Class TNurbsCurveNode

Unit

Declaration

type TNurbsCurveNode = class(TAbstractParametricGeometryNode)

Description

Visible NURBS curve in 3D.

Hierarchy

Overview

Methods

Protected function DirectEnumerateActive(Func: TEnumerateChildrenFunction): Pointer; override;
Public class function ForVRMLVersion(const Version: TX3DVersion): boolean; override;
Public function Proxy(var State: TX3DGraphTraverseState): TAbstractGeometryNode; override;
Public function LocalBoundingBox(State: TX3DGraphTraverseState; ProxyGeometry: TAbstractGeometryNode; ProxyState: TX3DGraphTraverseState): TBox3D; override;
Public function BoundingBox(State: TX3DGraphTraverseState; ProxyGeometry: TAbstractGeometryNode; ProxyState: TX3DGraphTraverseState): TBox3D; override;
Public function TrianglesCount(State: TX3DGraphTraverseState; ProxyGeometry: TAbstractGeometryNode; ProxyState: TX3DGraphTraverseState): Cardinal; override;
Public function InternalCoord(State: TX3DGraphTraverseState; out ACoord: TMFVec3f): boolean; override;
Public function CoordField: TSFNode; override;
Public procedure PiecewiseBezier;
Public function Point(const U: Single; const Tangent: PVector3 = nil): TVector3;
Public procedure CreateNode; override;
Public class function ClassX3DType: string; override;
Public procedure SetWeight(const Value: array of Double); overload;
Public procedure SetWeight(const Value: TDoubleList); overload;
Public procedure SetKnot(const Value: array of Double); overload;
Public procedure SetKnot(const Value: TDoubleList); overload;

Properties

Public property FdControlPoint: TSFNode read FFdControlPoint;
Public property ControlPoint: TAbstractCoordinateNode read GetControlPoint write SetControlPoint;
Public property FdTessellation: TSFInt32 read FFdTessellation;
Public property Tessellation: Integer read GetTessellation write SetTessellation;
Public property FdWeight: TMFDouble read FFdWeight;
Public property FdClosed: TSFBool read FFdClosed;
Public property Closed: Boolean read GetClosed write SetClosed;
Public property FdKnot: TMFDouble read FFdKnot;
Public property FdOrder: TSFInt32 read FFdOrder;
Public property Order: Integer read GetOrder write SetOrder;

Description

Methods

Protected function DirectEnumerateActive(Func: TEnumerateChildrenFunction): Pointer; override;

This item has no description. Showing description inherited from TX3DNode.DirectEnumerateActive.

Enumerate all active child nodes of given node.

"Active nodes" are the ones affecting current look or collisions, e.g. from Switch node only one child will be enumerated. See Traverse for more precise definition.

"Direct" means that this enumerates only direct descendants, i.e. this is not recursive. See methods like Traverse or EnumerateNodes if you want recursive behavior.

This can enumerate both VRML1Children nodes and nodes within TSFNode and TMFNode fields.

Default implementation in this class enumerates all Children nodes of VRML 1.0. If you need to remove some children for VRML 1.0 (e.g. for Switch or LOD nodes) or add some children for VRML 2.0 you have to override this. You do not need to call inherited when overriding this — in fact, you should not, if you want to omit some nodes.

Stops and returns immediately if Func returns non-nil for some child.

Public class function ForVRMLVersion(const Version: TX3DVersion): boolean; override;

This item has no description. Showing description inherited from TX3DNode.ForVRMLVersion.

Some nodes are present only in specific VRML/X3D version. This functions decides it.

For example some nodes can only work in VRML < 2.0, some others only in VRML >= 2.0. There are even some pairs of nodes: for example TConeNode_1 works with VRML < 2.0, TConeNode works with VRML >= 2.0.

NodesManager will use this.

Default implementation of this function returns always True. Generally, I don't try to set this too aggresively — in other words, for all cases when it's sensible, I allow nodes to be used in every VRML/X3D version, even when official specification doesn't. This means that when reading VRML 1.0 files actually a large part of VRML 2.0 is allowed too, and also while reading VRML 2.0 many constructs from VRML 1.0 (officially no longer present in VRML 2.0) are allowed too. I'm trying to support what I call a "sum of VRML 1.0 and 2.0".

In practice I only use this function when various VRML/X3D versions specify the same node name but

  • With different fields.

