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FSX Moving object according to view position?

dave hoeffgen

dave hoeffgen

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Hello,
First of all: I don't have much of an idea about SimConnect programming.

My question as the title already says: is it possible to dynamically reposition an injected (scenery) object according to the global view point position?
If so, what might be the performance costs of doing that every frame?

Thanks in advance for any hint :)
 
It would be possible though I'm not sure it's trivial to get the view point. Maybe I would be able to tell more if you specified what are you trying to achieve (please hit me up in PMs, I might take a while to get back to the forum)
 
If the eyepoint is attached to an aircraft (not sure for ground/tower views though), the aircraft's position, plus the variable "EYEPOINT POSITION" plus variable "STRUCT EYEPOINT DYNAMIC OFFSET" should give you the global eyepoint position. If you also need orientation, there is the variable "STRUCT EYEPOINT DYNAMIC ANGLE" which I believe is relative to the aircraft's attitude (0,0,0 looking straight out of the aircraft) so you'll need to do some math to get the orientation relative to the ground, but it can be done.

Moving one or a handful of objects every SIM_FRAME in my experience has no noticeable effect at all. The sim moves around a lot of ground vehicles and AI aircraft every frame already.

Are you trying to get a 2D overlay effect? Because there are other ways to do that.
 
yes it's (relatively) trivial for out of airplane views. I don't know about other outside views though
 
kabekew said:
If the eyepoint is attached to an aircraft (not sure for ground/tower views though), the aircraft's position, plus the variable "EYEPOINT POSITION" plus variable "STRUCT EYEPOINT DYNAMIC OFFSET" should give you the global eyepoint position.
Click to expand...

Unfortunately, it's not that easy. See this old post from a former ACES dev: https://blogs.technet.microsoft.com/engauged/2007/02/01/variable-astruct-eyepoint-dynamic-offset/
The dynamic offset just gives you the temporary position deltas during a bounce (dynamic event). It will then settle back to zero offsets.

There is a way of "reverse engineering" the global view/camera position using the Direct3D view matrix, but you'll need hacks into the running FS process to get those. Ugly stuff...Tried it, failed, gave up...

However, P3D offers an offical API function for that.
 
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