public MeshInstance(InstancedMeshGeometry parent, Vector3 translation)
{
if (parent == null)
{
throw new ArgumentNullException();
}
this.parent = parent;
this.translation = translation;
}
protected override void Initialise()
{
//create the camera
Xen.Ex.Camera.FirstPersonControlledCamera3D camera =
new Xen.Ex.Camera.FirstPersonControlledCamera3D(this.UpdateManager, Vector3.Zero);
camera.Projection.FarClip *= 10;
this.camera = camera;
//create the draw target.
drawToScreen = new DrawTargetScreen(this, camera);
//25,000 instances
const int instanceCount = 25000;
const float areaRadius = 500;
//create the mesh instance drawer, (but add it to the screen later)
InstancedMeshGeometry meshDrawer = new InstancedMeshGeometry(instanceCount);
//the instances are added to a StaticBinaryTreePartition, which sorts the items
//into a binary tree, for more efficient culling.
//This class assumes it's children do not move (ie they are static)
Xen.Ex.Scene.StaticBinaryTreePartition sceneTree = new Xen.Ex.Scene.StaticBinaryTreePartition();
//add it to the screen
drawToScreen.Add(sceneTree);
//create the instances
Random random = new Random();
for (int i = 0; i < instanceCount; i++)
{
//create a random position in a sphere
Vector3 position = new Vector3((float)(random.NextDouble() - .5),
(float)(random.NextDouble() - .5),
(float)(random.NextDouble() - .5));
position.Normalize();
position *= (float)Math.Sqrt(random.NextDouble()) * areaRadius;
//create the instance
MeshInstance instance = new MeshInstance(meshDrawer, position);
//add the instance to the StaticBinaryTreePartition
sceneTree.Add(instance);
}
//now add the drawer (instances will be drawn by the StaticBinaryPartition, before the drawer)
drawToScreen.Add(meshDrawer);
//Note that if the StaticBinaryTreePartition was not used, then
//in each frame, every single instance would perform a CullTest to the screen
//CullTests, despite their simplicity can be very costly in large numbers.
//The StaticBinaryTreePartition will usually perform a maximum number of CullTests
//that is approximately ~30% the number of children. (in this case, ~8000 tests)
//At it's best, when it's entirely off or on screen, it will perform only 1 or 2 CullTests.
//The number of cull tests performed will be displayed in debug builds of this tutorial:
//add some statusText to display on screen to show the stats
statusText = new TextElement();
statusText.Position = new Vector2(50, -50);
drawToScreen.Add(statusText);
}