    For example Cone and Cylinder have slightly different fields, due to the fact that VRML 2.0 resigned from using TSFBitMask fields.

  • With different behavior.

    For example definitions of Sphere for VRML 1.0 and 2.0 are practically equal. However, the behavior from where to take texture and material info is different — in VRML 1.0 we take last Texture2, Material etc. nodes, while in VRML 2.0 we look in parent Shape's "appearance" field. So once again two different Sphere classes are needed.

Public function Proxy(var State: TX3DGraphTraverseState): TAbstractGeometryNode; override;

This item has no description. Showing description inherited from TAbstractGeometryNode.Proxy.

Converts this node to another node class that may be better supported.

Typically, converts some complex geometry node (like Extrusion or Teapot) into more common node like IndexedFaceSet or IndexedTriangleSet. TShape class wraps this method into a more comfortable interface, that is TShape methods simply automatically convert geometry nodes to their proxy versions if needed.

In the base TAbstractGeometryNode class, returns Nil indicating that no conversion is known.

The resulting node's Name (if the result is not Nil) must be equal to our Name.

Some Proxy implementations (especially for VRML 1.0) will have to create new State (TX3DGraphTraverseState) instance along with a new geometry node. You should do this by copying the State into a new TX3DGraphTraverseState instance, and modyfying the State reference. Simply speaking, do

#
        State := TX3DGraphTraverseState.CreateCopy(State);

#)

You should not just modify the fields of the provided State instance. (Reasoning: some proxy methods rely on getting the original State, e.g. with original MaterialBinding, not the transformed state, to work correctly.)

You can modify State variable only when returning non-nil geometry.

Public function LocalBoundingBox(State: TX3DGraphTraverseState; ProxyGeometry: TAbstractGeometryNode; ProxyState: TX3DGraphTraverseState): TBox3D; override;

This item has no description.

Public function BoundingBox(State: TX3DGraphTraverseState; ProxyGeometry: TAbstractGeometryNode; ProxyState: TX3DGraphTraverseState): TBox3D; override;

This item has no description. Showing description inherited from TAbstractGeometryNode.BoundingBox.

Calculate bounding box of this geometry node. They require State of this node during VRML traverse state — this is mainly for VRML 1.0 nodes, that depend on such state.

LocalBoundingBox gives a bounding box ignoring current transformation (or, equivalently, assuming like Transform = IdentityMatrix). Normal BoundingBox gives a bounding box taking current transformation into account.

Notes for descendants implementors:

The default implementations of these methods in TAbstractGeometryNode try to be smart and cover all common bases, so that you have to do as little work as possible to implement working descendant.

  1. For nodes based on coordinates (when InternalCoord returns True), LocalBoundingBox and BoundingBox already have optimal and correct implementation in this class. Using Coord and CoordIndex, no other information is needed.

  2. For other nodes, we first check ProxyGeometry and ProxyState. If ProxyGeometry is non-nil, we assume these came from Proxy call and we will use them to calculate bounding boxes, local and not local.

    So for nodes with Proxy overridden, you don't have to implement bounding box calculation, instead a ProxyGeometry will be created and provided here by the caller. This will work Ok if Proxy node will have bounding box calculation implemented.

    You can always override these methods, if you don't want to use proxy (for example, maybe there exists much faster method to calculate bounding box, or maybe tighter bounding box may be calculated directly).

  3. For other nodes (not coordinate-based and without a proxy):

    The default implementation of LocalBoundingBox just calls BoundingBox with a specially modified State, such that Transform is identity.

    The default implementation of BoundingBox, in turn, just calls LocalBoundingBox and transforms this bounding box.

    So the default implementations call each other, and will loop infinitely... But if you override any one of them (local or not local), the other one will magically work.

    Note that the default implementation of LocalBoundingBox may be non-optimal as far as time is concerned, as we'll do useless multiplications by identity matrix. And the default implementation of BoundingBox may generate non-optimal bounding box, more direct approach (transforming each vertex) may give much tightier bounding box.

    So you only have to override one method — although if you want the best implementation, fastest and with the best tight bounding boxes, you may need to override both of them for some nodes.

Public function TrianglesCount(State: TX3DGraphTraverseState; ProxyGeometry: TAbstractGeometryNode; ProxyState: TX3DGraphTraverseState): Cardinal; override;

This item has no description.

