Fading object transparency

How do I fade object transparency in Node Editor?

I tried changing the Alpha value in Composite node, but it doesn’t work at all!

You have to fade to something else. What do you have plugged into the other slot? Do you have the output of the mix or alpha node plugged into a viewer or composite output?

Perhaps you could post a screen shot of the node setup?

perhaps a little more detail is needed. But you can fade an object:

by key framing the transparency in the property panel
by setting the property panel to 0, then using a texture to control the fade.
by separating the object from the background with object indexes and combining them in the node editor with an alpha-over node and key framing that.

There are a ton of different ways.

Maybe I found a solution, by watching a video. Here is a setup:

I use the Mix Node to control the transparency.

But I don’t know if it works with animation.

Place57 - I don’t want to do that, because my object has different textures and materials used by other objects that should not be transparent.

I want full control of which objects I want transparent, which is why I insist on making the layers transparent.

No it didn’t work out. Please help me! How do I make my objects in a given Layer transparent compared to the Scene layer, using the Compositor?

Change the cubes texture to single instance, then key frame the alpha. Or put the object you want to fade in a different render layer and use an alpha over node.

I tried the Alpha Over Node but it doesn’t give me any result.

I can’t figure out how to use the Alpha Node.

I want the white part (it should not be white, the alpha node made this!) to slowly disappear to show the development of the castle.

Render layer 1 contains everything BUT what you want to fade

Render layer 2 everything

The alpha over node factor fades the object. Obviously there is more to is because of the shadow, but this will get you stated.

I tried that, but the only thing the Alpha Over Node does is to make my scene lighter or darker.

Here is the total setup of my Nodes:

EDIT: I tried changing the nodes from the two image Inputs, but the ladders still only get its colour changed. It doesn’t disappear when I set it to 0.

For the alpha and mix node inputs, what you want to appear on top of the other needs to be on the bottom input, what you want on the bottom needs to be in the top input.

The alpha will fade from one input to the other. In your example that is from everything to just the ladder. so basically your render layers are not set up correctly to do what you are trying to do. You are close, but not there.

layer 1 = everything EXCEPT the ladder.
Layer 2, the lights
layer 3 the ladder

Render layer 1 = layer1, 2 and 3
Render layer 2 = 1 and 2

In the compositor Render layer 1 in the bottom of the alpha node, render layer 2 in the top input.

That was what I was trying to do, but it just makes the ladders totally black, instead of setting their visibility to 0.

The Alpha Node seems to not doing anything else than lighten or darkening my scene.

perhaps upload your blend file and we can see what is happening. Something is not set up right.

I got it working now. Yes, you were right, I didn’t set it up correctly as you described.

How do I get to add/disable shadows when fading the transparency?