/// <summary>
/// Constructs a <see cref="Configuration"/>.
/// </summary>
/// <param name="descriptor">A <see cref="ConfigurationDescriptor"/> for this configuration.</param>
/// <param name="features">A set of <see cref="Feature"/>(s) that should be enabled for this configuraton.
/// Exaclty zero or one camera mode must be enabled (see <see cref="Feature.UserFacingCamera"/> and <see cref="Feature.WorldFacingCamera"/>).
/// If zero camera modes are enabled, no camera texture will be available. Some platforms may support a configuration that does
/// not provide camera textures, which can be more performant if they are not necessary.
/// All <paramref name="features"/> must be supported by the <paramref name="descriptor"/>.</param>
/// <exception cref="System.InvalidOperationException">Thrown if multiple camera modes are enabled.</exception>
/// <exception cref="System.InvalidOperationException">Thrown if multiple tracking modes are enabled.</exception>
/// <exception cref="System.NotSupportedException">Thrown if the <paramref name="descriptor"/> does not support one or more <paramref name="features"/>.</exception>
public Configuration(ConfigurationDescriptor descriptor, Feature features)
{
if (!descriptor.capabilities.All(features))
{
throw new NotSupportedException($"The configuration does not support the following requested features: {features.SetDifference(descriptor.capabilities).ToStringList()}.");
}
var cameraMode = features.Cameras();
if (cameraMode.Any(Feature.AnyCamera))
{
if (cameraMode.Count() > 1)
{
throw new InvalidOperationException($"Either zero or one camera mode must be enabled. The following modes are enabled: {cameraMode.ToStringList()}");
}
}
var trackingMode = features.TrackingModes();
if (trackingMode.Count() > 1)
{
throw new InvalidOperationException($"Either zero or one tracking modes must be enabled. The following modes are enabled: {trackingMode.ToStringList()}");
}
this.descriptor = descriptor;
this.features = features;
}
/// <summary>
/// Selects a configuration from the given <paramref name="descriptors"/> and <paramref name="requestedFeatures"/>.
/// </summary>
/// <remarks>
/// Selection works as follows:
/// For each of the configuration <paramref name="descriptors"/>, compute the number of supported
/// <see cref="Feature"/>s that are present in <paramref name="requestedFeatures"/> and choose the
/// configuration descriptor with the highest count. <see cref="ConfigurationDescriptor.rank"/> is
/// used to break ties.
/// </remarks>
/// <param name="descriptors">A set of <see cref="ConfigurationDescriptor"/>s supported by the <see cref="XRSessionSubsystem"/>.</param>
/// <param name="requestedFeatures">A set of requested <see cref="Feature"/>s.</param>
/// <returns>The configuration that best matches the <paramref name="requestedFeatures"/>.</returns>
/// <exception cref="System.ArgumentException">Thrown if <paramref name="descriptors"/> does not contain any descriptors.</exception>
/// <exception cref="System.ArgumentException">Thrown if <paramref name="requestedFeatures"/> contains more than one tracking mode.</exception>
/// <exception cref="System.ArgumentException">Thrown if <paramref name="requestedFeatures"/> contains more than one camera mode.</exception>
public override Configuration ChooseConfiguration(NativeSlice <ConfigurationDescriptor> descriptors, Feature requestedFeatures)
{
if (descriptors.Length == 0)
{
throw new ArgumentException("No configuration descriptors to choose from.", nameof(descriptors));
}
if (requestedFeatures.Intersection(Feature.AnyTrackingMode).Count() > 1)
{
throw new ArgumentException($"Zero or one tracking mode must be requested. Requested tracking modes => {requestedFeatures.Intersection(Feature.AnyTrackingMode).ToStringList()}", nameof(requestedFeatures));
}
if (requestedFeatures.Intersection(Feature.AnyCamera).Count() > 1)
{
throw new ArgumentException($"Zero or one camera mode must be requested. Requested camera modes => {requestedFeatures.Intersection(Feature.AnyCamera).ToStringList()}", nameof(requestedFeatures));
}
int highestFeatureCount = -1;
int highestRank = int.MinValue;
ConfigurationDescriptor bestDescriptor = default;
foreach (var descriptor in descriptors)
{
int featureCount = requestedFeatures.Intersection(descriptor.capabilities).Count();
if ((featureCount > highestFeatureCount) ||
(featureCount == highestFeatureCount && descriptor.rank > highestRank))
{
highestFeatureCount = featureCount;
highestRank = descriptor.rank;
bestDescriptor = descriptor;
}
}
return(new Configuration(bestDescriptor, requestedFeatures.Intersection(bestDescriptor.capabilities)));
}