Interactable: allow specifying arbitrary 2D polygon for mouse interaction

[michaeldgg2]

Background

Interactable trait does not allow specifying non-rectangular region as mouse bounds...

[Desc("Used to enable mouse interaction on actors that are not Selectable.")]
public class InteractableInfo : TraitInfo, IMouseBoundsInfo
{
	[Desc("Defines a custom rectangle for mouse interaction with the actor.",
		"If null, the engine will guess an appropriate size based on the With*Body trait.",
		"The first two numbers define the width and height of the rectangle as a world distance.",
		"The (optional) second two numbers define an x and y offset from the actor center.")]
	public readonly WDist[] Bounds = null;

	// ...

... despite MouseoverBounds() method in IMouseBounds interface returning Polygon:

public interface IMouseBounds { Polygon MouseoverBounds(Actor self, WorldRenderer wr); }

PR description

This PR allows specifying arbitrary 2D polygon for mouse interaction that will be used instead of Bounds (or bounds generated using IAutoMouseBounds trait):

[Desc("Defines a custom 2D polygon for mouse interaction with the actor.",
	"If null, Bounds will be used instead",
	"Each vertex has two components (so two numbers), which define an x and y offset from the actor center.")]
public readonly int2[] Polygon = null;

Example in RA

This is how a (bit contrived) test case could look like in RA:

(here only Refinery has polygon mouse bounds, the rest of the buildings use normal rectangle)

Selectable:
	# Bounds: 3072, 2133, 0, 170
	DecorationBounds: 3072, 2986, 0, -85
	Polygon: 0,1194, 938,170, 3072,170, 3072,1621, 2560,1621, 1066,2303, 0,2303

I also added a debug trait RenderMouseBounds for use by modders in order to tweak the polygon, since the mouse bounds are not visible unlike the selection box. It's not essential for the PR, so I can remove it, if required.

More background (and a real use case)

In OpenE2140 we have a small issue with the mouse bounds for Refinery and Mine buildings. Both have conveyor belt on one entire tile, which "sticks" out of the main part of each building. The problem is that it's not possible to target the cell right below the conveyor belt:

With Interactable allowing to define polygon (in addition to normal rectangle), we can solve this issue very elegantly:

Actually this is how the mouse interaction works in the original Earth 2140:

[RoosterDragon]

Seems like a nice addition to me, and RenderMouseBounds is a lightweight addon so seems worth keeping for debugging utility.

[anvilvapre]

if i look at the example graphics, it seems to me it migh be nicer to draw 3d bounding box around a building. i.e. letting a selection/bounding box be part of the graphics of a building.

[abcdefg30]

Lgtm otherwise. Can you remove the testcase?

[abcdefg30]

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