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Mar 9 10 9:20 PM

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I think it is time for another lesson

I would like to know how to transform some parts of skins (logos, stripes, etc) into aplha channel (I think it is made by "baked" shadow texture from 3D max)...I saw in some mods that aplha channel is used as "template" for specular lighting..if I understand right...

I am a little confused...why it is done together by specular map texture and alpha chanell?? Earlier I thought that you can use specular map texture for specular lighting level or aplha chanell, but now it looks to me that somewhere both metods were used...

please can some g-motor-shaders-guru explain it to me like to a small child? thank you in advance

You might know me as CharleeSkywalker ;-)
3D modeler - Ferrari Dino, BMW 2002Ti, Ferrari 312PB

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Posts: 2,089 Models manager

#1 [url]

Mar 9 10 9:57 PM

as far as i know you can not use a specular mask texture and the alpha channel at same time to control the lighting and the amount of emap reflections. you can use one or the other method.

in fact is a question of performance/detail in my opinion.

if you lock the control of the lighting with one specular mask for all teams
you will save memory , (you can use DX1 or DX3 textures) but all cars will share the same mask,

here performace wins but the detail is not the best one

if you use the alpha channel of the main texture to control the lighting you are forced to use DX5 textures (much more mbytes) but you got the best detail as each car have its own reflections.
here the detail wins instead of performance

option 3
you can use the first one (locked mask) but diferent objects, as example different chassis can have different mask and select them with genstring or with diferent .gens ,

maybe what you saw is this.
in haltransparent materials like the windows you can use the specular mask texture to control lighting and the amount of reflections, more dark , less reflections and the alpha chanel to control the level of transparency , the more darkness more transparency.

you can use the texture that you take from 3dmax (ambient oclusion) when generating backin and use it as alpha chanel , it will need editing because not always the part with more "backing" will have less lighting , it can be a chomed part , or maybe you will have to decrease brightness in plastic parts , dirt....

i usually take one of the RGB colurs of the main texture (that who fits better with what i want in the alpha channel) and edit it a bit.

those are the shaders i use

in 3ds max and recent versions of 3dsimed:

- alpha channel controls the lighting

(cube map add alpha reflect T1) at least this is what i use

- specular mask control the lighting

(cube map specular map add grayscale reflect T1)

in older version of 3dsimed

- alpha channel controls the lighting

(base texture alpha)

- specular mask control the lighting

(specular grayscale)

sorry my english mate!


you can't touch neither my wife nor my .gmts

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Posts: 9,592 Site Admin

#2 [url]

Mar 9 10 11:38 PM

You can create an alpha channel from any image using photoshop.

- Change image mode from RGB to Lab Color ( Edit menu/Mode/Lab color)

- Go to channel tabs. Select 'lightness' layer and duplicate it to a new document

- Now undo the changes you did in the original image until it's again on its original RBG mode

- Go to the new document where you copied that lights layer and duplicate it to your original image. You'll see it's copied as an alpha channel.

- Now, modify that channel at your will. Easy, right? ;)


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#3 [url]

Mar 10 10 8:48 AM

great description!! thank you very much for your time and I hope it will help not only me!

You might know me as CharleeSkywalker ;-)
3D modeler - Ferrari Dino, BMW 2002Ti, Ferrari 312PB

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