How to set a slope of x.x %

[t.lemaitre]

Hi,

I'm using de the Draft Slope tool to build pipe:
https://www.freecadweb.org/wiki/Draft_Slope

However, I didn't find how to set a slope between two round values in % : I mean 0.5% or 2.3% for example.

It's quite strange because it seem possible if you read the wiki page precited.

Any idea to help me?

[vocx]

...
However, I didn't find how to set a slope between two round values in % : I mean 0.5% or 2.3% for example.
...

What is a slope of 5% in degrees? What about 2.3%? What do these numbers indicate?

Is 100% equal to 90 degrees? Measuring a slope in percentage may be a convention used in some fields, but it isn't very precise. It should be measured in degrees, or as the tangent of the angle of aperture.

[chrisb]

Is 100% equal to 90 degrees?

No, it's 45°. The percentage is in a rectangular triangle with one side horizontal and one side vertical the ratio of the length of the vertical line divided by the length of the horizontal line. So it is in fact the tangent function.

Measuring a slope in percentage may be a convention used in some fields, but it isn't very precise.

It is e.g. used for waste water pipes and it is very very precise. Tell a channel digger to place the tubes at an angle of 0.572939° and he will call you an idiot. Tell him he should have a drop of 1cm per meter is easy to implement.

[t.lemaitre]

Ok, now everybody speaks about the same thing : tangent is equal to percent of slope.

So, are you able to set a slope between two round values in % : I mean 0.5% or 2.3% for example?
If yes, I'd like to know how.

[vocx]

No, it's 45°.

Okay, so it has a definition. I wonder why OP doesn't use it then.

[openBrain]

Okay, so it has a definition. I wonder why OP doesn't use it then.

Sure it has a definition. The most universal usage (IMO) is for road grade.

[openBrain]

Ok, now everybody speaks about the same thing : tangent is equal to percent of slope.

So, are you able to set a slope between two round values in % : I mean 0.5% or 2.3% for example?
If yes, I'd like to know how.

You can't set values with 1/1000 precision as the input control is a QDoubleSpinBox that has a decimal precision of 2 (it's the default value in Qt).
As a workaround you can :

1. Hack a file
Go to this file @ this line and add a new line with same indentation with :

Code: Select all

self.spinbox.setDecimals(XXX)

Where 'XXX' is the decimal precision (eg. 3 if you want 1/1000 numbers)

This hack will create a permanent change but will (IMO) be overwritten when a new version is available.

2. Hack the GUI
Click on the Draft/SetSlope function to display the slope input field in the Task panel, then enter following in the Python Console :

Code: Select all

from PySide import QtCore, QtGui
QtCore.QTimer.singleShot(2500, lambda:QtGui.QApplication.focusObject().setDecimals(XXX))

Where 'XXX' is the decimal precision.
After validating the 2nd line, you get 2.5 seconds to set the cursor on the slope input field. When delay expires, the precision is changed.

This hack is a single shot one.

I almost never use Draft, so I won't discuss if it's right or wrong that this input field is limited to 2 decimals, if it should be aligned with application decimals, ...

EDIT : if you want same precision as application, use following as 'XXX' value :

Code: Select all

App.ParamGet("User parameter:BaseApp/Preferences/Units").GetInt("Decimals")

[t.lemaitre]

2. Hack the GUI
Click on the Draft/SetSlope function to display the slope input field in the Task panel, then enter following in the Python Console :

Code: Select all

from PySide import QtCore, QtGui
QtCore.QTimer.singleShot(2500, lambda:QtGui.QApplication.focusObject().setDecimals(XXX))

Where 'XXX' is the decimal precision.
After validating the 2nd line, you get 2.5 seconds to set the cursor on the slope input field. When delay expires, the precision is changed.

I tried it and it works! Thanks