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