Public function InternalCoord(State: TX3DGraphTraverseState; out ACoord: TMFVec3f): boolean; override;

This item has no description. Showing description inherited from TAbstractGeometryNode.InternalCoord.

Return node's list of coordinates. Returns False if node is not based on coordinates. Returns True and sets ACoord if the node is based on coordinates. Even when returns True, it can set ACoord = Nil, which means that node is based on coordinates but they are empty right now (so for example bounding box may be considered empty).

In base TAbstractGeometryNode class this always returns False.

Override this for descendants that have some kind of "coord" field, then this should return True and set ACoord to coord.point field, assuming that coord is set and specifies Coordinate node. Override this even if coordinates affect the look indirectly, e.g. NURBS "controlPoint" fields also should be returned here. Otherwise should return True and set ACoord = Nil.

For VRML 1.0, coord may be taken from State, that's why we have to pass current traverse state here.

Public function CoordField: TSFNode; override;

This item has no description. Showing description inherited from TAbstractGeometryNode.CoordField.

Node's "coord" field where you can place TCoordinateNode, or Nil if not available.

This gives you more possibilities than the InternalCoord and InternalCoordinates methods (as you can assign texCoord using this). However, it doesn't work for old VRML 1.0 (since they have coordinate information, but no "coord" field).

Public procedure PiecewiseBezier;

Make this NURBS curve equal to a piecewise Bezier curve by setting appropriate "knot". This looks at ControlPoint count and Order (set Order = 4 for a typical cubic Bezier curve).

Public function Point(const U: Single; const Tangent: PVector3 = nil): TVector3;

Get the position of a point on the curve.

The returned position is in the local transformation space of this shape. This method is guaranteed to work the same, regardless if this node is part of any TX3DRootNode and TCastleSceneCore or not.

Parameters
U
The place on a curve, in [0..1] range.
Tangent
Optional. If non-nil, will be set to the tangent, that is, direction in 3D in which the curve is going.
Public procedure CreateNode; override;

This item has no description. Showing description inherited from TAbstractParametricGeometryNode.CreateNode.

Automatically generated node properties.

Do not edit this file manually! To add new properties: - add them to the text files in tools/internal/x3d-nodes-to-pascal/nodes-specification/ , - and regenerate include files by running x3d-nodes-to-pascal

Public class function ClassX3DType: string; override;

This item has no description. Showing description inherited from TX3DNode.ClassX3DType.

Node type name in VRML/X3D, for this class. Normal VRML/X3D node classes should override this to return something non-empty, and then X3DType automatically will return the same value.

Empty for classes that don't have a hardcoded VRML/X3D node name, like a special TX3DUnknownNode. Such special classes should override then X3DType to return actual non-empty name there.

You usually should call X3DType. The only use of this method is that it works on classes (it's "class function"), without needing at actual instance.

Public procedure SetWeight(const Value: array of Double); overload;

This item has no description.

Public procedure SetWeight(const Value: TDoubleList); overload;

This item has no description.

Public procedure SetKnot(const Value: array of Double); overload;

This item has no description.

Public procedure SetKnot(const Value: TDoubleList); overload;

This item has no description.

Properties

Public property FdControlPoint: TSFNode read FFdControlPoint;

Internal wrapper for property ControlPoint. This wrapper API may change, we advise to access simpler ControlPoint instead.

Public property ControlPoint: TAbstractCoordinateNode read GetControlPoint write SetControlPoint;

This item has no description.

Public property FdTessellation: TSFInt32 read FFdTessellation;

Internal wrapper for property Tessellation. This wrapper API may change, we advise to access simpler Tessellation instead.

Public property Tessellation: Integer read GetTessellation write SetTessellation;

This item has no description.

Public property FdWeight: TMFDouble read FFdWeight;

Internal wrapper for property Weight. This wrapper API may change, we advise to access simpler Weight instead.

Public property FdClosed: TSFBool read FFdClosed;

Internal wrapper for property Closed. This wrapper API may change, we advise to access simpler Closed instead.

Public property Closed: Boolean read GetClosed write SetClosed;

This item has no description.

Public property FdKnot: TMFDouble read FFdKnot;

Internal wrapper for property Knot. This wrapper API may change, we advise to access simpler Knot instead.

Public property FdOrder: TSFInt32 read FFdOrder;

Internal wrapper for property Order. This wrapper API may change, we advise to access simpler Order instead.

Public property Order: Integer read GetOrder write SetOrder;

This item has no description.


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