Script Positioning Wrong When Vertical Offset Not Zero

[Jon Seamans]

When the vertical viewport offset ≠ 0°, the screen coordinate reference is not updated. Consequently the Moveto scripting functions don't locate properly. After a "move" I can recover the correct location by resetting the vertical offset to 0°. Equivalently, the Get_View_Data script shows unchanged screen-center coordinate data regardless of vertical offset.

[Alexander Wolf (alexwolf)]

Please attach reference script for checking

[Jon Seamans (silvy5)]

To my knowledge, the offset problem has existed in all versions since its introduction.

[Jon Seamans (silvy5)]

To check this, I pause the clock, select any object, center the object. Using the selected objects coordinates, I input those coordinates into these script commands:
     core.moveToAltAzi("Alt","Az"), or
     core.moveToRaDec("RA","Dec")

The correct response should be no motion at all since the selected object is centered, but in fact the object moves off center (downward for offsets < 0°)

I typically use the offset set to -32° as I much prefer a sky-dominated view compared to a roughly 50/50 sky/landscape view.

[gzotti (georg-zotti)]

This behaviour is intentional and critically required for the installation which gave intent to implement the vertical offset in the first place. Any possible change must be compatible with the original implementation, e.g. by introducing a flag as third parameter.

[Jon Seamans (silvy5)]

Interesting. I was thinking correcting the screen center coordinates would be straight forward knowing the projection transform. I guess there's more to the correction than a calculation.

Well the work-around is at least manageable as I've been changing the offset back and forth since the start.

Too bad there wasn't a script/hot key to toggle back to 0° more easily.

Thanks, Georg. At least it's a wishlist item now :)

Jon Seamans

[Alexander Wolf (alexwolf)]

The bug report was moved to https://github.com/Stellarium/stellarium/issues/444