Difference between revisions of "3ds Max: Exporting Transparent Textures"

In most cases these days, us 3D Studio Max modellers use gundalf's exporter, which is a very impressive and nifty tool. Before gundalf created his exporter, we had to use the Civilization IV NIF exporter instead. The Civ4 exporter is a very competent tool, with an amazing set of options... that have no bearing on Oblivion. It does have a few unique capabilities, however.

Another, much more common use of the Civ4 Nif Exporter over gundalf's exporter, is its ability to export transparant textures. The point of them is to give the illusion of complexity without adding to the poly count, and when used appropriately they can yield fantastic results. Bethesda use the method all the time. The leaves of a flower is one case where it's useful, frizzy edges on a rug (which is the example of this tutorial) is another.

Go ahead and open up the tutorial scene in 3D Studio Max. You'll see a top-down view of a rug, which uses textures from the Morrowind texture replacement mod "Morrowind Visual Pack". There are three textures in play; one for the center (Rug01.dds), one for the borders on the long ends (Rug03bd.dds), and one for the frizz on the short ends (RugBD01.dds). If you examine the latter texture you'll see it looks like it has pink paint on it. This is the way the texture's alpha layer looks - the one that creates the transparancy effect.  

On a sidenote, if you would like to learn more about creating your own transparant textures, I'd like to recommend my old [http://silgrad.com/cpo/faq_st_guides/detail.php?nr=415&kategorie=faq_st_guides Morrowind Icon Guide]. I wrote it years ago, for Morrowind modders in mind, on how to create icons for that game - but believe it or not, the same method works for creating transparant textures for use with Oblivion. All made possible by that little gem of a program, DXTBmp, which lets you create transparant DDS textures with a few easy clicks. It's especially handy for those of us - like me - who don't use Photoshop, though I imagine even Photoshop users would find the program has it's advantages.

The program, which is freeware and created by MWGraphics (no relation to Morrowind) can be [http://www.silgrad.com/wbb2/jgs_db.php?action=show&eintrags_id=6&katid=3 downloaded from our database]. Start by creating a texture where the part you want to be transparant is absolutely pitch black. Load it up in DXTBmp. Select "Alpha > Create Alpha Channel (Black)". If you get a popup, press Yes (some file formats, like tga I think, create defunct alpha channels by default, which the program replaces). Now the image is displayed in black and white on the small screen to the upper right. The visible part should be white, the invisible black. Now go to "Alpha > Apply Alpha to Image" and the black part will turn transparant grey in the main window. Lastly, go to "File -> Save as -> DDS Texture". The file format MUST be "DDS DXT1", otherwise it won't work. Presto, you're done.

Right then. If you haven't already, open up the material editor in the tutorial scene and check out the middle material slot, "Tx_Rug_FrizzyEdge". Notice it has two maps set up. Usually when modelling Oblivion models you only set up the Diffuse map, since that's the only one that can be exported. In this case, when we want to export a transparant texture through the Civ4 Nif Exporter, we'll make use of the Opacity map slot too. As you can see, both the diffuse and opacity slot uses Image Alpha as the Alpha Source, *but*, the diffuse slot uses RGB Intensity as the Mono Channel Output whereas the opacity map uses Alpha as the Mono Channel Output. This is what makes it work.