# Difference between revisions of "CADPart"

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The following Part node: | The following Part node: | ||

− | + | <b>CADPart { | |

− | + | center C | |

− | + | rotation R | |

− | + | scale S | |

− | + | scaleOrientation SR | |

− | + | translation T | |

− | + | children [...] | |

− | + | }</b> | |

is equivalent to the nested sequence of: | is equivalent to the nested sequence of: | ||

− | + | <b>CADPart { | |

− | + | translation T | |

− | + | children CADPart { | |

− | + | translation C | |

− | + | children CADPart { | |

− | + | rotation R | |

− | + | children CADPart { | |

− | + | rotation SR | |

− | + | children CADPart { | |

− | + | scale S | |

− | + | children CADPart { | |

− | + | rotation -SR | |

− | + | children CADPart { | |

− | + | translation -C | |

− | + | children [...] | |

− | + | }}}}}}}</b> | |

The ''name'' field documents the name of this part. | The ''name'' field documents the name of this part. | ||

* [[Node Reference]] | * [[Node Reference]] |

## Revision as of 15:28, 1 February 2006

## CADPart

CADPart : X3DGroupingNode, X3DProductStructureChildNode { MFNode [in] addChildren MFNode [in] removeChildren MFNode [in,out] children [] [CADFace] SFVec3f [in,out] center 0 0 0 (-∞,∞) SFNode [in,out] metadata NULL [X3DMetadataObject] SFString [in,out] name "" SFRotation [in,out] rotation 0 0 1 0 [-1,1] or (-∞,∞) SFVec3f [in,out] scale 1 1 1 (0,∞) SFRotation [in,out] scaleOrientation 0 0 1 0 [-1,1] or (-∞,∞) SFVec3f [in,out] translation 0 0 0 (-∞,∞) SFVec3f [] bboxCenter 0 0 0 (-∞,∞) SFVec3f [] bboxSize -1 -1 -1 [0,∞) or −1 −1 −1 }

The CADPart node is a grouping node that defines a coordinate system for its children that is relative to the coordinate systems of its ancestors. See the *Transformation hierarchy and Standard units and coordinate system* sections of the X3D specification for a description of coordinate systems and transformations.

The CADPart node represents the location and faces that constitute a part in the CAD model.

The *Grouping and children node types* section of the X3D specification provides a description of the *children*, *addChildren*, and *removeChildren* fields.

The *bboxCenter* and *bboxSize* fields specify a bounding box that encloses the children of the Part node. This is a hint that may be used for optimization purposes. The results are undefined if the specified bounding box is smaller than the actual bounding box of the children at any time. A default bboxSize value, (-1, -1, -1), implies that the bounding box is not specified and, if needed, shall be calculated by the browser. The bounding box shall be large enough at all times to enclose the union of the group's children's bounding boxes; it shall not include any transformations performed by the group itself (i.e., the bounding box is defined in the local coordinate system of the children).

The *translation*, *rotation*, scale, *scaleOrientation* and *center* fields define a geometric 3D transformation consisting of (in order):

1. a (possibly) non-uniform scale about an arbitrary point; 2. a rotation about an arbitrary point and axis; 3. a translation.

The *center* field specifies a translation offset from the origin of the local coordinate system (0,0,0). The *rotation* field specifies a rotation of the coordinate system. The *scale* field specifies a non-uniform scale of the coordinate system. scale values may have any value: positive, negative (indicating a reflection), or zero. A value of zero indicates that any child geometry shall not be displayed. The *scaleOrientation* specifies a rotation of the coordinate system before the scale (to specify scales in arbitrary orientations). The *scaleOrientation* applies only to the scale operation. The *translation* field specifies a translation to the coordinate system.

Given a 3-dimensional point P and Part node, P is transformed into point P' in its parent's coordinate system by a series of intermediate transformations. In matrix transformation notation, where C (center), SR (scaleOrientation), T (translation), R (rotation), and S (scale) are the equivalent transformation matrices,

P' = T * C * R * SR * S * -SR * -C * P

The following Part node:

**CADPart {
**

center C rotation R scale S scaleOrientation SR translation T children [...]

**}**

is equivalent to the nested sequence of:

**CADPart {
**

translation T children CADPart { translation C children CADPart { rotation R children CADPart { rotation SR children CADPart { scale S children CADPart { rotation -SR children CADPart { translation -C children [...]

**}}}}}}}**

The *name* field documents the name of this part.