Tips on Lighting & Texturing

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Mike Lorrey
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Tips on Lighting & Texturing

Post by Mike Lorrey »

First off, the Advanced Lighting Model offers some features to the builder that are quite nice, beyond what the standard SL/OS user has been used to. In addition to supporting more light sources being rendered in the viewers field of view, you can do more than flood a volume of a given radius with light now. You can adjust the Field of View of the light source (FOV) to narrow it like a spotlight. A good example of this is the dance floor at the OS Grid event center, which features colored spotlights that project both colored spots on the floor that rotate with the prims that generate the light emissions, but also project IMAGES.
You can apply an image to the light source settings, and by increasing the FOCUS to its max setting, bring the image into focus in the light beam upon land, avatars, or properly textured prims that it falls upon. You can multiply the brightness by overlapping identical light prims projecting the same light settings.
The types of textures on prims you project at matter, because if your texture has an alpha channel, and you are not using a specular texture with it, the light will go right through. Many TGA or PNG textures that do not appear to have any transparency are inadvertently created with alpha channels present, and so prims textured with them won't allow the light projection to fall upon them.
If however, you are using NORMALs (i.e. bumpmaps) and specular textures with your diffuse (regular) textures on the prims, you can capture the light on the prims surface if you set the specular settings highly (each can go as high as 255). Even with high transparency prims, without a graphics program generated specular texture, you can apply a blank white texture to the specular texture channel, and give it settings of 200 or more, and make it reflective/refractive while at the same time transparent.
I will post some images as examples of what can be done with these features.
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Mike Lorrey
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Re: Tips on Lighting & Texturing

Post by Mike Lorrey »

floodlight effects on prims_001.jpg
Okay, included is an example of several prims with different sorts of textures applied and other features implemented. The spotlight in this example is casting the yellow batman "TWH" logo of The Wrong Hands hacktivist group. The spotlight in question has 128 identical lights projecting this image at full brightness, no falloff, full focus.
The round FIC texture is an alpha that is interesting. Some parts of the image catch the light, some do not, The window frame alpha in the middle doesn't catch any of the light at all. The prims top and right have no features added and are plain no-alpha textures (although there are some interesting distinctions when doing this under water).
The prim center bottom is the same texture as the one at the top but has 2 percent transparency applied. It is not catching any of the cast image of the light, but is bright across its surface evenly. The similar prim to the bottom right has no transparency but a 2 percent glow. The bottom left prim is the same as these two but has the same texture applied to the bump map and specular textures, with specular settings both set up to 255. You can see the light faintly through the slight translucency.
I have advanced lighting model on, but not ambient occulsion. The prim center left is interesting. I had failed to make a radial alpha blend texture, but it is a TGA texture, so while it does not have any obvious transparent properties, it does have some odd refractive properties which are more evident when you view the prim from the side, including edge refraction.
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