/// <summary>
/// For an object 'node' that is being manipulated, this function returns
/// the offset (in world space) from the object's origin to to the point that is being
/// "snapped from". This calculation is determined by the snapping modes.</summary>
/// <param name="node">The object that is being snapped-to some other object</param>
/// <param name="snapFromMode">The "snap from" mode, as a string. See SnapFromModes property.
/// Pass in 'null' to get the default which is the offset to the pivot point.</param>
/// <param name="axisType">Whether the Y axis is up or down</param>
/// <returns>Offset from this object's origin to the "snap from" point, in world space</returns>
/// <remarks>Must be kept in sync with SnapFromModes property.</remarks>
public static Vec3F CalcSnapFromOffset(
ITransformable node,
string snapFromMode,
AxisSystemType axisType)
{
SnapFromMode mode = GetSnapFromMode(snapFromMode);
return(CalcSnapFromOffset(node, mode, axisType));
}
/// <summary>
/// Gets the vector in world space that points "up"</summary>
/// <param name="axis">The axis system indicating which axis is up</param>
/// <returns>The vector that points up</returns>
public static Vec3F GetUpVector(AxisSystemType axis)
{
if (axis == AxisSystemType.YIsUp)
{
return(new Vec3F(0, 1, 0));
}
else
{
return(new Vec3F(0, 0, 1));
}
}
/// <summary>
/// For an object 'node' that is being manipulated, this function returns
/// the offset (in world space) from the object's origin to to the point that is being
/// "snapped from". This calculation is determined by the snapping modes.</summary>
/// <param name="node">The object that is being snapped-to some other object</param>
/// <param name="snapFromMode">The "snap from" mode, as an enum</param>
/// <param name="axisType">Axis system type (y or z is up)</param>
/// <param name="pivot">Pass in either node.RotatePivot or node.ScalePivot</param>
/// <returns>Offset from this object's origin to the "snap from" point, in world space</returns>
/// <remarks>Must be kept in sync with SnapFromModes property.</remarks>
public static Vec3F CalcSnapFromOffset(
ITransformable node,
SnapFromMode snapFromMode,
AxisSystemType axisType, Vec3F pivot)
{
switch (snapFromMode)
{
case SnapFromMode.Pivot:
{
Vec3F offset;
Path <DomNode> path = new Path <DomNode>(node.Cast <DomNode>().Ancestry);
Matrix4F parentToWorld = TransformUtils.CalcPathTransform(path, path.Count - 2);
node.Transform.TransformVector(pivot, out offset); //local-to-parent
parentToWorld.TransformVector(offset, out offset); //parent-to-world
return(offset); //world
}
case SnapFromMode.Origin:
return(new Vec3F(0, 0, 0));
case SnapFromMode.BottomCenter:
{
Box box = node.BoundingBox;
Vec3F btmWorld;
if (axisType == AxisSystemType.YIsUp)
{
btmWorld = new Vec3F(
(box.Min.X + box.Max.X) * 0.5f,
box.Min.Y,
(box.Min.Z + box.Max.Z) * 0.5f);
}
else
{
btmWorld = new Vec3F(
(box.Min.X + box.Max.X) * 0.5f,
(box.Min.Y + box.Max.Y) * 0.5f,
box.Min.Z);
}
Vec3F origin = node.Transform.Translation;
Vec3F offset = btmWorld - origin; //local space offset
Path <DomNode> path = new Path <DomNode>(node.Cast <DomNode>().GetPath());
Matrix4F parentToWorld = TransformUtils.CalcPathTransform(path, path.Count - 2);
parentToWorld.TransformVector(offset, out offset);
return(offset);
}
default:
throw new ArgumentException("Invalid snap-from node");
}
}
/// <summary>
/// For an object 'node' that is being manipulated, this function returns
/// the offset (in world space) from the object's origin to to the point that is being
