|
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
//
// Description: 3D mesh implementation.
//
// See spec at http://avalon/medialayer/Specifications/Avalon3D%20API%20Spec.mht
//
//
using MS.Internal;
using MS.Internal.Media3D;
using MS.Internal.PresentationCore;
using MS.Utility;
using System;
using System.Diagnostics;
using System.Windows.Markup;
using System.Windows.Media.Composition;
namespace System.Windows.Media.Media3D
{
/// <summary>
/// MeshGeometry3D a straightforward triangle primitive.
/// </summary>
public sealed partial class MeshGeometry3D : Geometry3D
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
/// <summary>
/// Default Constructor.
/// </summary>
public MeshGeometry3D() {}
#endregion Constructors
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
#region Public Methods
/// <summary>
/// Get bounds for this MeshGeometry3D.
/// </summary>
public override Rect3D Bounds
{
get
{
ReadPreamble();
if (_cachedBounds.IsEmpty)
{
UpdateCachedBounds();
}
Debug_VerifyCachedBounds();
return _cachedBounds;
}
}
#endregion Public Methods
//------------------------------------------------------
//
// Public Properties
//
//------------------------------------------------------
//------------------------------------------------------
//
// Protected Methods
//
//------------------------------------------------------
#region Protected Methods
/// <summary>
/// Overriden to clear our bounds cache.
/// </summary>
protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
{
if (e.IsAValueChange || e.IsASubPropertyChange)
{
DependencyProperty dp = e.Property;
// We invalidate the cache here rather than in the InvalidateResourcePositions method
// because the later is not invoked in the event that the Point3DCollection is swapped
// out from underneath us. (In that case, the resource invalidation takes a different
// code path.)
if (dp == MeshGeometry3D.PositionsProperty)
{
SetCachedBoundsDirty();
}
}
base.OnPropertyChanged(e);
}
#endregion Protected Methods
//------------------------------------------------------
//
// Internal Methods
//
//------------------------------------------------------
#region Internal Methods
internal Rect GetTextureCoordinateBounds()
{
PointCollection tx = TextureCoordinates;
int count = (tx == null) ? 0 : tx.Count;
if (count > 0)
{
Point ptMin = tx[0];
Point ptMax = tx[0];
for (int i = 1; i < count; i++)
{
Point txPt = tx.Internal_GetItem(i);
double txx = txPt.X;
if (ptMin.X > txx)
{
ptMin.X = txx;
}
else if (ptMax.X < txx)
{
ptMax.X = txx;
}
double txy = txPt.Y;
if (ptMin.Y > txy)
{
ptMin.Y = txy;
}
else if (ptMax.Y < txy)
{
ptMax.Y = txy;
}
}
return new Rect(ptMin, ptMax);
}
else
{
return Rect.Empty;
}
}
//
// Hits the ray against the mesh
//
internal override void RayHitTestCore(
RayHitTestParameters rayParams,
FaceType hitTestableFaces)
{
Debug.Assert(hitTestableFaces != FaceType.None,
"Caller should make sure we're trying to hit something");
Point3DCollection positions = Positions;
if (positions == null)
{
return;
}
Point3D origin;
Vector3D direction;
rayParams.GetLocalLine(out origin, out direction);
Int32Collection indices = TriangleIndices;
// In the line case, we want to hit test all faces because we don't
// have a direction. This may differ from what faces we want to
// accept.
FaceType facesToHit;
if (rayParams.IsRay)
{
facesToHit = hitTestableFaces;
}
else
{
facesToHit = FaceType.Front | FaceType.Back;
}
//
// This code duplication is unfortunate but necessary. Breaking it down into methods
// further significantly impacts performance. About 5% improvement could be made
// by unrolling this code below even more.
//
// If futher perf investigation is done with this code, be sure to test NGEN assemblies only
// as JIT produces different, faster code than NGEN.
//
if (indices == null || indices.Count == 0)
{
FrugalStructList<Point3D> ps = positions._collection;
int count = ps.Count - (ps.Count % 3);
for (int i = count - 1; i >= 2; i -= 3)
{
int i0 = i - 2;
int i1 = i - 1;
int i2 = i;
Point3D v0 = ps[i0];
Point3D v1 = ps[i1];
Point3D v2 = ps[i2];
double hitTime;
Point barycentric;
// The line hit test is equivalent to a double sided
// triangle hit because it doesn't cull triangles based
// on winding
if (LineUtil.ComputeLineTriangleIntersection(
facesToHit,
ref origin,
ref direction,
ref v0,
ref v1,
ref v2,
out barycentric,
out hitTime
)
)
{
if (rayParams.IsRay)
{
ValidateRayHit(
rayParams,
ref origin,
ref direction,
hitTime,
i0,
i1,
i2,
ref barycentric
);
}
else
{
ValidateLineHit(
rayParams,
hitTestableFaces,
i0,
i1,
i2,
ref v0,
ref v1,
ref v2,
ref barycentric
);
}
}
}
}
else // indexed mesh
{
FrugalStructList<Point3D> ps = positions._collection;
FrugalStructList<int> idcs = indices._collection;
int count = idcs.Count;
int limit = ps.Count;
for (int i = 2; i < count; i += 3)
{
int i0 = idcs[i - 2];
int i1 = idcs[i - 1];
int i2 = idcs[i];
// Quit if we encounter an index out of range.
