Dynamic and Object Based Backgrounds

This page describes the principles and implementation of the XML based background system.

■ Dynamic Backgrounds: Basic Principles

openBVE supports several distinct types of backgrounds:

1. The original ‘texture’ based background. This wraps the specified texture around the viewing frustum a specified number of times.
2. ‘Dynamic’ backgrounds. These are made up of a series of texture based backgrounds, and which are changed at the appropriate time.
3. ‘Object’ backgrounds. A static object (.b3d , .csv or .x) may be used instead of the standard viewing frustum.

NOTE: No transition effects are supported for object based backgrounds.

Each individual background which you wish to use must be setup using a background XML file an example of which is shown below:

<?xml version="1.0" encoding="utf-8"?> <openBVE xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Background> <Time>00.00</Time> <Mode>FadeIn</Mode> <Repetitions>6</Repetitions> <Texture>Cloudy.png</Texture> </Background> <Background> <Time>10.00</Time> <Mode>FadeIn</Mode> <Repetitions>6</Repetitions> <Texture>Sunny.png</Texture> <TransitionTime>10</TransitionTime> </Background> </openBVE>

As you can see, the file is made up of one or more <Background> sections, each of which defines the background to be displayed at the point in time specified by Time.

■ Texture Backgrounds

A texture based background supports the following attributes:

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FileName must point to the image which you wish to display as the background texture.

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NumberOfRepetitions is the number of times the texture is to be wrapped horizontally around the viewing frustum.

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TransitionMode controls the transition effect to be used when this background is shown. Valid values are:

• FadeIn : The new background fades in.
• FadeOut : The old background fades out.
• None : No transition effect is performed. ( Negates TransitionTime )

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Time is the time in seconds which the transition effect takes to complete.

■ Dynamic Backgrounds

A dynamic background should simply be made up of multiple Background elements, and takes one further attribute:

GameTime is the 24-hour based time at which the transition to this background will begin.

■ Object Backgrounds

An object based background may also be used. With these, the specified object is rendered with it’s 0,0,0 co-ordinate centered upon the camera center.

Only .b3d , .csv and .x files with no animation are supported. No transition effects or other attributes are supported.

A sample XML is shown below:

<?xml version="1.0" encoding="utf-8"?> <openBVE xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Background> <Object>Background.csv</Object> </Background> </openBVE>