Are hand made bounds necessary?

[Duion]

I noticed in many of the classic Torque3D assets there is often a manually created bounds object in the model file, it is a cube with a custom material that encases the whole model.

From what I know the bounds object is used to calculated the LODing and in case of the player the collisions.

But I never create those bound objects and it works just fine, it seems to do that automatically.

So is there any benefit in generating bounds by hand?

[LukasPJ]

I guess one thing could be to shrink or grow it? Eg. Excluding some part of the model from the bounds computation?

Edit: in the case of the player, it might be excluding a sword from the bounds, so it doesn't collide with walls?

[Duion]

When the bounds are off you get console warning messages, as there are some in the default template with the turret I think, it constantly spams the console. "bounds exceed that of the shape" etc

And player weapons are excluded by default from collision, since they are not part of the player, but items that are picked up. Only in first person you have a retraction point that pseudo collides the weapon with walls, but this does not happen in third person, so it is just a visual thing, maybe you can get it to work in third person as well, but this is another topic.

Yes I could imagine that you could make the bounds smaller to exclude something from the LOD generation. Maybe a house with a big antenna that is very small could be excluded, so the shape does not become unnecessary big in calculating the LOD levels, but I have never seen that in action or being mentioned anywhere.

[Azaezel]

Bounds determin FOV culling, so if for instance you have a mesh which wll during the course of it's animation exeed the first-frame bounds detection algorithm, you'll need to extend to to the farthest set of possible corners to avoid flickering at the edges of the screen and the like.

[Duion]

So it is for animated objects only? But I saw bounds being provided for all prop models, like rocks etc in many of the default assets.

[Timmy]

So it is for animated objects only? But I saw bounds being provided for all prop models, like rocks etc in many of the default assets.

 

I'm pretty sure that is just left overs from the old days before the collada plugin was developed and the old DTS importer required a very strict hierarchy to import properly. As it is now, you only ever gotta worry about that for cases like az mentioned or you like to control the exact size of the bbox manually.

[Duion]

So they are no longer necessary. I noticed that with a lot of stuff in the node hierarchy, however some are still necessary.

Has somebody ever done the work investigating that what is still necessary and what not?