Having trouble making custom shapes

[edecena]

Hi everyone!

I am still learning and tinkering with After Effects.

I hope this isn't too much trouble but if anybody is willing to teach me or list the steps down on how to create a half circle/semicircle.

I am having trouble with that.

Thank you so much!

[Rick Gerard · Accepted solution]

There are two ways to create a half-circle. The first is to use the Ellipse tool to draw a circle by holding down the Shift key AND the Alt/Option key then clicking and dragging out the circle. The shift key constrains the ellipse to a perfect circle and the Alt/Option key changes the Parametric shape to a Bezier curve.   Then it is just a matter of deleting one of the vertices (points) editing the bezier handles on the two that are now opposite one another. This takes a bit of skill. Editing Bezier Paths is easier by far if you use the Pen tool (g) and the Alt/Option (convert vertex) or the Ctrl/Cmnd (select options and add point) modifier keys. 

The other way is to use Merge Paths and a Parametric Ellipse created by holding down the shift key while dragging out the circle and the Rectangle tool dragging out a rectangle. This method can be precise because you can use math to find the exact center of the circle and put the top edge of the rectangle exactly where it needs to be. Here is a step by step.

1. Select the Rectangle tool and draw any size rectangle anywhere in the comp
2. Select the Ellipse tool, making sure the shape layer is still selected and Shift + Drag a circle anywhere in the comp
3. Press uu to reveal all of the modified properties of the shape layer. You should see the size of both the Rectangle and Ellipse and you should see Transform Rectangle 1>Position and Transform Ellipse 1> Position and unlesss the Fill and Stroke are the default values you will see them too.
4. Reset both the Transform Rectangle1>position and Transform Ellipse1>Position to 0, 0 and they should end up in the center of the comp and be aligned with each other
5. Adjust the size of Ellipse 1 to your desired size
6. Make sure that Rectangle 1 is at least as high and wide as the diameter of Ellipse 1 - a little bigger is better
7. Subtract half of the Width or Half of the height of Rectangle 1 from the appropriate x or y Transform Rectangle1>Position property
8. The Rectangle should now perfectly bisect the circle
9. Select Contents then choose Add>Merge Paths to the shape layer
10. You should now have Merge paths below Ellipse 1 and Rectangle 1 and new fill and stroke below that
11. Set the Merge Paths to Subtract and you should see a perfect semi-circle
12. You can now delete the fill and in Rectangle 1 and Ellipse 1 - they are no longer part of the merged shape

Here's a screenshot that shows both methods with the modified properties of both shape layers revealed. 

This should get you started. You should also spend some time with the User Guide. Type Shape Layers in the Search Help field at the top right corner of AE to bring up a lot of useful resources.