beam

Beam Datum and Effect
IF YOU ARE LAZY AND DO NOT WANT TO READ, GO TO THE BOTTOM OF THE FILE AND USE THAT PROC!
This is the beam datum! It's a really neat effect for the game in drawing a line from one atom to another.
It has two parts:
The datum itself which manages redrawing the beam to constantly keep it pointing from the origin to the target.
The effect which is what the beams are made out of. They're placed in a line from the origin to target, rotated towards the target and snipped off at the end.
These effects are kept in a list and constantly created and destroyed (hence the proc names draw and reset, reset destroying all effects and draw creating more.)
You can add more special effects to the beam itself by changing what the drawn beam effects do. For example you can make a vine that pricks people by making the beam_type
include a crossed proc that damages the crosser. Examples in venus_human_trap.dm

Vars
anim_duration	Duration of the last animation, in deciseconds (matches the time= passed to animate()).
anim_from_origin_x	Last animation's "from" (where segments were seeded at draw time) — origin endpoint.
anim_from_target_x	Last animation's "from" — target endpoint.
anim_start_time	world.time at which the last animation began. Combined with anim_duration to estimate segments' current visual position mid-animation.
animate	If FALSE, redraws snap per update instead of using animate() interpolation.
beam_color	The color of the beam we're drawing.
beam_layer	the layer of our beam
beam_type	the objects placed in the elements list
elements	list of beam objects. These have their visuals set by the visuals var which is created on starting
emissive	If we use an emissive appearance
icon	icon used by the beam.
icon_state	icon state of the main segments of the beam
last_draw_valid	Whether we have a cached last-drawn geometry from a previous Draw().
last_origin_x	Last drawn origin tile/pixel coordinates (used as the "from" frame for animated redraws).
last_target_x	Last drawn target tile/pixel coordinates.
max_distance	The beam will qdel if it's longer than this many tiles.
origin	where the beam goes from
override_origin_pixel_x	If set will be used instead of origin's pixel_x in offset calculations
override_origin_pixel_y	If set will be used instead of origin's pixel_y in offset calculations
override_target_pixel_x	If set will be used instead of targets's pixel_x in offset calculations
override_target_pixel_y	If set will be used instead of targets's pixel_y in offset calculations
pending_animate_time	Animate time queued for the pending redraw. We take the largest (slowest glide) of any movers that triggered the redraw.
target	where the beam goes to
visuals	This is used as the visual_contents of beams, so you can apply one effect to this and the whole beam will look like that. never gets deleted on redrawing.
Procs
Draw	Creates the beam effects and places them in a line from the origin to the target. Sets their rotation to make the beams face the target, too.
Start	Proc called by the atom Beam() proc. Sets up signals, and draws the beam for the first time.
get_last_geometry	Returns the last drawn endpoints for reuse by inherit_glide(), or null if undrawn.
inherit_glide	Seeds the next Draw() from saved geometry so rebuilt beams glide instead of snapping.
redrawing	Triggered by signals set up when the beam is set up. If it's still sane to create a beam, it removes the old beam, creates a new one. Otherwise it kills the beam.
set_subsegment_appearance	sets the sprite of the segment, using the more performant viscontents by default

Var Details

var
anim_duration

Duration of the last animation, in deciseconds (matches the time= passed to animate()).

var
anim_from_origin_x

Last animation's "from" (where segments were seeded at draw time) — origin endpoint.

var
anim_from_target_x

Last animation's "from" — target endpoint.

var
anim_start_time

world.time at which the last animation began. Combined with anim_duration to estimate segments' current visual position mid-animation.

var
animate

If FALSE, redraws snap per update instead of using animate() interpolation.

var
beam_color

The color of the beam we're drawing.

var
beam_layer

the layer of our beam

var
beam_type

the objects placed in the elements list

var
elements
– /list

list of beam objects. These have their visuals set by the visuals var which is created on starting

var
emissive

If we use an emissive appearance

var
icon

icon used by the beam.

var
icon_state

icon state of the main segments of the beam

var
last_draw_valid

Whether we have a cached last-drawn geometry from a previous Draw().

var
last_origin_x

Last drawn origin tile/pixel coordinates (used as the "from" frame for animated redraws).

var
last_target_x

Last drawn target tile/pixel coordinates.

var
max_distance

The beam will qdel if it's longer than this many tiles.

var
origin
– /atom

where the beam goes from

var
override_origin_pixel_x

If set will be used instead of origin's pixel_x in offset calculations

var
override_origin_pixel_y

If set will be used instead of origin's pixel_y in offset calculations

var
override_target_pixel_x

If set will be used instead of targets's pixel_x in offset calculations

var
override_target_pixel_y

If set will be used instead of targets's pixel_y in offset calculations

var
pending_animate_time

Animate time queued for the pending redraw. We take the largest (slowest glide) of any movers that triggered the redraw.

var
target
– /atom

where the beam goes to

var
visuals
– /obj/effect/ebeam

This is used as the visual_contents of beams, so you can apply one effect to this and the whole beam will look like that. never gets deleted on redrawing.

Proc Details

proc
Draw
(/atom/movable/mover, /atom/oldloc)

Creates the beam effects and places them in a line from the origin to the target. Sets their rotation to make the beams face the target, too.

proc
Start
()

Proc called by the atom Beam() proc. Sets up signals, and draws the beam for the first time.

proc
get_last_geometry
()

Returns the last drawn endpoints for reuse by inherit_glide(), or null if undrawn.

proc
inherit_glide
(/list/geometry, animate_time)

Seeds the next Draw() from saved geometry so rebuilt beams glide instead of snapping.

proc
redrawing
(/atom/movable/mover, /atom/oldloc, direction)

Triggered by signals set up when the beam is set up. If it's still sane to create a beam, it removes the old beam, creates a new one. Otherwise it kills the beam.

Arguments: mover: either the origin of the beam or the target of the beam that moved. oldloc: from where mover moved. direction: in what direction mover moved from.

proc
set_subsegment_appearance
(/obj/effect/ebeam/segment)

sets the sprite of the segment, using the more performant viscontents by default

beam /datum/beam

Beam Datum and Effect

Vars

Procs

Var Details

var anim_duration

var anim_from_origin_x

var anim_from_target_x

var anim_start_time

var animate

var beam_color

var beam_layer

var beam_type

var elements – /list

var emissive

var icon

var icon_state

var last_draw_valid

var last_origin_x

var last_target_x

var max_distance

var origin – /atom

var override_origin_pixel_x

var override_origin_pixel_y

var override_target_pixel_x

var override_target_pixel_y

var pending_animate_time

var target – /atom

var visuals – /obj/effect/ebeam