// This is okay because the triangles we ignore are not rendered.
// (see: CMilMeshGeometry3DDuce::Realize)
if ((0 > i0 || i0 >= limit) ||
(0 > i1 || i1 >= limit) ||
(0 > i2 || i2 >= limit))
{
break;
}
Point3D v0 = ps[i0];
Point3D v1 = ps[i1];
Point3D v2 = ps[i2];
double hitTime;
Point barycentric;
if (LineUtil.ComputeLineTriangleIntersection(
facesToHit,
ref origin,
ref direction,
ref v0,
ref v1,
ref v2,
out barycentric,
out hitTime
)
)
{
if (rayParams.IsRay)
{
ValidateRayHit(
rayParams,
ref origin,
ref direction,
hitTime,
i0,
i1,
i2,
ref barycentric
);
}
else
{
ValidateLineHit(
rayParams,
hitTestableFaces,
i0,
i1,
i2,
ref v0,
ref v1,
ref v2,
ref barycentric
);
}
}
}
}
}
#endregion Internal Methods
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
#region Private Methods
//
// Processes a ray-triangle intersection to see if it's a valid hit. Unnecessary faces
// have already been culled by the ray-triange intersection routines.
//
// Shares some code with ValidateLineHit
//
private void ValidateRayHit(
RayHitTestParameters rayParams,
ref Point3D origin,
ref Vector3D direction,
double hitTime,
int i0,
int i1,
int i2,
ref Point barycentric
)
{
if (hitTime > 0)
{
Matrix3D worldTransformMatrix = rayParams.HasWorldTransformMatrix ? rayParams.WorldTransformMatrix : Matrix3D.Identity;
Point3D pointHit = origin + hitTime * direction;
Point3D worldPointHit = pointHit;
worldTransformMatrix.MultiplyPoint(ref worldPointHit);
// If we have a HitTestProjectionMatrix than this hit test originated
// at a Viewport3DVisual.
if (rayParams.HasHitTestProjectionMatrix)
{
// To test if we are in front of the far clipping plane what we
// do conceptually is project our hit point in world space into
// homogenous space and verify that it is on the correct side of
// the Z=1 plane.
//
// To save some cycles we only bother computing Z and W of the
// projected point and use a simple Z/W > 1 test to see if we
// are past the far plane.
//
// NOTE: HitTestProjectionMatrix is not just the camera matrices.
// It has an additional translation to move the ray to the
// origin. This extra translation does not effect this test.
Matrix3D m = rayParams.HitTestProjectionMatrix;
// We directly substitute 1 for p.W below:
double pz = worldPointHit.X * m.M13 + worldPointHit.Y * m.M23 + worldPointHit.Z * m.M33 + m.OffsetZ;
double pw = worldPointHit.X * m.M14 + worldPointHit.Y * m.M24 + worldPointHit.Z * m.M34 + m.M44;
// Early exit if pz/pw > 1. The negated logic is to reject NaNs.
if (!(pz / pw <= 1))
{
return;
}
Debug.Assert(!double.IsInfinity(pz / pw) && !double.IsNaN(pz / pw),
"Expected near/far tests to cull -Inf/+Inf and NaN.");
}
double dist = (worldPointHit - rayParams.Origin).Length;
Debug.Assert(dist > 0, "Distance is negative: " + dist);
if (rayParams.HasModelTransformMatrix)
{
rayParams.ModelTransformMatrix.MultiplyPoint(ref pointHit);
}
rayParams.ReportResult(this, pointHit, dist, i0, i1, i2, barycentric);
}
}
//
// Processes a ray-line intersection to see if it's a valid hit.
//
// Shares some code with ValidateRayHit
//
private void ValidateLineHit(
RayHitTestParameters rayParams,
FaceType facesToHit,
int i0,
int i1,
int i2,
ref Point3D v0,
ref Point3D v1,
ref Point3D v2,
ref Point barycentric
)
{
Matrix3D worldTransformMatrix = rayParams.HasWorldTransformMatrix ? rayParams.WorldTransformMatrix : Matrix3D.Identity;
// OK, we have an intersection with the LINE but that could be wrong on three
// accounts:
// 1. We could have hit the line on the wrong side of the ray's origin.
// 2. We may need to cull the intersection if it's beyond the far clipping
// plane (only if the hit test originated from a Viewport3DVisual.)
// 3. We could have hit a back-facing triangle
// We will transform the hit point back into world space to check these
// things & compute the correct distance from the origin to the hit point.
