Discussion What is the best strategy to create a mouse drag selection in 3d space ?

Hello,

I am working on a voxel editor. My goal is to be able to :
-> click = select a voxel
-> drag = extend voxel selection
-> release = confirm selection
-> user can rotate the object he is editing to see it from any angle.

Now, in order to extend user's selection, I am trying to interpret mouse mouvement in UI 2d space into World 3d space, and I am wondering what strategy would you adopt to achieve this ?

For now, I have two ideas.

Idea 1
a - Detect click from a collider
b - Consider an imaginary plane where pivot point is center of the voxel clicked
c - Every time mouse move :
--> Convert mouse position into viewport position
--> Cast a Ray from camera, if it does not hit the first collider :
------> Find point that intersect the imaginary plane
------> Use this point in space to know where to extend / decrease my selection
------> Return to b


Idea 2 :
a - Detect click from a collider
b - For each face of the cube on axis X and Z :
--> Draw an imaginary triangle that start from collider pivot point and interect face's edges
--> Convert this imaginary triangle in a UI zone
c- Every time mouse move :
--> Convert mouse position into viewport position
--> Cast a Ray from camera and find point that intersect the imaginary plane
--> Use this point in space to know where to extend / decrease my selection
--> Return to b


Do you think it is a good strategy ? Is there any other way you would suggest ?
Thanks