Now ya see it ... now ya don't !

[the Carpenter]

Hey ! What's the crow standing on ?

Oh ! It was just an invisible tree !


Anybody know why the tree would disappear like that ?
It's not a max_view issue.
Might it be that I was looking through a clip brush ?
I just dunno ?

Suggestions ?

[stefanhendriks]

Although i am not an expert, i think it somehow has to do with the fact the 'tree' is not visible from that point according to the engine. It probably does some sort of trace or calculation and fails there. Though when you come closer the angle changes and thus the above same calculation succeeds. I think its engine related, but for fun you could try to raise the tree with a few units and see if it happens again. I bet the engine only does a basic check to know if its visible... perhaps you can do something with setting 'size' of this object? THat could also help a bit.

[Pierre-Marie Baty]

Stefan is right in the principle, because I had the same glitch with the OpenGL port of Wolfenstein 3D (in which I put many MD2 models, which are basically the same thing as MDL models). Umm yep, I assume that that tree is a separate entity with a certain model, not a world brush.

To tell whether an entity is visible or not (and thus to decide if it should be drawn or not) one of the first checks the engine does is checking a direct line of sight to each of the model's "bones". These are particular points of the model which can eventually be articulated, in case the model is a skeleton or some sort of moving stuff. The problem is that some modelers just put 1 bone for their static models, which is the minimum for any model to compile successfully ; however with just 1 bone it's very inaccurate to tell that when this bone is visible the whole entity is, and completely wrong to say that when it is no longer visible, the whole entity is no longer visible either.

This is *one* of the reasons that may explain your problem, however I can't guarantee it's the right one. Try adding more bones at different locations in your model (do this with Milkshape 3D, for example) ; then, assign them the right vertices, recompile the .mdl file and try to see if the glitch vanishes or not.

[stefanhendriks]

age, i was almost right. Makes me feel i did not lose my 'touch' yet

[sfx1999]

It's because the tree is not in the PVS. You might want to turn the fence into a func_wall.

[Zacker]

I wrote a article about modelbehaviours a few months ago. You might want to read it at www.thefuture.dk as it relates to your problem.

I have always thought that the engine checked if the origin of the model was visible. Many mappers have had problems with models not showing up from certain angles. Its cool to know it can be fixed by attaching more of the mesh to bones.

Daano and Zyndrone had lots of problems with in Sandstorm and fixed it by lowering the model in the editor and therefore raising the origin.

[>BKA< T Wrecks]

Was that the reason why the pyramid disappeared from sight sometimes, or did this have to do with another problem?

[the Carpenter]

The fence IS a func_wall, already.
Another dude suggested that the tree is simply within another bsp node.
That doesn't explain why the bird is still bisible though.

Here;s what else was posted & it looks like it makes sense to me:

[sfx1999]

It does explain why the bird is still visible, actually. The bird is in a visible node.

You are going to have to find a way to make that node visible.Good luck with that.

One way is to turn the terrain into a func_wall, but that will look like shit.

Another way is to raise the terrain the tree is on upward.

[the Carpenter]

It's been fixed.
Thanks for your input guys.