fix: apply same delta from position to previous position when setParts runs #1074
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
fix: apply same delta from position to previous position when setParts runs
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Problem
Currently when setParts is run, it sets the position and positionPrev to the new total parts centre values. This is fine when the body is stable/constant when being set, however for actively moving objects this will cause the new body to have no delta between positions.
This factors in when calculating the new velocity during update: https://github.com/tylerfurtwangler/matter-js/blob/master/src/body/Body.js#L638
Fix
This change uses the existing body
positionPrevandpositionvalues to come up with a delta to apply to the body to keep the previous relative positions the same during a setParts call.Testing Notes
I am unfamiliar with the process, and can close this PR if more is required for the main repo. This can be seen by calling setParts on a falling object, the object "stalls" midair as it no longer has a positionPrev delta from position.