progs/trivial/tri-clear.c

   1 /*
   2  * Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and
   5  * its documentation for any purpose is hereby granted without fee, provided
   6  * that (i) the above copyright notices and this permission notice appear in
   7  * all copies of the software and related documentation, and (ii) the name of
   8  * Silicon Graphics may not be used in any advertising or
   9  * publicity relating to the software without the specific, prior written
  10  * permission of Silicon Graphics.
  11  *
  12  * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF
  13  * ANY KIND,
  14  * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
  15  * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
  16  *
  17  * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR
  18  * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  19  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  20  * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
  21  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  22  * OF THIS SOFTWARE.
  23  */
  24
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <stdlib.h>
  28 #include <GL/glut.h>
  29
  30
  31 #define CI_OFFSET_1 16
  32 #define CI_OFFSET_2 32
  33
  34 GLint Width = 250, Height = 250;
  35
  36 GLenum doubleBuffer;
  37
  38 static void Init(void)
  39 {
  40    fprintf(stderr, "GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
  41    fprintf(stderr, "GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
  42    fprintf(stderr, "GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
  43    fflush(stderr);
  44
  45     glClearColor(0.0, 0.0, 1.0, 0.0);
  46 }
  47
  48 static void Reshape(int width, int height)
  49 {
  50
  51     glViewport(0, 0, (GLint)width, (GLint)height);
  52
  53     glMatrixMode(GL_PROJECTION);
  54     glLoadIdentity();
  55     glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  56     glMatrixMode(GL_MODELVIEW);
  57 }
  58
  59 static void Key(unsigned char key, int x, int y)
  60 {
  61
  62     switch (key) {
  63       case 27:
  64         exit(1);
  65       default:
  66         break;
  67     }
  68
  69     glutPostRedisplay();
  70 }
  71
  72 static void Draw(void)
  73 {
  74    glClear(GL_COLOR_BUFFER_BIT);
  75
  76    glBegin(GL_TRIANGLES);
  77    glColor3f(0,0,.7);
  78    glVertex3f( 0.9, -0.9, -30.0);
  79    glColor3f(.8,0,0);
  80    glVertex3f( 0.9,  0.9, -30.0);
  81    glColor3f(0,.9,0);
  82    glVertex3f(-0.9,  0.0, -30.0);
  83    glEnd();
  84
  85    glEnable(GL_SCISSOR_TEST);
  86    glClearColor(1, 0, 1, 0);
  87    glScissor(Width / 2, Height / 2, Width - Width / 2, Height - Height / 2);
  88    glClear(GL_COLOR_BUFFER_BIT);
  89    glDisable(GL_SCISSOR_TEST);
  90
  91    glFlush();
  92
  93    if (doubleBuffer) {
  94       glutSwapBuffers();
  95    }
  96 }
  97
  98 static GLenum Args(int argc, char **argv)
  99 {
 100     GLint i;
 101
 102     doubleBuffer = GL_FALSE;
 103
 104     for (i = 1; i < argc; i++) {
 105         if (strcmp(argv[i], "-sb") == 0) {
 106             doubleBuffer = GL_FALSE;
 107         } else if (strcmp(argv[i], "-db") == 0) {
 108             doubleBuffer = GL_TRUE;
 109         } else {
 110             fprintf(stderr, "%s (Bad option).\n", argv[i]);
 111             return GL_FALSE;
 112         }
 113     }
 114     return GL_TRUE;
 115 }
 116
 117 int main(int argc, char **argv)
 118 {
 119     GLenum type;
 120
 121     glutInit(&argc, argv);
 122
 123     if (Args(argc, argv) == GL_FALSE) {
 124         exit(1);
 125     }
 126
 127     glutInitWindowPosition(100, 0); glutInitWindowSize( Width, Height);
 128
 129     type = GLUT_RGB;
 130     type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
 131     glutInitDisplayMode(type);
 132
 133     if (glutCreateWindow(*argv) == GL_FALSE) {
 134         exit(1);
 135     }
 136
 137     Init();
 138
 139     glutReshapeFunc(Reshape);
 140     glutKeyboardFunc(Key);
 141     glutDisplayFunc(Draw);
 142     glutMainLoop();
 143         return 0;
 144 }