Getting Vertex global position

[mb10]

@Monster

This method is for the final vector transformation [vectorB=transform(vectorA)]. It excludes further scale and further rotation as you get a vector not a matrix.
As you wrote the remaining 4th coordinate (vector scale) should be 1 and can be ignored.

The transformation matrix of affine transformations (translation/rotation/scale) in 3D space is at least a 3x4 matrix (2x3 in 2D). As it is much easier to multiply homogeneous matrices, therefore it is usually expressed as 4x4.

Beside the affine transformations there are the projection transformations which fill the unused part of the 4x4. These transformations are used to transform vectors from world space into camera space (as seen by the camera).

See wikipedia.

Stated all that, can the original problem (i.e.: “convert local vertex coordinates to global coordinates”) be solved with:

globalCoords = obj.worldOrientation*localCoords + obj.worldPosition

or not?

[torakunsama]

I does, for me!
And my second problem was solved by adding the object’s position to the final.
I’m still not very clear why, but I’m sure I’ll understand with a rested head!
Thank you all for the support! I can now move on!

[Monster]

@mb10

Stated all that, can the original problem (i.e.: “convert local vertex coordinates to global coordinates”) be solved with:

globalCoords = obj.worldOrientation*localCoords + obj.worldPosition

or not?

It is missing the scale part.

you need to multiply the rotation matrix (worldOrientation) with a scale matrix first

[mb10]

@Monster

It is missing the scale part.

Yes, the scale part is missing.

@Monster

you need to multiply the rotation matrix (worldOrientation) with a scale matrix first

No, scaling is not required in this case. See post #22.