Knockback3 should have some kind of Knockback2 relationship/constructor/behavior

[Cokemonkey11]

needs scoping/proposal

[Cokemonkey11]

Knockback3's design is to act as a kind of global physics system for units in a map. It behaves well when you use it for everything, and poorly if you mix and match.

The implication is that applying knockback to a unit in motion is an additive effect. setVel can be used when an instantaneous interruption is needed.

As such, scoping 2D knockback opens some questions:

• How should 2D knockback behave on a unit in 3D motion?
• How should 3D knockback behave on a unit in 2D motion?
• What constitutes a unit in 2D or 3D motion for answering the above?
• Should it be possible to force a 2D knockback with any guarantees?
• What should the behavior be for 3D knockback with horizontal trajectory? The same as a 2D knockback? What trajectory should act as threshold between the two?

[Cokemonkey11]

I propose adding a new:

public static add2d(unit u, real initial_speed, angle groundAngle)

• When applied to a unit with low velocity (configurable threshold), instantiates a Knockback3 with a 2d flag that behaves differently
• When any knockback is applied to a flying unit, this codepath is used instead
• When applied to a unit with 2d flag, behaves as add does
• When applied to a unit with velocity and no 2d flag, "elevates" to 3d and uses horizontal trajectory
• When a 3d knockback is applied to a unit with 2d flag, elevates to a 3d knockback, considering current velocity as simply 0 z component

What constitutes a unit in 2D or 3D motion for answering the above?

A unit is in 2d-only motion with the 2d flag.

Should it be possible to force a 2D knockback with any guarantees?

No, out of scope.

What should the behavior be for 3D knockback with horizontal trajectory? The same as a 2D knockback? What trajectory should act as threshold between the two?

Out of scope. Leave 3d knockback with horizontal trajectory unchanged.

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Leads to a new question: what special handling should 2d knockback have?

• Constant friction value (configurable, both air and ground)
• FX only for ground units
• setXY instead of setXYZ

Should 2d knockback consider heightmap?

No. Out of scope. Constant friction, no terrain-z consideration initially.