/// "snapped from". This calculation is determined by the snapping modes.</summary>
/// <param name="node">The object that is being snapped-to some other object</param>
/// <param name="snapFromMode">The "snap from" mode, as an enum</param>
/// <param name="axisType">Whether the Y axis is up or down</param>
/// <returns>Offset from this object's origin to the "snap from" point, in world space</returns>
/// <remarks>Must be kept in sync with SnapFromModes property.</remarks>
public static Vec3F CalcSnapFromOffset(
ITransformable node,
SnapFromMode snapFromMode,
AxisSystemType axisType)
{
Vec3F rotatePivot = new Vec3F();
if ((node.TransformationType & TransformationTypes.RotatePivot) != 0)
{
rotatePivot = node.RotatePivot;
}
return(CalcSnapFromOffset(node, snapFromMode, axisType, rotatePivot));
}
/// <summary>
/// Gets the vector in world space that points "up"</summary>
/// <param name="axis">The axis system indicating which axis is up</param>
/// <returns>The vector that points up</returns>
public static Vec3F GetUpVector(AxisSystemType axis)
{
if (axis == AxisSystemType.YIsUp)
return new Vec3F(0, 1, 0);
else
return new Vec3F(0, 0, 1);
}
/// <summary>
/// Given an object's current Euler angles and a surface normal, calculates
/// the Euler angles necessary to rotate the object so that its up-vector is
/// aligned with the surface normal</summary>
/// <param name="originalEulers">Original Euler angles, from an IRenderableNode.Rotation, for example</param>
/// <param name="surfaceNormal">A unit vector that the object should be rotate-snapped to</param>
/// <param name="upAxis">Whether the Y axis is up or down</param>
/// <returns>The resulting angles to be assigned to IRenderableNode.Rotation</returns>
/// <remarks>
/// Note that QuatF was attempted to be used, but I could not get it to work reliably
/// with the Matrix3F.GetEulerAngles(). Numerical instability? The basis vector
/// method below works well, except for when the target surface is 90 degrees different
/// than the starting up vector. In this case, the rotation around the up vector is lost
/// (gimbal lock), but the results are always valid in the sense that the up vector
/// is aligned with the surface normal. --Ron Little</remarks>
public static Vec3F RotateToVector(Vec3F originalEulers, Vec3F surfaceNormal, AxisSystemType upAxis)
{
// get basis vectors for the current rotation
Matrix3F rotMat = new Matrix3F();
rotMat.Rotation(originalEulers);
Vec3F a1 = rotMat.XAxis;
Vec3F a2 = rotMat.YAxis;
Vec3F a3 = rotMat.ZAxis;
// calculate destination basis vectors
Vec3F b1, b2, b3;
if (upAxis == AxisSystemType.YIsUp)
{
// a2 is the current up vector. b2 is the final up vector.
// now, find either a1 or a3, whichever is most orthogonal to surface
b2 = new Vec3F(surfaceNormal);
float a1DotS = Vec3F.Dot(a1, surfaceNormal);
float a3DotS = Vec3F.Dot(a3, surfaceNormal);
if (Math.Abs(a1DotS) < Math.Abs(a3DotS))
{
b1 = new Vec3F(a1);
b3 = Vec3F.Cross(b1, b2);
b1 = Vec3F.Cross(b2, b3);
}
else
{
b3 = new Vec3F(a3);
b1 = Vec3F.Cross(b2, b3);
b3 = Vec3F.Cross(b1, b2);
}
}
else
{
// a3 is the current up vector. b3 is the final up vector.
// now, find either a1 or a2, whichever is most orthogonal to surface
b3 = new Vec3F(surfaceNormal);
float a1DotS = Vec3F.Dot(a1, surfaceNormal);
float a2DotS = Vec3F.Dot(a2, surfaceNormal);
if (Math.Abs(a1DotS) < Math.Abs(a2DotS))
{
b1 = new Vec3F(a1);
b2 = Vec3F.Cross(b3, b1);
b1 = Vec3F.Cross(b2, b3);
}
else
{
b2 = new Vec3F(a2);
b1 = Vec3F.Cross(b2, b3);
b2 = Vec3F.Cross(b3, b1);
}
}
// in theory, this isn't necessary, but in practice...
