Image Alpha to Object Alpha

Commonly with game character hair, the ends of the hair strand fade to 0 transparency; the surface plane follows suit, fading away. How does one do this in blender in the internal renderer? I already know how to do it for true render, but internal render is my question. Preferably in texture view mode if possible.

Hi ChromeKaldra

In “true render” as you already know, you can use a procedural texture called “Blend” and add a “colour ramp” to vary the alpha output.

With the game engine, you can assign a self made alpha blending map, using a GRADUATED image map, (greyscale - 0-255), to control the alpha intensity. (You can also do this for the “true render”).

You can also control the alpha intensity using nodes and ramps.

I’ll do a scan to find some tutorial sections that will help you.

If you still need help with this topic, please update this thread.



Let’s try an example. If I have an image of a tree, that’s been cut out (png file), and I assign it to a plane. Is there some combination of settings that would allow me to view the tree without anything around it, as per the alpha? I’ve heard ctrl+D renders alphas as outlines, but I don’t want outlines.


I have done exactly the same thing myself, (but for the leaves of a tree). You can use a .TGA file, (or .png).

The trick is to set up an ALPHA channel LAYER, in a graphics package, such as GIMP. The black area will then be transparent and the white areas opaque, (though you can reverse this in Blender using negative alpha).

You will also need to use z transparency so that the alpha channel does not “PUNCH” a hole all the way through all the ojects in the scene.

I don’t think I can upload you an example at the moment, (limits of the network I am using), but I’ll dig you out an on-line tutorial, to help you out.

If any other member can supply an example for ChromeKaldra, much appreciated.

Regards to you.


Hi Chrome’

Googled: gimp alpha channel

First link from tutorials.

The alpha part is for you.

I’ll get you some GAME specific tutorials.

Also If you have GIMP. The help section is very good.

Gimp links below

You can use the “colour to alpha” command in GIMP layers menu to specify the colour to use as alpha.

So if you paint a tree on a white background. Use “colour to alpha” and select white FFFFFF as the colour to be transparent.

Add the alpha switch to your object in Blender, (textures tab influence and increase/ decrease the alpha adjustment as required).
Also, if the alpha does not visibly show, (when “P” key is pressed; adjust the Z buffered transparency in Materials to less than 1.0, depending on the amount of Alpha you need.

Please feel free to ask, if you need any more help.



Game specific texturing and alpha, (third part of tutorial).

It’s for Blender 2.49, but the principles are exactly the same, (just the buttons/controls are in a different location).