Cannot add constraint for mid-point of rectangle polyline shape

fredericklim

Hi, I am switching from Fusion 360 to BricsCAD.

I draw a rectangle, add horizontal and vertical constraints.

Than I add a line, I can add a coincident constraint at the end point of the line and the corner of rectangle.

I want the other line end constraint to the middle of top side of the rectangle, I use coincident and snap to mid-point, when I set the line endpoint to the mid-point of the top line of rectangle, failed with error "Could not create geometric constraint: Error adding constraint".

Enclosed is the screenshot, I want one of the line endpoint coincident to the top line of rectangle.

Sorry for my poor English.

fredericklim

I found if I explode the rectangle, I can constraint to the mid-point of the top line.

But I have another problem, I don't know how to add a coincident constraint so that the black line coincident to the top line of the rectangle.

Roy Klein Gebbinck

1. Start the _GcCoincident command.
2. Pick the endpoint of the vertical line.
3. Press Enter to select the Entity option.
4. Select the top of the rectangular shape.

fredericklim

@Roy Klein Gebbinck said:
1. Start the _GcCoincident command.
2. Pick the endpoint of the vertical line.
3. Press Enter to select the Entity option.
4. Select the top of the rectangular shape.

Ah I missed step 3. It works now. Thank you very much!

Roy Klein Gebbinck

@fredericklim:
BTW: The issue you mention in your original post is really a bug. In some cases BricsCAD is able to add the _GcCoincident constraint. It all depends on the order in which the constraints are added. You should send in a Support Request.

Adding the _GcCoincident constraint first and then the _GcHorizontal constraint will work. There is also no issue if the _GcHorizontal constraint was added right before the _GcCoincident constraint.

fredericklim

Yes I also think that would be a bug, If I add coincident constrain to the mid-point of right vertical line is OK, but the top horizontal line is not.

I will submit a support request.

Thank you.

fredericklim

@Roy Klein Gebbinck said:
Adding the _GcCoincident constraint first and then the _GcHorizontal constraint will work. There is also no issue if the _GcHorizontal constraint was added right before the _GcCoincident constraint.

I tried your constraint sequence and works.

The following sequences for assign a mid-point coincident constraint are failed:
Add a horizontal constrain on the top line, then a vertical constraint on the left or right vertical line.
Add horizontal constrain on the top line and the bottom line

But works if
Add a vertical constrain on left and right lines, add horizontal constrain on the bottom line, I can add mid-point constraint to the top line, very strange.

What constraint engine BricsCAD based on? D-Cubed dcm or in-house engine?

Roy Klein Gebbinck

http://worldcadaccess.typepad.com/blog/2011/10/exclusive-qa-what-it-means-now-that-bricsys-bought-ip-from-ledas.html

fredericklim

@Roy Klein Gebbinck said:
http://worldcadaccess.typepad.com/blog/2011/10/exclusive-qa-what-it-means-now-that-bricsys-bought-ip-from-ledas.html

I see. I wonder the mid-point coincident bug is in BricsCAD or LGS 2D. My bug report is not respond yet, the inconsistent behavior of constraint is not very usable to me.

I bought BricsCAD Platinum mainly because it has 3D constraint, but the 2D constraint is not even stable. Hopefully that will be fix in v18.

Roy Klein Gebbinck

FYI: 2D and 3D constraints should not be mixed.