progs/trivial/line-smooth.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 <math.h>
  26 #include <stdio.h>
  27 #include <string.h>
  28 #include <stdlib.h>
  29 #include <GL/glut.h>
  30
  31
  32 #define CI_OFFSET_1 16
  33 #define CI_OFFSET_2 32
  34
  35
  36 GLenum doubleBuffer;
  37 GLboolean smooth = GL_TRUE;
  38 GLfloat width = 1.0;
  39
  40
  41 static void Init(void)
  42 {
  43    float range[2], aarange[2];
  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    glGetFloatv(GL_LINE_WIDTH_RANGE, aarange);
  48    glGetFloatv(GL_ALIASED_LINE_WIDTH_RANGE, range);
  49    printf("Non-AA line width range: %f .. %f\n", range[0], range[1]);
  50    printf("AA line width range: %f .. %f\n", aarange[0], aarange[1]);
  51 }
  52
  53
  54 static void Reshape(int width, int height)
  55 {
  56    glViewport(0, 0, (GLint)width, (GLint)height);
  57    glMatrixMode(GL_PROJECTION);
  58    glLoadIdentity();
  59    glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  60    glMatrixMode(GL_MODELVIEW);
  61    glLoadIdentity();
  62    glTranslatef(0, 0, -30);
  63 }
  64
  65 static void Key(unsigned char key, int x, int y)
  66 {
  67    switch (key) {
  68    case 'w':
  69       width -= 0.5;
  70       if (width < 0.5)
  71          width = 0.5;
  72       break;
  73    case 'W':
  74       width += 0.5;
  75       break;
  76    case 's':
  77       smooth = !smooth;
  78       break;
  79    case 27:
  80       exit(1);
  81    default:
  82       return;
  83    }
  84    printf("LineWidth: %g\n", width);
  85    glutPostRedisplay();
  86 }
  87
  88
  89 static void Draw(void)
  90 {
  91    float a;
  92
  93    glClear(GL_COLOR_BUFFER_BIT);
  94
  95    glLineWidth(width);
  96
  97    if (smooth) {
  98       glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  99       glEnable(GL_BLEND);
 100       glEnable(GL_LINE_SMOOTH);
 101    }
 102
 103    glColor3f(1, 1, 1);
 104
 105    glBegin(GL_LINES);
 106    for (a = 0; a < 3.14159; a += 0.2) {
 107       float x = .9 * cos(a);
 108       float y = .9 * sin(a);
 109
 110       glVertex2f(-x, -y);
 111       glVertex2f( x,  y);
 112    }
 113    glEnd();
 114
 115    glDisable(GL_LINE_SMOOTH);
 116    glDisable(GL_BLEND);
 117
 118    glFlush();
 119
 120    if (doubleBuffer) {
 121       glutSwapBuffers();
 122    }
 123 }
 124
 125 static GLenum Args(int argc, char **argv)
 126 {
 127    GLint i;
 128
 129    doubleBuffer = GL_FALSE;
 130
 131    for (i = 1; i < argc; i++) {
 132       if (strcmp(argv[i], "-sb") == 0) {
 133          doubleBuffer = GL_FALSE;
 134       } else if (strcmp(argv[i], "-db") == 0) {
 135          doubleBuffer = GL_TRUE;
 136       } else {
 137          fprintf(stderr, "%s (Bad option).\n", argv[i]);
 138          return GL_FALSE;
 139       }
 140    }
 141    return GL_TRUE;
 142 }
 143
 144
 145 int main(int argc, char **argv)
 146 {
 147    GLenum type;
 148
 149    glutInit(&argc, argv);
 150
 151    if (Args(argc, argv) == GL_FALSE) {
 152       exit(1);
 153    }
 154
 155    glutInitWindowPosition(0, 0); glutInitWindowSize( 250, 250);
 156
 157    type = GLUT_RGB;
 158    type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
 159    glutInitDisplayMode(type);
 160
 161    if (glutCreateWindow(argv[0]) == GL_FALSE) {
 162       exit(1);
 163    }
 164
 165    Init();
 166
 167    glutReshapeFunc(Reshape);
 168    glutKeyboardFunc(Key);
 169    glutDisplayFunc(Draw);
 170    glutMainLoop();
 171    return 0;
 172 }