A fixture definition describes a lighting instrument, such as a multi-color light or a moving-head light, controllable over Artnet/DMX-512. Using such a definition makes it easier to use by assigning meaningful names to its functions, rather than working with raw DMX channel numbers.

A set of lighting fixture definitions usable with PIXILAB Blocks can be found here:

https://github.com/pixilab/blocks-fixtures

To use any of these definitions, do as follows:

1. Download the entire github repo as a ZIP and unpack (or clone the repo if yu're familiar with git).
2. Copy the desired brand name folder(s) into the fixtures directory located inside your PIXILAN-root directory.

The fixture definitions now appear grouped by brand and model under Manage, Artnet in Blocks.

A few basic and common fixture types can be found under the Generic brand. Due to the simple file format, it's quite easy to add a definition for other fixtures you want to use with Blocks, based on the information found below.

NOTE: These definitions were partially derived from the excellent Open Fixtures Library found at https://open-fixture-library.herokuapp.com

The fixtures directory holds a simple folder/file structure:

• It contains one subdirectory per supported brand, plus one named Generic, containing a few common definitions that aren't brand specific.
• Inside each subdirectory, there's a description file for each fixture, with the fixture's model name. These files have a .json extension, and are formatted according to the JSON standard.

The format of the data in each description file is defined by the following types (using typescript notation), where the top level object is of the FixtureDescriptor type:

interface FixtureDescriptor {
  channels: Channel[];  // The channels supported by this fixture
  note: string;  // Notes related to this fixture
}

interface Channel extends Named {
  type: ChannelTypes;
  defaultValue?: number; // What value to set channel to on system start-up (not normalized)
  normalized?: boolean; // Exposed as 0...1 value (else with its full range depending on resolution)
  hidden?: boolean; // Not shown in UI (used to represent "gaps" in the channel sequence)
  ranges?: Range[]; // When type is Ranges
}

type ChannelTypes = 'Analog//8'|'Analog//16'|'Analog//24'|'Ranges';

interface Range extends Named {
  first: number; last: number;  // First and last value corresponding to this mode
  discrete?: boolean; // Is discrete (single enum) value only, with no "range" within
}

Each FixtureDescriptor contains a list of channels. A channel can be of one of four types, where the first three represent an analog value wth 8, 16 or 24 bits resolution (mapping to one, two or three DMX channels). Such an analog value can also accept the following optional properties:

• defaultValue specifies the initial value of the channel. If not specified, the initial value will be zero.
• normalized set to true indicates that the value will be presented as 0…1 in the user interface. If not specified, or set to false, the value will be represented by its full numeric span (e.g., 0…255 for an 8-bit channel, 0…65535 for a 16-bit channel)
• hidden set to true hides the channel from the user interface, thereby blocking out "unused" slots in the channel space.

Alternatively the type is defined as 'Ranges', which describes a channel divided into sub-ranges, consisting of a number of consecutive values. These ranges are defined in the ranges array, specifying the lower and upper limits of each range.

If a range describes a single state (e.g., "strobe off"), the discrete flag is set to indicate this. Otherwise, the range is considered to also have a numeric value, mapping into whatever range is specified (e.g., a varying "strobe rate").

Here's an example of what the content of a description file can look like, taken from the generic Pan Tilt model:

{
  "note": "Moving Head, 8-bit",
  "channels": [
    {
      "name": "Pan",
      "type": "Analog_8",
      "normalized": true,
      "defaultValue": 127
    }, {
      "name": "Tilt",
      "type": "Analog_8",
      "normalized": true,
      "defaultValue": 127
    }
  ]
}