Dynamic Backgrounds

[leezer3]

https://github.com/leezer3/OpenBVE/pull/103 implements dynamic lighting.

The next step is to implement dynamic backgrounds which change with the time of day. (Obviously, we don't want a sunset at midnight!)

Some initial WIP in this branch: https://github.com/leezer3/OpenBVE/tree/DynamicBackground

TODO:

• Implement XML parser (Easy, can be based upon the lighting parser)]
• Implement fading in of new dynamic backgrounds.

Later Plans:

• Allow a static object to be passed as the background. (Important for BVE5, probably has some other interesting uses too)

[leezer3]

OK, this is a working XML for the branch above:

<?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>

Interesting new parameters:

• Mode: Sets whether this texture fades in, fades out or just switches.
• Transition Time: Sets the time in seconds for the transition to complete. At present, transitions take a fixed 0.8s, but I saw no reason to keep this!