progs/tests/antialias.c

   1 /* $Id: antialias.c,v 1.2 2003/03/29 16:42:57 brianp Exp $ */
   2
   3 /*
   4  * Test multisampling and polygon smoothing.
   5  *
   6  * Brian Paul
   7  * 4 November 2002
   8  */
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <math.h>
  13 #include <GL/glut.h>
  14
  15
  16 static GLfloat Zrot = 0;
  17 static GLboolean Anim = GL_TRUE;
  18 static GLboolean HaveMultisample = 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       PrintString("MULTISAMPLE");
  90    }
  91    glRasterPos2f(-0.8, -1.6);
  92    PrintString("No antialiasing");
  93    glRasterPos2f(1.6, -1.6);
  94    PrintString("GL_POLYGON_SMOOTH");
  95
  96    /* multisample */
  97    if (HaveMultisample) {
  98       glEnable(GL_DEPTH_TEST);
  99       glEnable(GL_MULTISAMPLE_ARB);
 100       glPushMatrix();
 101       glTranslatef(-2.5, 0, 0);
 102       glPushMatrix();
 103       glRotatef(Zrot, 0, 0, 1);
 104       DrawObject();
 105       glPopMatrix();
 106       glPopMatrix();
 107       glDisable(GL_MULTISAMPLE_ARB);
 108       glDisable(GL_DEPTH_TEST);
 109    }
 110
 111    /* non-aa */
 112    glEnable(GL_DEPTH_TEST);
 113    glPushMatrix();
 114    glTranslatef(0, 0, 0);
 115    glPushMatrix();
 116    glRotatef(Zrot, 0, 0, 1);
 117    DrawObject();
 118    glPopMatrix();
 119    glPopMatrix();
 120    glDisable(GL_DEPTH_TEST);
 121
 122    /* polygon smooth */
 123    glEnable(GL_POLYGON_SMOOTH);
 124    glEnable(GL_LINE_SMOOTH);
 125    glEnable(GL_BLEND);
 126    glPushMatrix();
 127    glTranslatef(2.5, 0, 0);
 128    glPushMatrix();
 129    glRotatef(Zrot, 0, 0, 1);
 130    DrawObject();
 131    glPopMatrix();
 132    glPopMatrix();
 133    glDisable(GL_LINE_SMOOTH);
 134    glDisable(GL_POLYGON_SMOOTH);
 135    glDisable(GL_BLEND);
 136
 137    glutSwapBuffers();
 138 }
 139
 140
 141 static void
 142 Reshape( int width, int height )
 143 {
 144    GLfloat ar = (float) width / (float) height;
 145    glViewport( 0, 0, width, height );
 146    glMatrixMode( GL_PROJECTION );
 147    glLoadIdentity();
 148    glOrtho(-2.0*ar, 2.0*ar, -2.0, 2.0, -1.0, 1.0);
 149    glMatrixMode( GL_MODELVIEW );
 150    glLoadIdentity();
 151 }
 152
 153
 154 static void
 155 Idle( void )
 156 {
 157    Zrot = 0.01 * glutGet(GLUT_ELAPSED_TIME);
 158    glutPostRedisplay();
 159 }
 160
 161
 162 static void
 163 Key( unsigned char key, int x, int y )
 164 {
 165    const GLfloat step = 1.0;
 166    (void) x;
 167    (void) y;
 168    switch (key) {
 169       case 'a':
 170          Anim = !Anim;
 171          if (Anim)
 172             glutIdleFunc(Idle);
 173          else
 174             glutIdleFunc(NULL);
 175          break;
 176       case 'z':
 177          Zrot = (int) (Zrot - step);
 178          break;
 179       case 'Z':
 180          Zrot = (int) (Zrot + step);
 181          break;
 182       case 27:
 183          exit(0);
 184          break;
 185    }
 186    glutPostRedisplay();
 187 }
 188
 189
 190 static void
 191 Init( void )
 192 {
 193    /* GLUT imposes the four samples/pixel requirement */
 194    int s;
 195    glGetIntegerv(GL_SAMPLES_ARB, &s);
 196    if (!glutExtensionSupported("GL_ARB_multisample") || s < 1) {
 197       printf("Warning: multisample antialiasing not supported.\n");
 198       HaveMultisample = GL_FALSE;
 199    }
 200    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 201    printf("GL_SAMPLES_ARB = %d\n", s);
 202
 203    glBlendFunc(GL_SRC_ALPHA, GL_ONE);
 204    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 205    glBlendFunc(GL_SRC_ALPHA_SATURATE, GL_ONE);
 206
 207    glGetIntegerv(GL_MULTISAMPLE_ARB, &s);
 208    printf("GL_MULTISAMPLE_ARB = %d\n", s);
 209 }
 210
 211
 212 int
 213 main( int argc, char *argv[] )
 214 {
 215    glutInit( &argc, argv );
 216    glutInitWindowPosition( 0, 0 );
 217    glutInitWindowSize( 600, 300 );
 218    glutInitDisplayMode( GLUT_RGB | GLUT_ALPHA | GLUT_DOUBLE |
 219                         GLUT_DEPTH | GLUT_MULTISAMPLE );
 220    glutCreateWindow(argv[0]);
 221    glutReshapeFunc( Reshape );
 222    glutKeyboardFunc( Key );
 223    glutDisplayFunc( Display );
 224    if (Anim)
 225       glutIdleFunc( Idle );
 226    Init();
 227    glutMainLoop();
 228    return 0;
 229 }