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Guest Studebaker-Lewis

Editing Mipmaps with alpha

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Hello you chapsI'm having a bit of a problem editing mipmaps.I have got this far:1. Opened the 24-bit BMP in Imagetool2. Created and extracted the mips.3. Edited these, then saved each one as xxx_1.bmp, xxx_2.bmp ...etc.4. Reopened xxx.bmp_0, then added MipMaps, the xxx_1, _2, _3.....bmp's. 5. Saved all this as 8-bit bmp.So far so good. As there's no provision for creating an alpha channel in Imagetool, I change over to DXTBitmap, and open the 8-bit bmp as normal image. The programme recognises the black background as an alpha channel, which shows up in the right hand window.The trouble starts here. If I preview the mips (DXT1) the previewer shows me not my edited mips, but ones obviously created by DXTBitmap, which break the image up too much for my purposes. So no surprise that it doesn't work in FS.It seems to me that I have taken a wrong turning somewhere here. Any offers?As this is my first message here, let me take this opportunity to thank everyone for the unwitting help you have given me so far. I've been looking in for a while now.Jerry

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Hi Jerry,This is my approach to working with alpha channels.I make then in my paint program as an extra channel. This way you can easily add and change them, just like adjusting the normal texture.Then I save the bitmap (with the alpha channel) in a format that ImageTool can read (usually I use PSD, but I have also used TGA before). It must be a format that is able to store the alpha channel of course.If you now open that texture in ImageTool you will see that the alpha channel has automatically been added. Just add the mipmaps and select the correct format (DXT1 or DXT3) and you are ready!

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Thanks, Arno, for the quick reply.Being an "advanced beginner" in Photoshop, this might take me a while to sort out.Jerry

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Not quite there yet, Arno.Reedited the mips in Photoshop, and selected the transparent area, the black one in my case, saved the selection, then saved the mip in 8-bit format.Unfortunately they all appeared completely black in Imagetool. Something amiss there!

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In Photoshop you need to add an extra channel. In the end there must be 4 channels in your image, red, green, blue and an alpha channel. In that last channel you then draw the transparancy information.You can find the channels on one of the tabs (where you also have the layers).PS. I would not advise using 8-bit in Photoshop, DXT textures are 16 bit, so you don't use the full quality.

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OK, Arno, worked fine the second time. I converted the images back into 24-bit. Thanks a lot.Without the editing, the masts would hardly be visible, even from a short distance awayJerry

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