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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Thank you for your response. I apologize for my late reply but there are many things going on now and I needed to finish the flower animation to fully understand your response. The following is what I now understand from my original post. Please comment and readjust my thinking where needed.
The center of the canvas is (0,0) point. Any object drawn uses this point as a reference. Each object is on a separate layer. Vertices and tangent positions are referenced to the center point of the canvas. If the origin is moved, its position is referenced to the center of the canvas with new x,y points.
By using CtrlA and the transform tool, an object’s vertices and tangents can all be selected together and moved without moving the origin.
Key Frames allow Synfig to place into memory all parameters associated with the key frame. Each key frame is used to interpolate the animation process. There are a number of interpolation types which I do not understand at this point.
Finally, the logic behind changing the origins of the dynamic vertices in the flower animation tutorial. I was unable to run SplineOrigin.sifz file. I got what appeared to be the written program for the file which I did not understand.
So my explanation:
When the dynamic vertices are formed, and since they are not placed exactly where they need to be, there is some misalignment of the vertices for each side of the flower bud. During animation, this misalignment makes the image distorted in appearance. By moving the origins the adjustment of the two dynamic vertices is adjusted into a coordinated shape which appears correct when animated. I will continue studying this concept with examples until I understand how to adjust the origins to “clean up” (for lack of a better description) the final animation.

Vertices yes, tangents are relative to their vertices, not center of the canvas.

This conception is a bit hard to grasp, but simply put, Keyframes are just markers in time (they don’t do anything on their own). The actual work (interpolation between values) are done by what in Synfig terminology is called waypoints. Future read: https://wiki.synfig.org/Keyframe

TCB interpolation can be tricky to understand, but other types should be easy. This should help: https://wiki.synfig.org/Waypoint#Interpolation

What? What kind of browser do you use? You supposed to download attached file to your computer. Try to right-click on the file->“Save link as/Save object as” (or something along those lines) and then you should be able to save it to your computer. After that, you can open it in Synfig (file->open).

OK, I got the animated file working. Did not open it in synfig ( I am new to this).

…“to which neighbor deactivated vertex will move to.”

As Vertex 1 is deactivated, the following happens:
With Vertex 1 origin set at 1.0, animation moves towards Vertex 2 (-30,30).
With Vertex 1 origin set at 0.0, animation moves towards Vertex 4 (30,-30).
Without extensive trial and error (“black magic” in the Flower Animation Tutorial), and just looking at the data in the Parameters Panel, how do I determine how the animation will proceed by changing the origin?

And what is the "origin referring to in this case? All origins, vertices and tangents, are defined as a x and y locations. But here, a single number is given. What does that number refer to?

Thanks for your patience.

Through trial and error. I wish I could say it’s not the case but sadly it is. Synfig has this problem of lacking tools in some areas.

It’s referencing to either previous neighbor (value 0), middle (0.5) or the next neighbor (1.0) and anything in-between those two. It doesn’t have to be an “x,y” parameter because it’s already known depending on neighbor it’s leaning to.