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/* $Id: antialias.c,v 1.1 2002/11/08 18:30:26 brianp Exp $ */
/*
* Test multisampling and polygon smoothing.
*
* Brian Paul
* 4 November 2002
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>
static GLfloat Zrot = 0;
static GLboolean Anim = GL_TRUE;
static GLboolean HaveMultisample = GL_TRUE;
static void
PrintString(const char *s)
{
while (*s) {
glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
s++;
}
}
static void
Polygon( GLint verts, GLfloat radius, GLfloat z )
{
int i;
for (i = 0; i < verts; i++) {
float a = (i * 2.0 * 3.14159) / verts;
float x = radius * cos(a);
float y = radius * sin(a);
glVertex3f(x, y, z);
}
}
static void
DrawObject( void )
{
glLineWidth(3.0);
glColor3f(1, 1, 1);
glBegin(GL_LINE_LOOP);
Polygon(12, 1.2, 0);
glEnd();
glLineWidth(1.0);
glColor3f(1, 1, 1);
glBegin(GL_LINE_LOOP);
Polygon(12, 1.1, 0);
glEnd();
glColor3f(1, 0, 0);
glBegin(GL_POLYGON);
Polygon(12, 0.4, 0.3);
glEnd();
glColor3f(0, 1, 0);
glBegin(GL_POLYGON);
Polygon(12, 0.6, 0.2);
glEnd();
glColor3f(0, 0, 1);
glBegin(GL_POLYGON);
Polygon(12, 0.8, 0.1);
glEnd();
glColor3f(1, 1, 1);
glBegin(GL_POLYGON);
Polygon(12, 1.0, 0);
glEnd();
}
static void
Display( void )
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glColor3f(1, 1, 1);
if (HaveMultisample) {
glRasterPos2f(-3.1, -1.6);
PrintString("MULTISAMPLE");
}
glRasterPos2f(-0.8, -1.6);
PrintString("No antialiasing");
glRasterPos2f(1.6, -1.6);
PrintString("GL_POLYGON_SMOOTH");
/* multisample */
if (HaveMultisample) {
glEnable(GL_DEPTH_TEST);
glEnable(GL_MULTISAMPLE_ARB);
glPushMatrix();
glTranslatef(-2.5, 0, 0);
glPushMatrix();
glRotatef(Zrot, 0, 0, 1);
DrawObject();
glPopMatrix();
glPopMatrix();
glDisable(GL_MULTISAMPLE_ARB);
glDisable(GL_DEPTH_TEST);
}
/* non-aa */
glEnable(GL_DEPTH_TEST);
glPushMatrix();
glTranslatef(0, 0, 0);
glPushMatrix();
glRotatef(Zrot, 0, 0, 1);
DrawObject();
glPopMatrix();
glPopMatrix();
glDisable(GL_DEPTH_TEST);
/* polygon smooth */
glEnable(GL_POLYGON_SMOOTH);
glEnable(GL_LINE_SMOOTH);
glEnable(GL_BLEND);
glPushMatrix();
glTranslatef(2.5, 0, 0);
glPushMatrix();
glRotatef(Zrot, 0, 0, 1);
DrawObject();
glPopMatrix();
glPopMatrix();
glDisable(GL_LINE_SMOOTH);
glDisable(GL_POLYGON_SMOOTH);
glDisable(GL_BLEND);
glutSwapBuffers();
}
static void
Reshape( int width, int height )
{
GLfloat ar = (float) width / (float) height;
glViewport( 0, 0, width, height );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho(-2.0*ar, 2.0*ar, -2.0, 2.0, -1.0, 1.0);
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
}
static void
Idle( void )
{
Zrot = 0.01 * glutGet(GLUT_ELAPSED_TIME);
glutPostRedisplay();
}
static void
Key( unsigned char key, int x, int y )
{
const GLfloat step = 1.0;
(void) x;
(void) y;
switch (key) {
case 'a':
Anim = !Anim;
if (Anim)
glutIdleFunc(Idle);
else
glutIdleFunc(NULL);
break;
case 'z':
Zrot = (int) (Zrot - step);
break;
case 'Z':
Zrot = (int) (Zrot + step);
break;
case 27:
exit(0);
break;
}
glutPostRedisplay();
}
static void
Init( void )
{
/* GLUT imposes the four samples/pixel requirement */
int s;
glGetIntegerv(GL_SAMPLES_ARB, &s);
if (!glutExtensionSupported("GL_ARB_multisample") || s < 1) {
printf("Warning: multisample antialiasing not supported.\n");
HaveMultisample = GL_FALSE;
}
printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
printf("GL_SAMPLES_ARB = %d\n", s);
glBlendFunc(GL_SRC_ALPHA, GL_ONE);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glBlendFunc(GL_SRC_ALPHA_SATURATE, GL_ONE);
}
int
main( int argc, char *argv[] )
{
glutInit( &argc, argv );
glutInitWindowPosition( 0, 0 );
glutInitWindowSize( 600, 300 );
glutInitDisplayMode( GLUT_RGB | GLUT_ALPHA | GLUT_DOUBLE |
GLUT_DEPTH | GLUT_MULTISAMPLE );
glutCreateWindow(argv[0]);
glutReshapeFunc( Reshape );
glutKeyboardFunc( Key );
glutDisplayFunc( Display );
if (Anim)
glutIdleFunc( Idle );
Init();
glutMainLoop();
return 0;
}
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