Lights

Creating a light

Lights in the FBX SDK are abstracted by the FbxLight class. A FbxLight is created like any other object in a scene.

By default, a FbxLight points along a node's negative Y axis.

// Create a node for our light in the scene.
FbxNode* lLightNode = FbxNode::Create(pScene, "lightNode");

// Create a light.
FbxLight* lLight = FbxLight::Create(pScene, "light");

// Set the node attribute of the light node.
lLightNode->SetNodeAttribute(lLight);

// Add the light node to the root node in the scene.
FbxNode* lRootNode = pScene->GetRootNode();
lRootNode->AddChild(lLightNode);

Light type

The behavior of the light can be defined by setting its FbxLight::LightType property.

// Set the type of the light to a spotlight.
lLight->LightType.Set(FbxLight::eSpot);

The following table summarizes the behavior of each light type.

Light Type (FbxLight::ELightType)	Description
FbxLight::eSpot	Light spreads in a conical shape from its origin, like a spotlight. The FbxLight::InnerAngle and FbxLight::OuterAngle properties determine the parameters of the cone in degrees.
FbxLight::ePoint	Light spreads uniformly in all directions from its origin.
FbxLight::eDirectional	Light spreads in a cylindrical shape from its origin.

Pointing a light

A spotlight or a directional light can be forced to consistently point towards a specific target in the scene. To do this, the light's node must have its target set using FbxNode::SetTarget(). The FbxMarker node attribute is used in the target node.

// Create a node to contain the marker. This will be our target node.
FbxNode* lTargetNode = FbxNode::Create(pScene, "targetNode");

// Create a marker node attribute.
FbxMarker* lMarker = FbxMarker::Create(pScene, "lightMarker");

// Set the marker as the target node's attribute.
lTargetNode->SetNodeAttribute(lMarker);

// Set our light node's target.
lLightNode->SetTarget(lTargetNode);

By default, a FbxNode uses its positive X axis as the aiming constraint. Recall that a newly created light points along the node's negative Y axis by default. To make the light point along the node's positive X axis, a rotation offset of 90 degrees must be applied to the light's node using FbxNode::SetPostTargetRotation(). Consult the "Node Target Management" section in the FbxNode class documentation for more information.

Color and Intensity

A light's color is defined in its FbxLight::Color property. The default RGB value of a light is (1.0, 1.0, 1.0), represented as a FbxDouble3.

// Set the light's color to (0, 1, 0.5).
lLight->Color.Set(FbxDouble3(0.0, 1.0, 0.5));

The intensity of a light is defined in its FbxLight::Intensity property. The default value of the intensity is 100.0, represented as a FbxDouble1.

// Set the light's intensity to 50.0
lLight->Intensity.Set(50.0)

Light decay

The decay type of the light is defined in its FbxLight::DecayType property.

// Set the decay type of the light to quadratic decay.
lLight->DecayType.Set(FbxLight::eQuadratic);

The following table summarizes the decay types available.

Decay Type (FbxLight::EDecayType)	Description
FbxLight::eNone	No decay. The light's intensity will not diminish with distance.
FbxLight::eLinear	Linear decay. The light's intensity will diminish linearly with the distance from the light.
FbxLight::eQuadratic	Quadratic decay. The light's intensity will diminish with the squared distance from the light. This is the most physically accurate decay rate.
FbxLight::eCubic	Cubic decay. The light's intensity will diminish with the cubed distance from the light.

Shadows

Shadows are enabled using the FbxLight::CastShadows boolean property. The color of the light's shadow is defined in the FbxLight::ShadowColor property. The default RGB value of a light's shadow is (0.0, 0.0, 0.0), represented as a FbxDouble3. A shadow texture may also be applied using FbxLight::SetShadowTexture().