Can a Polygon Collider 2D work with a Mesh Collider in Unity?

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EDIT: This is now a rather simple question. I have a 2D sprite that really needs the precision of a polygonal hitbox. The 2D, tile-based world around it uses a tile Mesh for efficiency reasons, and thus has a Mesh Collider.

Before, the tiles in the world were each GameObjects with Box Colliders and Rigidbody 2D's, and the ship and the tiles collided just fine. Now that I am using a Mesh Collider, however, they cannot collide. (I have read that this is because one is 2D and one is 3D.) So what should I do to get collisions (preferably with rigidbody physics) between a polygonal ship and a 2D tile mesh? [end edit]

In a 2D, tile-based, procedurally-generated, chunk-based exploration game (in Unity 4.5), I have a player ship which uses a Rigidbody 2D and a Polygon Collider 2D for collision detection.
This worked fine back when I used a Rigidbody 2D / Box Collider 2D for world tiles. However, this is horribly slow, so I replaced the discrete blocks with a tile mesh, using a Mesh Collider and other associated paraphernalia.

The problem is: I simply cannot get collision detection to work. I have tiles on the x-y plane, and the collision mesh (I can see it in the Scene View, so I know it works) consists of four rectangles perpendicular to the tile. (If you can't visualize this, I don't blame you. See here.)

What have I looked at so far? Well, I verified that the (2D) ship actually passes through the collision boxes in the Scene View. Also, neither of the colliders "Is Trigger".
Since there seems to be no official documentation on how to actually use meshes (is there? Where?), I can't find out whether Mesh Colliders and Polygon Colliders actually can interact. Because one is 2D and one is 3D, does this not work? If so, then what should I do instead? I tried using a Box Collider [3D] for the ship, but this didn't work either. I could have potentially made a mistake here, though.

Am I supposed to handle the collision manually (with the OnCollisionEntered [or something] method)? Before, the rigidbody2D objects handled everything automatically. Otherwise, is there any other possible reason the collision might not work?

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unity3dcollision-detectionmeshtileunity3d-2dtools
2D and 3D colliders use different physics engines and therefore do not interact with one another – LearnCocos2D
@LearnCocos2D Well, yes, that is what I expected. But what should I do, then? – Radon Rosborough
not try to mix them i guess, if you have to use a 3d collider then all of them have to be 3d colliders – LearnCocos2D
@LearnCocos2D But... there is no Polygon Collider 3D. – Radon Rosborough
@LearnCocos2D Basically, this isn't a technical, "is it possible to do this particular setup" question; but rather "what actual collider elements should I use to get collisions between a polygonal sprite and a 2D mesh?" – Radon Rosborough

2 Answers

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Well, I'm quite disappointed there seems to be no built-in way to do this in Unity. My solution was to attach a GameObject to the player that would read the block data from the world and create (pooled, of course) real but invisible "collider blocks" with Box Colliders 2D in a small area around the player, such that the player could collide with blocks near them. It works great, and I also implemented an algorithm to spawn rectangular collider blocks over groups of blocks; this eliminates the "ghost pixel" bug in the 2D physics engine.

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Uni2D plugin (https://www.assetstore.unity3d.com/en/#!/content/3826) automatically creates 3d colliders (as a group of mesh colliders) from any 2 texture with transparency. A bit expensive but works.