eu.mihosoft.jcsg

Class CSG

java.lang.Object

eu.mihosoft.jcsg.CSG

public class CSG
extends java.lang.Object

Constructive Solid Geometry (CSG). This implementation is a Java port of https://github.com/evanw/csg.js/ with some additional features like polygon extrude, transformations etc. Thanks to the author for creating the CSG.js library.

Implementation Details All CSG operations are implemented in terms of two functions, Node.clipTo(Node) and Node.invert(), which remove parts of a BSP tree inside another BSP tree and swap solid and empty space, respectively. To find the union of a and b, we want to remove everything in a inside b and everything in b inside a, then combine polygons from a and b into one solid:

     a.clipTo(b);
     b.clipTo(a);
     a.build(b.allPolygons());
 

The only tricky part is handling overlapping coplanar polygons in both trees. The code above keeps both copies, but we need to keep them in one tree and remove them in the other tree. To remove them from b we can clip the inverse of b against a. The code for union now looks like this:

     a.clipTo(b);
     b.clipTo(a);
     b.invert();
     b.clipTo(a);
     b.invert();
     a.build(b.allPolygons());
 

Subtraction and intersection naturally follow from set operations. If union is A | B, differenceion is A - B = ~(~A | B) and intersection is A & B = ~(~A | ~B) where ~ is the complement operator.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CSG.OptType

Method Summary

Modifier and Type	Method and Description
CSG	clone()
CSG	color(javafx.scene.paint.Color c)
CSG	difference(CSG... csgs) Return a new CSG solid representing the difference of this csg and the specified csgs.
CSG	difference(CSG csg) Return a new CSG solid representing the difference of this csg and the specified csg.
CSG	difference(java.util.List<CSG> csgs) Return a new CSG solid representing the difference of this csg and the specified csgs.
CSG	dumbUnion(CSG csg) Returns a csg consisting of the polygons of this csg and the specified csg.
static CSG	fromPolygons(java.util.List<Polygon> polygons) Constructs a CSG from a list of Polygon instances.
static CSG	fromPolygons(Polygon... polygons) Constructs a CSG from the specified Polygon instances.
static CSG	fromPolygons(PropertyStorage storage, java.util.List<Polygon> polygons) Constructs a CSG from a list of Polygon instances.
static CSG	fromPolygons(PropertyStorage storage, Polygon... polygons) Constructs a CSG from the specified Polygon instances.
Bounds	getBounds() Returns the bounds of this csg.
java.util.List<Polygon>	getPolygons()
CSG	hull() Returns the convex hull of this csg.
CSG	hull(CSG... csgs) Returns the convex hull of this csg and the union of the specified csgs.
CSG	hull(java.util.List<CSG> csgs) Returns the convex hull of this csg and the union of the specified csgs.
CSG	intersect(CSG... csgs) Return a new CSG solid representing the intersection of this csg and the specified csgs.
CSG	intersect(CSG csg) Return a new CSG solid representing the intersection of this csg and the specified csg.
CSG	intersect(java.util.List<CSG> csgs) Return a new CSG solid representing the intersection of this csg and the specified csgs.
CSG	optimization(CSG.OptType type) Defines the CSg optimization type.
static void	setDefaultOptType(CSG.OptType optType)
void	setOptType(CSG.OptType optType)
MeshContainer	toJavaFXMesh()
MeshContainer	toJavaFXMeshSimple() Returns the CSG as JavaFX triangle mesh.
ObjFile	toObj()
ObjFile	toObj(int maxNumberOfVerts)
java.lang.String	toObjString() Returns this csg in OBJ string format.
java.lang.StringBuilder	toObjString(java.lang.StringBuilder sb) Returns this csg in OBJ string format.
java.lang.String	toStlString() Returns this csg in STL string format.
java.lang.StringBuilder	toStlString(java.lang.StringBuilder sb) Returns this csg in STL string format.
CSG	transformed(eu.mihosoft.vvecmath.Transform transform) Returns a transformed copy of this CSG.
CSG	union(CSG... csgs) Return a new CSG solid representing the union of this csg and the specified csgs.
CSG	union(CSG csg) Return a new CSG solid representing the union of this csg and the specified csg.
CSG	union(java.util.List<CSG> csgs) Return a new CSG solid representing the union of this csg and the specified csgs.
CSG	weighted(WeightFunction f)

Methods inherited from class java.lang.Object

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

Method Detail

fromPolygons

public static CSG fromPolygons(java.util.List<Polygon> polygons)

Constructs a CSG from a list of Polygon instances.

