View Full Version : Texturing - Shaders / Specular, reflective etc. maps
07-21-2005, 07:53 PM
Can anyone tell me the difference between shaders and the various maps used in texturing - specular, reflection, and diffuse etc.
I've been reading Leigh Van Der Byl's fab tutorial on texturing for dummies, and although the texturing side of things is clearer, I'm more confused about exactly what shaders are for given all the information texture maps can hold.
Leigh also talks about using shaders in conjunction with maps (the BRDF shader to give 2 levels of specularity for example). I'm not entirely sure what he means by that - how do the two (shader and map) work together?
07-21-2005, 07:59 PM
OK, reading through, this question has partly been answered in the "Difference between shader and material" thread a bit further down, but I'm still slightly confused.
I use mainly use Maya, and occasionally 3DS Max - if I put all the reflective/specular/diffuse info in texture maps, can I not use shaders at all? Or is that a horrendous oversimplification?
It was mentioned that shaders do SSS work. Do the shaders depend on the renderer, or are shaders universal? In Maya I use Mental Ray (thinking about going to RenderMan when support for 6.5 comes out) and in 3DS, Brazil. Will I have to use different shaders in each to get the same effect?
07-21-2005, 08:07 PM
shaders are code that gather information from the scene elements to generate a certain look, you can bake certain more static elements but things like reflection are different at different angles. :)
They are largely depenndant on the renderer you use but if you can code you'll be able to use the renderman shading language in several, don't know baout Mental Ray though, but I believe not.
07-21-2005, 08:26 PM
Excellent thanks. Will check to see if there's a renderman SDK available.
07-21-2005, 08:41 PM
A shader is something you add to your scene to produce color. Depending on the 3d app you're using a shader can also mean the same thing as a material, which usually refers to the way a surface reflects light at the camera to produce its final color. Maps are ways of modulating the look of the shaders properties. So for example, a Blinn shader with no maps looks one way. If you add a color map, then it'll look the same except the color will shift depending on the map you've used. If you add a specularity map, then it'll again look the same except instead of a big highlight you'll get a highlight that appears stronger and weaker depending on the greyscale values of the map you've applied.
Each renderer / 3d app has a slightly different way of looking at shaders, so a Blinn shader in max may have more or less maps than a blinn shader in maya, but at the basic algorithm level they should be the same, it's up to each system to decide how much control they give the user. So if you're using different renderers and want the same look, use the same named shaders, but it won't be a 1 to 1 correspondence since they're not identical from a code perspective. But you should be able to get close.
07-22-2005, 09:18 PM
Thanks Neil, that was very helpful. I'll be doing most of the stuff in Maya, only going to Max when I absolutely have to, so it shouldn't be too much of a problem.
07-22-2005, 09:18 PM
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