Alpha Channel In Bump Map?

[|]Citadel[|]

After viewing some textures from Bundlemeshes of other mods; to learn and help me understand some procedures I noticed that there is an Alpha channel thats being used in the normal map file for vehicles, tanks and jets.

Now I realized that the colormap for Bundlemeshes can have an Alpha channel; this channel is the Specular Map.

But what is the Alpha map do or used for in the normal map?

[clivewil]

same thing, specularity. i noticed sometimes dice put the alpha in the _c and sometimes in the _b but i have never seen a different one in both at once. take a look at the UH-60, for the main mesh the alpha is in the _c but for the interior detail maps it's in the _b.

[|]Citadel[|]

there is one, but its for a static mesh. Its the texture for the sandbags.

located: EA GAMES\Battlefield 2\mods\bf2\Objects\staticobjects\military\textures\military_obj_01_de.dds

located: EA GAMES\Battlefield 2\mods\bf2\Objects\staticobjects\military\textures\military_obj_01_deb.dds

The alpha for the detail appears to be a specular map

But the alpha in the normal map appears to look like a Ambient Occlusion and not specular; as the 2 alpha's are completely different from eachother.

A lot of things DICE does is very inconsistent.

But how do you make your textures when you are texturing your jets? I know that you will take your rendered ambient occlusion map and put it onto your color in photoshop. But what about these alpha channels? do you use a spec map for both, always use 2048 x 2048, etc.

[clivewil]

But how do you make your textures when you are texturing your jets?

in my aircraft colour maps, the usual res i use is 2048x1024, DXT5 and the specular alpha goes here too.

the normalmaps i make are at the same res, usually DXT1, no alpha.

there is one, but its for a static mesh. Its the texture for the sandbags.

ah ok, i would have missed that easily because i haven't studied the statics very hard. but i have to wonder if it's any way connected to that weird reflective metallic-looking shader glitch the sandbags always seem to get?

[mschoeldgen[Xww2]]

Afaik the sandbags are the only objects in the game using the BaseDetailNDetailparallaxdetail technique. Thats probably the cause for their strange appearance on newer graphic cards.

And they didn't even fix it in 1.5

[|]Citadel[|]

Alright, note to self: don't use BaseDetailNDetailparallaxdetail

@ clivewil: Thank you for the info.

[Cassio]

Colormap _c

Color + Transparency channel (e.g. for windows)

Normalmap _b

Normal + Specular channel

By using "ColorMapGloss" shader technique you can overwrite the default setting and load the Specular channel from the colormap.

We're using both alpha channels on our Cars. edit: Now not anymore

*fixed post

Edited September 8, 2009 by Cassio

[clivewil]

We're using both alpha channels on our Cars

for what its worth, as soon as you add a normalmap to AlphaEnvMap, it kills the strong reflectivity which is desirable on many glass objects like aircraft canopies. (look at the AH-1Z for example.)

[Cassio]

Ah I did not notice that you loose the strong reflectivity!

However you can get it back partly when you make the glass parts on the normal specular white. (that's what I had @ cars)

The only purpose would be to control some reflectivity on glass then.. which makes the second channel pretty useless...

THX

Edited September 8, 2009 by Cassio

[clivewil]

the hardest part is identifying which material it is in the BF2 editor; it is usually but not always the last in the list for each LoD.

if you select this material in the editor and give it a SpecularStaticGloss value of about 8 and your windows suddenly go dark, you know you have the right material selected and can back it off to a more realistic value like 2 or 2.5.

repeat for each Geom and LoD until they are all set. if i adjust the wrong one, i just set it back to the default 0.15 and try the one above it.

opaque materials work in a similar way; by removing the _b channel you can have super-chrome reflections but obviously you lose the benefit of your normalmap (thanks to satnav for the tip) - for me the advantage of a normalmap outweighs having a chrome look in most cases, but no doubt it will come in handy somewhere

[Cassio]

Trying to summarize my testresults

It's really up to the user if he wants the specularity to load from colormap (ColorMapGloss) or normalmap.

If you want to have transparency however you can decide:

no normalmap = very high gloss | can be tweaked weaker/stronger with specularStaticGloss

white normalmap alpha = gloss

grey normalmap alpha = some gloss

black/no normalmap alpha = no gloss

Very high | White | Black

Hope that's all correct now

Edited September 8, 2009 by Cassio

[|]Citadel[|]

so when it comes to glass, or cockpit glass, its best to have seperate _c textures for it but dont give it normal maps?

[clivewil]

its best to have seperate _c textures for it but dont give it normal maps?

there's no gain in doing that, because it's the technique that determines its appearance so you can just give the glass its own tiny little space on the main texture sheet

[|]Citadel[|]

there's no gain in doing that, because it's the technique that determines its appearance so you can just give the glass its own tiny little space on the main texture sheet

Well I'd prefer for bundlemeshes to have it on the same texture, but I'm just trying to understand Cassio's post. Do you get the best envmap reflections without a yourtexture_b? or did he mean no alpha in the _b?

Edited September 9, 2009 by |]Citadel[|

[mschoeldgen[Xww2]]

look at Cassio's tests. Use the 'AlphaEnvmap' shader and omit any normalmap for the glass. This gives the highest possible gloss. You can then adjust its specularity with the 'specularStaticGloss' property in the editor.

[|]Citadel[|]

thank you