* Improve the collision detection algorithm so that Actor OnCollide
scripts get called more often WHILE an actor is moving, to prevent a
fast-moving actor from zipping right through the "solid" hitbox and
not giving the subject actor time to protest the movement.
* It's implemented by adding a `Settled` boolean to the OnCollide event
object. When the game is testing out movement, Settled=false to give
the actor a chance to say "I'm solid!" and have the moving party be
stopped early.
* After all this is done, for any pair of actors still with overlapping
hitboxes, OnCollide is called one last time with Settled=true. This is
when the actor should run its actions (like publishing messages to
other actors, changing state as in a trapdoor, etc.)
* The new collision detection algorithm works as follows:
* Stage 1 is the same as before, all mobile actors are moved and
tested against level geometry. They record their Original and New
position during this phase.
* Stage 2 is where we re-run that movement but ping actors being
intersected each step of the way. We trace the steps between
Original and New position, test OnCollide handler, and if it returns
false we move the mobile actor to the Last Good Position along the
trace.
* Stage 3 we run the final OnCollide(Settled=true) to let actors run
actions they wanted to for their collide handler, WITHOUT spamming
those actions during Stage 2.
* This should now allow for tweaking of gravity speed and player speed
without breaking all actor collision checking.
* Refactor texture caching in render.Engine:
* New interface method: NewTexture(filename string, image.Image)
* WASM immediately encodes the image to PNG and generates a JavaScript
`Image()` object to load it with a data URI and keep it in memory.
* SDL2 saves the bitmap to disk as it did before.
* WASM: deprecate the sessionStorage for holding image data. Session
storage methods panic if called. The image data is directly kept in
Go memory as a js.Value holding an Image().
* Shared Memory workaround: the level.Chunk.ToBitmap() function is where
chunk textures get cached, but it had no access to the render.Engine
used in the game. The `pkg/shmem` package holds global pointers to
common structures like the CurrentRenderEngine as a work-around.
* Also shmem.Flash() so Doodle can make its d.Flash() function
globally available, any sub-package can now flash text to the screen
regardless of source code location.
* JavaScript API for Doodads now has a global Flash() function
available.
* WASM: Handle window resize so Doodle can recompute its dimensions
instead of scaling/shrinking the view.
* Implement the pub/sub message passing system that lets the JavaScript
VM of one actor (say, a Button) send messages to other linked actors
in the level (say, an Electric Door)
* Buttons now emit a "power(true)" message while pressed and
"power(false)" when released. Sticky Buttons do not release and so do
not send the power(false) message.
* Electric Doors listen for the "power" event and open or close
themselves based on the boolean value received.
* If a Sticky Button receives power and is currently pressed down, it
will pop back up (reset to "off" position) and notify its linked
actors that they have lost power too. So if a Sticky Button held an
Electric Door open, and another Button powers the Sticky Button, it
would pop back up and also close the Electric Door.
* Add a Red Azulian as a test for mobile enemies.
* Its A.I. has it walk back and forth, changing directions when it
comes up against an obstacle for a few moments.
* It plays walking animations and can trigger collision events with
other Doodads, such as the Electric Door and Trapdoor.
* Move Gravity responsibility to the doodad scripts themselves.
* Call `Self.SetGravity(true)` to opt the Doodad in to gravity.
* The canvas.Loop() adds gravity to any doodad that has it enabled.
* CLI: fix the `doodad convert` command to share the same Palette when
converting each frame (layer) of a doodad so subsequent layers find
the correct color swatches for serialization.
* Scripting: add timers and intervals to Doodad scripts to allow them to
animate themselves or add delayed callbacks. The timers have the same
API as a web browser: setTimeout(), setInterval(), clearTimeout(),
clearInterval().
* Add support for uix.Actor to change its currently rendered layer in
the level. For example a Button Doodad can set its image to Layer 1
(pressed) when touched by the player, and Trapdoors can cycle through
their layers to animate opening and closing.
* Usage from a Doodad script: Self.ShowLayer(1)
* Default Doodads: added scripts for all Buttons, Doors, Keys and the
Trapdoor to run their various animations when touched (in the case of
Keys, destroy themselves when touched, because there is no player
inventory yet)
* Add the JavaScript system for Doodads to run their scripts in levels,
and wire initial OnCollide() handler support.
* CLI: Add a `doodad install-script` command to the doodad tool.
* Usage: `doodad install-script <index.js> <filename.doodad>`
* Add dev-assets folder for storing source files for the official
default doodads, sprites, levels, etc. and for now add a JavaScript
for the first test doodad.
