C++ The product of the Matrix and another type function does not exist?
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Hello!
I develop my plugin on C++ and trying to receive the same line of Python code:matrixA= c4d.utils.MatrixMove(c4d.Vector(0,10,0)) matrixB = myObject.GetMg().__mul__(matrixA)
MatrixMove func exists in a C++ help. But I can't find in C++ help the analogue of .mul function.
So does this function from a Python help: https://bit.ly/30dc2Ps
https://developers.maxon.net/docs/py/2023_2/modules/c4d/Matrix/index.html?highlight=mul#Matrix.mulexists for a C++?
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operator * does not work for you?
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Hi,
Cairyn is right, the operator you are looking for is *Cheers
Manuel -
@m_magalhaes @Cairyn
Hello guys.
No, the simple operator * between two matrixes shows an error.
Right now I've write it like this:matrixB = myObject->GetAbsPos() * matrixA;
also via operator*.
But I am not sure will GetAbsPos return the same (according I need only the position offset of matrix).
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Hello @yaya,
matrixB = myObject->GetAbsPos() * matrixA;
First of all,
BaseObject::GetAbsPos
returns aVector
, which in turn makes your calculation at least implicitly wrong, since you call the resultmatrixB
, implying that it is a matrix. But the product of a matrix M and a vector p is the vector p' transformed by M. There is also the fact that order matters in the C++ SDK, i.e., you are forced to write expressions in the canonical matrix-first order (in Python you are not restricted in such fashion, because Python handles operator overloading differently).Vector p; Matrix M; // Valid expression since Mat3 has an operator overload for M * p Vector q = M * p; // Invalid expression since Vec3 does not have an operator overload for p * M Vector r = p * M;
It might also be noteworthy that
Matrix
andVector
are only aliases originating from our classic API. The types have been replaced by a more versatile templated model of the atomic arithmetic types.Vector
is just atypedef
formaxon::Vec3<maxon::Float64, 1>
andMatrix
formaxon::Mat3<maxon::Vector64>
. You can find the relevant template descriptions in the Mat3< V > Struct Template and Vec3< T, STRIDE > Struct Template references.Cheers,
Ferdinand -
Hello @ferdinand
Thank you for a such detailed answer.
It is hard for me to understand all of it by eye, and I can't say right now is it what I search.
I need to receive in the result the point in 3d space which is attached to another point like it is a child of parent (only position is needed).So all construction serves to achieve a Vector point of a new position shifted by 10 units in a one of its local axis. (Vector(0,10,0))
I will finish my python-C++ rewriting and will test your example above.
Thank you! -
This post is deleted! -
Hello @ferdinand
I've tested it a bit and now I've finished with this:instead of this:
matrixA= c4d.utils.MatrixMove(c4d.Vector(0,10,0)) matrixB = myObject.GetMg().__mul__(matrixA)
to this:
Matrix matrix = MatrixMove(Vector(0, 10, 0)); Vector vector = myObject->GetMg() * matrix.off;
It looks it works for me.
Thank you again!