maspack.geometry

Class NURBSSurface

java.lang.Object

maspack.geometry.NURBSObject

maspack.geometry.NURBSSurface

All Implemented Interfaces:

HasRenderProps, IsRenderable, IsSelectable, Renderable

public class NURBSSurface
extends NURBSObject

Implements a NURBS surface

Field Summary

Fields inherited from interface maspack.render.IsRenderable

TRANSPARENT, TWO_DIMENSIONAL

Constructor Summary

Constructors

Constructor and Description
NURBSSurface() Creates an empty NURBS surface.
NURBSSurface(int du, int typeu, double[] knotsu, int dv, int typev, double[] knotsv, Vector4d[] ctrlPnts) Creates a NURBS surface using degree and knot values in the u and v directions, along with control points.

Method Summary

Modifier and Type	Method and Description
RenderProps	createRenderProps() Factory method to create render properties appropriate to this object.
void	eval(Point3d pnt, double u, double v) Evaluates the point on this surface corresponding to u and v.
int	getDegreeU() Returns the degree of this surface in the u direction.
int	getDegreeV() Returns the degree of this surface in the v direction.
double[]	getKnotsU() Returns the knots in the u direction.
double[]	getKnotsV() Returns the knots in the v direction.
void	getRangeU(double[] uStartEnd) Gets the range of the u parameter.
void	getRangeV(double[] vStartEnd) Gets the range of the v parameter.
int	getResolutionU() Returns the resolution used for rendering this surface along the u parameter.
int	getResolutionV() Returns the resolution used for rendering this surface along the v parameter.
NURBSCurve3d	getVCurve() Returns the NURBS curve controlling this surface in the v direction.
int	numKnotsU() Returns the number of knots in the u direction.
int	numKnotsV() Returns the number of knots in the v direction.
void	read(java.io.Reader reader) Reads this surface from a text description supplied by a reader.
void	render(Renderer renderer, RenderProps props, int flags)
void	set(int du, double[] knotsu, int dv, double[] knotsv, Vector4d[] ctrlPnts) Sets this NURBS surface using degree and knot values in the u and v directions, along with control points.
void	set(int du, int typeu, double[] knotsu, int dv, int typev, double[] knotsv, Vector4d[] ctrlPnts) Sets this NURBS surface using degree and knot values in the u and v directions, along with control points.
void	set(WavefrontReader.Surface surface, Vector4d[] allPnts)
void	setRangeU(double ustart, double uend) Sets the range of the u parameter.
void	setRangeV(double vstart, double vend) Sets the range of the v parameter.
void	setResolutionU(int res) Sets the resolution used for rendering this surface along the u parameter.
void	setResolutionV(int res) Sets the resolution used for rendering this surface along the v parameter.
void	setSphere(double x, double y, double z, double radius) Sets this surface to a 40-point sphere formed by sweeping a 5-point rational quadratic semi-circle about the z axis.
void	write(java.io.PrintWriter pw, java.lang.String fmtStr, boolean relative) Writes a text description of this NURBS object to a PrintWriter, using a subset of the Wavefront OBJ format as described in the documentation for the read method for this object.

Methods inherited from class maspack.geometry.NURBSObject

controlPointIsSelected, getControlPoint, getControlPoints, getDrawControlShape, getLineWidth, getObjToWorld, getObjToWorld, getPointSize, getRenderHints, getRenderProps, getSelection, isSelectable, numControlPoints, numSelectionQueriesNeeded, prerender, render, selectControlPoint, setDrawControlShape, setLineWidth, setObjToWorld, setPointSize, setRenderProps, transform, updateBounds, write, write

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NURBSSurface

public NURBSSurface()

Creates an empty NURBS surface.

NURBSSurface

public NURBSSurface(int du,
                    int typeu,
                    double[] knotsu,
                    int dv,
                    int typev,
                    double[] knotsv,
                    Vector4d[] ctrlPnts)

Creates a NURBS surface using degree and knot values in the u and v directions, along with control points. The surface may be open or closed in either the u or v directions. For information on how these arguments are constrained, see the general version of set.

Parameters:

du - degree in the u direction

typeu - u direction type, which must be either OPEN or CLOSED.

knotsu - knot values for the u direction

dv - degree in the v direction

typev - v direction type, which must be either OPEN or CLOSED.

knotsv - knot values for the v direction

ctrlPnts - control points

Throws:

java.lang.IllegalArgumentException - if constraints on the arguments are violated

See Also:

set(int,int,double[],int,int,double[],Vector4d[])

Method Detail

setResolutionU

public void setResolutionU(int res)

Sets the resolution used for rendering this surface along the u parameter. This is the number of linear segments used to plot the surface between it's minimum and maximum u values.

