progs/trivial/tri-scissor-tri.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
  44     glClearColor(0.0, 0.0, 1.0, 0.0);
  45 }
  46
  47 static void Reshape(int width, int height)
  48 {
  49
  50     glViewport(0, 0, (GLint)width, (GLint)height);
  51
  52     glMatrixMode(GL_PROJECTION);
  53     glLoadIdentity();
  54     glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  55     glMatrixMode(GL_MODELVIEW);
  56 }
  57
  58 static void Key(unsigned char key, int x, int y)
  59 {
  60
  61     switch (key) {
  62       case 27:
  63         exit(1);
  64       default:
  65         return;
  66     }
  67
  68     glutPostRedisplay();
  69 }
  70
  71 static void Draw(void)
  72 {
  73    glClear(GL_COLOR_BUFFER_BIT);
  74
  75    glBegin(GL_TRIANGLES);
  76    glColor3f(0,0,.7);
  77    glVertex3f( 0.9, -0.9, -30.0);
  78    glColor3f(.8,0,0);
  79    glVertex3f( 0.9,  0.9, -30.0);
  80    glColor3f(0,.9,0);
  81    glVertex3f(-0.9,  0.0, -30.0);
  82    glEnd();
  83
  84    glScissor(Width / 4, Height / 4, Width / 2, Height / 2);
  85    glEnable(GL_SCISSOR_TEST);
  86
  87    glBegin(GL_TRIANGLES);
  88    glColor3f(0,0,.7);
  89    glVertex3f(-0.9, -0.9, -30.0);
  90    glColor3f(.8,0,0);
  91    glVertex3f(-0.9,  0.9, -30.0);
  92    glColor3f(0,.9,0);
  93    glVertex3f( 0.9,  0.0, -30.0);
  94    glEnd();
  95
  96    glDisable(GL_SCISSOR_TEST);
  97
  98    glFlush();
  99
 100    if (doubleBuffer) {
 101       glutSwapBuffers();
 102    }
 103 }
 104
 105 static GLenum Args(int argc, char **argv)
 106 {
 107     GLint i;
 108
 109     doubleBuffer = GL_FALSE;
 110
 111     for (i = 1; i < argc; i++) {
 112         if (strcmp(argv[i], "-sb") == 0) {
 113             doubleBuffer = GL_FALSE;
 114         } else if (strcmp(argv[i], "-db") == 0) {
 115             doubleBuffer = GL_TRUE;
 116         } else {
 117             fprintf(stderr, "%s (Bad option).\n", argv[i]);
 118             return GL_FALSE;
 119         }
 120     }
 121     return GL_TRUE;
 122 }
 123
 124 int main(int argc, char **argv)
 125 {
 126     GLenum type;
 127
 128     glutInit(&argc, argv);
 129
 130     if (Args(argc, argv) == GL_FALSE) {
 131         exit(1);
 132     }
 133
 134     glutInitWindowPosition(100, 0); glutInitWindowSize(Width, Height);
 135
 136     type = GLUT_RGB;
 137     type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
 138     glutInitDisplayMode(type);
 139
 140     if (glutCreateWindow("First Tri") == GL_FALSE) {
 141         exit(1);
 142     }
 143
 144     Init();
 145
 146     glutReshapeFunc(Reshape);
 147     glutKeyboardFunc(Key);
 148     glutDisplayFunc(Draw);
 149     glutMainLoop();
 150         return 0;
 151 }