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IDProjectCategoryView StatusLast Update
0004695SketcherFeaturepublic2021-07-02 08:36
Reporterpaullee Assigned Toabdullah  
PrioritynormalSeverityfeatureReproducibilityhave not tried
Status assignedResolutionopen 
Product Version0.20 
Summary0004695: [Feature] 'Hard' Block Constraint / Non-Editable Edges
Description[Post-new-feature-cleanup] - Chrisb's comment

FreeCAD Forum Discussion:-
1. Edges with Block Constraints still Moves
2. Block Constraint

Desirable 'Hard' Block Constraint / Non-editable Edge Behaviour

Excerpt from above forum discussion thread :

"Now, it seems there are 2 'intended behaviour' needs to be implemented, one is 'hard' - the previous behaviour as depicted in wiki, and the new 'soft' one :D

I use extensively the Block Constraint in my model and in the SketchArch add-on, assuming the edge with Block Constraint would never move again :) The new user in the post I refer seems expected similar behaviour. My usescases e.g.:-

    1. The X, Y Axis and Origin never move
    2. Sometime edges in other placement / direction are needed as reference (we have Grid in architectural design)
    3. In below model, there are a few edges that are originally added making reference to edges of a Ramp
    4. They are Blocked and worked as 'External Geometry', not expected to be Driven - and Not Susceptible to 'Toponaming' problem
    5. Then I build few edges / geometry based on these reference line, those edges / geometry are driven by the Blocked Edges
    6. The thing now it become 'non-intuitive' to those used to old behaviour is that - when there are more dimensional added to the latter edges, then suddenly it would come to a moment, a turning point, that the Blocked Edge become Driven by those originally Be Driven in opposite way. (Try to illustrate in below screencaptures... the last one capture the Block Edge 'suddenly' move / 'be driven'.

Can a 'Hard Block' / 'Absolute Block' constraint be re-provided in addition to the one with new behaviour ? :D "

'Soft' Block Constraint Behaviour Introduced in Dec 2020

@abdullah :
" This is, as far as I see, the intended behaviour of the new Block constraint (introduced in December 2020).

The working of new Block can be summarised as: "Block on a geometry constraints anything else not being constraint by another constraint".

The old block constraint led to misleading behaviour (sometimes a dimension would be ignored while still showing the new value) and inconsistent behaviour (whether the constraint is ignored or shown as redundant/conflicting depends on the position of the dimensional constraint with respect to the block constraint in the list of constraints).

The new block always obeys any other existing constraint (no matter whether it is located before or after in the constraint list) and fixes the rest. It is my understanding that this is the wanted behaviour."

Steps To Reproduce(see above / forum discussion with links provided)
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2021-07-02 08:36

developer   ~0015725

Add [Post-new-feature-cleanup] following Chrisb's comment

Issue History

Date Modified Username Field Change
2021-07-02 06:32 paullee New Issue
2021-07-02 06:32 paullee Status new => assigned
2021-07-02 06:32 paullee Assigned To => abdullah
2021-07-02 06:32 paullee Tag Attached: sketcher
2021-07-02 08:36 paullee Description Updated
2021-07-02 08:36 paullee Note Added: 0015725