/// Converts TiltBrush brush strokes into linear USD BasisCurves.
static BrushCurvesSample GetCurvesSample(ExportUtils.SceneStatePayload payload,
List <Stroke> strokes,
Matrix4x4 mat44)
{
var sample = new BrushCurvesSample();
var times = new List <float>();
var pressures = new List <float>();
sample.doubleSided = true;
sample.orientation = USD.NET.Orientation.LeftHanded;
sample.basis = BasisCurvesSample.Basis.Bezier;
sample.type = BasisCurvesSample.CurveType.Linear;
sample.wrap = BasisCurvesSample.WrapMode.Nonperiodic;
sample.curveVertexCounts = strokes.Select(x => x.m_ControlPoints.Length).ToArray();
sample.transform = mat44;
int numCPs = sample.curveVertexCounts.Sum();
sample.points = new Vector3[numCPs];
sample.normals = new Vector3[numCPs];
sample.colors = new Color[numCPs];
int iKnot = 0;
foreach (Stroke stroke in strokes)
{
foreach (var cp in stroke.m_ControlPoints)
{
times.Add(cp.m_TimestampMs / 1000.0f);
pressures.Add(cp.m_Pressure);
}
foreach (var cp in stroke.m_ControlPoints)
{
// Normals in USD are stored in object/local space, just as points are.
sample.normals[iKnot] = cp.m_Orient * Vector3.up;
sample.points[iKnot] = cp.m_Pos;
sample.colors[iKnot] = stroke.m_Color.linear;
iKnot++;
}
}
{
Matrix4x4 basis = ExportUtils.GetFromUnity_Axes(payload);
Matrix4x4 units = Matrix4x4.Scale(Vector3.one * payload.exportUnitsFromAppUnits);
MathUtils.TransformVector3AsPoint(units * basis, 0, sample.points.Length, sample.points);
MathUtils.TransformVector3AsVector(basis, 0, sample.normals.Length, sample.normals);
}
sample.extent = new Bounds(sample.points[0], Vector3.zero);
for (int i = 0; i < sample.points.Length; i++)
{
sample.extent.Encapsulate(sample.points[i]);
}
sample.times = times.ToArray();
sample.pressures = pressures.ToArray();
return(sample);
}
