Using the External Compositing tag
Video: Using the External Compositing tagIn our final image in After Effects, we want to have the ability to have 2.5D type from After Effects stuck onto the face of this cube. In order to do that, we need to know the exact position in 3D space of the face of this cube. Back in the old days before the tight integration with After Effects, you used to have to make notation of the location of the face of that cube and write it down, and then After Effects put down that number numerically on the null object, or thing that you wanted to stick to the face of that cube.
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CINEMA 4D Essentials with Rob Garrott is a graduated introduction to this complex 3D modeling, rendering, and animation program, which breaks down into installments that can be completed within 2 hours. This installment covers the basics of rendering images and animation and compositing those elements and effects together into a single movie. Rob shows how to optimize your render settings and configure batch rendering for maximum efficiency. On the compositing side, he shows how to use the compositing tag and object buffers to create a flawless composite, and how to round-trip assets between CINEMA 4D and After Effects.
- How the CINEMA 4D render engine works
- Adjusting the render settings
- Rendering still images and animation
- Setting up multipass rendering
- Understanding the linear workflow
- Rendering and importing elements from After Effects
Using the External Compositing tag
In our final image in After Effects, we want to have the ability to have 2.5D type from After Effects stuck onto the face of this cube. In order to do that, we need to know the exact position in 3D space of the face of this cube. Back in the old days before the tight integration with After Effects, you used to have to make notation of the location of the face of that cube and write it down, and then After Effects put down that number numerically on the null object, or thing that you wanted to stick to the face of that cube.
As long as that object didn't move, then everything would work out great. But if the object moved at all, then everything broke down. Eventually though, we got something called the External Compositing tag. And the External Compositing tag allows you to send the position information of any object in CINEMA 4D out to After Effects. And this includes null objects, it includes clones from MoGraph, you name it. If it has position in CINEMA 4D, you can get that position into After Effects, and that's a really powerful thing. So it's a very simple thing to set up.
Really, all you need to do is add the External Compositing tag to an object. But in the case of our cube, it's a little bit different. If I select the cube object, and let's uncheck the Active Camera icon. I'm going to get rid of the Interactive Render Region by hitting Option+R or Alt+R on the keyboard. You can see that our cube has its axis point right exactly in the center. The trick to External Compositing tag is that whatever you put that tag on, it will send the exact position of, wherever the axis point is in space, that's what you'll get.
I want to have something stuck to the outside edge of this cube, this face right here. That's not where the axis is. If I put the Compositing tag on the cube, I'm going to get this location, not this location. So what I need to do is add a null object that's going to be in the right location and then put the External Compositing tag on that. So let's add a new null object to the scene and let's call this one Hero cube face. So let's make that null a child of the Hero Cube.
Then what we do is right-click on the Hero Cube face, and go to CINEMA 4D tags, and then External Compositing. The External Compositing tag has a few settings under it. The Children setting will give you the position of all the children in the scene. So for example, if I put the External Compositing tag on this cube's null here, it would give me the position information for all of these children if I check that box. I don't need that right now, so I'll leave it unchecked. The Cache option, we'll leave on, the Anchor Point, we want to leave in the center.
Now you can position it any one of these locations, we'll leave it in center. And then, you can generate either a solid or a null object. It generates a null object by default. You can have it generated solid if you want. Now I'm going to have it generate a solid just so we have that exact position, and it's easy to spot. I'm also going to make that solid square. So I'll make it 200x200. I'll leave the color red, so it's nice and easy to spot. So what I'll end up with After Effects is a red solid that's 200 pixels by 200 pixels with its anchor point in the exact center.
It will also have the exact name of the Hero Cube Face. Now that we've got the External Compositing tag set on the null object correctly, we need to position the null object in the right location. In order to do that, I want to select the Hero cube face null and go to the Coordinate Properties in the Attribute Manager. And then what I'd like to do is zero out its position. That's going to bring the null object from way over here on the right-hand side of the screen. It's at 0, 0, 0, and you can tell that because that little blue arrow is pointing off camera at the object.
We want to get that right to the center of this cube, and then we're going to position it on the outside. So if we go to the Coordinate Properties and Select that and hit 0, Tab, 0, Tab, 0, and you can see that the null object jumps right to the center of the cube. Then, if you go to the X property and type in -400, you're going to see that the null object jumps right to the outside edge of that cube. I knew that because the size of this cube is set to be 800 units across and so -400 is going to put it right on the outside edge.
And if I middle-mouse click, and go to the top view, and let's dolly in, I'll hold down the 2 key and drag to the right here, and then pan over with the 1 key. You can see that my null object is right on the outside edge. And so if we click back in the center here, now I know that, that null object is going to be exactly in the right place for us when we get to After Effects. Now rather than import that in After Effects right now, we're going to do that in a later movie. In this movie, I just wanted to focus on getting the tag applied.
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