UI destroys float precision #39861

New Issue

Michael Siffi · 2014-04-23T17:48:28+02:00

Michael Siffi commented

2014-04-23 17:48:28 +02:00

System Information
Windows 7

Blender Version
Broken: 2.70

Short description of error
UI displays float with lowered precision, BUT also overwrites real value

Exact steps for others to reproduce the error

create object
go to the N Panel, enter 90 as Rotation X. It is saved as 1.5708 internally.
switch to Radians. Its still 1.5708 internally.
click inside the Rotation X menu again, don't change anything.
Click somehwere else. The internal value now changed to 1.571.
Broken

The rounding is off. It seems to be based on what is displayed in that field, not what the actual value was internally.

**System Information** Windows 7 **Blender Version** Broken: 2.70 **Short description of error** UI displays float with lowered precision, BUT also overwrites real value **Exact steps for others to reproduce the error** 1. create object 2. go to the N Panel, enter 90 as Rotation X. It is saved as 1.5708 internally. 3. switch to Radians. Its still 1.5708 internally. 4. click inside the Rotation X menu again, don't change anything. 5. Click somehwere else. The internal value now changed to 1.571. 6. Broken The rounding is off. It seems to be based on what is displayed in that field, not what the actual value was internally.

Michael Siffi commented

2014-04-23 17:48:28 +02:00

Changed status to: 'Open'

Michael Siffi commented

2014-04-23 17:48:28 +02:00

Added subscriber: @miksi

Bastien Montagne commented

2014-04-23 18:10:02 +02:00

Added subscribers: @ideasman42, @mont29

Bastien Montagne commented

2014-04-23 18:10:02 +02:00

Well, clicking outside of controls validates the edit, you have to use escape to quit without validating. Summoning Campbell here, but imho this is not a bug at all?

Well, clicking outside of controls **validates** the edit, you have to use escape to quit without validating. Summoning Campbell here, but imho this is not a bug at all?

Michael Siffi commented

2014-04-23 18:17:14 +02:00

I disagree. This is unexpected behavior to an extent where it is a bug. You can't even Tab through the values without messing all values up. Either make a option for "float precision display" or don't force value change if nothing changed.

Campbell Barton commented

2014-04-24 10:06:40 +02:00

Not sure its useful to quibble about this being a bug or not.

Lets say its something that could be improved... (Maybe a TODO?)

Theres a few issues here...

Blender number buttons intentionally reduce precision (otherwise we get lots of floating point issues with display).
Common angles in radians don't show as round numbers.
To click somewhere else when editing a button is the same as pressing Enter.

Some possible solutions.

Display radians with 1 extra precision, this seems reasonable that an angle like 90deg should be editable without truncating useful precision. (Though this is also a bit of a workaround, IMHO its an acceptable one)
Attempt to be clever about precision. (I rather not do this... will explain below).

We could try to workaround this by storing the lost precision in a number button and apply it back after,

possible solution:

internal: 1.00001
display: 1.0
edit the button: stores the delta: 0.00001
user enters value (2 for example).
delta is applied back to the result
new internal: 2.00001
new display: 2.0

This means at least if you make minor adjustments precision won't be lost, however it can backfire if you enter 2 and really want 2.0 not 2.00001.

So, prefer just make radians show higher precision.

Not sure its useful to quibble about this being a bug or not. Lets say its something that could be improved... (Maybe a TODO?) Theres a few issues here... - Blender number buttons intentionally reduce precision (otherwise we get lots of floating point issues with display). - Common angles in radians don't show as round numbers. - To **click somewhere else** when editing a button is the same as pressing **Enter**. Some possible solutions. - Display radians with 1 extra precision, this seems reasonable that an angle like 90deg should be editable without truncating useful precision. *(Though this is also a bit of a workaround, IMHO its an acceptable one)* - Attempt to be clever about precision. *(I rather not do this... will explain below)*. We could try to workaround this by storing the lost precision in a number button and apply it back after, possible solution: - internal: `1.00001` - display: `1.0` - edit the button: *stores the delta:* `0.00001` - user enters value (2 for example). - delta is applied back to the result - new internal: `2.00001` - new display: `2.0` This means at least if you make minor adjustments precision won't be lost, however it can backfire if you enter `2` and really want `2.0` **not** `2.00001`. So, prefer just make radians show higher precision.

Bastien Montagne self-assigned this 2014-04-24 10:19:22 +02:00

Bastien Montagne commented

2014-04-24 10:19:22 +02:00

Talked with Campbell, we’ll simply add more precision to radians here… Doing otherwise would lead to too much troubles. :)