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diff --git a/progs/trivial/tri-z.c b/progs/trivial/tri-z.c
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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+ * Unpublished-- rights reserved under the copyright laws of the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.
+ */
+
+#include <GL/glut.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+static int leftFirst = GL_TRUE;
+
+static struct { GLenum func; const char *str; } funcs[] =
+ {
+ { GL_LESS, "GL_LESS" },
+ { GL_LEQUAL, "GL_LEQUAL" },
+ { GL_GREATER, "GL_GREATER" },
+ { GL_GEQUAL, "GL_GEQUAL" },
+ { GL_EQUAL, "GL_EQUAL" },
+ { GL_NOTEQUAL, "GL_NOTEQUAL" },
+ { GL_ALWAYS, "GL_ALWAYS" },
+ { GL_NEVER, "GL_NEVER" },
+ };
+
+#define NUM_FUNCS (sizeof(funcs) / sizeof(funcs[0]))
+
+static int curFunc = 0;
+static double clearVal = 1.0;
+
+
+static void usage(void)
+{
+ printf("t - toggle rendering order of triangles\n");
+ printf("c - toggle Z clear value between 0, 1\n");
+ printf("f - cycle through depth test functions\n");
+}
+
+
+static void init(void)
+{
+ glEnable(GL_DEPTH_TEST);
+ glClearColor (1.0, 0.0, 0.0, 0.0);
+}
+
+static void drawLeftTriangle(void)
+{
+ /* draw yellow triangle on LHS of screen */
+ glBegin (GL_TRIANGLES);
+ glColor4f(1.0, 1.0, 0.0, 0.75);
+ glVertex3f(0.1, 0.9, -1.0);
+ glVertex3f(0.1, 0.1, -1.0);
+ glVertex3f(0.8, 0.5, 1.0);
+ glEnd();
+}
+
+static void drawRightTriangle(void)
+{
+ /* draw cyan triangle on RHS of screen */
+ glBegin (GL_TRIANGLES);
+ glColor4f(0.0, 1.0, 1.0, 0.75);
+ glVertex3f(0.9, 0.9, 0.0);
+ glVertex3f(0.2, 0.5, 0.0);
+ glVertex3f(0.9, 0.1, 0.0);
+ glEnd();
+}
+
+void display(void)
+{
+ printf("GL_CLEAR_DEPTH = %f GL_DEPTH_FUNC = %s\n",
+ clearVal, funcs[curFunc].str);
+ glClearDepth(clearVal);
+ glDepthFunc(funcs[curFunc].func);
+
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+ if (leftFirst) {
+ drawLeftTriangle();
+ drawRightTriangle();
+ }
+ else {
+ drawRightTriangle();
+ drawLeftTriangle();
+ }
+
+ glFlush();
+}
+
+void reshape(int w, int h)
+{
+ glViewport(0, 0, (GLsizei) w, (GLsizei) h);
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ if (w <= h)
+ gluOrtho2D (0.0, 1.0, 0.0, 1.0*(GLfloat)h/(GLfloat)w);
+ else
+ gluOrtho2D (0.0, 1.0*(GLfloat)w/(GLfloat)h, 0.0, 1.0);
+}
+
+/* ARGSUSED1 */
+void keyboard(unsigned char key, int x, int y)
+{
+ switch (key) {
+ case 'c':
+ case 'C':
+ clearVal = 1.0 - clearVal;
+ glutPostRedisplay();
+ break;
+ case 'f':
+ case 'F':
+ curFunc = (curFunc + 1) % NUM_FUNCS;
+ glutPostRedisplay();
+ break;
+ case 't':
+ case 'T':
+ leftFirst = !leftFirst;
+ glutPostRedisplay();
+ break;
+ case 27: /* Escape key */
+ exit(0);
+ break;
+ default:
+ break;
+ }
+}
+
+/* Main Loop
+ * Open window with initial window size, title bar,
+ * RGBA display mode, and handle input events.
+ */
+int main(int argc, char** argv)
+{
+ glutInit(&argc, argv);
+ glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
+ glutInitWindowSize (200, 200);
+ glutCreateWindow (argv[0]);
+ glutReshapeFunc (reshape);
+ glutKeyboardFunc (keyboard);
+ glutDisplayFunc (display);
+ init();
+ usage();
+ glutMainLoop();
+ return 0;
+}