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Moving an entity from A to B over time - how?

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Currently I got system that snaps a particular entity from location A to location B. So it's an instant movement.


What I need is the following. I need to move entity from A to B, not snap it, over the course of time. So instead of an instant snap, it will move from A to B in 2 sec (for example).


My guess it that I need to advance coordinate in SetWorldOrigin(I think that's what I use currently to change location of the entity) in a loop, but I am having brain fart and can't put it all together. I am thinking it could be SetWorldOrigin( currentOrigin ) where currentOrigin = ( destinationB - currentOrigin ) / granularity.


vector currentOrigin = sourceA;

vector granularity = '100 100 100' ;


delta = ( destinationB - currentOrigin ) / granularity;


loop begins

SetWorldOrigin( currentOrigin );

currentOrigin = currentOrigin + delta;

loop ends


Something like that?


I assume time should be in the condition of the loop? If so, how to I plug it in and have it updated? What if time runs out, but entity is still in between source and destination ? How would I make it where entity will move from A to B in the given time, guaranteed ? Thanks!


EDIT: Should I do something like the following ?


currentTime = time;


while (currentTime <= 2sec) {

... code in the loop from above ...

currentTime = currentTime + timeIncrement;



and timeIncrement probably would be 2 sec / ( (B - A) / 2 sec ) ?

Edited by motorsep

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Have a look at the script events for idMovers. I expect most if not all of those are vanilla doom3. To achieve what you are trying to do, you can specify either the speed or the time to reach the goal before calling moveToPos(x,y,z).


If that's no good, then you want to move your entity a fraction of the total distance each tic. You shouldn't rely on tics being spaced evenly in time, because other things might slow down the frame rate. So use the game clock. Something like:

vector destinationOrigin = $target.getOrigin(); // or whatever
vector startingOrigin = $mover.getOrigin();
vector journey = sys.vecLength( destinationOrigin - startingOrigin );
float moveStartTime = sys.getTime();
float journeyTime = 3; // seconds
float distance = sys.vecLength( journey );
float travelled = 0;

while ( travelled < distance )
  float timePassed = sys.getTime() - moveStartTime;
  float fracCompleted = timePassed /  journeyTime;
  $mover.setOrigin( startingOrigin + fracCompleted * journey );
  travelled = sys.vecLength( $mover.getOrigin() - startingOrigin );


Edit: I see I mixed game code and script code in that example. If using a script, you want to sys.waitFrame() in the loop. If in game code, don't loop but set it up so the code in the loop gets called once per frame.

Edited by SteveL

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Translated to script language... I don't like leaving hybrid code lying around :) Although hopefully you can use the existing idMover script events which let you use a natural looking acceleration and deceleration time too.

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Thanks, I'll try digesting it after work :)


I can't use idMove script events on non-func_mover entity. And since what I am doing is totally free form (entity follows player with delay), func_mover is a no-go.

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