A little node question

A little node question

Hi all,

I feel a bit dumb to be asking simple things like this, but I just can't get the solution.
Using nodes, how do you have one texture act as an alpha channel on another texture? For example, you have a vegetation image texture, but only want it to show up on the black parts of a turbulence texture. Also, how would you then place a third texture in the area blocked by the alpha, to say, have the dirt in between the vegetation? I've taken a look at the built in rusted metal texture, but I can't understand what's going on there.

Thanks!
Andreu

Hi Andreu,
the first part should be quite easy: simply link your turbulence node to the "transparency" property of a standard material;
for the second you can try with a mix node but i'm far from understanding how everything works... dumb here too:tongue:

cheers,
A

-edit: try a mix node with vegetation in col1, dirt in col2 and your turbulence in "mix". you probably don't need transparency anymore

Using nodes, how do you have one texture act as an alpha channel on another texture?

Click to expand...

You feed one texture into the other texture's color.

Simple example: grab a checkerboard texture -- plug it into a material shader's diffuse channel.

Now grab a voronoi texture and plug it into the color0 of the checkerboard.

More complex example:

You want snow on a terrain but (a) above a certain height and (b) biased towards horizontal surfaces.

You use a state node to get position and normal (of thing being rendered) info.

To measure "horizontalness" you use the norm of the cross product of an upward pointing constant vector (0,1,0) and the normal. To get position you take the y component of the position vector via a vec2float node.

To use these values to create a material you plug them into a mix node (as the mix value). (A texture node is a mix node with a predefined function driving the mix value.)

I hope that makes sense -- let me know what bits don't.

Thanks for your answer, podperson! The first part explains nicely what I was after. As for the second part, I can frankly say I don't understand zip! It's gonna take some time...
Thanks anyway!

mmm... seems i've completely misunderstood your question, Andreu. Sorry... :redface: