View source for Splines and Single Fixtures

[[ru:Сплайны и одиночные приборы]] [[en:Splines and Single Fixtures]] [[zh:样条和单个固定装置]]
Every fixture in a Light Stream project is one of two kinds: a '''single fixture''' or a '''spline''' — a line along which a chain of fixtures is arranged. This choice determines how the fixtures are addressed, how they are patched, and how easy it will be to change their layout later. Below is how they differ, what to choose for a particular object, and how to convert one into the other if the choice turns out to be wrong.

How both are drawn is covered in the article [[Adding Splines and Fixtures]]. What fixture types exist and how many channels they have is covered in the article [[Виды и типы приборов]].

== The Difference in Short ==

; Single Fixture
: An independent object: its own name, its own address, its own universe, its own fixture type. In the '''Fixtures''' window it occupies a separate row, and on the '''Mapping''' field it looks like a point. It can be moved, addressed, and patched independently of its neighbors.

; Spline
: A line with fixtures arranged along it. A spline is a single object: one name, one starting address, one fixture type for all the fixtures on the line. The program arranges the fixtures along the line itself and assigns them consecutive addresses itself. In the '''Fixtures''' window a spline occupies a single row, no matter how many fixtures are on it — whether 10 or 500.

The main practical consequence: a spline is managed as a whole, while single fixtures are managed one at a time.

{| class="wikitable"
! !! Single Fixtures !! Spline
|-
| In the '''Fixtures''' window || one row per fixture || a single row for the whole line
|-
| Address || set for each fixture || set for the first one, the rest are calculated automatically
|-
| Patching || each fixture is moved to a port separately || moved to a port as a whole, in one action
|-
| Fixture count || changed by adding and removing fixtures || the '''Fixture Count''' parameter in the properties
|-
| Layout || arbitrary: it stays wherever it was placed || along a line whose shape is edited via vertices
|-
| Fixture order || set by their addresses || set by the line's direction, flipped with the '''Reverse''' button
|-
| Selection on the field || a single fixture can be selected || the entire line is selected
|-
| Link to 3D || with a single fixture in the '''3D View''' window || with the spline in the '''3D View''' window
|}

For effects there is no difference: both the fixtures on a spline and single fixtures get their color based on their position on the '''Mapping''' field. The fixture kind is chosen for convenience when working with the project and with addressing, not for the picture itself.

== How to Tell Them Apart on the Mapping Field ==

* Fixtures of both kinds are drawn as green dots; selected ones are red.
* The fixtures of a spline are connected by a dark gray line. It is there only for clarity — the fixtures emit light, not the line. Showing the lines is toggled with the menu item '''View → 2D Mapping → Show Splines''' and is enabled by default.
* The first fixture of a spline is outlined in white. This is the start of the line: addressing counts from it, and it is the one the '''Reverse''' button swaps with the last one.
* If the fixtures aren't labeled, enable what you need in the same menu: '''Show Pixel Numbers''', '''Show Fixture Universes''', '''Show Fixture Multi-addresses'''. The '''Show Pixel Grid''' item turns on the field's grid, which is handy for checking whether the fixtures are lined up evenly.

In the '''Fixtures''' window a spline and a single fixture are distinguished by the icon to the left of the name: for a spline it's a polyline, for a single fixture it's the fixture itself. You can be certain by checking the '''Properties''' window: a spline has the '''Fixture Count''', '''Smooth''', and '''Distribution Type''' parameters there, while a single fixture doesn't.

== What to Choose for a Particular Object ==

'''Spline''' — when fixtures run in a row along a single line and are addressed consecutively:

* LED strips, bars, pixel tubes;
* garlands and strings of lights;
* facade outlines, cornices, window openings, railings;
* any long row of identical fixtures connected to a single port.

'''Single fixtures''' — when each fixture stands on its own:

* spotlights, floodlights, beam fixtures;
* individual points on an object placed without a common pattern;
* fixtures of different types mixed together;
* fixtures that need non-sequential addresses or different ports.

A '''matrix''' is usually built out of splines: you draw one row, give it the needed fixture count, and get the remaining rows with the '''Duplicate''' tool — it makes a given number of copies with a constant X and Y offset and a constant address offset.

General rule of thumb: the longer the row of identical fixtures on a single line, the more it pays off to use a spline. Five hundred separately placed fixtures means five hundred rows in the '''Fixtures''' window and five hundred addresses that have to be tracked manually; the same row as a spline is one row, one address, and one count parameter.

== Addressing ==

This is the most noticeable difference between the two kinds, and it's the reason a layout most often needs to be redone.

=== For a Spline ===

The properties set the '''Address''' and '''Universe''' — these apply to the first fixture on the line. From there the program calculates everything itself:

* the step between fixtures equals the number of channels of the selected fixture type plus the value of the '''Address Offset''' parameter (0 by default, meaning the addresses run back to back);
* when the fixtures stop fitting into a universe, the rest of the spline automatically moves on to the next one; on a port switched to '''SPI''' mode a fixture is never split — the next fixture simply starts at the first address of the next universe;
* in the '''Fixtures''' window, next to the spline, the occupied range is shown as '''U1-1-300''': the port's starting universe, the first address, and the last address.

Any change — the fixture count, the fixture type, the address offset, a reverse — recalculates the addressing of the whole line at once. Fixtures inside a spline are never addressed manually: that's the price of the convenience.

=== For Single Fixtures ===

The address and universe are set for each fixture individually. To avoid doing this by hand, fixtures are placed with '''Auto-patching''' enabled — then each next fixture gets the address right after the previous one. Addresses for fixtures already placed can be recalculated: right-click the port in the '''Fixtures''' window → '''Recalculate Fixture Addresses'''.

Keep in mind: the value entered into the '''Address''' field of the '''Properties''' window is applied to all fixtures currently selected in the '''Fixtures''' window. If you need to fix the address of just one fixture, deselect the rest.

For details on patching and distributing fixtures across ports, see the article [[Patching Fixtures]].

=== Addressing Errors ===

If fixtures or splines go beyond the universes allocated to a port, or their addresses overlap, the row in the '''Fixtures''' window is colored red — and so is the port itself, along with it. A red row means the signal won't reach these fixtures: fix the addresses, the fixture count on the spline, or the number of universes per port.

== Properties ==

Some parameters exist for both kinds, some only for a spline.

{| class="wikitable"
! Parameter !! Single Fixture !! Spline !! What it does
|-
| '''Name''' || yes || yes || The name in the '''Fixtures''' window. Clear names save a lot of time when patching.
|-
| '''Visibility''' || yes || yes || A disabled fixture is not displayed on the field and cannot be selected with the mouse; the linked object in the '''3D View''' is hidden along with it.
|-
| '''Address''', '''Universe''' || yes || yes || For a spline — the address and universe of the first fixture on the line.
|-
| '''Fixture Type''' || yes || yes || A button showing the current fixture's name; opens the [[Fixture Library]]. For a spline, changing the type changes it for every fixture on the line at once.
|-
| '''Go to 3D Fixture''' || yes || yes || Finds and selects the linked object in the '''3D View''' window. If there are several linked objects, the program offers to pick the one you need from a list.
|-
| '''Distribution Type''' || — || yes || '''Uniform''' — the fixtures are spread along the entire length of the line, and you set their number. '''Fixed Pixels''' — a fixture is placed at every vertex of the line, and the fixture count equals the number of vertices.
|-
| '''Fixture Count''' || — || yes || How many fixtures are on the line. Only changes with uniform distribution; with fixed pixels the field shows the number of vertices, and the entered value has no effect.
|-
| '''Address Offset''' || — || yes || How many channels to skip between adjacent fixtures on the line.
|-
| '''Reverse''' || — || yes || Flips the order of the fixtures: the first one becomes the last.
|-
| '''Smooth''' || — || yes || Rounds off the corners of the line: instead of a polyline you get a smooth curve.
|-
| '''Snap to Pixels''' || — || yes || Places the fixtures of the line exactly onto the cells of the pixel grid.
|}

A spline's properties are applied to every selected spline at once. This is handy when you need to set identical settings for a dozen identical bars: select them all and enter the value once.

== Converting One Kind Into the Other ==

The choice isn't final. The toolbar of the '''Mapping''' window has two buttons — '''Convert to Spline''' and '''Convert to Fixtures''' (in earlier versions they were called '''Link''' and '''Unlink'''). The selection for them is usually made with the '''Selection and Movement''' tool; both buttons are disabled while in spline edit mode. Any conversion can be undone with '''Ctrl+Z'''.

=== From Single Fixtures to a Spline ===

# Take the '''Selection and Movement''' tool and select two or more single fixtures.
# Click '''Convert to Spline'''.

What you get:

* the line passes through the positions of the selected fixtures, one fixture per vertex — the new spline is assigned the '''Fixed Pixels''' distribution type;
* the order of the vertices is determined by the '''addresses''', not by the selection order: the line is built from the fixture with the lowest address to the fixture with the highest;
* the address, universe, fixture type, and port are taken from the first fixture — for the rest they will be reassigned to match the line's shared numbering;
* snap to pixels is off for the new spline, so the fixtures stay exactly where they were;
* the original single fixtures are removed from the project, and the new spline is selected right away.

Before converting, it's worth checking the addresses: if they aren't set in the same order the fixtures follow on the object, the line will come out tangled. It's easier to patch the fixtures in order first and only then combine them into a spline.

The button is disabled if only one fixture is selected, if a spline is among the selection, or if spline edit mode is active.

=== From a Spline to Single Fixtures ===

# Select one or more splines.
# Click '''Convert to Fixtures'''.

Every fixture on the line becomes independent: it stays in place, keeps its address and universe, and ends up on the same port the spline was on; within the port the fixtures are arranged in ascending order of address, and their names are derived from the fixture type with sequential numbers. The line itself disappears along with its parameters — smoothing, reverse, fixture count, and distribution type.

The conversion is useful when:

* part of the line's fixtures need to be moved to another port or another converter;
* the fixtures need non-sequential addresses;
* you need to delete or move individual fixtures rather than the whole line.

After converting, check the link to the '''3D View''' window: it was created for the spline, and the new single fixtures will need it assigned again. See the article [[Linking 2D and 3D]] for that.

== Frequently Asked Questions ==

* '''The fixture count on the spline won't change.''' The '''Fixed Pixels''' distribution type is selected — with it, the fixture count equals the number of vertices on the line. Switch to '''Uniform''' or add vertices in spline edit mode.
* '''How do I select a single fixture inside a spline?''' You can't: a spline is selected, addressed, and moved only as a whole. If you need access to individual fixtures, convert the spline to fixtures.
* '''The animation runs along the line in the wrong direction.''' For a spline, click '''Reverse'''; for single fixtures, check the order of the addresses.
* '''The \"Convert to Spline\" button is disabled.''' You need to select at least two single fixtures and exit spline edit mode.
* '''The row of a fixture or spline in the \"Fixtures\" window has turned red.''' The addresses went beyond the port's universes or overlapped with a neighbor's addresses.
* '''The fixtures on the spline aren't aligned to the grid cells.''' Enable '''Snap to Pixels''' in its properties.
* '''There are too many fixtures and it's impossible to find anything in the list.''' Combine rows of identical fixtures into splines: instead of hundreds of rows in the '''Fixtures''' window there will be just one per line, and the addresses will be calculated automatically.