Image bm729.GIF Active Object
3D Graphics
The active object element serves to select the 3D object that is supposed to be manipulated. When created, each 3D object will return a unique identification number (abbreviated as ID), by means of which the object may be referred to later. By reading the active object element the currently selected active object can be found. Also by this element one of three predefined objects having fix identification numbers 0 through 2 may be selected.
An object having the identification number of 0 is the scene. The scene is an empty group containing no visible object. It is only other objects that can be linked to it. Each newly created object is linked to the scene as the default status. The scene is the basic reference point for the other objects' transformations. The scene itself cannot be transformed (translated, rotated or scaled). From the scene other objects can inherit the surface definition or the basic texture. The scene object can neither be deleted nor it can be linked to another object. The setting of the scene switch object texture magnification filter determines whether the background texture for scene will be filtered.
An object having the identification number of 1 is the camera. The camera may be transformed and linked to other objects in the same manner as any other object, but it cannot be deleted. When starting the program the camera is oriented in the positive z axis direction as a default setting (i.e. the basic direction, any rotation being equal to 0) and translated back by 2 units (i.e. the z translation = -2, the other translations = 0).
The last predefined object carries number 2. This is the default scene lighting. This object can be deleted. The default lighting is the directional light of the white color having the X and Y rotation values of 45 degrees and the following translation values: X = -10, Y = 10, Z = -10 (Note: The directional light does not use any translation, the translation is prepared for the possibility of transition to another light type). Thus, the scene is lighted from the upper left corner.

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