progs/trivial/tri-mask-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 GLint Width = 250, Height = 250;
  32 GLenum doubleBuffer;
  33 GLint Win;
  34 GLboolean Rmask = GL_TRUE, Gmask = GL_FALSE, Bmask = GL_TRUE;
  35
  36
  37 static void Init(void)
  38 {
  39    fprintf(stderr, "GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
  40    fprintf(stderr, "GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
  41    fprintf(stderr, "GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
  42    glClearColor(0.0, 0.0, 1.0, 0.0);
  43 }
  44
  45 static void Reshape(int width, int height)
  46 {
  47    glViewport(0, 0, (GLint)width, (GLint)height);
  48    glMatrixMode(GL_PROJECTION);
  49    glLoadIdentity();
  50    glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  51    glMatrixMode(GL_MODELVIEW);
  52 }
  53
  54 static void Key(unsigned char key, int x, int y)
  55 {
  56    switch (key) {
  57    case 'r':
  58       Rmask = !Rmask;
  59       break;
  60    case 'g':
  61       Gmask = !Gmask;
  62       break;
  63    case 'b':
  64       Bmask = !Bmask;
  65       break;
  66    case 27:
  67       glutDestroyWindow(Win);
  68       exit(1);
  69    default:
  70       return;
  71    }
  72    glutPostRedisplay();
  73 }
  74
  75 static void Draw(void)
  76 {
  77    printf("ColorMask = %d, %d, %d\n", Rmask, Gmask, Bmask);
  78    glColorMask(1,1,1,1);
  79
  80    glClear(GL_COLOR_BUFFER_BIT);
  81
  82    /* right triangle: green */
  83    glBegin(GL_TRIANGLES);
  84    glColor3f(0,1,0);
  85    glVertex3f( 0.9, -0.9, -30.0);
  86    glVertex3f( 0.9,  0.9, -30.0);
  87    glVertex3f(-0.9,  0.0, -30.0);
  88    glEnd();
  89
  90    glColorMask(Rmask, Gmask, Bmask, 0);
  91
  92    /* left triangle: white&mask: purple   middle region: white */
  93    glBegin(GL_TRIANGLES);
  94    glColor3f(1,1,1);
  95    glVertex3f(-0.9, -0.9, -30.0);
  96    glVertex3f(-0.9,  0.9, -30.0);
  97    glVertex3f( 0.9,  0.0, -30.0);
  98    glEnd();
  99
 100    glDisable(GL_SCISSOR_TEST);
 101
 102    glFlush();
 103
 104    if (doubleBuffer) {
 105       glutSwapBuffers();
 106    }
 107 }
 108
 109 static GLenum Args(int argc, char **argv)
 110 {
 111    GLint i;
 112
 113    doubleBuffer = GL_FALSE;
 114
 115    for (i = 1; i < argc; i++) {
 116       if (strcmp(argv[i], "-sb") == 0) {
 117          doubleBuffer = GL_FALSE;
 118       }
 119       else if (strcmp(argv[i], "-db") == 0) {
 120          doubleBuffer = GL_TRUE;
 121       }
 122       else {
 123          fprintf(stderr, "%s (Bad option).\n", argv[i]);
 124          return GL_FALSE;
 125       }
 126    }
 127    return GL_TRUE;
 128 }
 129
 130
 131 int main(int argc, char **argv)
 132 {
 133    GLenum type;
 134
 135    glutInit(&argc, argv);
 136
 137    if (Args(argc, argv) == GL_FALSE) {
 138       exit(1);
 139    }
 140
 141    type = GLUT_RGB;
 142    type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
 143
 144    glutInitWindowPosition(100, 0); glutInitWindowSize(Width, Height);
 145    glutInitDisplayMode(type);
 146    Win = glutCreateWindow("First Tri");
 147    Init();
 148    glutReshapeFunc(Reshape);
 149    glutKeyboardFunc(Key);
 150    glutDisplayFunc(Draw);
 151    glutMainLoop();
 152    return 0;
 153 }