Particle system simulation space

[ZanEtherial]

Hey, it’s yo boi again, with yet another question/problem.

In this lecture at 11:30 Gary wants to make the ballista bolts stop chasing towards the direction where the target enemy is moving.

To do it, he changes the simulation space, from Local to World, so it decouple when it fires and could be now follow a trajectory.

The problem that i have with that, is when i change to world, for some reason the particle now stop collide with the enemy and does not work anymore.

The lecture is getting some years in the back, did Unity changes some behaviours of the particle system in the meantime and now there is some other option to tweak for what Gary wanted to achieve?

[Nina]

Hi Zan,

This is the first time I’m reading about this problem. Since other students don’t seem to experience it, I doubt that Unity changed the behaviour on purpose. It would not make any sense in the gameplay because the simulation space is not supposed to change the general behaviour of a particle, just its ‘origin’.

Check if the Collision module is still enabled.

Which version of Unity do you use? Maybe you are experiencing a bug in your version.

[ZanEtherial]

Yeah seems i need to test further what cause this, and the fact that i’m alone in this, it’s suggesting that i made some questionable and dumb thing somewhere, at first doing just fine but now it is going to bite me.

At this point i’m 99% sure that is my fault.

I will update the situation, hopefully with the solution.

[ZanEtherial]

Yep, totally my fault, again it’s on my OCD…

When we added the collider to the enemies, Gary went to the good old reliable box collider…me? nah…i wanted the same shape of the enemy mesh, we cannot have a box sticking out like paesants so i went for a mesh collider.

It was so good, fits perfectly, wonder why we always go for a box instead of that…

Well, appearently you need to crank up the dimension of the particle collider, otherwise you just constantly miss the target, making all the “doing things with perfect fit” invane, and i’m questioning at this point how the mesh collider actually works and why it is evil…

I’m going in a corner in fetal position for a bit…

[Nina]

Making the collider the same shape as the mesh is not OCD but something that intuitively makes sense. However, the problem is the physics simulation which is optimised for speed, not precision. This is not some ancient knowledge you are born with but something somebody needs to tell you. The more complex the collider is, the more Unity has to calculate and the more likely it is that the simulation will miss a collision, especially when it comes to fast moving objects.

That’s why we try to use the simplest collider whenever possible: the BoxCollider. It is the most performant one and does the job in most cases. The MeshCollider becomes handy if your game requires a more precise shape and if you need an overall shape that cannot be approximated with a BoxCollider. In Argon Assault, nobody will notice if the particle missed the enemy by 2 pixels. Or let’s rather say: We create games for people who are willing to immerse themselves in our fantasy world which comes with its own rules. We don’t create games for people who expect that lasers in games actually fly at the speed of light. (Our fancy particles would not be visible in that case.)

In fact, we fake a lot in games. If you are interested in this subject, do some research on old games that had to run smoothly on weak computers or consoles. You’ll be surprised how many creative solutions exist just for reasons of performance optimisation. And there are also cases where we exaggerate things because copying the real world makes the game feel boring. A popular example is Super Mario’s jump skill.

I hope this made sense and will help you with future decisions in your games.