Parameters:

polygons - polygons

Returns:

a CSG instance

fromPolygons

public static CSG fromPolygons(Polygon... polygons)

Constructs a CSG from the specified Polygon instances.

Parameters:

polygons - polygons

Returns:

a CSG instance

fromPolygons

public static CSG fromPolygons(PropertyStorage storage,
                               java.util.List<Polygon> polygons)

Constructs a CSG from a list of Polygon instances.

Parameters:

storage - shared storage

polygons - polygons

Returns:

a CSG instance

fromPolygons

public static CSG fromPolygons(PropertyStorage storage,
                               Polygon... polygons)

Constructs a CSG from the specified Polygon instances.

Parameters:

storage - shared storage

polygons - polygons

Returns:

a CSG instance

clone

public CSG clone()

Overrides:

clone in class java.lang.Object

getPolygons

public java.util.List<Polygon> getPolygons()

Returns:

the polygons of this CSG

optimization

public CSG optimization(CSG.OptType type)

Defines the CSg optimization type.

Parameters:

type - optimization type

Returns:

this CSG

union

public CSG union(CSG csg)

Return a new CSG solid representing the union of this csg and the specified csg. Note: Neither this csg nor the specified csg are weighted.

    A.union(B)

    +-------+            +-------+
    |       |            |       |
    |   A   |            |       |
    |    +--+----+   =   |       +----+
    +----+--+    |       +----+       |
         |   B   |            |       |
         |       |            |       |
         +-------+            +-------+
 

Parameters:

csg - other csg

Returns:

union of this csg and the specified csg

dumbUnion

public CSG dumbUnion(CSG csg)

Returns a csg consisting of the polygons of this csg and the specified csg. The purpose of this method is to allow fast union operations for objects that do not intersect.

WARNING: this method does not apply the csg algorithms. Therefore, please ensure that this csg and the specified csg do not intersect.

Parameters:

csg - csg

Returns:

a csg consisting of the polygons of this csg and the specified csg

union

public CSG union(java.util.List<CSG> csgs)

Return a new CSG solid representing the union of this csg and the specified csgs. Note: Neither this csg nor the specified csg are weighted.

    A.union(B)

    +-------+            +-------+
    |       |            |       |
    |   A   |            |       |
    |    +--+----+   =   |       +----+
    +----+--+    |       +----+       |
         |   B   |            |       |
         |       |            |       |
         +-------+            +-------+
 

Parameters:

csgs - other csgs

Returns:

union of this csg and the specified csgs

union

public CSG union(CSG... csgs)

Return a new CSG solid representing the union of this csg and the specified csgs. Note: Neither this csg nor the specified csg are weighted.

    A.union(B)

    +-------+            +-------+
    |       |            |       |
    |   A   |            |       |
    |    +--+----+   =   |       +----+
    +----+--+    |       +----+       |
         |   B   |            |       |
         |       |            |       |
         +-------+            +-------+
 

Parameters:

csgs - other csgs

Returns:

union of this csg and the specified csgs

hull

public CSG hull()

Returns the convex hull of this csg.

Returns:

the convex hull of this csg

hull

public CSG hull(java.util.List<CSG> csgs)

Returns the convex hull of this csg and the union of the specified csgs.

Parameters:

csgs - csgs

Returns:

the convex hull of this csg and the specified csgs

hull

public CSG hull(CSG... csgs)

Returns the convex hull of this csg and the union of the specified csgs.

Parameters:

csgs - csgs

Returns:

the convex hull of this csg and the specified csgs

difference

public CSG difference(java.util.List<CSG> csgs)

Return a new CSG solid representing the difference of this csg and the specified csgs. Note: Neither this csg nor the specified csgs are weighted.

