We will continue working on the first scene of the Mygrafico whiteboard animation, which will be used as a branding video for the company on their YouTube channel. In the last Motion^R tutorial, we drew the Bezier motion path that will guide the arm when drawing the line art on to the screen. Now we will use that same Bezier path to create the mask that will reveal the line art as the arm animates.

We will duplicate the Bezier path that we drew previously and turn the duplicate in to a mask over the line art. Because the path is the same color as the background, it hides the line art underneath until we animate the mask to reveal the line art.

1. Right-click on the Bezier_Lineart layer that we drew previously (now under the Motion Path layer) and choose Duplicate. Drag the Bezier_Lineart copy layer into the Lineart group and place it above the Lineart graphic layer. Turn off the visibility of the original Bezier_Lineart path layer.
   
   
2. Some of the Lineart will probably be visible from under the Bezier_Lineart copy layer. Let's widen the width of the path from 10 to 30 (Inspector - Shape - Style - Outline). If you can still see the Lineart underneath, increase the width until you cannot.
   
   
3. In the Layers pane, right-click on the Lineart graphic layer and choose Add Image Mask. Drag the Bezier_Lineart copy layer into the new Image Mask layer.
   
   
4. The visibility of the Bezier_Lineart copy layer should now be turned off. Move the Playhead to the first frame of the Timeline.
   
   We will use two keyframes and the Last Point Offset property of the Bezier_Lineart copy layer to animate the image mask to reveal the line art.
   
   
5. With the Bezier_Lineart copy layer still selected, go to Inspector - Shape - Style - Outline and move the Last Point Offset slider to zero.
   
   
6. Click the Add Keyframe icon to the right of the Last Point Offset slider to add a keyframe to the first frame of the Timeline.
   
   
7. Move the Playhead to the end of the motion path, which we have set to 2 seconds on the Timeline (at the 02:00 mark). Go back to the Outline section and move the slider back to 100%. This should add a second keyframe at the 2 seconds position on the Timeline.
   
   
8. In the Timeline, drag the right edge of the Image Mask layer to the 02:00 mark on the Timeline.
   
   

Test the animation. Save your work.

https://www.mygrafico.com/