Add the option to enable local/relative horizontal and vertical sketch constraints to view.

[jhgaA9FT5]

I always have to guess whether I need to use the horizontal or the vertical constrain when sketching, since it's relative to the global coordinate system.
After using other 3D softwares I've relied on that the vertical and horizontal constrains were placed relative to the orientation of the view.
I don't find it efficient having to always keep track of the global coordination system when sketching, since I often rotate or orient parts and drawings.
It just bugs me a lot every time I select the "wrong" option even though it's "right" choice for my exact view.
Or even rework those constrains entirely. When sketching, I don't care to which coordinate system those points are vertical or horizontal, they just have to be in-line with each other.

[swalton]

The screenshot shows that the horizontal and vertical sketch constraints are tied to the local sketch coordinate system.  Horizontal matches the local x-axis and vertical matches the local y-axis. 

My understanding is that Inventor will try to rotate the view to match the local coordinate system.  I tend to redefine the sketch coordinate system to match the view I want to see when opening the sketch.

[jhgaA9FT5]

@swaltonI see. But this still doesn't make the constraints more intuitive to work with.

My wish for any software that I work with, is that it works for me and makes trivial/repetitive tasks easier and faster and not against me. The longer we need to spend on checking coordinate systems and our views' relationship to those coordinate systems, the more time we end up wasting time that the software could save us.

So my wish is just that vertical and horizontal constraints will display relative to your view's orientation and the software must decide if the constraint I wish to put down is horizontal or vertical in the global coordinate system afterward. What I mean is if I put down a horizontal constrain (relative to my view) the line is horizontal to me, but since the software knows that relative to the global coordinate system it is vertical, it registers it as a vertical constraint but places it horizontal to my view.

[MattH_Work]

Do you appreciate that in your original screenshot, you have the axis shown. The thicker of the two lines is ALWAYS horizontal.

As you zoom, pan, orbit, the model itself is never moving, just the camera. In your screenshot, horizontal is displayed on screen as up/down, because the camera is rotated 90°, not because the model is.

Use the thicker line as an indicator of what Inventor considers horizontal. Also, you can use <shift> to switch horizontal or vertical constraints to their opposite on the fly

[jhgaA9FT5]

@MattH_Work 
I wasn't aware of both your inputs, which both helped immensely. Thank you for letting me know.