 A.difference(B)

 +-------+            +-------+
 |       |            |       |
 |   A   |            |       |
 |    +--+----+   =   |    +--+
 +----+--+    |       +----+
      |   B   |
      |       |
      +-------+
 

Parameters:

csgs - other csgs

Returns:

difference of this csg and the specified csgs

difference

public CSG difference(CSG... csgs)

Return a new CSG solid representing the difference of this csg and the specified csgs. Note: Neither this csg nor the specified csgs are weighted.

 A.difference(B)

 +-------+            +-------+
 |       |            |       |
 |   A   |            |       |
 |    +--+----+   =   |    +--+
 +----+--+    |       +----+
      |   B   |
      |       |
      +-------+
 

Parameters:

csgs - other csgs

Returns:

difference of this csg and the specified csgs

difference

public CSG difference(CSG csg)

Return a new CSG solid representing the difference of this csg and the specified csg. Note: Neither this csg nor the specified csg are weighted.

 A.difference(B)

 +-------+            +-------+
 |       |            |       |
 |   A   |            |       |
 |    +--+----+   =   |    +--+
 +----+--+    |       +----+
      |   B   |
      |       |
      +-------+
 

Parameters:

csg - other csg

Returns:

difference of this csg and the specified csg

intersect

public CSG intersect(CSG csg)

Return a new CSG solid representing the intersection of this csg and the specified csg. Note: Neither this csg nor the specified csg are weighted.

     A.intersect(B)

     +-------+
     |       |
     |   A   |
     |    +--+----+   =   +--+
     +----+--+    |       +--+
          |   B   |
          |       |
          +-------+
 }
 

Parameters:

csg - other csg

Returns:

intersection of this csg and the specified csg

intersect

public CSG intersect(java.util.List<CSG> csgs)

Return a new CSG solid representing the intersection of this csg and the specified csgs. Note: Neither this csg nor the specified csgs are weighted.

     A.intersect(B)

     +-------+
     |       |
     |   A   |
     |    +--+----+   =   +--+
     +----+--+    |       +--+
          |   B   |
          |       |
          +-------+
 }
 

Parameters:

csgs - other csgs

Returns:

intersection of this csg and the specified csgs

intersect

public CSG intersect(CSG... csgs)

Return a new CSG solid representing the intersection of this csg and the specified csgs. Note: Neither this csg nor the specified csgs are weighted.

     A.intersect(B)

     +-------+
     |       |
     |   A   |
     |    +--+----+   =   +--+
     +----+--+    |       +--+
          |   B   |
          |       |
          +-------+
 }
 

Parameters:

csgs - other csgs

Returns:

intersection of this csg and the specified csgs

toStlString

public java.lang.String toStlString()

Returns this csg in STL string format.

Returns:

this csg in STL string format

toStlString

public java.lang.StringBuilder toStlString(java.lang.StringBuilder sb)

Returns this csg in STL string format.

Parameters:

sb - string builder

Returns:

the specified string builder

color

public CSG color(javafx.scene.paint.Color c)

toObj

public ObjFile toObj()

toObj

public ObjFile toObj(int maxNumberOfVerts)

toObjString

public java.lang.StringBuilder toObjString(java.lang.StringBuilder sb)

Returns this csg in OBJ string format.

Parameters:

sb - string builder

Returns:

the specified string builder

toObjString

public java.lang.String toObjString()

Returns this csg in OBJ string format.

Returns:

this csg in OBJ string format

weighted

public CSG weighted(WeightFunction f)

transformed

public CSG transformed(eu.mihosoft.vvecmath.Transform transform)

Returns a transformed copy of this CSG.

Parameters:

transform - the transform to apply

Returns:

a transformed copy of this CSG

toJavaFXMesh

public MeshContainer toJavaFXMesh()

toJavaFXMeshSimple

public MeshContainer toJavaFXMeshSimple()

Returns the CSG as JavaFX triangle mesh.

Returns:

the CSG as JavaFX triangle mesh

getBounds

public Bounds getBounds()

Returns the bounds of this csg.

Returns:

bouds of this csg

setDefaultOptType

public static void setDefaultOptType(CSG.OptType optType)

Parameters:

optType - the optType to set

setOptType

public void setOptType(CSG.OptType optType)

Parameters:

optType - the optType to set