Generally, when transforming a difference between two points, `p1`
and `p2`, with a matrix `m`, we would like the following property
to hold:
```
m * (p1 - p2) == m * p1 - m * p2
```
Unfortunately, it wasn't like this before, because matrices have a
translation component, which is non-linear. In `m * p1 - m * p2`,
the translations of `m * p1` and `m * p2` are the same and therefore
cancel out each other. However, in `m * (p1 - p2)` the translation
stays.
In order to preserve this property, introduce a new `PointDelta`
type which is not subject to translation when transformed by a matrix.
For now, the following operations are supported:
* `Point - Point -> PointDelta`
* `Point + PointDelta -> Point`
* `Point += PointDelta`
* `Point - PointDelta -> Point`
* `Point -= PointDelta`
As a consequence, the expression `position + global_to_local_matrix * mouse_delta`
in `update_drag()` now ignores translation, which fixes#817.
Flash does not support nested mask regions and instead merges them
into a single clip region.
For example, this occurs when using a dynamic text field as a mask.
One mask layer contains the glyphs, while the second layer is the
bounds of the text field. The text field bounds end up being
ignored when the text field is used as a mask, allowing the text
outside the bounds to be visible.
Add `CommandList::maskers_in_progress` to keep track of the mask
state and discard drawing commands for inner maskers.
Fixes#9664.
This matches the Context3D docs. Calling 'present' swaps
the buffers.
I wasn't certain if we actually need a double-buffered depth
texture, but I included one just to be safe.
Now that most of the complicated Context3D methods have been
implemented, we can simplify the overall design. Instead of queueing
up commands and having `present` execute them in a loop, we
can execute each command immediately. The key insight is that
a `RenderPass` is only needed for `DrawTriangles`, so we don't
have to store it in `Context3D` and deal with complicated lifetime
issues.
The old behavior gave us implicit double-buffering behavior,
since nothing would get rendered until a 'present' call.
Now that a 'drawTriangles' call will immediately submit
a draw command, we need to implement actual double buffering.
This is done in the next commit.
* `global_to_local` returns `None` if the object has zero scale.
* Adjust AVM `globalToLocal` methods to return the untransformed
point on failure.
* Add `DisplayObject::mouse_to_local` to handle AVM `mouseX`
and `mouseY` coordinates. For zero scale objects, these end up
returning values based on the twips-to-pixels scale,
divided by 20.
* Add `Matrix::determinant`.
* Rename `Matrix::invert` to `inverse`.
* `Matrix::inverse` return an `Option`, with `None` returned
for non-invertible matrices.
* AMV `Matrix::invert` duplicates the code as the behavior is
different (works in f64 and not twips, etc.)
Nathan Adams