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BVH.cs
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BVH.cs
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using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Foundation;
using MathNet.Numerics.LinearAlgebra;
using MathNet.Numerics.LinearAlgebra.Double;
namespace Gladius
{
/// <summary>
/// Parses BVH files into nodes and a sequence of motions.
/// Exposes methods to execute each motion frame on the nodes.
/// </summary>
public class BVH
{
/// <summary>
/// Opens and parses the BVH file at the specifie path.
/// </summary>
public BVH(string path) {
var fm = new NSFileManager();
if (path == null || !fm.FileExists(path))
throw new Exception($"Could not find file '{Path.GetFileName(path)}'.");
var data = fm.Contents(path);
var contents = new NSString(data, NSStringEncoding.UTF8).ToString();
var lines = contents.Split(new[] { Environment.NewLine, "\r", "\n" }, StringSplitOptions.RemoveEmptyEntries);
var lineCounter = 1; // start with first line of hierarchy, which should be ROOT
while (true) {
Roots.Add(ParseNode(lines, ref lineCounter));
lineCounter++;
if (!lines[lineCounter].TrimStart(' ').StartsWith("ROOT", StringComparison.InvariantCulture))
break;
}
if (!string.Equals(lines[lineCounter], "MOTION"))
throw new Exception($"Expected MOTION but encountered invalid line: {lines[lineCounter]}");
lineCounter += 2; // skip the "Frames: x" line and get "Frame Time: y"
FrameTimeSecs = double.Parse(lines[lineCounter].Split('\t')[1]);
lineCounter++;
for (; lineCounter < lines.Length; lineCounter++) {
var motions = lines[lineCounter]
.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
.Select(double.Parse).ToList();
for (var i = 0; i < motions.Count; i++)
_channels.ElementAt(i).Key.Motions.Add(motions[i]);
}
}
public List<Node> Roots { get; } = new List<Node>();
public bool PlayOneFrame() {
_frame++;
if (_channels.Any(kv => _frame >= kv.Key.Motions.Count))
return false;
foreach (var kv in _channels) {
var current = kv.Key.Motions[_frame];
var last = _frame > 0 ? kv.Key.Motions[_frame - 1] : 0.0;
switch (kv.Key.Type) {
case MotionChannelType.Xposition:
kv.Value.Offset[0] = current;
break;
case MotionChannelType.Yposition:
kv.Value.Offset[1] = current;
break;
case MotionChannelType.Zposition:
kv.Value.Offset[2] = current;
break;
case MotionChannelType.Zrotation: {
kv.Value.ApplyTransformation(Transformation.Rotate(Plane.XY, current - last));
break;
}
case MotionChannelType.Xrotation: {
var degrees = kv.Key.Motions[_frame];
kv.Value.ApplyTransformation(Transformation.Rotate(Plane.YZ, current - last));
break;
}
case MotionChannelType.Yrotation: {
var degrees = kv.Key.Motions[_frame];
kv.Value.ApplyTransformation(Transformation.Rotate(Plane.XZ, current - last));
break;
}
default:
throw new NotSupportedException($"Motion channel type '{kv.Key.Type}' is not supported");
}
}
return true;
}
private int _frame = -1;
private Dictionary<MotionChannel, Node> _channels = new Dictionary<MotionChannel, Node>();
public double FrameTimeSecs { get; }
private Node ParseNode(string[] lines, ref int lineCounter, Node parent = null) {
// first line, e.g. "ROOT Hips" or "JOINT Spine"
var line = lines[lineCounter];
var trimmed = line.TrimStart(' ');
var endSite = false;
string name = null;
if (trimmed.StartsWith("ROOT", StringComparison.InvariantCulture)) {
if (trimmed.Length > 5)
name = trimmed.Substring(5);
} else if (trimmed.StartsWith("JOINT", StringComparison.InvariantCulture)) {
if (trimmed.Length > 6)
name = trimmed.Substring(6);
} else if (line.Contains("End Site"))
endSite = true;
else
throw new Exception($"Encountered invalid line: {line}");
// second line, "{"
lineCounter++;
line = lines[lineCounter];
trimmed = line.TrimStart(' ');
if (!string.Equals(trimmed, "{", StringComparison.InvariantCulture))
throw new Exception($"Encountered invalid line: {line}");
// third line, "OFFSET ..."
lineCounter++;
line = lines[lineCounter];
trimmed = line.TrimStart(' ');
if (!trimmed.StartsWith("OFFSET", StringComparison.InvariantCulture))
throw new Exception($"Encountered invalid line: {line}");
var offsetParts = trimmed
.Split(' ')
.Skip(1)
.Select(double.Parse)
.ToArray();
var node = parent == null
? Node.NewRoot(new DenseVector(offsetParts), name)
: parent.CreateAndAddChild(new DenseVector(offsetParts), name);
if (!endSite) {
// fourth line, "CHANNELS ..."
lineCounter++;
line = lines[lineCounter];
trimmed = line.TrimStart(' ');
if (!trimmed.StartsWith("CHANNELS", StringComparison.InvariantCulture))
throw new Exception($"Encountered invalid line: {line}");
var channels = trimmed
.Split(' ').Skip(2)
.Select(str => (MotionChannelType)Enum.Parse(typeof(MotionChannelType), str))
.Select(t => new MotionChannel { Type = t }).ToList();
foreach (var channel in channels)
_channels[channel] = node;
}
while (true) {
lineCounter++;
line = lines[lineCounter];
trimmed = line.TrimStart(' ');
if (!string.Equals(trimmed, "}", StringComparison.InvariantCulture))
ParseNode(lines, ref lineCounter, node);
else
return node;
}
}
}
}