Particle system to make gun and bullet drop screen
Bullets: Use particle system to make bullets fall automatically in the range, without any additional direction of the initial velocity to achieve the natural fall effect, to the ground for the collision of the body to give, and increase the friction coefficient to make the rebound is not so high. In a series of numerical adjustments, such as random size range, etc.
Guns:
Same setup, but reduce the particle count to 1 and give a larger friction coefficient. But since the direction is fixed and very stiff, I k a rotation animation on the original gun, so as to simulate the rotation caused by the thrust of the muzzle still firing the gun.
This simulates a more accurate gravity effect using arithmetic, and will also be more efficient.