Developer's Tip - Textures

Texture Guidelines

Textures are a very important part of your 3D world. They can set the mood, add detail to a model, and basically help make your world look as real as possible. There is no doubt about it, textures are a major part of our worlds. It is important, therefore, to make sure your textures are as lean as possible so that you don't bog down people who visit your world. If your world is too slow then nobody will stay around long enough to see all your hard work. Here are some points to keep in mind while making and using textures:

Texture Size

With the flexibility to add textures larger than 128x128 pixels with versions 3.0+ comes great artistic flexibility. But like Spiderman says, "with great power comes great responsibility" (or something like that…how does it go again, Shamus?). Care must be taken when using large textures for a few reasons. Keep in mind that a 256x256 texture is actually FOUR times larger than a 128x128, and SIXTEEN times larger than a 64x64! So use them only when necessary. Keep in mind how many pixels you are likely to see on the object in world. A small soda can that you walk by will almost never take up more than 64 pixels of your screen; so don't make the texture larger than that…all those pixels would go to waste! Also, keep in mind that most video cards still out there do not support textures larger than 256x256 pixels. If you want to use that lovely 512x512 pixel texture in your favorite grand hall, fine. Keep in mind, though, that if you want everyone to see it at full size, you might want to break it up into four smaller textures.

Another point to keep in mind is that all texture dimensions must be powers of two. Which is to say that they must be 2, 4, 8, 16, 32, 64, 128, 256, etc. They do not have to be square however. Some acceptable texture sizes could be: 128x64 32x256(filmstrip) If any texture's height is any multiple of its width then the texture becomes an animated filmstrip.

So making textures only as large as necessary is important. What else? The number of textures that can be seen at one time is also important. If every texture that is visible at once can fit into your video memory, then your world will run smoothly. If you have a large number of textures that take up more space than available video memory, then your computer needs to constantly swap textures in and out of video memory, which is not as efficient. So if you want your world to run smoothly, don't just dump in every texture that you find. Be selective. Make sure you have enough variety to make it interesting but be careful not to go overboard.

Texture File Size and Compression

Active Worlds uses the .jpg file compression format for all images but texture masks. Most programs allow you to choose the level of compression. High levels of compression will result in a small file but also a low quality image, while low levels of compression will result in higher quality images and larger file sizes. So why compress your textures at all? Well anybody to visit your world will need to download all of your textures. By compressing the file, you can reduce the download time significantly! Also, some programs like Adobe Photoshop save unnecessary information along with the file in jpg format. Make sure to turn off any options like saving thumbnails. In version 5.5 of Photoshop, use the "Save for web" feature instead of "save as". This will produce much smaller jpg file sizes. Additionally, you may want to get a program designed specifically for saving jpegs for the web. There are some free programs available on the internet if you search for jpeg compression utilities.

I hope this document helps you to master the use of textures for a fast beautiful world! Happy building!

-Oleyo :)

If you have a question about building objects that you would like to see answered in this section of the Newsletter, please send it to tstips@activeworlds.com.