How do I use alpha channels in textures?

~ 0 min
2010-10-27 00:50

Strata Live 3D CX and the Meson platform support using per-pixel alpha transparency in textures. This can be useful, for example, for creating ventiliation grills without using excessive geometry. These are the steps to follow:

1. Use PNG files with transparency for the texture. PNG is the only file format supported by Live 3D that will read in the alpha transparency information.

2. Open or Import the model into Strata Live 3D. Use the Windows > Materials menu item to open the Materials palette. Find the PNG material, and right click on it. Select Web Settings... from the menu.

3. Select 32 bit ARGB bit depth. This tells the viewer that you want to use Alpha channels, so a full 32 bit color representation is required.

Note that if you are using this for a ventillation grill or other repeating pattern like that, it might be a good idea to set the MIP-map setting to "On with Blur" as well. That forces the MIP-level selector to bias toward the lower resolution texture, which can help reduce Moiré patterns.

Pixel-level alpha channels are in addition to material level alpha (which you can change using the Edit... menu item in the Materials palette, or you can animate with a Sequence). And both of these are in addition to Object-level alpha, which you can expose simply by making an object public (right-click the object in the hierarchy view and use the menu items).

One performance note: Using alpha channels of any kind requires that the scene be sorted every scene, to ensure parts layer correctly. This can slow update rate for very large scenes, so use alpha channels only when needed.

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