(2018-03-14, 9:07)Jarema Wrote: According to Scripting API documentation. LDCad have module match included described here http://lua-users.org/wiki/MathLibraryTutorial.

(2018-03-14, 16:57)Joscha Wrote: It doesn't seem to support algebraic functions.

(2018-03-14, 18:33)Roland Melkert Wrote: If all you need is matrix and vector math I did add support for that through the ldc module as LDraw is heavily depended on matrix math.

But the ldc matrix math is highly targeted on LDraw usage, so if you need more complicated things you might need to use something like:
https://github.com/anaef/lua-linear

(2018-03-14, 22:15)Joscha Wrote: Hi Roland

Yes, all I need is vector and matrix math. My problem is, I would like to rotate a part and I would like to know (or use it in the script) the new position of a specific point of this part. This would usually be a simple coordinate system rotation multiplying a vector with the rotation matrix. The most suitable command seems to be 'transform'. Only somehow it does not behave fully like this. It seems to flip my part by 180°.

Furthermore, is there any way to access the location of the parts center? I mean the rotation matrix always rotates a part around its center. If I like to rotate it around another center during a script I would have to rotate and translate it. This seems to be confusing.

(2018-03-15, 14:05)Joscha Wrote: Coming back to the matrix type. You describe that it is a 4x4 matrix initialised as identity matrix. But for the location and orientation only 12 elements are used. Do the four remaining elements contain information?

(2018-03-15, 18:13)Roland Melkert Wrote:

Code:

local matrix=ldc.matrix()
matrix:setTranslate(center:getInverted())
matrix:mulAB(rotation)
matrix:mulTranslateAB(center)

mulAB with a matrix using a vector in its constructor acts like a translate as it is basically an alias, but it can be very confusing.

(2018-03-16, 9:08)Jarema Wrote: As with another pool of questions. Because I have never been strong... in mathematics. I ask how to determine the angle of inclination of a given part with respect to a given axis ?

(2018-03-16, 17:15)Jarema Wrote: How calculate the angle of Technic Axle 6 relative to the Y axis.   See attached file.

(2018-03-16, 9:08)Jarema Wrote: As with another pool of questions. Because I have never been strong... in mathematics. I ask how to determine the angle of inclination of a given part with respect to a given axis ?

(2018-03-17, 17:31)Jarema Wrote: I discovered Today, that genTools.lua in default\modules have triangleAngle and trianglePlacementAngles. I hope that this module will be regularly enriched with new, stand-alone functions

(2018-03-14, 23:55)Roland Melkert Wrote: To rotate around another center you do indeed need to apply a translate, like so:

Code:

local center=ldc.vector(10, 0, 10) --some alternative center.
local rotation=ldc.matrix()
rotation:setRotate(45, 0, 1, 0) --e.g 45 deg rotate around y

--build transformation matrix
local matrix=ldc.matrix()
matrix:setTranslate(center:getInverted())
matrix:mulAB(rotation)
matrix:mulTranslateAB(center)

--Apply it to brick(s), e.g the first one in the model
local ref=ldc.subfile():getRef(1)
local refMatrix=ref:getPosOri()
refMatrix:mulAB(matrix)
ref:setPosOri(refMatrix)

Roland, I have to come back to your code above. I applied it successfully. Thank you! But I do not understand the getInverted command. How to invert a vector? The command should be only for matrices, shouldn't it?

(2018-03-25, 9:12)Joscha Wrote: Roland, I have to come back to your code above. I applied it successfully. Thank you! But I do not understand the getInverted command. How to invert a vector? The command should be only for matrices, shouldn't it?

(2018-03-25, 17:31)Roland Melkert Wrote:

(2018-03-25, 9:12)Joscha Wrote: Roland, I have to come back to your code above. I applied it successfully. Thank you! But I do not understand the getInverted command. How to invert a vector? The command should be only for matrices, shouldn't it?

getInverted only flips the signs of xyz, so e.g. (1,-2,3) returns (-1,2,-3).

I named it inverted as its goal is the same, to "undo" the vectors content (1+ -1 = 0) just as an inverted matrix can be used to get identity back when multiplying with the original.