Progress update and questions about collision in 3DS Max

[DreamBliss]

OK so I sat down tonight and tried again. Windows 7 64-bit Ultimate. 3DS Max 2010 32-bit. Using the CWE 9.02 Max 2010 plugins.

Did some experimentation. Made an octagonal floor - base of a shape similar to the huts I made years ago. Duplicated my shape, extruded it about 2 units (Max units set to feet, grid units to 128), placed it under the floor, then hid it. Wanted to test that too. Made the rest of the room shape, then made a sort of single surrounding wall for the flat wall part of the room shape. Didn't bother making collision for the ceiling. Loaded it, sequence number issues, archived all previous ages I built, loaded, black screen, had to crash out, Drizzled it again (apparently necessary after removing the other ages I made), loaded up, perfect. Collision on floor and along walls. Hidden collision objects attached to ignore NoShow worked perfectly. Only one issue, I used exact collision for the type. So now to the question part of this thread...

I understand now that we use terrain proxies for collision. I can also guess that exact collision uses whatever exact shape you made. But the shape has to be a closed object. I mean it can be a closed object around a hollow center or a closed object around a closed center, but it has to be a closed object with thickness (2 sides.) So you can't use a plane or anything that is open like a hollow room with single inward facing sides. The only exception is terrain - it can be a plane I think (I believe this was one of the first things I tried.) Do I have this about right?

OK now we step into the area I'm not sure about... Christopher said something like, "a hull uses the outside bounding box..." Could someone elaborate? He also said that using exact collision could slow things down. He suggested I use proxies for larger ages. I assume this means, using my round hut object as an example, I would have to make a bunch of overlapping squares in a ring around the object, setting them all to box?

I want to get this straight in my head, because I have been, up to now, a shape modeller. That is I don't use box modeling techniques. I draw shapes and extrude them. But I may need to change my approach here for the quickest, most efficient way to deal with making collision as I build an age. Can't really do shape modeling without spending lots of additional time making terrain proxy boxes for everything. Really have to be able to figure out how to model and make my collision as I go. If I start a video tutorial series as I intend, I need to be sure to teach the quickest, best and most efficient means of age building with all needed collision and game objects. So if you could help me understand the specifics of each collision type I would appreciate it! We need a WIKI page for this anyway, as the subject is not covered. If nobody else wants to write it, I would be wiling to, provided I have been properly instructed and understand the subject well enough.

OK, I'm really tired. Going to bed...

[Luna]

There is something on the wiki about it here -> http://www.guildofwriters.org/wiki/Max: ... collisions. Afaik it doesn't have to be a terrain, that's just the example.

Exact should follow the model, even when it's hollow. I'm wondering whether you may have had problems with the normals of the faces. A face has collision on the side the normal is pointing from.
Hull : Let's say I have a donut and wrap it into paper. You would only see the donut's outside shape, not the hole inside. That is what a hull collider does. It's an easy way to use a collider with less polygons than your exact model so it has a better perfomance.

Proxies I'm not sure about, but Cristopher may mean that for complicated objects it's better to make a simple low polygon model of the object and use that as collider. For example with your round hut, you could make a cylinder that isn't as "round" and doesn't follow the shape exactly, but close enough to serve. With "use alternate shape" you can tell the engine to use the cylinder for collision. You only need to make sure the cylinder is invisible in game. Because the alternate shape has less polygons the physics calculations are less heavy for the engine and computer.

[tachzusamm]

I understand now that we use terrain proxies for collision. I can also guess that exact collision uses whatever exact shape you made. But the shape has to be a closed object. I mean it can be a closed object around a hollow center or a closed object around a closed center, but it has to be a closed object with thickness (2 sides.) So you can't use a plane or anything that is open like a hollow room with single inward facing sides. The only exception is terrain - it can be a plane I think (I believe this was one of the first things I tried.) Do I have this about right?

Actually, those collision meshes behave a bit strange. Difficult to explain, but let me try.
First, let's talk about building for URU CC. Normally, a single plane would be sufficient; but under some circumstances, they don't work well. In fact, they do give collision, but sometimes they appear in the Age in a slightly different location than they have in the design file (either Max or Blender). Really confusing, because you can barely find out what's wrong when you don't get collision where you expect it - and you can't see the objects in the Age. This happens with a chance of 100% if you're using subworlds - but if can happen as well in normal Ages. So, using always volumes (closed meshes) is a good idea, and you're good to go.
Planes as terrain in normal Ages work well, but in Subworlds they surely fail.

Now, if you're building for MOUL, I've heard that in this case single planes are sufficient. Tzar Hoikas said something about that some while ago, if I remember correctly. Maybe he can enlighten us. I'm not sure if it's a better idea to use volumes as coliders in MOUL as well - but I assume it will not be a problem.

This wiki page gives valuable information, even if you use Max (because a mesh is still a mesh):
http://www.guildofwriters.org/wiki/SubWorlds

[Christopher]

He also said that using exact collision could slow things down. He suggested I use proxies for larger ages. I assume this means, using my round hut object as an example, I would have to make a bunch of overlapping squares in a ring around the object, setting them all to box?

Imagine you have a high poly tree with a lot of leaves. You don't want your avatar to collide with every single leave. So you make a proxy consisting of a Cylinder around the trunk and a Sphere around the Top. This way the engine has a lot less physix-calculations to do and the game runs smoother.

Christopher

[DreamBliss]

OK, thank you for the links, read and saved them.

It looks as if I was wrong, collision in Max seems to be covered. But I would still like to see an entire WIKI page dedicated to exhaustively covering collision in Max, and specifically for Max. You know something with pictures and examples of each type, where they are best used, differences, if any, between MOUL and Uru CC. This subject threw me off a little when I started, and I have some experienced with this sort of thing. Imagine what a newcomer to age building must feel like! But you guys (and girls, as applicable) have all been awesome! Thank you.

Well I'm off to see if I can get Blender and PyPRP to work. Then I owe Christopher some experimentation to get the Destiny Client running properly on my machine. Busy busy busy...

Thanks again everyone!