example of SetObjectRotationQuat

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basjak

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Posted: 17th May 2013 01:12 Edited at: 17th May 2013 01:23

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am trying to make rotation using euler (no problem at all) and quaternion (problem)

did anyone work on it? please correct my example:

(am ok in term of understanding the quaternion mathematic but it seems am not managing to apply it in here.)

+ Code Snippet

setdisplayaspect(320/480.0)
setvirtualresolution(320,480)

createlightdirectional(1,0,-20,1000,255,255,255)


loadimage(1,"kkk.png")

CreateObjectcone( 1, 3,3,3 )
setobjectcolor(1,0,125,0,255)
SetObjectposition( 1,3,0,0 )
`rotateobjectlocalx(1,45)

CreateObjectcone( 2, 3,3,3 )
setobjectcolor(2,0,125,0,255)
SetObjectposition( 2,-3,0,0 )
`rotateobjectlocalx(2,45)

do
   if getpointerstate()
   y#=y#+1
   SetObjectRotation( 1, 45, y#, 0 )
   SetObjectRotationQuat( 2, w#,x#,y#,z# )  ` don't know what to do with it.
   endif
    sync()
loop

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basjak

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Posted: 17th May 2013 01:22 Edited at: 17th May 2013 01:24

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--
sorry the message seemed to be posted twice so I deleted this one.

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Markus

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Posted: 17th May 2013 13:38 Edited at: 17th May 2013 13:40

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SetObjectRotation is ok for a start angle at all axis but there is a axis order. one axis can affect a other.

its better you rotate relativ and not absolute.
RotateObjectLocalX
RotateObjectLocalY
RotateObjectLocalZ
RotateObjectGlobalX
RotateObjectGlobalY
RotateObjectGlobalZ

Quaternion i can't explain
http://en.wikipedia.org/wiki/Quaternion

a little bit you can read in help file, F1 over command SetObjectRotationQuat

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Van B

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Posted: 17th May 2013 14:21

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One good example might be a rolling ball, like a pool ball for example. You might use the local rotation to set it as random, like a random orientation - but then use the global rotation on X and Z depending on the objects movement, to replicate the ball rolling around a table. I've actually made a pool table simulation using 3D pool balls controlled via sprites with Box2D, works remarkably well - just a shame that Box2D doesn't really cut it for a pool game (at least as far as I can tell).

The local rotations affect the object locally, so if you rotate an object locally on 2 or more axis, it can be difficult to predict the results, especially if Z rotation comes into play. Local rotation is good when you only need to rotate one axis, like turning a turret, you'd rotate on the Y axis - but if you needed to rotate the turret up and down, rotating on the X axis globally would work - but rotating on the X axis locally would probably not.

I got a fever, and the only prescription, is more memes.

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basjak

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Posted: 17th May 2013 14:30

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thanks guys, I don't have a problem with local and global rotation.

the Quaternion system is better in solving real life cases where we need to make a smooth rotation from one point to another. however, it seems that am unable to apply it here.

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Brendy boy

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Posted: 18th May 2013 02:42 Edited at: 18th May 2013 02:43

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x#,y#,z# are directions of a rotation axis and w# is amount of rotation around that axis

For example:
-you want to rotate an object around y axis for 33 degrees:
x#=0, y#=1, z#=0, w#=33

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basjak

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Posted: 19th May 2013 15:28

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still not working:

+ Code Snippet

setdisplayaspect(320/480.0)
setvirtualresolution(320,480)
setclearcolor(0,0,125)

createlightdirectional(1,0,-20,1000,255,255,255)

CreateObjectcone( 1, 3,3,3 )
setobjectcolor(1,125,125,0,255)
SetObjectposition( 1,3,0,0 )


do
   if getpointerstate()
   y#=y#+3
    SetObjectRotationQuat( 1, y#,0,1,0 )
   endif
    sync()
loop

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Brendy boy

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Posted: 19th May 2013 21:40

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are you sure that parameters are in that order - w#,x#,y#,z#?
I don't have AppGameKit so i can't check but maybe they're in different order - have you tried x#,y#,z#,w#?

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basjak

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Posted: 19th May 2013 22:26

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yep the parameters are w#,x#,y#,z#. I already tried x#,y#,z#,w# as I thought there could be something wrong but didn't work.

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lilpissywilly

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Posted: 19th May 2013 22:30

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Quote: "y#=y#+3"

Aren't the quaternions supposed to be between 0.0-1.0?

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Marl

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Posted: 19th May 2013 22:49 Edited at: 19th May 2013 23:05

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Indeed, I can't see anywhere that says the values are angles.
(but then I can't see anywhere that says they are not)

For the command GetObjectQuatY, it states "Returns the Y component of the object's current rotation converted to a quaternion."

The use of the word "converted", suggests it's a bit more complex.

You can add the following to show the current angle

+ Code Snippet

print( str( y#) + " : " + str(  GetObjectAngleY( 1 )) )

Sadly, none of this helped me find an answer and the wiki page just gave me a headache

So I think we need a maths expert or the guy who included this in AppGameKit

EDIT:

Limiting to 0.0 to 1.0 with the following;

+ Code Snippet

		y# = y# + (3.0/360.0)
		y# = y# - floor( y# )

Does give Y rotation - kind of - but it's not the full picture yet

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Markus

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Posted: 19th May 2013 23:04 Edited at: 19th May 2013 23:07

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this turn around a axis.

+ Code Snippet

//MR

setdisplayaspect(320/480.0)
setvirtualresolution(320,480)
setclearcolor(0,0,125)

createlightdirectional(1,0,-1,1,255,255,255)

CreateObjectcone( 1, 3,3,3 )
setobjectcolor(1,125,125,0,255)
SetObjectposition( 1,0,0,5 )

setcameraposition(1,0,0,-5)
setcameralookat(1,0,0,5,0)

do

    //axis
    ax#=0.0
    ay#=1.0
    az#=0.0

    //angle in degree
    theta# = theta# + 1.0
    w#   =   cos(theta#)
    x#   =   ax# * sin(theta#)
    y#   =   ay# * sin(theta#)
    z#   =   az# * sin(theta#)

    SetObjectRotationQuat( 1, w#,x#,y#,z# )

    sync()
loop

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Marl

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Posted: 19th May 2013 23:28

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Markus, you are the man

I got more out of 10 short lines of code than the pages upon pages of math gibberish and doublespeak in the Wiki.

Makes sense that it would be sines and cosines if the range is 0 to 1, though it wouldn't have hurt to mention that in the docs.

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