Lights

Evergine uses an advanced lighting mode to simulate how light affect geometries. It also supports multiple lights in the scene, allowing a wide range of environment and possibilities.

Every type of light is modelled in Evergine using a Light component.

Create a Light in Evergine Studio

In the Entities Hierarchy panel of your Scene Editor, click the "Add Entity and select Light, then choose the kind of light you want to create:

Point Light
Directional Light
Sphere Area Light
Spot Light
Disc Area Light
Rectangle Area Light
Rube Area Light

We discuss the light types later in this article.

Create Light

Additionally we can create photometric lights from the same panel with theese options:

Photometric Point Light
Photometric Directional Light
Photometric Sphere Area Light
Photometric Spot Light
Photometric Disc Area Light
Photometric Rectangle Area Light
Photometric Rube Area Light

Create Light

Create Light from code

The following sample code can be used to instantiate a new basic new point light entity in a scene.

protected override void CreateScene()
{
    // Create a new light entity.
    Entity pointLightEntity = new Entity()
        .AddComponent(new Transform3D())
        .AddComponent(new PointLight()
        {
            Color = Color.Red,
            Intensity = 3,
            LightRange = 10
        });

    // Add the light entity to the entity manager.
    this.Managers.EntityManager.Add(pointLightEntity);
}

Basic light properties

These are the basic properties that almost all the lights have.

Property	Description
Is Enabled	If the light is on / off.
Shadow Enabled	Enable/disable shadow mapping for this light.

Photometric / Non photometric lights

Photometric lights use photometric (lighting units) allowing you to define precisely lights as they would be in the real world. They are configured using physical parameters. Evergine supports both photometric and non photometric lights, and it offers all the same light types duplicated depending this choice.

Common Photometric properties

Every photometric light (no matter what type it is) defines this parameters, additionally each specific type of light defines its own intensity unit properties.

Property	Description
Color By Temperature	Indicates if the light color will be overrided using the light temperature.
Temperature	The light temperature in Kelvin (K). When ColorByTemperature is true, the light color is overrided by the light temperature.

Note

Light Intensity unit depends on the light type (for example, PointLights are measured in Lumens, whether DirectionalLights are measured in Lux)

Non photometric lights properties

For contrary, if you create regular lights, you could use the basic light properties:

Property	Description
Color	The RGB color tint of the light.
Intensity	The light intensity value in a non-standard unit. Greater values will produce brighter illumination.

Types of lights

There are different types of lights, each one useful for a different scenario. In general terms, lights are divided in two general categories:

Directional Lights: These lights have unlimited boundaries, and every object is affected by this light type.
Volume Lights: The light influence is delimited by a range.
Area Lights: A subtype of volume lights that emulate lights coming from an area instead of a point in the space.

Directional Lights / Photometric Directional Light

Directional Light

Directional lights are lights that comes uniformly from one direction and at infinited distance. They're used to simulate distant light sources like the sun. It uses the forward vector of its entity Transform3D for calculating the light direction.

In case of using a Photometric Directional Light, the intensity is measured using the following property:

Photometric Property	Description
Illuminance (Lux)	The light Illuminance measured in Lux. Indicates the total luminous flux incident on a surface, per unit area.

Volume Lights

Volume lights are a common type of lights in which the light source comes from a specific point in the space, and its intensity decays with the distance.

Property	Description
Light Range	The light range in meters.

In case of using a Volume Photometric Lights, the intensity is measured using the following property:

Photometric Property	Description
Luminous Power (Lumen)	The light luminous flux in Lumen

Point Light / Photometric Point Light

Point Light

A point light is located at a point in space and it emits light in all directions equally within its sphere range. Its intensity decays with distance from the light, reaching zero at its maximum range. It's useful for local lights like lamps.

Spot Light / Photometric Spot Light

Spot Light

A spot light is also placed in a specific location and it has a range over which the light decays. However, spot lights are also constrained by an angle, defining a cone shape light.