openBrain wrote: ↑
Sat Jun 15, 2019 6:24 pm
According its location jmaustpc is probably at bed now.
Yes, I was. It's early Sunday afternoon here now, and it's winter.
I had a nice sleep in, my children cooked me a fancy breakfast in bed, but then I had to go out in the cold, fix the goats' water supply which had decided to leak, feed the cows and feed the calves their milk bottles, get a bit more fire wood, split some up and then load the fire up, now my kids are complaining that the house it too hot! They opened the door to let out some heat, they are dancing, inventing a dance that is about 50% ballet to pop-music. Australian hard wood is a great fuel, when your farm grows far more than you could ever burn its cheap, plentiful, renewable and not polluting, and if you load the fire up and turn the air down, it will burn for 10 hours over night or more. Good quality dry Aussie hard wood burns with very little smoke, and since there are only 4 houses within a kilometre in any direction from my house, no one would ever notice or care even if there was some smoke. Anyway, now I am getting some FreeCAD time!
asdaf wrote: ↑
Sat Jun 15, 2019 5:49 pm
Could I bother you to post a file with example of that method?
I can if you need it but I think OpenBrain has fixed that. Honestly an Expression id a quick easy way to do this, much more flexible and powerful than just linking to geometry, but of course with that power comes the possibility of complexity. So once you have used it for simple things, it can be fun to start looking at just how complex you can make it.
have a look at the wiki page, its full of useful information, Expressions
especially for now this part of the page Expressions#Reference_To_CAD-Data
and the section immediately below it about global constants/spreadsheets.
In practice you have to name a constraint first to reference it in an expression, other wise it is too difficult to determine which constraint you want and referencing them by their number as given to them on creation is not reliable because this is simply their order of creation, and a constraint's number will, or can, change if others created earlier are deleted etc.
Another tip on constraint numbers, in Python the first one is not 1, it is 0, hence this can be confusing as people often think they want for example the 8th constraint so they have to know to call constraint 7 not constraint 8 which is in fact the 9th constraint since counting started at 0 not 1.