progs/tests/antialias.c

   1
   2 /*
   3  * Test multisampling and polygon smoothing.
   4  *
   5  * Brian Paul
   6  * 4 November 2002
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <math.h>
  12 #include <GL/glut.h>
  13
  14
  15 static GLfloat Zrot = 0;
  16 static GLboolean Anim = GL_TRUE;
  17 static GLboolean HaveMultisample = GL_TRUE;
  18 static GLboolean DoMultisample = GL_TRUE;
  19
  20
  21 static void
  22 PrintString(const char *s)
  23 {
  24    while (*s) {
  25       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  26       s++;
  27    }
  28 }
  29
  30
  31 static void
  32 Polygon( GLint verts, GLfloat radius, GLfloat z )
  33 {
  34    int i;
  35    for (i = 0; i < verts; i++) {
  36       float a = (i * 2.0 * 3.14159) / verts;
  37       float x = radius * cos(a);
  38       float y = radius * sin(a);
  39       glVertex3f(x, y, z);
  40    }
  41 }
  42
  43
  44 static void
  45 DrawObject( void )
  46 {
  47    glLineWidth(3.0);
  48    glColor3f(1, 1, 1);
  49    glBegin(GL_LINE_LOOP);
  50    Polygon(12, 1.2, 0);
  51    glEnd();
  52
  53    glLineWidth(1.0);
  54    glColor3f(1, 1, 1);
  55    glBegin(GL_LINE_LOOP);
  56    Polygon(12, 1.1, 0);
  57    glEnd();
  58
  59    glColor3f(1, 0, 0);
  60    glBegin(GL_POLYGON);
  61    Polygon(12, 0.4, 0.3);
  62    glEnd();
  63
  64    glColor3f(0, 1, 0);
  65    glBegin(GL_POLYGON);
  66    Polygon(12, 0.6, 0.2);
  67    glEnd();
  68
  69    glColor3f(0, 0, 1);
  70    glBegin(GL_POLYGON);
  71    Polygon(12, 0.8, 0.1);
  72    glEnd();
  73
  74    glColor3f(1, 1, 1);
  75    glBegin(GL_POLYGON);
  76    Polygon(12, 1.0, 0);
  77    glEnd();
  78 }
  79
  80
  81 static void
  82 Display( void )
  83 {
  84    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  85
  86    glColor3f(1, 1, 1);
  87    if (HaveMultisample) {
  88       glRasterPos2f(-3.1, -1.6);
  89       if (DoMultisample)
  90          PrintString("MULTISAMPLE");
  91       else
  92          PrintString("MULTISAMPLE (off)");
  93    }
  94    glRasterPos2f(-0.8, -1.6);
  95    PrintString("No antialiasing");
  96    glRasterPos2f(1.6, -1.6);
  97    PrintString("GL_POLYGON_SMOOTH");
  98
  99    /* multisample */
 100    if (HaveMultisample) {
 101       glEnable(GL_DEPTH_TEST);
 102       if (DoMultisample)
 103          glEnable(GL_MULTISAMPLE_ARB);
 104       glPushMatrix();
 105       glTranslatef(-2.5, 0, 0);
 106       glPushMatrix();
 107       glRotatef(Zrot, 0, 0, 1);
 108       DrawObject();
 109       glPopMatrix();
 110       glPopMatrix();
 111       glDisable(GL_MULTISAMPLE_ARB);
 112       glDisable(GL_DEPTH_TEST);
 113    }
 114
 115    /* non-aa */
 116    glEnable(GL_DEPTH_TEST);
 117    glPushMatrix();
 118    glTranslatef(0, 0, 0);
 119    glPushMatrix();
 120    glRotatef(Zrot, 0, 0, 1);
 121    DrawObject();
 122    glPopMatrix();
 123    glPopMatrix();
 124    glDisable(GL_DEPTH_TEST);
 125
 126    /* polygon smooth */
 127    glEnable(GL_POLYGON_SMOOTH);
 128    glEnable(GL_LINE_SMOOTH);
 129    glEnable(GL_BLEND);
 130    glPushMatrix();
 131    glTranslatef(2.5, 0, 0);
 132    glPushMatrix();
 133    glRotatef(Zrot, 0, 0, 1);
 134    DrawObject();
 135    glPopMatrix();
 136    glPopMatrix();
 137    glDisable(GL_LINE_SMOOTH);
 138    glDisable(GL_POLYGON_SMOOTH);
 139    glDisable(GL_BLEND);
 140
 141    glutSwapBuffers();
 142 }
 143
 144
 145 static void
 146 Reshape( int width, int height )
 147 {
 148    GLfloat ar = (float) width / (float) height;
 149    glViewport( 0, 0, width, height );
 150    glMatrixMode( GL_PROJECTION );
 151    glLoadIdentity();
 152    glOrtho(-2.0*ar, 2.0*ar, -2.0, 2.0, -1.0, 1.0);
 153    glMatrixMode( GL_MODELVIEW );
 154    glLoadIdentity();
 155 }
 156
 157
 158 static void
 159 Idle( void )
 160 {
 161    Zrot = 0.01 * glutGet(GLUT_ELAPSED_TIME);
 162    glutPostRedisplay();
 163 }
 164
 165
 166 static void
 167 Key( unsigned char key, int x, int y )
 168 {
 169    const GLfloat step = 1.0;
 170    (void) x;
 171    (void) y;
 172    switch (key) {
 173       case 'a':
 174          Anim = !Anim;
 175          if (Anim)
 176             glutIdleFunc(Idle);
 177          else
 178             glutIdleFunc(NULL);
 179          break;
 180       case 'm':
 181          DoMultisample = !DoMultisample;
 182          break;
 183       case 'z':
 184          Zrot = (int) (Zrot - step);
 185          break;
 186       case 'Z':
 187          Zrot = (int) (Zrot + step);
 188          break;
 189       case 27:
 190          exit(0);
 191          break;
 192    }
 193    glutPostRedisplay();
 194 }
 195
 196
 197 static void
 198 Init( void )
 199 {
 200    /* GLUT imposes the four samples/pixel requirement */
 201    int s;
 202    glGetIntegerv(GL_SAMPLES_ARB, &s);
 203    if (!glutExtensionSupported("GL_ARB_multisample") || s < 1) {
 204       printf("Warning: multisample antialiasing not supported.\n");
 205       HaveMultisample = GL_FALSE;
 206    }
 207    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 208    printf("GL_SAMPLES_ARB = %d\n", s);
 209
 210    glBlendFunc(GL_SRC_ALPHA, GL_ONE);
 211    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 212    glBlendFunc(GL_SRC_ALPHA_SATURATE, GL_ONE);
 213
 214    glGetIntegerv(GL_MULTISAMPLE_ARB, &s);
 215    printf("GL_MULTISAMPLE_ARB = %d\n", s);
 216 }
 217
 218
 219 int
 220 main( int argc, char *argv[] )
 221 {
 222    glutInit( &argc, argv );
 223    glutInitWindowPosition( 0, 0 );
 224    glutInitWindowSize( 600, 300 );
 225    glutInitDisplayMode( GLUT_RGB | GLUT_ALPHA | GLUT_DOUBLE |
 226                         GLUT_DEPTH | GLUT_MULTISAMPLE );
 227    glutCreateWindow(argv[0]);
 228    glutReshapeFunc( Reshape );
 229    glutKeyboardFunc( Key );
 230    glutDisplayFunc( Display );
 231    if (Anim)
 232       glutIdleFunc( Idle );
 233    Init();
 234    glutMainLoop();
 235    return 0;
 236 }