I'm trying to properly account for the movement of a large creature in D&D 5e, playing on a square grid. The creature needs to move through a double-wide doorway and then move to its right, effectively a movement around a corner. I'm aware of the rules for corners:
Corners. Diagonal movement can’t cross the corner of a wall, large tree, or other terrain feature that fills its space.
The crux of my question is what point or area "can't cross the corner". Borrowing the grid example from this answer, assume the large creature has passed through a doorway and is occupying squares B2, B3, C2, and C3. It needs to move to squares A3, A4, B3, and B4.
It would take one square (5ft) for a medium creature to move from B2 to A3, B3 to A4, or C2 to B3. Moving from C3 to B4 would require two squares (10ft). Does the majority apply, or the most limiting? I've reviewed several questions here but still think there's room for interpretation either way.
This answer is about hostile creatures, not an obstruction like a corner, but implies it's the center of the creature's square that's relevant for movement:
There is no recognition of the longer path between two diagonal centers than between two truly adjacent centers.
A liberal interpretation would imply the creature's center is already past the corner (between rows B and C) and would not encounter this obstacle. Only if the creature fully filled all 4 squares would it's "southeast" appendages encounter the corner.
The following picture represents the specific in-game situation. The yellow line (10 feet distance) crosses the corner and would result in 20 feet of movement according to the "corner rule". However, the green line is 15 feet of movement, with the middle segment the one relevant to this question. The green line does not impact a corner; in fact, it's 3.5 feet away from it. A creature 7 feet wide would not impact it.
Most convincing to me is a visual interpretation. The rules are unambiguous for the situation on a 5-foot grid of moving between green squares with the red square representing an something that "fills its space":
However, consider this same 5-foot grid, but the obstacle in the red square does not fill its space, taking up only half of it:
Since in this case the obstacle does not completely fill the space, I believe the "corner rule" doesn't apply, and RAW would only require 5 feet of movement.
Now, consider the specific question asked regarding a large creature. Scaling the above situation up by 2x we see the following on a 5-foot grid:
If the previous 5-foot "does not fill the space" resulted in 5 foot movement, then this scaled up interpretation would imply a movement between the two green 10-foot squares would only require 10 feet of movement; the first half of which is the specific example in this question.
Given the above examples, does this movement require one square (5 feet) or two squares (10 feet) of movement?
I'd prefer a RAW interpretation if it exists, a RAI otherwise.