WorldUV (Blender addon)

This tool adds Hammer Editor-style triplanar UV unwrapping to Blender. Faces save their parameters for easy adjusting and copying to other faces. Perfect for blocking out a level.

Install: Blender > Edit > Preferences > Install > select file

Planned: I intend to have world projection use world space axis.
Updates:
1.0.2: Fixed an issue with world space unwrapping when an object wasn't at world origin.
1.0.1: Added tooltip text to buttons

V Guide below V

Grid

Fac: the factor by which the grid is scaled.

Reset: reset the grid size to 1 unit.

Plus: multiply the grid size by Fac

Minus: divide the grid size by Fac

Parameters

Pick: pick the parameters from active selected face.

Unwrap

Unwrap: unwrap the UVs with the current parameters.

Reapply: reapply the selected face's parameters, if present.

Projection

All: UVs will unwrap from all directions in a triplanar manner.

X, Y, Z: UVs will only unwrap from the selected axis.

World: UVs will be positioned and rotated relative to the world origin.

Object: UVs will be positioned  relative to the object's origin.

Faces: UVs will be unwrapped relative to the bounds of the selected faces. This option is contextual to the current selection, so the Reapply function may result in a different unwrap.

Scale

Units to UV space. A scale of 2 will result in a texture repeating every 2 units, while a scale of 4 will result in a texture repeating every 4 units.

Shift

The distance a texture is shifted in steps.

Plus and minus: shift the texture one full step.

Arrows: randomize the shift value.

Steps

The number of discrete steps in a texture. Matching this number to the number of tiles, bricks, or boards in a texture will make the Shift functionality more useful.

Face Settings

Selection overlay: disable the highlight overlay on selected faces, to make texture aligning easier.

Lock and Unlock: lock or unlock to prevent the selected faces from being modified by WorldUV. The icon will show whether the active selected face is locked.