7 Replies Latest reply: Oct 9, 2012 6:00 PM by fox_m
andynick Level 5 Level 5 (4,840 points)

I have a line drawn with B-Spline and I want it to be narrower at the arrow end than it is at the start.

How can I do this without using an airbrush line (I want the arrow on the end)?


Screen Shot 2012-10-08 at 08.45.57.png

Thanks in advance.


Final Cut Pro X, Mac OS X (10.7.5)
  • 1. Re: Add perspective to a shape
    fox_m Level 4 Level 4 (3,810 points)

    You can make a wickedly cool arrow by:


    1) draw a very short vertical line - about 10—30 pixels long


    2) set the Brush Type of your b-spline to Image


    3) drop the Line into the image well -- in the Stroke tab, set Align Brush Angle (go back to Style)


    4) set the spacing to 1% | width to something like 3 (minimum)


    5) select the adjust item tool (last tool under the Transform list)


    6) Mouse over the b-spline line: typically there are two very small + markers on the line - one at each end. Where you need more -- hold down the option key and click on the line. Near the arrow end, add two more of these points (you'll need to separate them slightly to begin with).  Click on the circles that appear and control points will appear. For the one nearest the end, drag one far out from the circle; for the one just past that one, drag the control points near the line. Now slide one of those controls (the circle ON the line) towards the other until the back of the arrow head "squares" off. Select the control points on the ends of the lines to set your tapers.


    This image shows the "tail" width over stroke control (also notice the "curve effect" on the arrow head!) :


    Screen Shot 2012-10-08 at 4.17.37 AM.png


    You can do the same thing with Airbrush if you need a softer "brush profile" but you get rounded ends instead of the squared off end shown above.



  • 2. Re: Add perspective to a shape
    andynick Level 5 Level 5 (4,840 points)

    Thanks - that's very impressive.

    Your instructions were very clear, and I got it to work - but it made the old Mac Pro's eyes water!


    Despite it's age (early 2009) it seems pretty potent - 2 x 2.26 GHz Quad-Core with 16 GB RAM and ATI Radeon HD 5870 Video Card. It runs on Lion 10.7.5 with Motion 5 projects and media on a 2TB G-Tech G-Raid (FW800) but it's really struggling with this. Nearly everything else I do with Motion 5 is instant.


    I use the Mac Pro every day with Final Cut Pro X, which is notorious for needing lots of power and RAM but as with M5, it dances along (most of the time).


    Before adding my vertical shape line, the B-Spline is sandwiched between a background image and another image with alpha channel (which masks off the arrow so that it appears to go behind a fence etc). The B-Spline has a Write On Behaviour (nothing else).


    Screen Shot 2012-10-08 at 12.12.04.png


    I need to create quite a few (simple) animated line projects like this, and at this rate, it would take forever. Am I doing something wrong?


  • 3. Re: Add perspective to a shape
    andynick Level 5 Level 5 (4,840 points)

    I think I found what I'm looking for . . .


    For anyone interested, using the Distort Tool (in the Select/Transform list at the far left of the Toolbar) will give the illusion of perspective in a shape.


    Screen Shot 2012-10-08 at 13.17.17.png


    Being somewhat 'ham-fisted' when it comes to Motion, I'm struggling with this, but at least if I use the Distort Tool, my Mac doesn't threaten to tantrum.


  • 4. Re: Add perspective to a shape
    fox_m Level 4 Level 4 (3,810 points)

    Another way to go is Add a Camera and rotate the shape on the X-axis about -45 to -55 degrees. It will be faster than the distort filter (although I doubt noticeably so), and increase the Angle of View of the camera (around 110 to 125 degrees or so.) Moving the line in + Z-space will increase the effect (or moving the camera closer to the subject.) [Turn off 3D for all groups you don't want affected by the camera.]


    The problem with the method I outlined earlier is that you are creating a zero speed emitter with 1000s of lines.

  • 5. Re: Add perspective to a shape
    andynick Level 5 Level 5 (4,840 points)

    Thanks so much - I'm working on this (and it looks very promising).


  • 6. Re: Add perspective to a shape
    andynick Level 5 Level 5 (4,840 points)

    Thanks again, that works brilliantly - but now I can't get a mask to work on the shape.

    I want the shape (write-on arrow) to appear as though it goes behind some trees and fences etc, but even if I isolate the shape, adding a mask either doesn't work at all, or masks out the entire shape.

    I must be missing something simple.


  • 7. Re: Add perspective to a shape
    fox_m Level 4 Level 4 (3,810 points)

    That's going to take more work. Take a look at the Arrows in the content library (Arrow 01 - 14). To get the arrow moving in and out of a 3D scene, my best suggestion would be to animate the transforms/rotations on the layer -- more of a "fly through" than draw through.


    There is also Track Points that can be applied to animate the shape of the line (which you can do nicely but with a lot of work with B-Spline curves). Track the points to the Crosshair Minute images (they can be set to invisible and animated independently). Put all the crosshair images in their own group, and if you go this route, animate the Crosshair *Group* in space... the line, if tracking correctly, will follow the "plane" of points (very interesting effect.)


    When you mask something like this -- try masking the group instead of the shape. (You might have to switch the group to Fixed Resolution.)