Day and Night Cycles in TGEA

For the files: www.box.com/s/4cd4c05f5ef7b5e079c4 or shoot me an email if they're unavailable.


First thing's first, this resource was written for TGEA 1.7 beta 2. Beta 1 has a problem initializing new shaders to the skybox class. Extract the engine files into the engine/source/terrain folder. Do a fresh recompile and then get ready to add some new code.

Copy SkyP.hlsl and SkyV.hlsl into your game/shaders folder.

Once you've recompiled, add the following code to your scriptsAndAssets/client/scripts/shaders.cs file:

new ShaderData( SkyShader )
{
   DXVertexShaderFile 	= "shaders/skyV.hlsl";
   DXPixelShaderFile 	= "shaders/skyP.hlsl";
   pixVersion = 2.0;
};

Next, copy scriptsAndAssets/server/scripts/DayNight.cs into the corresponding folder. Open game.cs and ender the following code below the other execs:

exec("./dayNight.cs");

Now, very important:

Two extra material lists must be added to your sky object. If they are not, your mission WILL NOT load up.

In your mission file, edit the sky object so that the material lists look like:

materialList = "scriptsAndAssets/data/skies/Skies/sky_day.dml";
sunsetList = "scriptsAndAssets/data/skies/Skies/sky_sunset.dml";
nightList = "scriptsAndAssets/data/skies/Skies/sky_night.dml";

Basically, materialList controls the mid-day sky, sunsetList controls the sunset sky, and nightList controls the night-time sky. Depending on your sun object's elevation, the sky's coloring will change based on the skyboxes.

Now that all is in place, you can use the DayNight function. The DayNight function uses a schedule to manipulate a sun object for a user-inputed duration of time. The function modifies the sun's azimuth and elevation. The change in elevation is statically set to add one or subtract one. The lower the change, the subtler the effect. Ideally, the change in azimuth should be twice as much as the change in elevation. (Because the total amount of elevation you can move is 180 and the total amount of azimuth you can move is 360 before going back to the point of origin.) Your sun's base elevation and azimuth should also keep this into account. To keep things simple, I set both of mine to zero so that when the function is called, it increases/decreases them at the same rate.

So, in the mission editor name your sun something along the lines of "GreatSun" or "MySun" and then call the dayNight function like this:

DayNight(GreatSun,50);

Where 50 is the time in milliseconds before the next sun update. I hope this resource is helpful to people. Really, a lot of interesting effects can be done with this. It is well-suited to handle an Oblivion-type of simulation using a persistent world. Since the time of day is locked to the sun's elevation, it's easy to save and adjust.