OVRSharp Transformation Demo

program.cs

using System.Diagnostics;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Numerics;

using OVRSharp;
using OVRSharp.Math;

using Valve.VR;

var app = new Application(Application.ApplicationType.Overlay);

while (!app.OVRSystem.IsTrackedDeviceConnected(OpenVR.k_unTrackedDeviceIndex_Hmd))
    Thread.Sleep(100);

List<Overlay> overlays = new();

Overlay Create(string? name = null)
{
    using var bmp = new Bitmap(100, 100);

    name ??= "unknown." + Guid.NewGuid();

    {
        using var grph = Graphics.FromImage(bmp);

        grph.Clear(Color.White);

        var font = SystemFonts.CaptionFont ?? SystemFonts.DefaultFont;
        font = new Font(font.FontFamily, 20f, FontStyle.Bold);

        var size = grph.MeasureString(name, font);

        grph.DrawString(name, font, Brushes.Black, new PointF((bmp.Width - size.Width) / 2, (bmp.Height - size.Height) / 2));
        grph.Flush();
    }

    var path = Path.GetTempFileName();

    using var stream = File.OpenWrite(path);
    bmp.Save(stream, ImageFormat.Png);

    Thread.Sleep(100);

    var o = new Overlay("test." + name, "TEST") {
        WidthInMeters = 0.25f,
    };

    Thread.Sleep(100);

    o.SetTextureFromFile(path);
    o.SetFlag(VROverlayFlags.SortWithNonSceneOverlays, true);
    o.WidthInMeters = 0.25f;
    o.Transform = default;
    o.Show();

    overlays.Add(o);

    return o;
}

const float frameCount = 100;

void AnimateVector(int frame, int frameStart, out Vector3 mat, Vector3 from, Vector3 to)
{
    frame -= frameStart;

    if (frame <= 0)
        mat = from;
    else if (frame >= frameCount)
        mat = to;
    else
        mat = Vector3.Lerp(from, to, frame / frameCount);
}

void AnimateTranslate(int frame, int frameStart, out Matrix4x4 mat, Vector3 from, Vector3 to)
{
    AnimateVector(frame, frameStart, out var v, from, to);

    mat = Matrix4x4.CreateTranslation(v);
}

void AnimateRotate(int frame, int frameStart, out Matrix4x4 mat, Vector3 from, Vector3 to)
{
    AnimateVector(frame, frameStart, out var v, from, to);

    mat = Matrix4x4.CreateFromYawPitchRoll(v.Y, v.X, v.Z);
}

var TEST = Create("TEST");
var PARENT = Create("PARENT");

try
{
    var localPos = Vector3.UnitX * 0.25f;
    var localRot = Vector3.UnitY * (MathF.PI / -2);

    var parentPos = Vector3.UnitZ * -0.5f;
    var parentRot = Vector3.UnitY * (MathF.PI / 4);

    TEST.Transform = Matrix4x4.Identity.ToHmdMatrix3x4();
    PARENT.Transform = Matrix4x4.Identity.ToHmdMatrix3x4();

    for (int i = 0; i < 400; i++)
    {
        if (i % 100 == 0)
        {
            Console.WriteLine("\nPress any key to continue.");
            Console.ReadKey(intercept: true);
        }

        AnimateTranslate(i, 0, out var lt, Vector3.Zero, localPos);
        AnimateRotate(i, 100, out var lr, Vector3.Zero, localRot);
        AnimateRotate(i, 200, out var pr, Vector3.Zero, parentRot);
        AnimateTranslate(i, 300, out var pt, Vector3.Zero, parentPos);

        var local = lr * lt;
        var parent = pr * pt;

        var final = local * parent;

        PARENT.Transform = parent.ToHmdMatrix34_t();
        TEST.Transform = final.ToHmdMatrix34_t();

        Console.Write($"\rFrame: {i}");
        await Task.Delay(10);
    }

    Console.WriteLine();
    Console.WriteLine("Press any key to quit.");
    Console.ReadKey(intercept: true);
}
finally
{
    foreach (var o in overlays)
        o.Destroy();
}