H3DU.BSplineSurface
### new H3DU.BSplineSurface(controlPoints, knotsU, knotsV, [bits])
Augments: Surface
A surface evaluator object for a B-spline (basis spline) surface, whose edges are made up of B-spline curves. For more on B-spline curves, see the constructor for BSplineCurve.
Parameters
controlPoints(Type: Array.<Array.<Array.<number»>)
An array of control point arrays, which in turn contain a number of control points. Each control point is an array with the same length as the other control points. It is assumed that:<ul> <li>The length of this parameter is the number of control points in each row of the V axis. <li>The length of the first control point array is the number of control points in each column of the U axis. <li>The first control point’s length represents the size of all the control points. </ul>knotsU(Type: Array.<number>)
Knot vector of the surface, along the U axis. For more information, see BSplineCurve.knotsV(Type: Array.<number>)
Knot vector of the surface, along the V axis.bits(Type: number) (optional)
Bits for defining input and controlling output. Zero or more of BSplineCurve.DIVIDE_BIT. If null, undefined, or omitted, no bits are set.
Examples
Together with ‘convertToHomogen’ given in the BSplineCurve documentation, the following function can be used to convert an array of arrays of control points, each consisting of conventional coordinates and a weight, to homogeneous coordinates. For example, the single-control point array ‘[[[2, 3, 4, 0.1]]]’ becomes ‘[[[0.2, 0.3, 0.4, 0.1]]]’; the return value can then be used in the BSplineSurface constructor to create a rational B-Spline surface.
function convertSurfaceToHomogen(cp) {
var ret = [];
for(var i = 0; i < cp.length; i++) {
ret.push(convertToHomogen(cp[i]));
}
return ret;
};
Methods
- bitangent
Finds the bitangent vector at the given point on the surface. - clamped
Creates a B-spline surface with uniform knots, except that the surface’s edges lie on the edges of the control point array. - evaluate
Evaluates the surface function based on a point in a B-spline surface. - fromBezierSurface
Creates a B-spline surface from the control points of a Bézier surface. - getControlPoints
Gets a reference to the array of control point arrays used in this surface object. - getKnots
Gets a reference to the array of knot vectors used in this curve object. - tangent
Finds the tangent vector at the given point on the surface. - uniform
Creates a B-spline surface with uniform knots.
### H3DU.BSplineSurface#bitangent(u, v)
Finds the bitangent vector at the given point on the surface.
Parameters
u(Type: number)
U coordinate of the surface to evaluate.v(Type: number)
V coordinate of the surface to evaluate.
Return Value
An array giving the bitangent vector. It will have as many elements as a control point (or one fewer if DIVIDE_BIT is set), as specified in the constructor. (Type: Array.<number>)
### (static) H3DU.BSplineSurface.clamped(controlPoints, [degreeU], [degreeV], [bits])
Creates a B-spline surface with uniform knots, except that the surface’s edges lie on the edges of the control point array.
Parameters
controlPoints(Type: Array.<Array.<Array.<number»>)
Array of control point arrays as specified in the BSplineSurface constructor.degreeU(Type: number) (optional)
Degree of the B-spline surface along the U axis. For example, 3 means a degree-3 (cubic) curve. If null, undefined, or omitted, the default is 3.degreeV(Type: number) (optional)
Degree of the B-spline surface along the V axis If null, undefined, or omitted, the default is 3.bits(Type: number) (optional)
Bits as specified in the BSplineSurface constructor.
Return Value
Return value. The first knot of the curve will be 0 and the last knot will be 1. (Type: BSplineSurface)
### H3DU.BSplineSurface#evaluate(u, v)
Evaluates the surface function based on a point in a B-spline surface.
Parameters
u(Type: number)
U coordinate of the surface to evaluate.v(Type: number)
V coordinate of the surface to evaluate.
Return Value
An array of the result of the evaluation. It will have as many elements as a control point (or one fewer if DIVIDE_BIT is set), as specified in the constructor. (Type: Array.<number>)
### (static) H3DU.BSplineSurface.fromBezierSurface(controlPoints, [bits])
Creates a B-spline surface from the control points of a Bézier surface.
Parameters
controlPoints(Type: Array.<Array.<Array.<number»>)
An array of control point arrays, which in turn contain a number of control points. Each control point is an array with the same length as the other control points. It is assumed that:<ul> <li>The length of this parameter minus 1 represents the degree of the Bézier surface along the V axis. For example, a degree-3 (cubic) surface along the V axis contains 4 control points, one in each control point array. A degree of 1 on both the U and V axes results in a flat surface. <li>The length of the first control point array minus 1 represents the degree of the Bézier surface along the U axis. <li>The number of elements in the first control point represents the number of elements in all the control points. </ul>bits(Type: number) (optional)
Bits as specified in the BSplineSurface constructor.
Return Value
Return value. (Type: BSplineSurface)
### H3DU.BSplineSurface#getControlPoints()
Gets a reference to the array of control point arrays used in this surface object.
Return Value
An object described in the constructor to BSplineCurve. (Type: Array.<Array.<number»)
### H3DU.BSplineSurface#getKnots()
Gets a reference to the array of knot vectors used in this curve object.
Return Value
An object described in the constructor to BSplineSurface. (Type: Array.<Array.<number»)
### H3DU.BSplineSurface#tangent(u, v)
Finds the tangent vector at the given point on the surface.
Parameters
u(Type: number)
U coordinate of the surface to evaluate.v(Type: number)
V coordinate of the surface to evaluate.
Return Value
An array giving the tangent vector. It will have as many elements as a control point (or one fewer if DIVIDE_BIT is set), as specified in the constructor. (Type: Array.<number>)
### (static) H3DU.BSplineSurface.uniform(controlPoints, [degreeU], [degreeV], [bits])
Creates a B-spline surface with uniform knots.
Parameters
controlPoints(Type: Array.<Array.<Array.<number»>)
Array of control point arrays as specified in the BSplineSurface constructor.degreeU(Type: number) (optional)
Degree of the B-spline surface along the U axis. For example, 3 means a degree-3 (cubic) curve. If null, undefined, or omitted, the default is 3.degreeV(Type: number) (optional)
Degree of the B-spline surface along the V axis If null, undefined, or omitted, the default is 3.bits(Type: number) (optional)
Bits as specified in the BSplineSurface constructor.
Return Value
Return value. The first knot of the curve will be 0 and the last knot will be 1. (Type: BSplineSurface)