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