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• ##### Unreal Awards $275k in Latest Round of Unreal Dev Grants • ##### Unreal 4.16 Released • ##### Microsoft's Slim AR Form Factor • ##### YoYo Games Releases GameMaker 2 Education edition View more ### Image of the Day Submit IOTD | Top Screenshots ### The latest, straight to your Inbox. Subscribe to GameDev.net Direct to receive the latest updates and exclusive content. Sign up now # Weired Acis transformation matrix Old topic! Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic. 2 replies to this topic ### #1dgcoventry Members Posted 16 April 2011 - 01:36 AM I have queried an ACIS solid in AutoCAD using autolisp and have extracted what appears to be a transformation matrix: transform$-1 0.965925826289068 -0.258819045102521 0 0.258819045102521 0.965925826289068 0 0 0 1 -1.63832380999416 3.11204436836534 0 1 rotate no_reflect no_shear #

Dose anyone recognise this kind of entity?

It sort of looks like a 4x4 transformation matrix (regarding the 0 0 0 1 line in the middle), but the arguments only have fourteen reals.

### #2haegarr  Members

Posted 16 April 2011 - 02:55 AM

No documentation found, but a transform description can be anything (see e.g. the transform node of X3D).

transform $-1 0.965925826289068 -0.258819045102521 0 0.258819045102521 0.965925826289068 0 0 0 1 -1.63832380999416 3.11204436836534 0 1 rotate no_reflect no_shear # I'd say that 0.965925826289068 -0.258819045102521 0 0.258819045102521 0.965925826289068 0 0 0 1 is a 3D rotation by 15 degree around the z axis, given as a affine matrix. I'd further assume that the subsequent 1.63832380999416 3.11204436836534 0 defines a affine position. I have no clue what the leading -1 and trailing 1 mean. The latter one may perhaps be a scaling factor, but then for uniform scaling only. If you want to investigate this w/o having access to a documentation, try to apply well known transformations and look at the resulting numbers. ### #3dgcoventry Members Posted 17 April 2011 - 03:20 PM No documentation found, but a transform description can be anything (see e.g. the transform node of X3D). transform$-1 0.965925826289068 -0.258819045102521 0 0.258819045102521 0.965925826289068 0 0 0 1 -1.63832380999416 3.11204436836534 0 1 rotate no_reflect no_shear #

I'd say that
0.965925826289068 -0.258819045102521 0
0.258819045102521 0.965925826289068 0
0 0 1
is a 3D rotation by 15 degree around the z axis, given as a affine matrix. I'd further assume that the subsequent
1.63832380999416 3.11204436836534 0
defines a affine position. I have no clue what the leading -1 and trailing 1 mean. The latter one may perhaps be a scaling factor, but then for uniform scaling only. If you want to investigate this w/o having access to a documentation, try to apply well known transformations and look at the resulting numbers.

Thanks Haegarr,

That does sound very likely.

I have searched for documentation on this but have been unable to find any.

I'll do what you suggest and see if the numbers tally.

Old topic!

Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.