* New doodads: Switches.
* They come in four varieties: wall switch (background element, with
"ON/OFF" text) and three side-profile switches for the floor, left
or right walls.
* On collision with the player, they flip their state from "OFF" to
"ON" or vice versa. If the player walks away and then collides
again, the switch flips again.
* Can be used to open/close Electric Doors when turned on/off. Their
default state is "off"
* If a switch receives a power signal from another linked switch, it
sets its own state to match. So, two "on/off" switches that are
connected to a door AND to each other will both flip on/off when one
of them flips.
* Update the Level Collision logic to support Decoration, Fire and Water
pixel collisions.
* Previously, ALL pixels in the level were acting as though solid.
* Non-solid pixels don't count for collision detection, but their
attributes (fire and water) are collected and returned.
* Updated the MenuScene to support loading a map file in Play Mode
instead of Edit Mode. Updated the title screen menu to add a button
for playing levels instead of editing them.
* Wrote some documentation.
* Implement the handler code for `return false` when actors are
colliding with each other and wish to act like solid walls.
* The locked doors will `return false` when they're closed and the
colliding actor does not have the matching key.
* Add arbitrary key/value storage to Actors. The colored keys will set
an actor value "key:%TITLE%" on the one who touched the key before
destroying itself. The colored doors check that key when touched to
decide whether to open.
* The trapdoor now only opens if you're touching it from the top (your
overlap box Y value is 0), but if you touch it from below and the door
is closed, it acts like a solid object.
* Events.OnCollide now receives a CollideEvent object, which makes
available the .Actor who collided and the .Overlap rect which is
zero-relative to the target actor. Doodad scripts can use the .Overlap
to see WHERE in their own box the other actor has intruded.
* Update the LockedDoor and ElectricDoor doodads to detect when the
player has entered their inner rect (since their doors are narrower
than their doodad size)
* Update the Button doodads to only press in when the player actually
touches them (because their sizes are shorter than their doodad
height)
* Update the Trapdoor to only trigger its animation when the board
along its top has been touched, not when the empty space below was
touched from the bottom.
* Events.OnLeave now implemented and fires when an actor who was
previously intersecting your doodad has left.
* The engine detects when an event JS callback returns false.
Eventually, the OnCollide can return false to signify the collision is
not accepted and the actor should be bumped away as if they hit solid
geometry.
* Add sync.WaitGroup to some parts of the level collision detection
function and Canvas.Loop() to speed up the frame rate by load
balancing some work in parallel across multiple cores.
* Improves FPS from 30 to 55+ even for busy scenes with lots of mobile
enemies walking around.
* Before the level collision optimization, framerate would sometimes dip
to 30 FPS simply to move the player character on a completely blank
map!
* 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)
* Move all collision code into the pkg/collision package.
* pkg/doodads/collision.go -> pkg/collision/collide_level.go
* pkg/doodads/collide_actors.go for new Actor collide support
* Add initial collision detection code between actors in Play Mode.
