Principal Light Classes

The following are the primary classes used for working with lights in the 3ds Max SDK.

• LightObject - This is a base class for plug-in lights. It has a method used to retrieve the light's properties at a certain time, a method to create an ObjLightDesc object. It also has methods that allow the many properties of the light to be read and altered.
• GenLight - This is also a possible candidate for plug-in lights to sub-class from. This class, sub-classed from LightObject, provides a set of additional methods (for example access to the controllers handling the animation of the light's properties).
• LightscapeLight - This class derives from GenLight, and is the base class for all Photometric lights. This class provides methods for getting and setting photometric settings, such as distribution and intensity.
• Light - This class describes the properties of the lights used in the interactive renderer. See Light methods in Class GraphicsWindow for a list of methods that use this class.
• DefaultLight - An array of these objects is passed in the Render::Open() method of a renderer plug-in. This class contains the transformation matrix of the light and a LightState object (described below) that describes the characteristics of the light.
• LightState - This structure describes the properties of a light. When the method LightObject::EvalLightState() is called, the LightState structure is updated. This is used, for example, by many of the file format export plug-ins to grab data about the lights they are exporting.
• LightDesc - This class has a single method LightDesc::Illuminate() used to determine the color and direction of the light striking a point. It has two public data members that indicate if the diffuse and/or specular color of objects should be affected by the light.
• ObjLightDesc - This class derives from LightDesc (described above). There is an instance of this class for every instance of a light in the scene. The renderer asks each light in the scene to create one of these objects by calling LightObject::CreateLightDesc() and passing it the light node. This class has data members that provide information such as a pointer to the node for the light, a LightState object, various transformation matrices that provide conversions between the light's space and world and camera space. It has a method to retrieve the lights exclusion list, and a method to update the light's data members in this class once per render. It also has a method used in computing volume lighting effects, TraverseVolume().