Flower Animation Tutorial 2/4

Working with Gerco Ballintijn"s animated flower video tutorial and would like to know the logic behind changing the dynamic verticies to 1.0 and 0.5. in part 2 when forming the stem?
Also in the written document Animating Shapes “Growing a Flower…” a note is made to be "certain that the shape’s origin is set to “0,0…” without explanation as to why except that it will prevent further “headaches” in the future.

In fact, the whole origin concept is confusing me. I understand x,y coordinate system and when I change the origin of an object, I expect the object to move to those points. When an origin point is defined in the parameters panel, what reference are those points related to on the canvas? I change the value origin in the parameters panel but nothing happens on the canvas.

A final question, when the stem is created, an origin is created on the canvas, why is the origin placed where it is and not in the center or bottom left, etc. of the transform tool window on the canvas?

Thanks for the help.


Origin of vertex (don’t confuse with “Origin” of shape that has green dot icon) is here to determine how shape will be interpolated after you deactivate some of its vertexes. More clearly, to which neighbor deactivated vertex will move to. It’s better to illustrate using a simple example: SplineOrigin.sifz (1.0 KB)

The 1st vertex is deactivated at 1 second and its origin is set to 0.5. Pay attention how the shape interpolates. Now, set origin to 0.0 or 1.0 and check it again, the conception should become clear. Although I advise you not to use this technique during several limitations (you cannot remove those waypoints and set custom interpolation).

About “Origin” (the green dot), it’s actually pretty simple. Basically, it’s just an additional offset to the shape. Say you have a shape with 3 vertexes with the following X,Y: 0,0/1,1/2,0. If you set Origin to 1,0 then you shift the whole shape by X=1, but the shape’s coordinates would remain as they were, because shape is drawn first an after that “Origin” is applied. Therefore, if two or more shapes are linked with different offset then result would probably not be as expected.

Not sure I understand this one. Because by default, it’s set to 0,0, e.g. no additional offset and 0,0 is a center of the canvas.

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