Measurement tool Initial Implementations

[nancywan1004]

My initial implementations for the measure tool. Core features include:

• Activate the measure tool in the bottom toolbar and to see the distance input show up in the scene panel
• Select a start and an end point to measure and see the distance in the scene panel
• Change the value of the distance input to change the scale, and vice versa
• Deactivate the tool and the line in the scene will disappear and the distance will be reset

To improve:

• The scale might tweak a minor bit as I make different measurements (i.e. sometimes 0.997, sometimes 1.011)
• Sometimes the line would disappear as I set the distance/scale directly (will need some investigations)
• The look of the line(how it renders) might not be the best for now

Would appreciate further feedback :)

Picture for reference:

Fixes #35

[AlexMorgand]

Nice contribution!

Maybe a minor request, some measurement tools like to add text above the measurement line.
I think it's useful when you add several measurements (like for a room).

Maybe future work.

[slimbuck]

Thank you for this @nancywan1004! It's one of the highest requested features from our users.

I would like to make a few changes to your PR before merging. I will try get to this in the next few days.

The things I'd like to change:

• move the measure UI to the same place as the other tools, just above the bottom toolbar
• try improve the visuals
• possibly support 3 points
• possibly store the points per splat