Elements are actions Photon 2 executes as part of animated sequences. In most contexts, elements are simply individual lights. However, elements can also be sounds, bone manipulation, and more.

Elements are most commonly lights. Photon 2 supports four different types of lights, each with their own benefits and drawbacks.

2D lights (sometimes called "sprites") are flat materials drawn in 3D space with an artificial glow effect. They are very closely related to the lights in Photon LE.

2D lights are best suited for flat surfaces and are the most flexible in terms of appearance. They have a moderate-to-high impact on performance as they rely on computationally expensive visibility calculations in addition to advanced post-processing effects.

• Supports intensity transitions: Yes.

Mesh lights are 3D models that leverage a bloom shader for glow effects. They are extracted from sub-materials in a .MDL file. They have a light impact on performance and allow for sophisticated shapes that 2D lights cannot feasibly do.

Mesh lights typically require familiarity with 3D modeling software to create and are generally less vivid in appearance (although they can be combined with 2D lighting).

They are most commonly utilized for normal vehicle lights where a 2D shape would not be practical.

• Supports intensity transitions: Yes.

When creating models to be used for standard vehicle lighting, you can take advantage of Photon's standardized, placeholder materials located in the materials/photon/vehicle folder. (In the future, this is planned to enable more automation when configuring component files.)

Projected lights illuminate the world and models and can be configured to cast shadows. They have no visible light source and must therefore be paired with a 2D light or mesh light for a realistic appearance. They are integral for illumination functionality but are extremely expensive to render. As a single-player effect, however, they can be highly effective.

Projected lights are a core offering of the Source engine.

• Supports intensity transitions: Yes.

Dynamic lights are similar to projected lights but are less performance heavy, have a lower fidelity, and are not as controllable. They have a built-in fade in, fade-out behavior that cannot be removed, and are therefore not usually appropriate for flashing lights.

They are best utilized as a low-impact ambience effect, license plate light, or interior light.

• Supports intensity transitions: No.

Refers to sub-materials. Allows the element to change as parent model's sub-material. Sub-materials have the best performance of any light, but are very limited in functionality and fidelity.

• Supports intensity transitions: No.

Sound elements play and control different sounds. Various sound attributes can be manipulated using state parameters. Sound elements are used for sirens (using siren speaker components) and can be used for flashing sound effects.

Bone elements control one axis of a model's bone. Bone elements have four primary activities:

1. Rotate Continuously rotates the bone in one direction at a specified speed.
2. Sweep Moves the bone back and forth between two angles. The start angle, stop angle, move speed, and pause time are user configurable.
3. Fixed Rotates the bone to a specific angle and then stops. The target angle and speed are configurable.
4. Spot User-manipulated positioning (still under development).

Bone elements can be configured to adjust a "proxy state," which other elements can reference and use as states on their own. This is utilized to enable light colors to change depending on the current angle of the bone. This is primarily for the Vision SLR lightbar.

The performance impact of bone elements is generally negligible as there typically aren't very many.

Sequence elements configure a model's current sequence, which is used to trigger model animations. The term "sequence" in this context has no relation with component sequences.

Pose elements manipulate a model's pose parameters. Each element can be mapped to one pose parameter. Pose element states configure a gain speed, loss speed, and target value (between 0 and 1).

In the image above, the Valor's feet pose parameter alternates between extended and retracted.

COMPONENT.Templates = {
   ["Pose"] = {
      PoseTemplate = {
         GainSpeed = 1, -- Speed when value increases
         LossSpeed = 0.6, -- Speed when value decreases
         States = {
            -- These are available by default
            ["OFF"] = { Target = 0 },
            ["ON"] = { Target = 1 },
            -- Custom state
            ["HALF"] = { Target = 0.5 },
         }
      }
   }
}

COMPONENT.Elements = {
   -- Implicit element syntax
   [1] = { "PoseTemplate", "pose_param_name" },
   -- Explicit element syntax
   [2] = { "PoseTemplate", Parameter = "pose_param_name", GainSpeed = 2, LossSpeed = 3 }
}

Virtual elements are invisible and are designed for user-interface animation.

These are shared Photon Element properties.

-- This is a common use-case when simulating incandescent lights. 
COMPONENT.Templates = {
   ["2D"] = {
      My2dTemplate = {
         -- Whenever an element stops receiving inputs, it will apply the deactivation state.
         -- In this example, it causes the light to fade out.
         DeactivationState = "~OFF"
      }
   }
}

Element groups allow for multiple elements to be referenced by one shared name. Elements can belong to an unlimited number of groups and eliminate the need to track multiple indexes of related elements.

COMPONENT.ElementGroups = {
   ["ODD"] = { 1, 3, 5, 7 },
   ["EVEN"] = { 2, 4, 6, 8 },
   ["ALL"] = { 1, 2, 3, 4, 5, 6, 7, 8 }
}

COMPONENT.Segments = {
   MySegment = {
      Frames = {
         -- These two frames are functionally identical
         [1] = "[R] ODD [B] EVEN",
         [2] = "[R] 1 3 5 7 [B] 2 4 6 8",
         -- These two are also identical
         [3] = "[W] ALL",
         [4] = "[W] 1 2 3 4 5 6 7 8",
      },
      Sequences = {}
   }
}

Intensity transitions enable fade-in, fade-out behavior on compatible light elements. States must be manually configured to enable intensity transitions. States that utilize intensity transitions are prefixed with ~ by convention for easy identification. For example, a fade-out state is commonly be called ~OFF, and a fade-in state to red would be ~RED.

On models that have body groups with different light variations or configurations, you can configure an element to only be enabled when specific body group conditions are met.

Specifying within a template:

COMPONENT.Templates = {
   ["2D"] = {
      ["ForwardHotFeet"] = {
         RequiredBodyGroups = {
            -- Requires the "Hotfeet" body group to be 0
            ["Hotfeet"] = 0,
         }
      }
   }
}

Specifying within an element definition:

COMONENT.Elements = {
   -- Enabled only when Hotfeet is 0
   [1] = { "ForwardHotFeet", Vector( 1, 2, 3), Angle( 0, -90, 0 ), RequiredBodyGroups = { ["Hotfeet"] = 0 } },
   -- Enabled when Hotfeet is 0 or 1
   [2] = { "ForwardHotFeet", Vector( 1, 2, 3), Angle( 0, -90, 0 ), RequiredBodyGroups = { ["Hotfeet"] = { 0, 1 } } }
   -- Same as #2, uses a body group index instead of name
   [3] = { "ForwardHotFeet", Vector( 1, 2, 3), Angle( 0, -90, 0 ), RequiredBodyGroups = { [1] = { 0, 1 } } }
}