Overlaying 2 transparent images on another texture I'm new to the exchange, I am going around in circles trying to get my nodes setup correctly in blender cycles. The basic setup is that I have a brick texture, which I want to overlay/mix 2 grunge textures with transparency in. However, although everything appears fine in material view, which is how I want things to appear, when rendered everything is black. I've eliminated lighting as a problem. I've read article after article on using transparent images in cycles as well as watched several youtube videos, but still my setup seems to be wrong. Maybe what I am trying to do isn't possible.

I've uploaded the blend file to my onedrive, so you can take a look at it, bare in mind I am no artist and this is a simple model for uploading to a virtual world, so it's nothing fancy and I'm still learning, so my geometry might be a little rubbish too. lol

If someone could set things up for me, I would appreciate it, then I can learn from what I see.

The blend file can be found here: https://pkamc-my.sharepoint.com/:u:/g/personal/atlockey_myoffice365_site/EQcTn5iMnZdHpNzOjup10XoBXa1WnJrgr1239vGw4osPpw?e=9KHroh

Cheers

Andy
You're mixing up shaders with texture compositing operations.

The shaders are the ones with the green sockets, and you should never connect other colours to the green sockets or vice-versa.

The yellow and gray sockets are used for colours and values respectively. In practice it means you'll use the yellow sockets to add colour textures to your shaders inputs, and grayscale textures (or single values) to control properties.

(that's a gross over-simplification, but it will help to have a minimum grasp of what you should/shoudn't connect to each type of socket).

With the above in mind, remember that you can mix and combine textures BEFORE connecting them to a shader. So in this case you should use mixRGB nodes to combine them and plug the result to the shader.

In your example of brick texture and grunge textures it would be just matter of blending the first grunge texture over the brick texture (using a mix node if the grunge one has alpha channel will do, but you could also use a different blending and connect the second texture's alpha to the Fac input to drive the mix).

Once you did that, the output of that mix will be textures 1 and 2 blended, so you only need to add another mix and blend the third texture over.

That will be your "combined" texture that you will plug to the colour socket of your shader (most likely a diffuse shader). 

You can add further work to your shader if you need some glossiness or other surface properties to your material, but that's basically the procedure of combining textures.

*) Note that mixing two shaders (one transparent and an emissive/reflective one) to create a material with transparency based on a texture's alpha is a completely different procedure.