A Small Question About Displacements

Just a small question about displacement maps, do they count as models? I ask because they don't appear to have any thickness, it doesn't show the actual displacement in Hammer, and they don't block vis. These are all traits of models aren't they?

Ya they really do resemble models. If you look at the cost/performance indicator (bind a key to +showbudget, and press that key in game to see a graphical presentation of the cost of various elements) you will see that displacements have their own bar there, so I guess the answer to your question is no ...

They are however very cheap for the engine to render - a lot cheaper than if you were to create the same kind of terrain using the old triangle method ...

I have had some displacement objects that had... um, well, mass I suppose is the right word for it Wasn't just flat.

Umm ... Care to elaborate on that G.Ballblue? Maybe even show a pic?

bringing one up, hang on

Not flat :razz:

Aha! Well, I do believe that when he said "they have no thickness" he
meant in Hammer - were the acutal displacement doen't show up on the
grid - just in the 3D view. On the grid all you see is the outline of
the base brush of the displacement surface(s) ...

... and they're also flat in game ....

A displacement surface is just a height map, Yes it has no thickness (that is what a height map is. It doesnt block vis, and is not considered csg...it is considered bsp. So yo can clip to it, it wont block vis (thats why its good to put a no draw texture behind it), and it doesnt prevent leaks.

If you have played UT then you know their open maps are just one gigantic room with a height map in it (with props). This is the basic concept that we have to follow when we make displacement surfaces.

And as a little handy feature, we can make a height map in any direction :biggrin: (verry handy for making cliffs)

Umm ... G.Ballblue - what do you mean they are flat in game? They are only flat in game if you don't alter the height of any of the vertices ... But then there would be no point in making a face a displacement - You lost me mate ...

<DIV class=quote>
<DIV class=quotetitle>? quoting Fakedawg</DIV>
<DIV class=quotetext>Umm ... G.Ballblue - what do you mean they are flat in game? They are only flat in game if you don't alter the height of any of the vertices ... But then there would be no point in making a face a displacement - You lost me mate ... </DIV></DIV>

Some are flat.

Some have depth.
I don't really understand why Hammer decides whats flat and what has depth, but you will come across displacements with depth, and some that are flat.

Hey mate, the answer is simple, your making a mistake i made for a bit, make SURE you select all sides of the brush when u create the displacement, if you only select one face then the others vanish.

No, only the sides you want to make a displacement map need to be selected. Otherwise you'll create multiple dismaps, wich isn't always necessary. For most terrain, only the top face is enough. For cliffs, a side and the top face would be a good option. It depends on what you're aiming for.

<DIV class=quote>
<DIV class=quotetitle>? quoting Captain P</DIV>
<DIV class=quotetext>No, only the sides you want to make a displacement map need to be selected. Otherwise you'll create multiple dismaps, wich isn't always necessary. For most terrain, only the top face is enough. For cliffs, a side and the top face would be a good option. It depends on what you're aiming for. </DIV></DIV>
?? but if you do that all other faces become invisible and cannot be textured?

Exactly, and in most circumstances you won't NEED to have the other
sides of the brush visible. As Captain P said, if you were making an
uneven piece of ground, why are you likely to need anything other than
the top surface to be visible? If you do need them visible, you could
make them displacement surfaces too, or you could make another ACTUAL
brush in that location as opposed to a brush with a displacement
surface on it (which stops the brush from blocking VIS, and generally
acts different from a normal brush). There is no hard rule what to do
here, it depends on the circumstances really.