Possible bridging or bridge detection regression #2636

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Vicious-one opened this Issue Feb 6, 2015 · 9 comments

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@Vicious-one
Contributor

Strange bridge region detection was encountered when trying to bridge the fins:
bridge-detection-fail-fins-120

1.2.0 binary (bridges detected, but regions are too grown):
bridge-detection-fail-120

Current(right bridging region not detected at all, but accidentally the infill is more appropriate):
bridge-detection-fail-127

STL and config:
http://vserv.sinp.msu.ru/temp/bridge-detection-fail.tar.gz

There is also no way to force bridge detection completely off to work around the issue using this particular model, and "detect bridging perimeters" option also has no noticable effect.

Please note that both 1.2.0 and 1.2.7-dev versions are clearly faulty, but in different ways.

May be related to #2618, #2635 and #2646

@Vicious-one
Contributor

When trying to avoid the problem by shifting bridges to different layers, I've also noticed that bridge infill pattern angle is not applied to the bridges besides the left (first processed?) one:
bridge-detection-fail-127-3
bridge-detection-fail-127-2

@Vicious-one
Contributor

yunofix

@Vicious-one
Contributor

Seems that bridging infill angle is applied only to one of the bridges:
bridge-detection-fail-127-4
bridge-detection-fail-127-5
bridge-detection-fail-127-6
bridge-detection-fail-127-7

@Vicious-one
Contributor

Processing bridge at layer 46:
Angle -1.000000:
Processing bridge at layer 46:
Angle 1.570795:
Processing bridge at layer 106:
Angle 1.396263:
Processing bridge at layer 106:
Angle -1.000000:

BridgeDetector::detect_angle() sets angle to -1 which results in applying default infill angle for current layer.

A little poking revealed that somehow BridgeDetector constructor support check reports missing bridge support.

@Vicious-one
Contributor

@alexrj -- please revert 379cde3 so everyone can have proper multiple bridges again!

@alexrj
Owner
alexrj commented Feb 27, 2015

I fixed that regression. Thank you for reporting it :-)

@alexrj alexrj closed this Feb 27, 2015
@alexrj alexrj added the Fixed label Feb 27, 2015
@alexrj alexrj added this to the 1.2.7 milestone Feb 27, 2015
@Vicious-one
Contributor

Thanks, now it seems to be working as before.
One question remains, though: the calculated angle seems strange, doesn't it?
bridge-detection-fail-127-8
bridge-detection-fail-127-9

@Vicious-one
Contributor

Okay, having seen the best angle calculation algorithm, the angles do not seem strange anymore, but the fact that they are not symmetric still does.

Never mind though, I'll just play a little with detection method.

@Vicious-one
Contributor

I've changed line interval to 1/4 extrusion width and consistently getting more sane results.

(double line_increment = this->extrusion_width/4.0; BridgeDetector.cpp:116)
div4-1
div4-2
div4-3
div4-4
div4-5
div4-6
div4-7
So maybe increasing the "line test" resolution is not a bad idea.

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