b1.Normalize();
b2.Normalize();
b3.Normalize();
// construct new rotation matrix and extract euler angles
rotMat.XAxis = b1;
rotMat.YAxis = b2;
rotMat.ZAxis = b3;
Vec3F newEulers = new Vec3F();
rotMat.GetEulerAngles(out newEulers.X, out newEulers.Y, out newEulers.Z);
return newEulers;
}
/// <summary>
/// For an object 'node' that is being manipulated, this function returns
/// the offset (in world space) from the object's origin to to the point that is being
/// "snapped from". This calculation is determined by the snapping modes.</summary>
/// <param name="node">The object that is being snapped-to some other object</param>
/// <param name="snapFromMode">The "snap from" mode, as an enum</param>
/// <param name="axisType">Whether the Y axis is up or down</param>
/// <returns>Offset from this object's origin to the "snap from" point, in world space</returns>
/// <remarks>Must be kept in sync with SnapFromModes property.</remarks>
public static Vec3F CalcSnapFromOffset(
ITransformable node,
SnapFromMode snapFromMode,
AxisSystemType axisType)
{
Vec3F rotatePivot = new Vec3F();
if ((node.TransformationType & TransformationTypes.RotatePivot) != 0)
rotatePivot = node.RotatePivot;
return CalcSnapFromOffset(node, snapFromMode, axisType, rotatePivot);
}
/// <summary>
/// For an object 'node' that is being manipulated, this function returns
/// the offset (in world space) from the object's origin to to the point that is being
/// "snapped from". This calculation is determined by the snapping modes.</summary>
/// <param name="node">The object that is being snapped-to some other object</param>
/// <param name="snapFromMode">The "snap from" mode, as a string. See SnapFromModes property.
/// Pass in 'null' to get the default which is the offset to the pivot point.</param>
/// <param name="axisType">Whether the Y axis is up or down</param>
/// <returns>Offset from this object's origin to the "snap from" point, in world space</returns>
/// <remarks>Must be kept in sync with SnapFromModes property.</remarks>
public static Vec3F CalcSnapFromOffset(
ITransformable node,
string snapFromMode,
AxisSystemType axisType)
{
SnapFromMode mode = GetSnapFromMode(snapFromMode);
return CalcSnapFromOffset(node, mode, axisType);
}
/// <summary>
/// For an object 'node' that is being manipulated, this function returns
/// the offset (in world space) from the object's origin to to the point that is being
/// "snapped from". This calculation is determined by the snapping modes.</summary>
/// <param name="node">The object that is being snapped-to some other object</param>
/// <param name="snapFromMode">The "snap from" mode, as an enum</param>
/// <param name="axisType">Axis system type (y or z is up)</param>
/// <param name="pivot">Pass in either node.RotatePivot or node.ScalePivot</param>
/// <returns>Offset from this object's origin to the "snap from" point, in world space</returns>
/// <remarks>Must be kept in sync with SnapFromModes property.</remarks>
public static Vec3F CalcSnapFromOffset(
ITransformable node,
SnapFromMode snapFromMode,
AxisSystemType axisType, Vec3F pivot)
{
switch (snapFromMode)
{
case SnapFromMode.Pivot:
{
Vec3F offset;
Path<DomNode> path = new Path<DomNode>(node.Cast<DomNode>().Ancestry);
Matrix4F parentToWorld = TransformUtils.CalcPathTransform(path, path.Count - 2);
node.Transform.TransformVector(pivot, out offset); //local-to-parent
parentToWorld.TransformVector(offset, out offset); //parent-to-world
return offset; //world
}
