Creating maneuver nodes by dragging orbital points

[Bobe]

The current maneuver interface is fairly decent, it gets the job done. However, at times it becomes a bit fiddly and often frustrating. So instead of having to drag on the axes around the node, why not be able to click and drag on points on the orbital path?

For example, if you want to increase your apoapsis, select the maneuver node point as usual and then click and drag the apoapsis marker and drag it to the desired location. The same information you get when you hover over a marker would be displayed as you drag it.

What I envision is that when you create a maneuver node (MN), three markers are added to your craft's current orbit; a P/A (periapsis/apoapsis) marker on the opposite side of the MN and two I (inclination) markers on the two perpendicular sides of the orbit between the MN and P/A marker.

Dragging the P/A marker lets you set the desired periapsis or apopasis, which would be determined automatically based on whether the point was further or closer than the current apoapsis or periapsis. This action would only affect prograde or retrograde vectors.

To change radial vectors, you would perhaps hold shift and drag the P/A marker, which similarly would restrict prograde and retrograde changes.

Finally, to alter inclination, simply drag either of the two I markers, which also would restrict prograde, retrograde and radial vectors.

Finally finally (reminded by Kahusa), the MN itself would be able to be dragged along the orbital path like normal. Possibly you could hold Alt while dragging the P/A marker to adjust the MN position at the same time as the periapsis/apoapsis position.

I think from a usability standpoint this would be a much better system and it allows the user to choose where they want to go and let the game determine the necessary burn parameters rather than the other way around. Some of you may see this as "easy mode", and perhaps you should be able to choose which system you want to use, but to me it just seems like the more logical approach.

After all, when planning real life missions (although they are infinitely more complex than KSP), they know where and when they need to be and then work out how they need to get there, they don't just enter values and see where it gets them.

I hope all of that made sense, and if it doesn't I'll see if I can't mock up something to illustrate it.

Edited January 11, 2014 by Bobe

[vexx32]

Dragging the markers directly results in a very frustrating situation. If you drag it with the camera set at a weird angle, you may quickly find that it's actually gone quite far from where you wanted, due to the camera angle.

[Bobe]

Dragging the markers directly results in a very frustrating situation. If you drag it with the camera set at a weird angle, you may quickly find that it's actually gone quite far from where you wanted, due to the camera angle.

What I may have failed to convey by saying certain vectors are restricted is that the markers would only move in one direction/dimension. For example, the P/A marker would only move towards or away from the the center of the orbit, it would remain in the same plane and on the same axis. Similarly, when dragging the I markers, they would only move along one axis on the same plane (ie. it would just tilt the orbital path).

In other words, even if you move your mouse around wildly, the point will still remain in a sensible location with the other parameters of the orbit unchanged.

[Kasuha]

It's not clear where would you like to drag inclination markers. They don't go anywhere if you're doing your inclination change right.

Another question is, where should that maneuver appear. Because there's whole lot of different maneuvers which could put your apoapsis at the place where you dragged it. Perhaps it might be better if you had to place the maneuver first, then pull its orbital markers instead.

But that still covers just part of all possible (and needed) maneuvers. You don't just need to set up your apoapsis or inclination. You need to get an encounter. You need to kill relative speed. You need a transfer burn. You need braking burn. You need trajectory correction. Also in many cases, you want to do multiple things at once and by dragging one, you're destroying the other.

[Bobe]

It's not clear where would you like to drag inclination markers. They don't go anywhere if you're doing your inclination change right.

Maybe this will help you understand:

In both cases, regardless of where the mouse goes, the P/A and I markers only move up or down (in an arc in the case of the I markers obviously) relative to the camera angle. If the angle were different, they would still only move along those axes, but the direction would be different relative to the camera. I'm sure you know what I mean.

Another question is, where should that maneuver appear. Because there's whole lot of different maneuvers which could put your apoapsis at the place where you dragged it. Perhaps it might be better if you had to place the maneuver first, then pull its orbital markers instead.

For example, if you want to increase your apoapsis, select the maneuver node point as usual and then click and drag the apoapsis marker and drag it to the desired location.

I don't see an issue with multiple maneuvers. Once you have one set, you would be able to create a maneuver on that projected orbit and do the same thing.

But that still covers just part of all possible (and needed) maneuvers. You don't just need to set up your apoapsis or inclination. You need to get an encounter. You need to kill relative speed. You need a transfer burn. You need braking burn. You need trajectory correction.

Sorry, I did forget to mention that you would be able to drag the maneuver node along your current orbital path like normal, except that would be the only action on the node itself. To get an encounter, you would just grab the P/A, drag it to the target's orbital path and then drag the MN along the path. Alternatively, maybe you would be able to hold Alt and drag the P/A marker which would allow you to adjust the MN position at the same time as the periapsis/apoapsis position.

Of course, this system might not be best for all cases, so it would make sense to be able to switch between the two systems.

Also in many cases, you want to do multiple things at once and by dragging one, you're destroying the other.

This system prevents exactly that. The current system, as you know, is vector-based, meaning your projected orbit is determined by individual changes in prograde/retrograde, radial in/out and normal/anti-normal. So for example if you increased your normal vector, your periapsis/apoapsis would be affected since the game is only concerned about adjusting your inclination and doesn't compensate for anything else.

This system would be projection-based, meaning you set what you want your orbit to change to and the game does some simple MechJeb-esque magic to determine in what direction to burn and for how long.

Edited January 11, 2014 by Bobe

[Kasuha]

Maybe this will help you understand:

http://i.imgur.com/KfvvYy0l.jpg

In both cases, regardless of where the mouse goes, the P/A and I markers only move up or down (in an arc in the case of the I markers obviously) relative to the camera angle. If the angle were different, they would still only move along those axes, but the direction would be different relative to the camera. I'm sure you know what I mean.

I'm sorry but your picture does not make sense. Inclination points mark intersection of your orbital plane with certain other plane, usually plane of another orbit. If you want these two planes to match, you need to rotate your orbit around the axis given by the two inclination points, not around your major axis. Inclination points don't move at all in such maneuver.

[Bobe]

I'm sorry but your picture does not make sense. Inclination points mark intersection of your orbital plane with certain other plane, usually plane of another orbit. If you want these two planes to match, you need to rotate your orbit around the axis given by the two inclination points, not around your major axis. Inclination points don't move at all in such maneuver.

You're confusing my inclination markers with the ascending/descending nodes. The markers are simply nodes that can be dragged to set your desired orbit.

When changing your inclination, you would [ideally] set a maneuver node at either the ascending or descending node, then you would drag one of the two inclination markers that appear on either side of it as illustrated in the diagram. It is exactly the same as setting a maneuver node in the current system and dragging on the normal/anti-normal axes, except that this compensates for the change in eccentricity.

The current periapsis, apoapsis, ascending node and descending node would remain in their original positions on your current orbit just as they do with the current system.