Projectiles in openGL(need help)

[evildotaing]

I want to launch a projectile in openGL where when I click my left mouse button, it would shoot a sphere to the position where I am facing. BUt I already confused about the distance to launch. I use this code to launch projectile but my program crashed.

void CProjectile::render()
{
	glPushMatrix();
	glColor3f(1,1,0);
		glTranslatef(theCamera-> Forward.x  - theCamera-> Position.x  , theCamera->Forward.y - theCamera-> Position.y, theCamera-> Forward.z - theCamera->Position.z);
			drawSphere();
	glPopMatrix();
}

void CProjectile::drawSphere()
{
	glSolidSphere(10,10,10);
}

thePosition is the position of the camera, Forward is the direction I am looking in the camera, am I done it wrong. Please help. Thank you.