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Dark GDK / How to get a Forward Vector?

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endre3000
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Posted: 27th May 2009 01:02
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Can someone show me how I might get a "forward vector" from a given 3D object? I would like to use it to then maintain, for example, a camera in line with the object. Thanks
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Diggsey
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Posted: 27th May 2009 13:36 Edited at: 27th May 2009 13:36
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Get the object position, using dbGetObjectPositionX/Y/Z, then use dbMoveObject with a distance of 1, and get the new position. Subtract the old position from the new position and you have the normalized forward vector. You might then want to reposition the object back at its old position.


New DBPro IDE + integrated debugger!
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endre3000
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Posted: 27th May 2009 22:01
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Thanks, pretty creative, wouldn't have thought of that! Odd how GDK has things like dbMoveObject but not something like dbGetForwardVector, considering the previous function would need that vector to do its job.
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Mireben
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Posted: 28th May 2009 08:59 Edited at: 28th May 2009 09:01
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It should be simpler to use the dbObjectAngleX, dbObjectAngleY and dbObjectAngleZ functions to get the direction of the object and use the angles to set up the camera.

I looked up these functions in the documentation since I was pretty sure they exist. I hope they work but I haven't used them yet, because I have an object class which stores always the direction the object is facing (it is needed for my movement functions). That is yet another solution you can try.
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endre3000
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Posted: 28th May 2009 11:43
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Yeah... you're right. I guess I could get a normalized vector by taking cos(theta) (eg. dot product) of all angles to get each component. Thanks for the heads up.

It did work as Diggsey suggested though.

BTW, Mireben, do you have any suggestions for my other, somewhat related, more boggling camera problem?
http://forum.thegamecreators.com/?m=forum_view&t=151402&b=22
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