How did you arrive at the constant 6.28f in the below lines

onst int kSegments = 30;
const GLfloat kRadianIncr = 6.28f/kSegments;

GLfloat d;

float p1x=0.0;
float p1y=0.0;
float p1z=0.0;

const float p1radius = 8.0;
const float p2radius = 8.0;
float yRotationAngle = 0.0f;
int k=0,l=0;
float p2x=0.0;
float p2y=0.0;
float p2z=0.0;

void collision (void) {
d = sqrt(((p1x – p2x) * (p1x – p2x)) + ((p1y – p2y) * (p1y – p2y))+ ((p1z – p2z) * (p1z – p2z)));
}

void pointz (void) {
glPushMatrix();
if (d 2.0)
k=1;
if(p1x2.0)
l=1;
if(p2y 360.0f) // If we have rotated beyond 360 degrees (a full rotation)
yRotationAngle -= 360.0f; // Subtract 360 degrees off of our rotation

}

void reshape (int w, int h) {
glViewport (0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
gluPerspective (60, (GLfloat)w / (GLfloat)h, 1.0, 100.0);
glMatrixMode (GL_MODELVIEW);
}

void keyboard (unsigned char key, int x, int y) {
if (key==’q') {
p1z = p1z – 0.1;
}

if (key==’z') {
p1z = p1z + 0.1;
}

if (key==’w') {
p1y = p1y + 0.1;
}

if (key==’s') {
p1y = p1y – 0.1;
}

if (key==’a') {
p1x = p1x – 0.1;
}

if (key==’d') {
p1x = p1x + 0.1;
}

if (key==’i') {
p2y = p2y + 0.1;
}

if (key==’k') {
p2y = p2y – 0.1;
}

if (key==’j') {
p2x = p2x – 0.1;
}

if (key==’l') {
p2x = p2x + 0.1;
}

if (key==27) { //27 is the ascii code for the ESC key
exit (0); //end the program
}
}

int main (int argc, char **argv) {
glutInit (&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE); //set up the double buffering
glutInitWindowSize (500, 500);
glutInitWindowPosition (100, 100);
glutCreateWindow (“A basic OpenGL Window”);
glutDisplayFunc (display);
glutIdleFunc (display);
glutReshapeFunc (reshape);
glutKeyboardFunc (keyboard);//the call for the keyboard function.
glutMainLoop ();
return 0;
}
but there is no collision?
plz clear me this topic.
thanks in advance.
“

static void drawCircle (int r) {
CIRCLE circle;
glBegin(GL_LINE_LOOP);
int i = 0;
const int kSegments = 30;
const GLfloat kRadianIncr = 6.28f/kSegments;
for (i = 0; i < kSegments; i++)
{
GLfloat angleRadians = kRadianIncr*i;
circle.x = r * cos(angleRadians);
circle.y = r * sin(angleRadians);
glVertex3f(circle.x,circle.y,0);
}
glEnd();
}

Yes you can, but the point of this tutorial is to show you don’t need a third party library to make these shapes. This also gives you more control, you can put this inside of a VBO easily, unlike glu methods.

Cheers,
Swiftless

Cheers, o.

Sure, just make sure you add a glVertex call before and after the loop to set the start and end points.

Cheers,
Swiftless