Parameters:

res - rendering resolution for u

See Also:

getResolutionU()

getResolutionU

public int getResolutionU()

Returns the resolution used for rendering this surface along the u parameter.

Returns:

rendering resolution for u

See Also:

setResolutionU(int)

setResolutionV

public void setResolutionV(int res)

Sets the resolution used for rendering this surface along the v parameter. This is the number of linear segments used to plot the surface between it's minimum and maximum v values.

Parameters:

res - rendering resolution for v

See Also:

getResolutionV()

getResolutionV

public int getResolutionV()

Returns the resolution used for rendering this surface along the v parameter.

Returns:

rendering resolution for v

See Also:

setResolutionV(int)

setRangeU

public void setRangeU(double ustart,
                      double uend)

Sets the range of the u parameter. If necessary, ustart and uend are clipped so that they lie in the range knots[d-1] to knots[numk-d], where d, knots, and numk describe the degree, knots, and number of knots associated with u.

Parameters:

ustart - minimum u parameter

uend - maximum u parameter

See Also:

getRangeU(double[])

getRangeU

public void getRangeU(double[] uStartEnd)

Gets the range of the u parameter.

Parameters:

uStartEnd - returns the ustart and uend values, in elements 0 and 1, respectively.

See Also:

setRangeU(double, double)

setRangeV

public void setRangeV(double vstart,
                      double vend)

Sets the range of the v parameter. If necessary, vstart and vend are clipped so that they lie in the range knots[d-1] to knots[numk-d], where d, knots, and numk describe the degree, knots, and number of knots associated with v.

Parameters:

vstart - minimum v parameter

vend - maximum v parameter

See Also:

getRangeV(double[])

getRangeV

public void getRangeV(double[] vStartEnd)

Gets the range of the v parameter.

Parameters:

vStartEnd - returns the vstart and vend values, in elements 0 and 1, respectively.

See Also:

setRangeV(double, double)

set

public void set(int du,
                double[] knotsu,
                int dv,
                double[] knotsv,
                Vector4d[] ctrlPnts)

Sets this NURBS surface using degree and knot values in the u and v directions, along with control points. For information on how these arguments are constrained, see the more general version of set.

Parameters:

du - degree in the u direction

knotsu - knot values for the u direction

dv - degree in the v direction

knotsv - knot values for the v direction

ctrlPnts - control points

Throws:

java.lang.IllegalArgumentException - if constraints on the arguments are violated

See Also:

set(int,int,double[],int,int,double[],Vector4d[])

set

public void set(int du,
                int typeu,
                double[] knotsu,
                int dv,
                int typev,
                double[] knotsv,
                Vector4d[] ctrlPnts)

Sets this NURBS surface using degree and knot values in the u and v directions, along with control points. The surface may be open or closed in either the u or v directions.

Let du, numku, and numcu be the degree, number of knots, and number of control points associated with the u direction. The degree must be 1 or greater. If the u direction is open, then

numcu = numku - du + 1

and if it is closed,

numcu = numku - 2*du + 1

Analogous results hold for the v direction. The total number of control points is numcu*numcv, and so the ctrlPnts argument must be at least this length. Control points should be arranged so that the first set of v control points comes first, followed by the second set, etc.

This method automatically sets ustart, uend, vstart, and vend (see setRangeU and setRangeV) to to knotsu[du-1], knotsu[numku-du], knotsv[dv-1], and knotsv[numkv-dv].

The control points are specified as 4-vectors, where their spatial location is given by x, y, and z and their weight is given by w. The points should not be in homogeneous form; i.e., x, y, and z should not be premultipled by w.

Parameters:

du - degree in the u direction

typeu - u direction type, which must be either OPEN or CLOSED.

knotsu - knot values for the u direction

dv - degree in the v direction

typev - v direction type, which must be either OPEN or CLOSED.

knotsv - knot values for the v direction

ctrlPnts - control points

Throws:

java.lang.IllegalArgumentException - if constraints on the arguments are violated

setSphere

public void setSphere(double x,
                      double y,
                      double z,
                      double radius)

Sets this surface to a 40-point sphere formed by sweeping a 5-point rational quadratic semi-circle about the z axis.

Parameters:

x - center x coordinate

y - center y coordinate

z - center z coordinate

radius - circle radius

Throws:

java.lang.IllegalArgumentException - if radius is non-positive

eval

public void eval(Point3d pnt,
                 double u,
                 double v)

Evaluates the point on this surface corresponding to u and v. These values are clipped, if necessary, to the range [ustart, uend] and [vstart, vend].

Parameters:

pnt - returns the surface point value

u - u parameter value

v - v parameter value

render

public void render(Renderer renderer,
                   RenderProps props,
                   int flags)

Specified by:

render in class NURBSObject

getVCurve

public NURBSCurve3d getVCurve()

Returns the NURBS curve controlling this surface in the v direction.

