Teaching After Effects To Draw

CATEGORIES: After Effects, Tutorials | Marcus Geduld | October 13, 2005

After Effects ships with a ton of snazzy paint effects (Stroke, Scribble, Vegas, Vector Paint, Paint…), so the clunky old Write-on effect is generally ignored. Though it’s lacking advanced features, it does do something the other effects neglect: it keeps track of the virtual brush’s location at each point-in-time in a property called Brush Position. This is particularly useful when you want to use an expression to link a paint stroke to another effect. The following example should illustrate why you should keep Write-on in your arsenal. Adobe, if you’re listening, could we have Brush Position properties in the more advanced paint effects?

STEP 1:

Import an image of a crayon (against a transparent background). Use the Pan Behind Tool to move the crayon’s anchor point onto its nib. Rotate the crayon so that its nib is facing three o’clock. You need to do this, because in a later step you’re going to use the Orient to Path command to make the crayon automatically point towards the direction it’s moving. In order for this to work, After Effects needs to know which side of the crayon is its front and which is its back. It will assume that the front is the side facing three o’clock.

STEP 2:

Press command+Y (PC: control+Y) to add a new solid. The solid can be any color (you won’t see the color in the final result), but make sure that it’s comp size. With the solid (not the crayon) selected in the Timeline, use the Pen Tool to draw a path that represents the shape you’d like the crayon to draw. Alternately, you can paste in a path from Illustrator or Photoshop.

STEP 3:

With the solid layer selected, type M to reveal the mask (path) you just created in the Timeline. Select its Mask Shape property (click the word “Mask Shape” in the Timeline) and then press command+x (PC: control+x) to cut the mask to the clipboard.

STEP 4:

Add Effect > Stylize > Write-on to the solid layer. Twirl open the Effects group in the Timeline (solid layer), twirl open the Write-on effect, select the Brush Position property (click the words “Brush Position”), and press command+v (PC: control+v) to paste the path back from the clipboard. Since you have the Brush Position property selected, the path will paste as brush keyframes rather than as a mask. Press F2 to deselect the keyframes. Now drag the final (right-most) keyframe to a later point-in-time to slow down the Write-on animation.

STEP 5:

Park the Current Time Indicator halfway through the animation to see what it looks like. The Write-on “line” may look more like dots than a solid line. Adjust the following Write-on properties until you like the look of the line: Brush Spacing (to add more dots), Brush Size (to thicken the line), Brush Hardness (to soften the edges) and Color. For the Color property, choose the color of the crayon. (You click the eyedropper and sample the color from the crayon’s nib.) Set the Paint Style parameter to On Transparent. This will make the solid’s background vanish, leaving just the path.

STEP 6:

To make the line look a bit less computer generated and a bit more hand drawn, add Effect > Stylize > Roughen Edges (left at its default settings) and Effect > Noise > Noise HLS. Play around with the Noise HLS settings until you like the look.

STEP 7:

If necessary, move the crayon layer to the top of the stack. Twirl open Timeline groups until you can see both Crayon Layer > Position and Solid Layer > Effects > Write-on > Brush Position. option+click (PC: alt+click) the stop watch to the left of the crayon’s Position property. This will add an expression to Position. Drag the Pickwhip icon (the spiral to the left of the expression) to the Brush Position property and release the mouse button when the pointer is hovering over the words “Brush Position.” Now the Brush Position of the Write-on Effect will control the Position of the crayon.

STEP 8:

With the Crayon layer selected, choose Layer > Transform > Auto-Orient from the main menu. In the Auto-Orientation window, select the Orient Along Path option and click OK.

Congratulations! You’ve just spent ten minutes teaching After Effects to do something that a five-year-old child can do in ten seconds. Ah, but can the child render his results out as a Quicktime video? Not a chance!

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