4. Vizatimi i rrethit

Te gjithe primitivat e meparshme qe kemi permendur realizojne ndertimet nepermjet vijave te drejta. Ekzistojne algoritme si Algoritmi I Pikes se Mesit qe mund te konvertoje forma si rrethi dhe figura te tjera hiporbelike.

Theta eshte nje kend 0-360 grad, keshtu qe ne mund te marrim kordinatat (x,y) te pikes pergjate rrethit, pra vetem duke caktuar nje sasi te madhe pikash dhe vizatojme segmente qe i bashkojne, figura do te ngjaje tamam si rreth. Ne shembullin e meposhtem kemi percaktuar 100 pika per vizatimin e rrethit. 

#define PI 3.14

GLint circle_points=100;

void MyCircle2f(GLfloat centerx, GLfloat centery, GLfloat radius){

GLint i;

GLdouble theta;

glBegin(GL_POLYGON);

for(i=0;i<circle_points;i++){

theta=2*PI*i/circle_points; //kendi ne radian

glVertex2f(centerx+radius*cos(theta), centery+radius*sin(theta));

}

glEnd();

}

Shembull:

void Display(void){

glClear(GL_COLOR_BUFFER_BIT); //fshijme te gjitha pixelat me ngjyren e specifikuar

glColor3f(1.0,0.8,0.1);

MyCircle2f(80.,85.,10.);

//vizatojme syte

glBegin(GL_POINTS);

glColor3f(0.0,0.0,0.0);

glVertex2f(77.,88.);

glVertex2f(83.,88.);

glEnd();

//vizatojme trupin poligonal

glColor3f(0.8,0.0,0.9);

glBegin(GL_POLYGON);

glVertex2f(75.,75.);

glVertex2f(85.,75.);

glVertex2f(100.,30.);

glVertex2f(60.,30.);

glEnd();

//vizatojme kembet

glColor3f(1.0,0.0,0.1);

glRectf(70.,5.,75.,30.);

glRectf(80.,5.,90.,30.);

//vizatojme vijat per krahet

glBegin(GL_LINES);

glVertex2f(74.,70.);

glVertex2f(50.,50.);

glEnd();

glBegin(GL_LINES);

glVertex2f(86.,70.);

glVertex2f(110.,50.);

glEnd();

glFlush();

} void init()

{

glClearColor(1.0,0.0,0.0,1.0);

glPointSize(5.0); //percaktojme madhesine e pikave 5 pixela

glViewport(0,0,320,240);

gluOrtho2D(0.0,160.0,0.0,120.0);

}

int main(int argc, char* argv[])

{

glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);

glutInitWindowSize(320,240);

glutCreateWindow("Figure");

init();

glutDisplayFunc(Display);

glutMainLoop();

}

Rezultati i shembullit te mesiperm: