core: Return false for shape hitTests on zero-scale graphics

[Herschel]

If a graphic has a scaleX or scaleY of 0, a shape hitTest(x, y, true) should return false, even on the exact location of the object. Note that a bounds hitTest(x, y, false) still returns true on the exact location of the object. Bail out on the hitTest immediately when we detect no width or height.

Fix with the following changes:

• Change Matrix::invert to Matrix::inverse and make it fallible, returning None for non-invertible matrices. (An object with zero scale will have a non-invertible matrix for its transform).
• Change DisplayObject::global_to_local_matrix and DisplayObject::global_to_local fallible. These return None when the object has zero scale.
• Adjust all places in core that used these to properly handle these methods returning None. All overrides of hit_test_shape will return false in this case.

Bonus:

• Fix clip.globalToLocal(point) when the clip has zero scale: point will be unaffected.
• Fix clip._xmouse/_ymouse/etc. when the clip has zero scale: a 1/20 scale matrix (twips-to-pixels) is used.
  • Added DisplayObject::mouse_to_local to handle these cases.

Fixes #6906.

[Herschel]

I decided on a more thorough way to solve this by making Matrix::inverse, DisplayObject::global_to_local return an Option. This way any caller has to explicitly handle the case when the object is zero scale and the matrix has no inverse.

[Toad06]

Thanks for your work on this. This looks good to me based on testing, I haven't found any issue or regression.

Mentioning that this game now works would be a nice addition to ruffle-rs/ruffle-rs.github.io#132. 😉

[szefkaf]

@Toad06 please note that the quality of this game dropped dramatically to 18-20fps sometimes after these fixes when more sprites are on the screen. In the version I fixed it stays at over 30 frames per second just like in the original Flash version. Please compare Level 1 Bob-omb Battlefield (left door in Castle) in both versions. In the new version of Ruffle, even the jump sound can't keep up with real Mario's jump on mid-range laptops. I'm a little afraid that it will have its consequences in other games that will simply be too slow to play especially on mobiles.