Re: [svgwg] Confusion about the description of this algorithm listed in SMIL Animation doc. (#838)

Hi, @fsoder . Thank you for your explaination.
In order to figure it out, I also have done some drawings about the timeline to make every pieces reasonable.

I'd like to express my understanding to collect some corrections if I made any mistakes.
So please correct me if any.

So, as a conclusion, the algorithm is trying to find a specific time point within `d` - the simple duration. This spcific time point will be exactly at which the animation starts visibly. It could be any time point inside simple duration not the "zero" point of simple duration. 

I think `rD` means `resolved delay` which refers to  the delay between rAt and rTo.
Assumes that rAt is now. rTo could be in the future or in the past.
If rTo is in the past, there is no delay, same as `If rD < 0 then rD is set to 0.`
Otherwise, it means the beginning of animation is not yet. We need to wait or it may also start right away if negative offset is considered.

Imagine a horizontal timeline axis which directs right as its positive direction. Acitve duration lay on this axis and its start point is rTo. Negative offset will pull the whole `active duation` left along the axis. 

Considering repeat behavior applied on the `active duration`, there would be serveral intervals included in it.
Imagine there is one of the intervals which is most close to rTo.
And the distance between the left end of the interval and rTo is `REM`.

If `rD` is shorter than `REM`, then the animation beginning should be at `REM - rD` within `d`.
If `rD` is longer than `REM`, the the animation beginning should be at `d + REM - rD` within `d`.

Hmm... I think it's better to illustrate the concept by images.

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Received on Thursday, 22 April 2021 11:21:38 UTC