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[Closed] .dir property of objects

 
 venx
Sep 24, 2010 12:05 pm

It is not clear how the .dir property of an object works.

  1. I create a teapot ( in Top) and use this code to set the object’s z direction face the x axis:

    XAxis = [1,0,0]
    $teapot01.dir = XAxis

  2. I create another teapot, this time I MANUALLY rotate the object about y axis, again to make its z along xaxis.

     Why are the 2 results different ?
 Setting it with .dir  introduces another rotation about x- axis.

 What is going on?

 Is it to align the gizmo's vectors along the positive directions of the axes of 
 the world space ?

    It will be very nice if someone can find time to answer this.

    Thanks in advance.

    venx

1 Reply
 Gravey
Sep 24, 2010 12:05 pm

it seems to be that when you set the .dir property, it’s actually calculating a new transform matrix internally and applying that to the object. It would be calculated like this:

zVec = [1,0,0] -- the value that you set .dir to here
 xVec = normalize (cross [0,0,1] zVec) -- cross the world up axis with the z vector to get the x vector
 yVec = normalize (cross zVec xVec) -- cross the z and x vectors to get the y vector
 newTransform = matrix3 xVec yVec zVec obj.pos