Textures
There is no facility to make textures directly in Second Life™. External software, typically Adobe Photoshop® is used, although most image editors can be used.
You can upload textures that are:
- TGA, PNG, BMP and JPG - although on upload they are all converted to jpeg2000
- have sides which are powers of 2 pixels long in the range 32-1024
- not necessarily square: 32 X 1024 is fine for making a banner.
TGA files are preferred because you get less corruption during conversion to jpeg2000.
TGA transparency is achieved by an alpha channel. Only one alpha channel per file, otherwise things get confused! Shading from 0-255 (black to white) in the channel gives variable levels of transparency with 0 being wholly transparent, 255 being solid. It is the only format which allows transparency information to be uploaded - although PNG files support this it is ignored by the conversion process.
Second Life (along with just about everything else) suffers alpha-sorting problems: it's a weakness of the graphic card rather than Second Life although it is more commonly observed in Second Life because builders don't recognise the problem. Surfaces close to each other than each contain alpha channels (even if the alpha channel is completely white) will "flicker" and appear to fight for position. This is largely unavoidable for translucent curtains in front of windows, but means you should avoid alpha channels unless you are going to use them and it can make building tricky (plants, windows, curtains etc.).
Creating clothes and skins for Second Life (usually) involves photoshop as well (there are clothes, particularly skirts, which are made from prims. Hair is almost always prims these days, although new residents wear “Linden Hair”). The skin and clothes layers are created on templates available from Chip Midnight, Robin Wood or Linden Lab. The first two sets are 1024 X 1024, the Linden Lab set is 512 X 512. Final clothes and skin textures should be converted to 512 X 512 pixels before uploading: internally all clothes layers are converted to this size if necessary then composited and sent to the client for rendering as a single 512 X 512 texture for each of the 3 parts (lower body, upper body, head).
Tips and tricks:
- Smaller textures load faster - less "grey" time.
- Texture sheets will all load at once - this can make a whole building or a whole piece of furniture rez in at once - but there will be longer grey time.
- The more MB of textures you use the harder you make the viewer's computer work
- Textures have three levels of detail that roughly correspond to:
- far
- medium
- near
- Only when viewing the "near" texture will you be able to read text etc.
- All three of these will be sent to your machine in that order and will show in that order
- Prims rez from near to far and Second Life uses object culling: a nearby notice board should load before something in the background. Large nearby objects will speed rezzing at first because they will occlude distant objects and prevent them rezzing.
- If a texture is already in the client's cache it will load at full resolution as soon as the signal to draw it is processed
- This means, if you use the notice board approach or similar, you may want to use core textures from your main build to speed rezzing of the main build when it becomes visible. These textures could be on the top, bottom, or inside of hollowed prim that is not normally visible.
- Alpha textures almost always come with a halo because the mapping is not 100% precise in the bitmap. Simply adding a solid background in a neutral colour similar to the bulk of the texture on one base layer can overcome this, particularly for textures which do not have much colour variation. The Flaming Pear Solidify A, B and C filters (under free downloads) can automatically create a more immediately colour-matched halo by "smearing" the colours of the design a little so they overlie the halo.
- In discussion, someone asked how you can make a texture lighter in Second Life. You can't is the simple answer, only darker. It is worth creating your textures (particularly ones with the same colour throughout) lighter and less intense in colour (or even white) than required for their current activity and then colouring them in world. This will, for many textures, allow you to reuse them in other settings too.
- In similar vein, the Second Life client tries quite hard to shadow textures and change their colours according to the sun's position. If you want your buildings to have consistent shadows and highlights, don't set the building to fullbright - which makes them always look as if they're lit by the noon sun. However, fullbright is excellent for important signs: it makes them stand out from the rest of the material except at noon and ensures they are always easily legible, even at midnight.
Although not strictly a tips and tricks for the texture-savvy, this blog post about importing presentations for the non-expert contains a lot of useful information and could well be useful to point your teaching staff at too!
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