case SnapFromMode.Origin:
return new Vec3F(0, 0, 0);
case SnapFromMode.BottomCenter:
{
Box box = node.BoundingBox;
Vec3F btmWorld;
if (axisType == AxisSystemType.YIsUp)
{
btmWorld = new Vec3F(
(box.Min.X + box.Max.X) * 0.5f,
box.Min.Y,
(box.Min.Z + box.Max.Z) * 0.5f);
}
else
{
btmWorld = new Vec3F(
(box.Min.X + box.Max.X) * 0.5f,
(box.Min.Y + box.Max.Y) * 0.5f,
box.Min.Z);
}
Vec3F origin = node.Transform.Translation;
Vec3F offset = btmWorld - origin; //local space offset
Path<DomNode> path = new Path<DomNode>(node.Cast<DomNode>().GetPath());
Matrix4F parentToWorld = TransformUtils.CalcPathTransform(path, path.Count - 2);
parentToWorld.TransformVector(offset, out offset);
return offset;
}
default:
throw new ArgumentException("Invalid snap-from node");
}
}
/// <summary>
/// Given an object's current Euler angles and a surface normal, calculates
/// the Euler angles necessary to rotate the object so that its up-vector is
/// aligned with the surface normal</summary>
/// <param name="originalEulers">Original Euler angles, from an IRenderableNode.Rotation, for example</param>
/// <param name="surfaceNormal">A unit vector that the object should be rotate-snapped to</param>
/// <param name="upAxis">Whether the Y axis is up or down</param>
/// <returns>The resulting angles to be assigned to IRenderableNode.Rotation</returns>
/// <remarks>
/// Note that QuatF was attempted to be used, but I could not get it to work reliably
/// with the Matrix3F.GetEulerAngles(). Numerical instability? The basis vector
/// method below works well, except for when the target surface is 90 degrees different
/// than the starting up vector. In this case, the rotation around the up vector is lost
/// (gimbal lock), but the results are always valid in the sense that the up vector
/// is aligned with the surface normal. --Ron Little</remarks>
public static Vec3F RotateToVector(Vec3F originalEulers, Vec3F surfaceNormal, AxisSystemType upAxis)
{
// get basis vectors for the current rotation
Matrix3F rotMat = new Matrix3F();
rotMat.Rotation(originalEulers);
Vec3F a1 = rotMat.XAxis;
Vec3F a2 = rotMat.YAxis;
Vec3F a3 = rotMat.ZAxis;
// calculate destination basis vectors
Vec3F b1, b2, b3;
if (upAxis == AxisSystemType.YIsUp)
{
// a2 is the current up vector. b2 is the final up vector.
// now, find either a1 or a3, whichever is most orthogonal to surface
b2 = new Vec3F(surfaceNormal);
float a1DotS = Vec3F.Dot(a1, surfaceNormal);
float a3DotS = Vec3F.Dot(a3, surfaceNormal);
if (Math.Abs(a1DotS) < Math.Abs(a3DotS))
{
b1 = new Vec3F(a1);
b3 = Vec3F.Cross(b1, b2);
b1 = Vec3F.Cross(b2, b3);
}
else
{
b3 = new Vec3F(a3);
b1 = Vec3F.Cross(b2, b3);
b3 = Vec3F.Cross(b1, b2);
}
}
else
{
// a3 is the current up vector. b3 is the final up vector.
// now, find either a1 or a2, whichever is most orthogonal to surface
b3 = new Vec3F(surfaceNormal);
float a1DotS = Vec3F.Dot(a1, surfaceNormal);
float a2DotS = Vec3F.Dot(a2, surfaceNormal);
if (Math.Abs(a1DotS) < Math.Abs(a2DotS))
{
b1 = new Vec3F(a1);
b2 = Vec3F.Cross(b3, b1);
b1 = Vec3F.Cross(b2, b3);
}
else
{
b2 = new Vec3F(a2);
b1 = Vec3F.Cross(b2, b3);
b2 = Vec3F.Cross(b3, b1);
}
}
// in theory, this isn't necessary, but in practice...
b1.Normalize();
b2.Normalize();
b3.Normalize();
// construct new rotation matrix and extract euler angles
rotMat.XAxis = b1;
rotMat.YAxis = b2;
rotMat.ZAxis = b3;
Vec3F newEulers = new Vec3F();
rotMat.GetEulerAngles(out newEulers.X, out newEulers.Y, out newEulers.Z);
return(newEulers);
}
