How to convert 3D coords to 2D one (sketch)

SOLIDWORKS API/VBA Macros
1

How is it possible to convert 3D coords from a point in a selected model face to a 2D coords sketch?

Example: 3D coords (point on face)
X = 0
Y = 0
Z = -100

After conversion: 2D coords (sketch)
X = 100
Y = 0

The 2D coords will be the sketch entity input coords.

2

Each sketch has a certain orientation. To go from the model orientation to the sketch orientation, we have the ModelToSketchTransform matrix:
https://help.solidworks.com/2025/english/api/sldworksapi/SolidWorks.Interop.sldworks~SolidWorks.Interop.sldworks.ISketch~ModelToSketchTransform.html

If you are working with an assembly, each component also has its own transformation matrix. See Transform2:
https://help.solidworks.com/2025/english/api/sldworksapi/SolidWorks.Interop.sldworks~SolidWorks.Interop.sldworks.IComponent2~Transform2.html

You need to multiply your sketch values with the correct transformation matrix, in the right order, to go from one coordinate system to the other.

Your x-value is reversed, so the sketch is probably created on the back of one of the planes.