Setting Up Null Objects

[LOTS_OF_PYRO]

I'm just foing to 1st off say this.

I am definitely an amature at Adobe Software. And every single one of you that respond back to me for my questions are fantastic and I stank you for that! 🙂

What I've been trying tro do lately is setup a Fixed Path such as a Circle and attach an element to move on a cirular path via Null Object.

I've never really understood what a Null Object is or it's actual use. I've been messing around with trying to play with Lighting Effects that would be fixed to that Circular Orbit Path from the circle(s) and then the other end is fixed in 1 position.

Think of a visual where you look at the Speedometer in your car and how the needle is fixed to the centre and it's onto the path there the tip of the needle will gow around the outer edge by the numbers. Instead of having that needel fixed only to that spacing. Have that needle go a full 360.

Maybe I'm just missing a function in the Nuill Objet Settings to set it on a fixed Circular Path? I'm not too sure

Any good tips/tricks on how to understrand Null Objects and Fixed Shape Paths better?

[Rick Gerard]

A Null object is a 100 X 100 solid that has the anchor point set to 0, 0, and it does not render and no pixels from the null are used in the calculations. Nulls are an easy and handy place to store Effects/Expression Controls. They are also useful as parents or children of other layers or as sources for transform properties to be used by expressions. They basically make your life easier.

When you set up parenting between layers the anchor point, position, and rotation property of the child layer (the layer with the parent layers name in the Parent and Link column) all become zero. The position, scale, and rotation of the child are now tied to the transform properties of the parent layer. The anchor point gets shifted to the anchor point of the parent layer, but the Child Layer's position is now calculated from the anchor point of the parent. If the Position Property of a child layer becomes the anchor point of the parent layer + the distance of the child from the parent. This offsets the child layer from the parent allowing you to maintain that difference. Scale and rotation are now relative to the parent layer.

If you want to have a child layer rotate around in a circle with the Parent as the center you just offset the child layer from the parent. The distance between the Anchor Point of the Child Layer and the Anchor Point of the Parent becomes the radius of the circle. You can match things up mathematically or visually. 

If you want the needle of a speedometer to rotate around the dial all you have to do is put the anchor point of the needle layer where the axel would be and rotate the layer. There is no need for parenting. 

If you have a separate graphic you want to stick to the tip of the needle, then you position the graphic over the tip of the needle and make the needle the parent. Now the graphic is attached to the needle.

Since you are new I strongly suggest you spend 20 minutes in the Learn workspace and learn the basics. Just follow the prompts and you'll get a basic understanding of the standard way of manipulating layers. Then spend some time with the User Guide. It is always available from this forum, from the After Effects Product Page, or in the online AE manual. 

[MarekMularczyk]

If you just want to animate a speedometer needle, you can import a graphic of the needle and then use Anchor Point tool to move the anchor point to the bottom of the needle (from where it's going to rotate like a speedometer needle). Then, you just rotate the needle as much as you want.

No need for a Null Object.