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/glew.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 static GLboolean DoMultisample = GL_TRUE;
  20
  21
  22 static void
  23 PrintString(const char *s)
  24 {
  25    while (*s) {
  26       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  27       s++;
  28    }
  29 }
  30
  31
  32 static void
  33 doPolygon( GLint verts, GLfloat radius, GLfloat z )
  34 {
  35    int i;
  36    for (i = 0; i < verts; i++) {
  37       float a = (i * 2.0 * 3.14159) / verts;
  38       float x = radius * cos(a);
  39       float y = radius * sin(a);
  40       glVertex3f(x, y, z);
  41    }
  42 }
  43
  44
  45 static void
  46 DrawObject( void )
  47 {
  48    glLineWidth(3.0);
  49    glColor3f(1, 1, 1);
  50    glBegin(GL_LINE_LOOP);
  51    doPolygon(12, 1.2, 0);
  52    glEnd();
  53
  54    glLineWidth(1.0);
  55    glColor3f(1, 1, 1);
  56    glBegin(GL_LINE_LOOP);
  57    doPolygon(12, 1.1, 0);
  58    glEnd();
  59
  60    glColor3f(1, 0, 0);
  61    glBegin(GL_POLYGON);
  62    doPolygon(12, 0.4, 0.3);
  63    glEnd();
  64
  65    glColor3f(0, 1, 0);
  66    glBegin(GL_POLYGON);
  67    doPolygon(12, 0.6, 0.2);
  68    glEnd();
  69
  70    glColor3f(0, 0, 1);
  71    glBegin(GL_POLYGON);
  72    doPolygon(12, 0.8, 0.1);
  73    glEnd();
  74
  75    glColor3f(1, 1, 1);
  76    glBegin(GL_POLYGON);
  77    doPolygon(12, 1.0, 0);
  78    glEnd();
  79 }
  80
  81
  82 static void
  83 Display( void )
  84 {
  85    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  86
  87    glColor3f(1, 1, 1);
  88    if (HaveMultisample) {
  89       glRasterPos2f(-3.1, -1.6);
  90       if (DoMultisample)
  91          PrintString("MULTISAMPLE");
  92       else
  93          PrintString("MULTISAMPLE (off)");
  94    }
  95    glRasterPos2f(-0.8, -1.6);
  96    PrintString("No antialiasing");
  97    glRasterPos2f(1.6, -1.6);
  98    PrintString("GL_POLYGON_SMOOTH");
  99
 100    /* multisample */
 101    if (HaveMultisample) {
 102       glEnable(GL_DEPTH_TEST);
 103       if (DoMultisample)
 104          glEnable(GL_MULTISAMPLE_ARB);
 105       glPushMatrix();
 106       glTranslatef(-2.5, 0, 0);
 107       glPushMatrix();
 108       glRotatef(Zrot, 0, 0, 1);
 109       DrawObject();
 110       glPopMatrix();
 111       glPopMatrix();
 112       glDisable(GL_MULTISAMPLE_ARB);
 113       glDisable(GL_DEPTH_TEST);
 114    }
 115
 116    /* non-aa */
 117    glEnable(GL_DEPTH_TEST);
 118    glPushMatrix();
 119    glTranslatef(0, 0, 0);
 120    glPushMatrix();
 121    glRotatef(Zrot, 0, 0, 1);
 122    DrawObject();
 123    glPopMatrix();
 124    glPopMatrix();
 125    glDisable(GL_DEPTH_TEST);
 126
 127    /* polygon smooth */
 128    glEnable(GL_POLYGON_SMOOTH);
 129    glEnable(GL_LINE_SMOOTH);
 130    glEnable(GL_BLEND);
 131    glPushMatrix();
 132    glTranslatef(2.5, 0, 0);
 133    glPushMatrix();
 134    glRotatef(Zrot, 0, 0, 1);
 135    DrawObject();
 136    glPopMatrix();
 137    glPopMatrix();
 138    glDisable(GL_LINE_SMOOTH);
 139    glDisable(GL_POLYGON_SMOOTH);
 140    glDisable(GL_BLEND);
 141
 142    glutSwapBuffers();
 143 }
 144
 145
 146 static void
 147 Reshape( int width, int height )
 148 {
 149    GLfloat ar = (float) width / (float) height;
 150    glViewport( 0, 0, width, height );
 151    glMatrixMode( GL_PROJECTION );
 152    glLoadIdentity();
 153    glOrtho(-2.0*ar, 2.0*ar, -2.0, 2.0, -1.0, 1.0);
 154    glMatrixMode( GL_MODELVIEW );
 155    glLoadIdentity();
 156 }
 157
 158
 159 static void
 160 Idle( void )
 161 {
 162    Zrot = 0.01 * glutGet(GLUT_ELAPSED_TIME);
 163    glutPostRedisplay();
 164 }
 165
 166
 167 static void
 168 Key( unsigned char key, int x, int y )
 169 {
 170    const GLfloat step = 1.0;
 171    (void) x;
 172    (void) y;
 173    switch (key) {
 174       case 'a':
 175          Anim = !Anim;
 176          if (Anim)
 177             glutIdleFunc(Idle);
 178          else
 179             glutIdleFunc(NULL);
 180          break;
 181       case 'm':
 182          DoMultisample = !DoMultisample;
 183          break;
 184       case 'z':
 185          Zrot = (int) (Zrot - step);
 186          break;
 187       case 'Z':
 188          Zrot = (int) (Zrot + step);
 189          break;
 190       case 27:
 191          exit(0);
 192          break;
 193    }
 194    glutPostRedisplay();
 195 }
 196
 197
 198 static void
 199 Init( void )
 200 {
 201    /* GLUT imposes the four samples/pixel requirement */
 202    int s;
 203    glGetIntegerv(GL_SAMPLES_ARB, &s);
 204    if (!glutExtensionSupported("GL_ARB_multisample") || s < 1) {
 205       printf("Warning: multisample antialiasing not supported.\n");
 206       HaveMultisample = GL_FALSE;
 207    }
 208    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 209    printf("GL_SAMPLES_ARB = %d\n", s);
 210
 211    glBlendFunc(GL_SRC_ALPHA, GL_ONE);
 212    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 213    glBlendFunc(GL_SRC_ALPHA_SATURATE, GL_ONE);
 214
 215    glGetIntegerv(GL_MULTISAMPLE_ARB, &s);
 216    printf("GL_MULTISAMPLE_ARB = %d\n", s);
 217 }
 218
 219
 220 int
 221 main( int argc, char *argv[] )
 222 {
 223    glutInit( &argc, argv );
 224    glutInitWindowPosition( 0, 0 );
 225    glutInitWindowSize( 600, 300 );
 226    glutInitDisplayMode( GLUT_RGB | GLUT_ALPHA | GLUT_DOUBLE |
 227                         GLUT_DEPTH | GLUT_MULTISAMPLE );
 228    glutCreateWindow(argv[0]);
 229    glewInit();
 230    glutReshapeFunc( Reshape );
 231    glutKeyboardFunc( Key );
 232    glutDisplayFunc( Display );
 233    if (Anim)
 234       glutIdleFunc( Idle );
 235    Init();
 236    glutMainLoop();
 237    return 0;
 238 }