The Harvest Moon Consortium

[Pstemarie]

I was having some texture seam issues with a few tiles, and while chatting with OMB I accidentally indexed the Map Channel from "1" to "2". Much to my surprise it resolved the issue I was having.



So what exactly does this Map Channel do?

[Estelindis]

Would you believe that I've never noticed that...?

So, any ideas anyone?

[Pstemarie]

Map Channels

You can control the type of mapping coordinates and the placement of the mapping gizmo for each bitmap in a material that uses multiple bitmaps by assigning explicit map channels to the bitmaps. In the Material Editor you assign each map a different channel number, then you add multiple UVW Map modifiers to the object's modifier stack, each UVW Map modifier is set to a different map channel. To change the type of mapping or gizmo placement for a particular bitmap, you select one of the UVW Map modifiers in the modifier stack and change the parameters. You can change the name of a UVW Map modifier in the Edit Modifier Stack dialog to correlate the modifier to the bitmap.

Someone care to translate

[Christopher]

NWN only supports on channel on meshes. The only way we get around that is alpha textures, or environment textures. That's a fast answer, but basically correct as far as I know.

[Pstemarie]

NWN only supports on channel on meshes. The only way we get around that is alpha textures, or environment textures. That's a fast answer, but basically correct as far as I know.

I'm only using one texture on the meshes - but what I found interesting was the way that changing the map channel seemed to resolve any texture seams that were appearing where two objects (meshes) met.

It would seem that when you add a UVW Map Modifier to all the meshes in a GMAX scene then change the Map Channel, all the textures appear to be remapped in the same scale. Thus, when using the same texture on two adjacent meshes (as in a building that crosses tiles), its a lot easier to get the texture mapping correct - Indeed it would seem GMAX does the correcting for you!

Now I just need someone to confirm my suspicion.

[Pstemarie]

I think I figured out what Map Channels are used for...

It seems that when you modify a UVW Map, GMAX stores the original settings in another channel (the next channel in the index) then overwrites the existing channel (whatever channel you have listed in the box - see image above) with the new UVW coordinates. This function allows you to "reset" a UVW Map if you *bleep* it up by mistake (as I've done too many times to count).

Now for some more testing to confirm my findings...

[Chandigar]

I can translate... I actually had to look it up a bit because I never really use it.

Essentially, each material you create can be assigned to a specific channel. This means that only UVW modifiers (a UVW modifier is a modifier that changes the scale of a texture and its position on an object) with the same channel will apply to that material. In other words, if you create a bark material that is set to channel 2, a UVW modifier applied to that object must also be set to channel 2 or it won't affect the material. FYI, By default, everything is set to channel 1.

How does this apply to NWN? I don't think it does, really.

This is because NORMALLY you can, say, create a cube and use a subobject selection (ie select a single face or side of the cube) and apply a different material to it. If each of those materials has a different channel, you can then select the whole cube, apply a bunch of UVW modifiers on it with different channels and each UVW modifier only affects the material with the same channel.

NWN, on the other hand, doesn't accept multiple materials on the same mesh... you have to break the object up and apply a single standard material to each polygon that you want to be different (as far as I know). In this case, there's no reason to use a map channel because each texture can be channel 1 without any conflicts.

Clearer?

Now, what might have happened is that someone may have built a model using map channels, then broke it up at the end before exporting to NWN. In this case, the channel info may be saved along with the mesh. I assume you imported someone else's models instead of creating your own from scratch? This might be a carryover problem from that.

[Michael DarkAngel]

Now, what might have happened is that someone may have built a model using map channels, then broke it up at the end before exporting to NWN. In this case, the channel info may be saved along with the mesh. I assume you imported someone else's models instead of creating your own from scratch? This might be a carryover problem from that.

This would not be the case. As you said yourself NWN does not allow for multiple textures on a single mesh. Therefore, there would be no reason to save map channel information in the model file.

I could see this happening if it were a saved max file, but not an imported NWN mdl file.


MDA

[Chandigar]

This would not be the case. As you said yourself NWN does not allow for multiple textures on a single mesh. Therefore, there would be no reason to save map channel information in the model file.

I could see this happening if it were a saved max file, but not an imported NWN mdl file.

oh, I assumed pstemarie changed the map channels in the .mdl file and not in gmax. I seem to remember a couple material based vestigial bits in the .mdl file that aren't used in game though... and a lot of the 2da's etc have entries that are no longer in use so its not impossible to imagine a map channel bit in the mdl file thats no longer in use.

[lord rosenkrantz]

I reckon that no matter the material ID set on each face, the engine always considers it ID #1 and applies the texture specified in the "bitmap" field. One can use as many materials in gmax/3dsmax as needed (for ease of modeling for example, like being able to select a specific group of faces at will, based on their material ID), and it'll be safely ignored in game.
Of course, the only mesh type for which material IDs are relevant is the various walkmesh types.