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 = 300, Height = 300;
  35
  36 GLenum doubleBuffer;
  37
  38 /* scissor bounds */
  39 static GLint Left, Right, Bottom, Top;
  40
  41
  42 static void Init(void)
  43 {
  44    fprintf(stderr, "GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
  45    fprintf(stderr, "GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
  46    fprintf(stderr, "GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
  47    fflush(stderr);
  48
  49     glClearColor(0.0, 0.0, 1.0, 0.0);
  50 }
  51
  52 static void Reshape(int width, int height)
  53 {
  54     glViewport(0, 0, (GLint)width, (GLint)height);
  55
  56     glMatrixMode(GL_PROJECTION);
  57     glLoadIdentity();
  58     glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  59     glMatrixMode(GL_MODELVIEW);
  60
  61     Width = width;
  62     Height = height;
  63
  64     Left = Width / 4;
  65     Right = Width * 3 / 4;
  66     Bottom = Height / 4;
  67     Top = Height * 3 / 4;
  68 }
  69
  70 static void Key(unsigned char key, int x, int y)
  71 {
  72    int step = 2;
  73    switch (key) {
  74    case 'l':
  75       Left -= step;
  76       break;
  77    case 'L':
  78       Left += step;
  79       break;
  80    case 'r':
  81       Right -= step;
  82       break;
  83    case 'R':
  84       Right += step;
  85       break;
  86    case 'b':
  87       Bottom -= step;
  88       break;
  89    case 'B':
  90       Bottom += step;
  91       break;
  92    case 't':
  93       Top -= step;
  94       break;
  95    case 'T':
  96       Top += step;
  97       break;
  98    case 27:
  99       exit(1);
 100    default:
 101       ;
 102    }
 103
 104    glutPostRedisplay();
 105 }
 106
 107 static void Draw(void)
 108 {
 109    glClear(GL_COLOR_BUFFER_BIT);
 110
 111    glBegin(GL_TRIANGLES);
 112    glColor3f(0,0,.7);
 113    glVertex3f( 0.9, -0.9, -30.0);
 114    glColor3f(.8,0,0);
 115    glVertex3f( 0.9,  0.9, -30.0);
 116    glColor3f(0,.9,0);
 117    glVertex3f(-0.9,  0.0, -30.0);
 118    glEnd();
 119
 120    printf("Scissor %d, %d .. %d, %d\n", Left, Bottom, Right, Top);
 121    glScissor(Left, Bottom, Right-Left, Top-Bottom);
 122    glEnable(GL_SCISSOR_TEST);
 123
 124    glBegin(GL_TRIANGLES);
 125    glColor3f(0,0,.7);
 126    glVertex3f(-0.9, -0.9, -30.0);
 127    glColor3f(.8,0,0);
 128    glVertex3f(-0.9,  0.9, -30.0);
 129    glColor3f(0,.9,0);
 130    glVertex3f( 0.9,  0.0, -30.0);
 131    glEnd();
 132
 133    glDisable(GL_SCISSOR_TEST);
 134
 135    glFlush();
 136
 137    if (doubleBuffer) {
 138       glutSwapBuffers();
 139    }
 140 }
 141
 142 static GLenum Args(int argc, char **argv)
 143 {
 144     GLint i;
 145
 146     doubleBuffer = GL_FALSE;
 147
 148     for (i = 1; i < argc; i++) {
 149         if (strcmp(argv[i], "-sb") == 0) {
 150             doubleBuffer = GL_FALSE;
 151         } else if (strcmp(argv[i], "-db") == 0) {
 152             doubleBuffer = GL_TRUE;
 153         } else {
 154             fprintf(stderr, "%s (Bad option).\n", argv[i]);
 155             return GL_FALSE;
 156         }
 157     }
 158     return GL_TRUE;
 159 }
 160
 161 int main(int argc, char **argv)
 162 {
 163     GLenum type;
 164
 165     glutInit(&argc, argv);
 166
 167     if (Args(argc, argv) == GL_FALSE) {
 168         exit(1);
 169     }
 170
 171     glutInitWindowPosition(100, 0); glutInitWindowSize(Width, Height);
 172
 173     type = GLUT_RGB;
 174     type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
 175     glutInitDisplayMode(type);
 176
 177     if (glutCreateWindow(*argv) == GL_FALSE) {
 178         exit(1);
 179     }
 180
 181     Init();
 182
 183     glutReshapeFunc(Reshape);
 184     glutKeyboardFunc(Key);
 185     glutDisplayFunc(Draw);
 186     glutMainLoop();
 187         return 0;
 188 }