Add directionality to walls

[kwvanderlinde]

Identify the Bug or Feature request

Resolves #5080

Description of the Change

Walls can have one of these enumerated directions:

• Left
• Right
• Both

An arrow indicates to the user what the direction of the wall is. If there is no arrow, the direction is Both.

Walls can also have overrides applies for different types of "vision" blocking (sights, lights, and auras):

• SameDirection (default) means that blocking for this type works in the same direction as the wall.
• ReverseDirection means that blocking for this type works opposite to the wall's direction (no effect if wall direction is Both).
• ForceBoth means that blocking for this type works as if the wall's direction is Both.
• Disabled means that blocking for this type is disabled for this wall.

Movement blocking does not support directionality yet as there are extra complexities for it that would go way beyond this change. But it support has been added for the ForceBoth and Disabled options, with ForceBoth being the default for movement blocking.

The way the user modifies these properties is through a new control panel:

This control panel with show the properties of the currently selected wall (if there is one). When drawing new walls, the properties set in the control panel will be applied to the new walls.

The XML for walls includes the new information as child elements of the <wall> elements, e.g.:

<wall from="8A647D10EE1B4AFA8BEF4B93AEFB624D" to="E3A964F13221428582E491AB3D3D3764">
  <direction>Left</direction>
  <movementDirection>Disabled</movementDirection>
  <sightDirection>SameDirection</sightDirection>
  <lightDirection>ReverseDirection</lightDirection>
  <auraDirection>ForceBoth</auraDirection>
</wall>

There is some code maintenance as well. The biggest point here is that Vertex and Wall are more basic values - they don't depend on their parent WallTopology, and can be more easily constructed and serialized. This makes the private VertexInternal and WallInternal obsolete and they have been removed. Wall and Vertex have also been moved out of the WallTopology class just to make it less busy.

Possible Drawbacks

Merging behaviour regarding direction modifiers for sights, lights, and auras could be a bit surprising with the various case work in play.

Documentation Notes

Walls can have one of these directions:

• Left
• Right
• Both

If "Both", the wall blocks in both directions. If "Left" or "Right" the wall only blocks in that particular direction. The interpretation of "Left" and "Right" depends on the heading of the wall, i.e., which one of the wall's endpoints is the start of the wall and which one is the end of the wall. To make the direction clear to the user, an arrow is drawn through the wall to indicate the direction:

To support different directional effects, sights, lights, and auras can be configured to override the wall direction. In this example, a directional wall models a one-way mirror:

The Troll is unable to see out of the room due to the wall's direction:

But the Elf is able to see into the room through the one-way mirror:

Also notice that the orange light inside the room is allowed through the wall beccause the Light option is set to "Reverse Direction".

This next example represents a cliff face, with a Troll at the bottom and an Elf at the top. As in the previous example, the Elf and see the Troll, but the Troll can't see the Elf. But this time the Troll's light is not allowed through the wall to illuminate the top of the cliff, because the Light option is set to "Same Direction".

Release Notes

• Added directions to walls, with ability for sights, lights, and auras to modify the direction.

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