标题: Billboard (Physics Behavior) [打印本页] 作者: Asen 时间: 2011-10-19 10:31 标题: Billboard (Physics Behavior)
Billboard (Physics Behavior)
Summary
Causes the parent object to always face the camera, with a variety of options.
Category
Latest Behaviors
Author
Gavin Kistner
Difficulty
(Reference)
Time to Complete
5 Minutes
Downloads
Click Here
to download the associated files.
(This document covers version 0.9.1 of the 'Billboard' behavior, current as of 2005-Feb-23)
Description
This behavior is primarily useful for simulating a 3D object by using an image map on a flat object, and causing that object to always face the camera as it or the camera moves.
To cause the object to face the correct camera, you must choose the camera which will be rendering the layer with the object, using the
Render Camera
option. You may alternatively choose any other object, to cause the parent of this behavior to face that object.
There are two types of billboarding available:
Face Camera
– the object rotates so that it is always facing the eye point of the camera. The object behaves like a small animal always watching a predator, even if the predator is walking past the animal without looking at it.
Match Camera Rotation
– the object rotates so that it always faces the same direction as the camera. (Also known as “side-of-the-road” billboarding; as the camera moves past the object, the object will behave like a billboard on the side of the road, showing its edge as the camera goes by. Flat and Depth Text objects use this type of billboarding.)
For both types of billboarding, there is the option to either let the object rotate on all axes (the default) or to only rotate around the global y-axis by using the
Y-Axis Only?
property. For smoke and other particle effects, you likely will want to leave this unchecked. For cases where the object is sitting in the ground (such as a tree), you will want to check this property so that the object does not tilt forward and backward as the camera rises and falls.
By default, this behavior assumes that the ‘front’ of the object is the negative Z side. You may use the
Front Axis
advanced property to change which local axis of the object should be rotated to face the camera.
To cause particles created by the Particle Emitter behavior to billboard, attach this behavior
to the Particle Emitter behavior itself
.
Basic Properties
Render Camera
The camera which will be rendering the scene.
Billboard Type
Always face the camera, or only match its rotation.
Y-Axis Only?
Only rotate the object about the global y-axis?
Advanced Properties
Front Axis
The axis and direction that specifies the 'front' direction of the parent object.
Start Immediately?
Start immediately, or wait for the Enable action to be called?
