
+ * picksquare.c
+ * Use of multiple names and picking are demonstrated.
+ * A 3x3 grid of squares is drawn. When the left mouse
+ * button is pressed, all squares under the cursor position
+ * have their color changed.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <GL/glut.h>
+
+int board[3][3]; /* amount of color for each square */
+
+/* Clear color value for every square on the board */
+void init(void)
+{
+ int i, j;
+ for (i = 0; i < 3; i++)
+ for (j = 0; j < 3; j ++)
+ board[i][j] = 0;
+ glClearColor (0.0, 0.0, 0.0, 0.0);
+}
+
+/* The nine squares are drawn. In selection mode, each
+ * square is given two names: one for the row and the
+ * other for the column on the grid. The color of each
+ * square is determined by its position on the grid, and
+ * the value in the board[][] array.
+ */
+void drawSquares(GLenum mode)
+{
+ GLuint i, j;
+ for (i = 0; i < 3; i++) {
+ if (mode == GL_SELECT)
+ glLoadName (i);
+ for (j = 0; j < 3; j ++) {
+ if (mode == GL_SELECT)
+ glPushName (j);
+ glColor3f ((GLfloat) i/3.0, (GLfloat) j/3.0,
+ (GLfloat) board[i][j]/3.0);
+ glRecti (i, j, i+1, j+1);
+ if (mode == GL_SELECT)
+ glPopName ();
+ }
+ }
+}
+
+/* processHits prints out the contents of the
+ * selection array.
+ */
+void processHits (GLint hits, GLuint buffer[])
+{
+ unsigned int i, j;
+ GLuint ii, jj, 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 this hit = %d\n", names); ptr++;
+ printf(" z1 is %g;", (float) *ptr/0x7fffffff); ptr++;
+ printf(" z2 is %g\n", (float) *ptr/0x7fffffff); ptr++;
+ printf (" names are ");
+ for (j = 0; j < names; j++) { /* for each name */
+ printf ("%d ", *ptr);
+ if (j == 0) /* set row and column */
+ ii = *ptr;
+ else if (j == 1)
+ jj = *ptr;
+ ptr++;
+ }
+ printf ("\n");
+ board[ii][jj] = (board[ii][jj] + 1) % 3;
+ }
+}
+
+/* pickSquares() sets up selection mode, name stack,
+ * and projection matrix for picking. Then the
+ * objects are drawn.
+ */
+#define BUFSIZE 512
+
+void pickSquares(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(0);
+
+ 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);
+ gluOrtho2D (0.0, 3.0, 0.0, 3.0);
+ drawSquares (GL_SELECT);
+
+ glMatrixMode (GL_PROJECTION);
+ glPopMatrix ();
+ glFlush ();
+
+ hits = glRenderMode (GL_RENDER);
+ processHits (hits, selectBuf);
+ glutPostRedisplay();
+}
+
+void display(void)
+{
+ glClear(GL_COLOR_BUFFER_BIT);
+ drawSquares (GL_RENDER);
+ glFlush();
+}
+
+void reshape(int w, int h)
+{
+ glViewport(0, 0, w, h);
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ gluOrtho2D (0.0, 3.0, 0.0, 3.0);
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+}
+
+/* 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);
+ glutInitWindowSize (100, 100);
+ glutInitWindowPosition (100, 100);
+ glutCreateWindow (argv[0]);
+ init ();
+ glutReshapeFunc (reshape);
+ glutDisplayFunc(display);
+ glutMouseFunc (pickSquares);
+ glutKeyboardFunc (keyboard);
+ glutMainLoop();
+ return 0;
+}