Problem with simple setup.

I just learned how to use render layers , but i have two problems.

I want the object on layer 2 ( middle cube) wich is blurred to be behind the 1st cube , not like now that its just mixed , like the example.

the other thing that happens , is that first blender renders the first layer , and then it render the other and mix both renders ,but when this happens i dont know why the final render gets darker ,

another question , by self experience i know that if i export a tga for example with a cube a light and the background all black , it renders an image with everything that was the black background as alpha ,

so , can i use a color background an still use alpha ? it seems that if i use a color for the backgrounf this goes to the tga as a semi alpha color , how do i render a composition with many objects on different layers and a blue backround for example ?

Hi giorgio,

The content in the wiki is pretty thorough and should answer most of your questions…

You can often find example blends with some careful searching. I don’t have any good personal examples I can post but I can make a screen shot or two of a project when I get to work tomorrow.

Could someone still explain me how to do what i ask and the darken issue ?

Render the foreground box on a new render layer so you can sandwich the middle box in between.

Use AlphaOver instead of Mix nodes to put it all together.

secundar is right, your questions are answered in the wiki. As for backgrounds, to render the sky as a pure alpha, make sure key is selected in the render output options.