alpha mapping preview

James · Sat Mar 13, 2010 9:22 pm

You could in theory invert the output of a multiply node, as the multiply node outputs a number, that number can then be inverted...

Sat Mar 13, 2010 9:34 pm

James wrote:You could in theory invert the output of a multiply node, as the multiply node outputs a number, that number can then be inverted...

Of course. I was just replying to Roubal's suggestion to just put an invert checkbox on a texture node. You couldn't invert anything other than a texture with that.

James · Sat Mar 13, 2010 10:34 pm

Aah, sorry, didn't look into the context enough.

Sat Mar 13, 2010 11:49 pm

A very useful (IMHO) and time saving thing would be display of the material in the right panel when clicking or overing an input triangle on the mesh node in the graph editor.

Oups, sorry...maybe I should find the right topic to say that.

Sun Mar 14, 2010 7:56 am

Oh, one more thing, regarding normal maps - remember Blender has inverted normalmap axes. While it's possible to fix these manually in Photoshop, native support would be nice. It's no big deal - you just have to invert the red and green channels.

Sun Mar 14, 2010 12:48 pm

MadMinstrel wrote:Oh, one more thing, regarding normal maps - remember Blender has inverted normalmap axes. While it's possible to fix these manually in Photoshop, native support would be nice. It's no big deal - you just have to invert the red and green channels.

I am a Blender user, and I didn't know that. I often make Normal maps in Crazy Bump and use them in Blender, and I have never encountered a problem.

Sun Mar 14, 2010 1:28 pm

This is more a problem of having no real standard as how the normalmap channels are pointing , even worse, ATI and Nvidia had those different implemented which caused that stupid invert red/green channel problem .. same with game engines .. Id Software used the same as nvidia, while Crytek decided to use the ATI way ..
As if there where not enough bad examples like the different ways of where the z axis in most apps is pointing to

radiance · Sun Mar 14, 2010 5:17 pm

I've never used normal maps before,
but i assume the flipping of red/green channels means that the maps are generated in either a lefthanded or righthanded coordinate system ?

eg, maya and octane are Y up, and blender is Z up

Right?

Radiance

Sun Mar 14, 2010 6:08 pm

Nvidia and ATI simply have opposite expectations about the green channel representing the x-axis.
Nvidia assumes its facing downwards while ATI wants it to point upwards.. the reason is not to my knowledge.
Red is mostly untouched, but even that can be messed up by some exotic tools.

One of the better blogs about shader, and specifically normalmaps, is the one of Ben Cloward, one of the guys who wrote the Max Plugin "ShaderFX"..
http://www.bencloward.com/tutorials_normal_maps1.shtml
A bunch of older infos but still quite good

Sun Mar 14, 2010 6:23 pm

If memory serves, in blender R(0..255) is X(-1..1), G(0..255) is Y(-1..1). In most other software R(0..255) is X(1..-1), G(0..255) is Y(1..-1). B(0..255) is Z(0..1) for both blender and others. You should definitely check up on that though, it's just off the top of my head and I'm not really a programmer.