Fix for freestyle iterators with for loops #38213

New Issue

Folkert de Vries · 2014-01-14T17:34:58+01:00

Folkert de Vries commented

2014-01-14 17:34:58 +01:00

Hello,

As I mentioned some time ago there is a problem with using freestyle iterators in for loops. briefly the problem is that the object returned by next(it), which is implicitly called by a for loop, did not match the it.object: the two were out of sync. an example:

it2 = iter(stroke)
for svert in it2:

  - this will currently crash on the final iteration
  - since it2.object then doesn't exist.

    print(it2, svert, it2.object)

To solve this problem, the iterator and the next() method have to be brought back into sync. To achieve this I added an attribute to BPy_StrokeVertexIterator, "at_start", that tells the next() whether to increment. this attribute is false on default, so the first call to next() won't increment the iterator, thus getting the for loop and the iterator back into sync.

I've implemented this for StrokeVertexIterators only for now, to check whether this change is allowed and if there are any possible problems I've overlooked.

one further point: I've changed the reversed attribute to be a bool (instead of int), but it seems this attribute is not used anywhere. removing it would make iternext() quite a bit shorter.

patch:
freestyle_iterator_fix.diff

Hello, As I mentioned some time ago there is a problem with using freestyle iterators in for loops. briefly the problem is that the object returned by next(it), which is implicitly called by a for loop, did not match the it.object: the two were out of sync. an example: ``` it2 = iter(stroke) for svert in it2: ``` - this will currently crash on the final iteration - since it2.object then doesn't exist. ``` print(it2, svert, it2.object) ``` To solve this problem, the iterator and the next() method have to be brought back into sync. To achieve this I added an attribute to BPy_StrokeVertexIterator, "at_start", that tells the next() whether to increment. this attribute is false on default, so the first call to next() won't increment the iterator, thus getting the for loop and the iterator back into sync. I've implemented this for StrokeVertexIterators only for now, to check whether this change is allowed and if there are any possible problems I've overlooked. one further point: I've changed the reversed attribute to be a bool (instead of int), but it seems this attribute is not used anywhere. removing it would make iternext() quite a bit shorter. patch: [freestyle_iterator_fix.diff](https://archive.blender.org/developer/F68315/freestyle_iterator_fix.diff)

Folkert de Vries commented

2014-01-14 17:34:58 +01:00

Changed status to: 'Open'

Tamito Kajiyama was assigned by Folkert de Vries

2014-01-14 17:34:58 +01:00

Folkert de Vries commented

2014-01-14 17:34:58 +01:00

Added subscriber: @flokkievids

Folkert de Vries commented

2014-01-14 19:06:17 +01:00

quick update to the diff: object duplication wasn't correctly handled

new patch:
freestyle_iterator_fix_v2.diff

quick update to the diff: object duplication wasn't correctly handled new patch: [freestyle_iterator_fix_v2.diff](https://archive.blender.org/developer/F68340/freestyle_iterator_fix_v2.diff)

Bastien Montagne commented

2014-01-15 14:28:57 +01:00

Added subscriber: @mont29

Bastien Montagne commented

2014-01-15 14:28:57 +01:00

@flokkievids: For patches, creating diff (https://developer.blender.org/differential/diff/create/) is usually a better solution, helps the reviewing process. ;)

Folkert de Vries commented

2014-01-16 21:40:08 +01:00

@mont29 : thanks, I created [D222](https://developer.blender.org/D222) with an updated version.

@mont29 : thanks, I created [[D222](https://archive.blender.org/developer/D222)](https://developer.blender.org/D222) with an updated version.

Tamito Kajiyama commented

2014-02-02 14:12:13 +01:00

Changed status from 'Open' to: 'Resolved'

Tamito Kajiyama closed this issue

2014-02-02 14:12:13 +01:00

Tamito Kajiyama commented

2014-02-02 14:12:13 +01:00

I have just pushed the proposed changes in D222 through 5 separate commits a169989, 41d778f, bab88fe, e9e2813, and b58beed.
Many thanks to @flokkievids for the contribution and sustained efforts on code revisions!

I have just pushed the proposed changes in [D222](https://archive.blender.org/developer/D222) through 5 separate commits a169989, 41d778f, bab88fe, e9e2813, and b58beed. Many thanks to @flokkievids for the contribution and sustained efforts on code revisions!

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Fix for freestyle iterators with for loops #38213