Edited 5/16/19. This was a beginner question, and I worded it all wrong because there was so much stuff I didn't understand.

My understanding now is that before creating an animation I need to create all the objects I expect to need in the 3-D View panel. I can't add a new object once there are lots of keyframes and tweening happening, because the existing keyframes may interfere with the new object. There are also mysterious things called "actions" using advanced editors that I know I will never understand.

When I create a Material with .5 alpha, I cannot assign it to the selected object.

I'm looking for a solution that tweens the alpha property of an object, so that an object gains or loses visibility gradually. If this really cannot be done in Blender, please someone post "this cannot be done in Blender". I would be surprised, since Blender can do everything else.

I apologize for being such a beginner. I started learning using cgcookie.com, but after the success of the first course I couldn't keep up with the fast videos and had to quit. I now search the web to learn each new thing I need in Blender, so this question of animating the alpha channel is probably useful for others, too.

  • $\begingroup$ Please specify what render engine you are using $\endgroup$ – user1853 May 16 '19 at 14:25
  • $\begingroup$ I want it to work when playing the animation in Blender. As I understand it, there is a default Blender render engine as well as others, and it shouldn't matter which engine is used. If I'm wrong, remember I warned you that I'm a beginner. $\endgroup$ – David Spector May 16 '19 at 18:12
  • $\begingroup$ the way to deal with transparency is different for each render engine, therefore it does matter what render engine you are using. $\endgroup$ – user1853 May 16 '19 at 18:48
  • $\begingroup$ Then please give a separate answer for each render engine, if you know the answers. Unfortunately, those who know seem to remain silent. It is even possible that Blender does not support animating transparency at all. $\endgroup$ – David Spector May 16 '19 at 22:38

The outliner displays ALL object in the scene independent of keyframes. You can add and delete objects from your scene anytime on any keyframe.

However if you want your object to show up at a certain keyframe just animate its visibility by pressing I while hovering over the visibility icon of the object thus adding a keyframe for that property.

You could also do a search for the answers, since you are not the first one to have this kind of problem ;) https://stackoverflow.com/questions/8844389/how-to-make-an-object-invisible-at-a-particular-keyframe-without-moving-it-in-bl

  • $\begingroup$ I think that it takes two operations to create a special Restrict View keyframe. First, create the keyframe by hovering over the eye in the object shown in the Outliner Editor and pressing 'i'. Second, click the eye to the desired state, visible or invisible, and click 'i' again. After two such keyframes are created, look in the Dope Sheet editor to see the range of the effect. Also, in the Dope Sheet Editor, you can select the diamonds for a keyframe, click Delete key, then choose Delete Keyframe to delete a keyframe. Not obvious! $\endgroup$ – David Spector Apr 16 '19 at 18:50
  • $\begingroup$ You may also want to make sure you key the camera icon as well for render visibility. $\endgroup$ – Sazerac Apr 16 '19 at 23:42

Here is one possible solution I found when I was having the same problem. You have to be using cycles rendering engine. In object properties panel menu go down to cycles settings and in Ray visibility you can uncheck camera. This check box can be animated and driven. I don’t know how to do this for collections. This seems to be on a per object basis unfortunately.


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