Returns:

v direction curve

getDegreeU

public int getDegreeU()

Returns the degree of this surface in the u direction.

Returns:

degree in the u direction

numKnotsU

public int numKnotsU()

Returns the number of knots in the u direction.

Returns:

number of knots in the u direction

getKnotsU

public double[] getKnotsU()

Returns the knots in the u direction.

Returns:

knot values in the u direction

getDegreeV

public int getDegreeV()

Returns the degree of this surface in the v direction.

Returns:

degree in the v direction

numKnotsV

public int numKnotsV()

Returns the number of knots in the v direction.

Returns:

number of knots in the v direction

getKnotsV

public double[] getKnotsV()

Returns the knots in the v direction.

Returns:

knot values in the v direction

read

public void read(java.io.Reader reader)
          throws java.io.IOException

Reads this surface from a text description supplied by a reader. The allowed format is a subset of the Alias Wavefront OBJ format for surfaces, and consists of a set of statements, one per line (lines can be continued, if necessary, using the line continuation character \).

The allowed statements are:

• Vertex definition of the form

  v x y z [w]

  each giving the x, y, and z values for a control point (with an optional weighting value w which defaults to 1 if omitted).
• Degree statement of the form

  deg du dv

  where du and dv are degree of the surface in the u and v directions. A degree statement must precede a surface statement (described below).
• Surface statement of the form

  surf ustart uend vstart vend i0 i1 ...

  where ustart, uend, vstart, and vend give the minimum and maximum values for the u and v surface parameters, and i0, i1, etc. give the indices of the control points defined by the vertex statements. Control points are indexed, starting at 1, by their order of occurance. If the index value is negative, then it gives the relative location of a control point with respect to the surface statement, where -1 is the closest preceding, -2 is the next closest preceding, etc. There should be numcu*numcv control points in all, where numcu and numcv are described in set, and the points should be ordered so that the first set of v points comes first, followed by the second set, etc.
• A u parameter statement of the form

  parm u [closed] k0 k1 ...

  where closed is an optional keyword indicating that the surface is closed in u direction, and k0, k1, etc. are the u direction knot values. The u parameter statement must follow the surface statement and precede the end statement (described below).
• A v parameter statement of the form

  parm v [closed] k0 k1 ...

  which is analogous to the u parameter statement.
• An end statement of the form

  end

  This must be placed after the curve and parameter statements.

The total number of control points and knots must match as described in the documentation for set. Explicit knot values may be omitted for either u or v, in which case an appropriate number of uniformly-spaced knots is created with start and end values corresponding to 0 and 1.

As an example, here are the statements that define a simple bezier surface patch:

 v -10.0 0.0 10.0 1.0
 v -5.0 5.0 10.0 1.0
 v 5.0 5.0 10.0 1.0
 v 10.0 0.0 10.0 1.0
 v -10.0 0.0 5.0 1.0
 v -5.0 5.0 5.0 1.0
 v 5.0 5.0 5.0 1.0
 v 10.0 0.0 5.0 1.0
 v -10.0 0.0 -5.0 1.0
 v -5.0 5.0 -5.0 1.0
 v 5.0 5.0 -5.0 1.0
 v 10.0 0.0 -5.0 1.0
 v -10.0 0.0 -10.0 1.0
 v -5.0 5.0 -10.0 1.0
 v 5.0 5.0 -10.0 1.0
 v 10.0 0.0 -10.0 1.0
 deg 3 3
 surf 0.0 1.0 0.0 1.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
 parm u 0.0 0.0 0.0 1.0 1.0 1.0
 parm v 0.0 0.0 0.0 1.0 1.0 1.0
 end
 

Parameters:

reader - providing the text input

Throws:

java.io.IOException - if an I/O or format error occurs

set

public void set(WavefrontReader.Surface surface,
                Vector4d[] allPnts)

write

public void write(java.io.PrintWriter pw,
                  java.lang.String fmtStr,
                  boolean relative)
           throws java.io.IOException

Writes a text description of this NURBS object to a PrintWriter, using a subset of the Wavefront OBJ format as described in the documentation for the read method for this object.

Specified by:

write in class NURBSObject

Parameters:

pw - PrintWriter for outputing the text description

fmtStr - printf-style format string for formatting the floating point values (e.g., "%g", "%10.3f").

relative - if true, then control point indices are written as negative values giving their location relative to the curv statement.

Throws:

java.io.IOException - if an I/O error occurs

createRenderProps

public RenderProps createRenderProps()

Factory method to create render properties appropriate to this object.

Returns:

new render properties for this object