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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+ * Unpublished-- rights reserved under the copyright laws of the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.
+ */
+/*
+ * fog.c
+ * This program draws 5 red teapots, each at a different
+ * z distance from the eye, in different types of fog.
+ * Pressing the left mouse button chooses between 3 types of
+ * fog: exponential, exponential squared, and linear.
+ * In this program, there is a fixed density value, as well
+ * as fixed start and end values for the linear fog.
+ */
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glut.h>
+
+GLint fogMode;
+
+void
+selectFog(int mode)
+{
+ switch(mode) {
+ case GL_LINEAR:
+ glFogf(GL_FOG_START, 1.0);
+ glFogf(GL_FOG_END, 5.0);
+ /* falls through */
+ case GL_EXP2:
+ case GL_EXP:
+ glFogi(GL_FOG_MODE, mode);
+ glutPostRedisplay();
+ break;
+ case 0:
+ exit(0);
+ }
+}
+
+/* Initialize z-buffer, projection matrix, light source,
+ * and lighting model. Do not specify a material property here.
+ */
+void
+myinit(void)
+{
+ GLfloat position[] =
+ {0.0, 3.0, 3.0, 0.0};
+ GLfloat local_view[] =
+ {0.0};
+
+ glEnable(GL_DEPTH_TEST);
+ glDepthFunc(GL_LESS);
+
+ glLightfv(GL_LIGHT0, GL_POSITION, position);
+ glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);
+
+ glFrontFace(GL_CW);
+ glEnable(GL_LIGHTING);
+ glEnable(GL_LIGHT0);
+ glEnable(GL_AUTO_NORMAL);
+ glEnable(GL_NORMALIZE);
+ glEnable(GL_FOG);
+ {
+ GLfloat fogColor[4] =
+ {0.5, 0.5, 0.5, 1.0};
+
+ fogMode = GL_EXP;
+ glFogi(GL_FOG_MODE, fogMode);
+ glFogfv(GL_FOG_COLOR, fogColor);
+ glFogf(GL_FOG_DENSITY, 0.35);
+ glHint(GL_FOG_HINT, GL_DONT_CARE);
+ glClearColor(0.5, 0.5, 0.5, 1.0);
+ }
+}
+
+void
+renderRedTeapot(GLfloat x, GLfloat y, GLfloat z)
+{
+ float mat[4];
+
+ glPushMatrix();
+ glTranslatef(x, y, z);
+ mat[0] = 0.1745;
+ mat[1] = 0.01175;
+ mat[2] = 0.01175;
+ mat[3] = 1.0;
+ glMaterialfv(GL_FRONT, GL_AMBIENT, mat);
+ mat[0] = 0.61424;
+ mat[1] = 0.04136;
+ mat[2] = 0.04136;
+ glMaterialfv(GL_FRONT, GL_DIFFUSE, mat);
+ mat[0] = 0.727811;
+ mat[1] = 0.626959;
+ mat[2] = 0.626959;
+ glMaterialfv(GL_FRONT, GL_SPECULAR, mat);
+ glMaterialf(GL_FRONT, GL_SHININESS, 0.6 * 128.0);
+ glutSolidTeapot(1.0);
+ glPopMatrix();
+}
+
+/* display() draws 5 teapots at different z positions.
+ */
+void
+display(void)
+{
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+ renderRedTeapot(-4.0, -0.5, -1.0);
+ renderRedTeapot(-2.0, -0.5, -2.0);
+ renderRedTeapot(0.0, -0.5, -3.0);
+ renderRedTeapot(2.0, -0.5, -4.0);
+ renderRedTeapot(4.0, -0.5, -5.0);
+ glFlush();
+}
+
+void
+myReshape(int w, int h)
+{
+ glViewport(0, 0, w, h);
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ if (w <= (h * 3))
+ glOrtho(-6.0, 6.0, -2.0 * ((GLfloat) h * 3) / (GLfloat) w,
+ 2.0 * ((GLfloat) h * 3) / (GLfloat) w, 0.0, 10.0);
+ else
+ glOrtho(-6.0 * (GLfloat) w / ((GLfloat) h * 3),
+ 6.0 * (GLfloat) w / ((GLfloat) h * 3), -2.0, 2.0, 0.0, 10.0);
+ 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)
+{
+ glutInit(&argc, argv);
+ glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
+ glutInitWindowSize(450, 150);
+ glutCreateWindow(argv[0]);
+ myinit();
+ glutReshapeFunc(myReshape);
+ glutDisplayFunc(display);
+ glutCreateMenu(selectFog);
+ glutAddMenuEntry("Fog EXP", GL_EXP);
+ glutAddMenuEntry("Fog EXP2", GL_EXP2);
+ glutAddMenuEntry("Fog LINEAR", GL_LINEAR);
+ glutAddMenuEntry("Quit", 0);
+ glutAttachMenu(GLUT_RIGHT_BUTTON);
+ glutMainLoop();
+ return 0; /* ANSI C requires main to return int. */
+}