// Hit point in model space
Point3D pointHit = M3DUtil.Interpolate(ref v0, ref v1, ref v2, ref barycentric);
Point3D worldPointHit = pointHit;
worldTransformMatrix.MultiplyPoint(ref worldPointHit);
// Vector from origin to hit point
Vector3D hitVector = worldPointHit - rayParams.Origin;
Vector3D originalDirection = rayParams.Direction;
double rayDistanceUnnormalized = Vector3D.DotProduct(originalDirection, hitVector);
if (rayDistanceUnnormalized > 0)
{
// If we have a HitTestProjectionMatrix than this hit test originated
// at a Viewport3DVisual.
if (rayParams.HasHitTestProjectionMatrix)
{
// To test if we are in front of the far clipping plane what we
// do conceptually is project our hit point in world space into
// homogenous space and verify that it is on the correct side of
// the Z=1 plane.
//
// To save some cycles we only bother computing Z and W of the
// projected point and use a simple Z/W > 1 test to see if we
// are past the far plane.
//
// NOTE: HitTestProjectionMatrix is not just the camera matrices.
// It has an additional translation to move the ray to the
// origin. This extra translation does not effect this test.
Matrix3D m = rayParams.HitTestProjectionMatrix;
// We directly substitute 1 for p.W below:
double pz = worldPointHit.X * m.M13 + worldPointHit.Y * m.M23 + worldPointHit.Z * m.M33 + m.OffsetZ;
double pw = worldPointHit.X * m.M14 + worldPointHit.Y * m.M24 + worldPointHit.Z * m.M34 + m.M44;
// Early exit if pz/pw > 1. The negated logic is to reject NaNs.
if (!(pz / pw <= 1))
{
return;
}
Debug.Assert(!double.IsInfinity(pz / pw) && !double.IsNaN(pz / pw),
"Expected near/far tests to cull -Inf/+Inf and NaN.");
}
Point3D a = v0, b = v1, c = v2;
worldTransformMatrix.MultiplyPoint(ref a);
worldTransformMatrix.MultiplyPoint(ref b);
worldTransformMatrix.MultiplyPoint(ref c);
Vector3D normal = Vector3D.CrossProduct(b - a, c - a);
double cullSign = -Vector3D.DotProduct(normal, hitVector);
double det = worldTransformMatrix.Determinant;
bool frontFace = (cullSign > 0) == (det >= 0);
if (((facesToHit & FaceType.Front) == FaceType.Front && frontFace) || ((facesToHit & FaceType.Back) == FaceType.Back && !frontFace))
{
double dist = hitVector.Length;
if (rayParams.HasModelTransformMatrix)
{
rayParams.ModelTransformMatrix.MultiplyPoint(ref pointHit);
}
rayParams.ReportResult(this, pointHit, dist, i0, i1, i2, barycentric);
}
}
}
// Updates the _cachedBounds member to the current bounds of the mesh.
// This method must be called before accessing _cachedBounds if
// _cachedBounds.IsEmpty is true. Otherwise the _cachedBounds are
// current and do not need to be recomputed. See also Debug_VerifyCachedBounds.
private void UpdateCachedBounds()
{
Debug.Assert(_cachedBounds.IsEmpty,
"PERF: Caller should verify that bounds are dirty before recomputing.");
_cachedBounds = M3DUtil.ComputeAxisAlignedBoundingBox(Positions);
}
// Sets _cachedBounds to Rect3D.Empty (indicating that the bounds are no
// longer valid.)
private void SetCachedBoundsDirty()
{
_cachedBounds = Rect3D.Empty;
}
#endregion Private Methods
//------------------------------------------------------
//
// DEBUG
//
//------------------------------------------------------
#region DEBUG
// Always call this method before accessing _cachedBounds. On
[Conditional("DEBUG")]
private void Debug_VerifyCachedBounds()
{
Rect3D actualBounds = M3DUtil.ComputeAxisAlignedBoundingBox(Positions);
// The funny boolean logic below avoids asserts when the cached
// bounds contain NaNs. (NaN != NaN)
bool areEqual =
!(_cachedBounds.X < actualBounds.X || _cachedBounds.X > actualBounds.X) &&
!(_cachedBounds.Y < actualBounds.Y || _cachedBounds.Y > actualBounds.Y) &&
!(_cachedBounds.Z < actualBounds.Z || _cachedBounds.Z > actualBounds.Z) &&
!(_cachedBounds.SizeX < actualBounds.SizeX || _cachedBounds.SizeX > actualBounds.SizeX) &&
!(_cachedBounds.SizeY < actualBounds.SizeY || _cachedBounds.SizeY > actualBounds.SizeY) &&
!(_cachedBounds.SizeZ < actualBounds.SizeZ || _cachedBounds.SizeZ > actualBounds.SizeZ);
if (!areEqual)
{
if (_cachedBounds == Rect3D.Empty)
{
Debug.Fail("Cached bounds are invalid. Caller needs to check for IsEmpty and call UpdateCachedBounds.");
}
else
{
Debug.Fail("Cached bounds are invalid. We missed a call to SetCachedBoundsDirty.");
}
}
}
#endregion DEBUG
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
#region Private Fields
// If the _cachedBounds are empty it means that the cache is invalid. The user must
// check for this case and call UpdateCachedBounds if the cache is invalid. (There
// is no way to distinguish between actually caching "Empty" when there are no
// positions and the cache being invalid - but computing bounds in this case is
// very fast.)
private Rect3D _cachedBounds = Rect3D.Empty;
#endregion Private Fields
}
}
|