• Adobe After Effects Expressions

  math.sin broken?

  Posted by Paul Roper on January 14, 2011 at 9:18 pm

  Hello

  Either I am dong something wrong, or my computer cannot do maths. I am trying to influence an expression’s value by a bell-shaped curve, so I thought I’d multiply it by the sin of a value. But my Math.sin function is begin very weird. To check it, I’ve made a couple of text layers to display the results; I have, on a text layer’s source text:
  
  thisComp.layer(“Tube”).transform.scale[0]/1.66667

  (“Tube”‘s scale goes from 0 to 150, hence the /1.66667 to keep it between 0 and 90)

  and my second layer’s text is:

  Math.sin(thisComp.layer(“text”).text.sourceText)

  …so when the input value is, for example, 18.67, my calculator tells me that sin(18.67) is 0.32, but After Effects think it’s -0.17702228.

  My input value is keyframed to smoothly go from 0 to 90, but on each frame, the Math.sin value to anywhere from -0.99 ish to 0.99 ish, whereas I was expecting a smooth, sinusoidal-shaped transition from 0 to 1 (which is what my calculator gives me and we remember from school!)

  Any thoughts???

  (It’s not an issue with the text layers themselves – when I used the formulae to control an angle, they produce the same results…that’s why I created the text layers to check what’s going on).

  Paul Roper replied 15 years, 4 months ago 1 Member · 1 Reply
• 1 Reply

• 

  Paul Roper

  January 14, 2011 at 9:57 pm

  Ahhhhhhhhhhh…………radians, not degrees! That’s my problem! A quick degreesToRadians saved the day.

Reply to this Discussion! Login or Sign Up