Home Page > KernelCAD Components > Interfaces > IBoolSectionEx
IBoolSectionEx Inteface
IBoolSectionEx Interface
IBoolSectionEx interface is an enhanced version of IBoolSection,
which returns information about the intersection curve of the two objects.
See also Cross View
sample and BoolOp Sample
HRESULT Execute(
EBooleanOperation operation, ISection* object, VARIANT_BOOL createIntersLine,
IArray** edges )
Parameters
operation  [in] member of
EBooleanOperation
enumeration indicating the operation to perform
object  [in] reference to the second object
for the operation. (The first object is the section which implements this IBoolSectionEx interface)
createIntersLine  [in] If true a set of Line Strip
objects representing intersection line will be created and added as child of the
first section (the section where this interface was queried form). See remarks
for more details
edges  [out, retval] Array of isolated intersection
loops. Each element has type IArray, elements in the
later array have type IVertex. See remarks
Remarks
Performs operation indicated by operation on the section where this IBoolSectionEx was queried from
and object. This method also allows performing subtraction of a
programmatically defined plane from the object. See details in
Planar Subtract.
If createIntersLine parameter is true a new empty
object will be created and added as new child of the first section. The object
will act as a group (container for its children). The objects will have one or
more child objects of Line Strip
type one per linked piece of intersection. For example, subtraction of a long
and thin cylinder from a sphere will have two closed isolated intersection
loops. In that case the newly added object will have two children one per each
intersection loop. Coordinates of points in the lines and other information can
be obtained via ISectionPointSet
and
ISectionLineStrip
queried form the relevant child. See BoolOp Sample
for an example.
The returned edges array contains information abut
the isolated linked intersection loops. Each loop is an array (IArray)
of IVertex
elements, which can be used to obtain coordinates and normals to the surface at
the intersection points. See
Cross View sample for an
example. This calculation is not performed and NULL will be
returned if createIntersLine is false.
IVertex
obtained above contains all normals to the resulting surface. The most frequent
case when two surfaces are smooth around the intersection curve the vertex
contains two normals on the left (side of surface of the first object, where
this interface was queried form) and right hand side of the intersection curve.
Often there are several normals on each side, for example when intersection
curve crosses an edge of either surface. In some cases (planar
subtract or case when the second object is not a closed surface and edges do
not intersect) the intersection curve becomes an edge of the resulting surface,
so the vertex can have only single normal, the one which belongs to the first
surface.
To find out which normals in the vertex belong to which side of the curve
query IUserData
from the IVertex
and call IUserData.GetData. The
returned cnt number is count of normals which belong to the first
surface (normals on the left). Normals 0 to cnt1 in
the vertex belong to the first surface, the rest belong to the second surface.
HRESULT STDMETHODCALLTYPE Execute2(
ISection* object,
EBoolOpContext* context )
Parameters
object  [in] reference to the
second object
for the operation. (The first object is the section which implements
this IBoolSectionEx interface)
context  [in, out]  additional input and output
parameters for the operation. See remarks
Remarks
Performs operation indicated by context.operation
on the section where this IBoolSectionEx was queried from and object. This method also allows performing subtraction of a
programmatically defined plane from the object. See details in
Planar Subtract.
If context.execute is false, only
intersection loops are calculated and the Boolean operation is not executed,
which significantly improves performance.
If context.intersectionLine is true a new empty
object will be created and added as new child of the first section. The object
will act as a group (container for its children). The objects will have one or
more child objects of Line Strip
type one per linked piece of intersection. For example, subtraction of a long
and thin cylinder from a sphere will have two closed isolated intersection
loops. In that case the newly added object will have two children one per each
intersection loop. Coordinates of points in the lines and other information can
be obtained via ISectionPointSet
and
ISectionLineStrip
queried form the relevant child. See BoolOp Sample
for an example.
If context.needEdges is true
context.edges will contain information abut the
calculated intersection curve. This calculation is not performed context.intersectionLine
is false. The curve consists of the isolated linked intersection loops.
Each loop is an array (IArray) of
IVertex
elements, which can be used to obtain coordinates and normals to the surface at
the intersection points. See remarks for the previous method for more
details. See
Cross View sample for an
example.
context.edges array must be created by the caller. To
create the array call
Create or
Create2 method of
IDIObjectGenerator interface with
parameter eType set to eObjTypeArray
member of EObjectType enumeration.
Query IArray
from the returned IUnknown interface. After call to
this Execute2() method the array will contain elements which in turn are arrays
too. More exactly arrays of vertices.
If separateComponents is true and the first object becomes
divided into several isolated pieces, the pieces will become separate objects.
The initial first object will be replaced with one if the pieces. The other
pieces will be added as new children of the first object. Selection of pieces
for the parent and children is random.
Note: All elements of the context structure must be initialized before the call. Details
HRESULT STDMETHODCALLTYPE CreateExtendedContext(
IDictionary_KC** contextExt)
Parameters
contextExt  [out, retval] The created and returned context
Remarks
Creates a context with extra options for the Execute3 method below. All
parameters have the default values
HRESULT Execute3(
EBooleanOperation operation, ISection** object,
IDictionary_KC* contextExt)
Parameters
operation  [in] member of
EBooleanOperation
enumeration indicating the operation to perform
object  [in] reference to the
second object for the operation. (The first object is the section which implements
this IBoolSectionEx interface)
contextExt  [in] A null reference or a context created
by the CreateExtendedContext() method above, which contains additional options for the operation.
See remarks
Remarks
Performs operation specified by operation
on the section where this IBoolSectionEx was queried from and object.
The significant difference with the Execute2 method is that the
InclideChildren*
properties below, allow boolean operations on groups of objects
contextExt has the following parameters:
Name 
Type 
Description 
Default Value 
OperationID 
Integer 
Valie must coinside with one of
EBooleanOperation enumeration. Overrides value
specified by operation 
EBooleanOperation.eBoolOpSubtract 
CreateLine 
Boolean 
If true intersection line of the two surfaces will be added to the model. See
comments for the
createIntersLine parameter above for details 
false 
IntersectionLineOnly 
Boolean 
If true only intersection line is calculated 
false 
ReturnIntersection 
Boolean 
Same as context.needEdges parameter above 
false 
SeparateComponents 
Boolean 
Same as separateComponents parameter above 
false 
EdgeArray 
Variant 
IArray created by the caller. See comments for the context.edges parameter above 
null 
IncludeChildrenThis 
Boolean 
If true children and all other descendants of the first (this) object will be
included in the operation 
false 
IncludeChildrenOther 
Boolean 
If true children and all other descendants of object
will be included in the operation 
false 
HRESULT Clip(IObjectOriented* objectClipper, VARIANT_BOOL needTopLinkedComponentOnly)
Parameters
objectClipper  [in] The object to be clipped with
needTopLinkedComponentOnly  [in] See remarks
Remarks
Clips the object, which implements this interface with objectClipper
needTopLinkedComponentOnly has effect only when objectClipper
has natural diection of its internal area. In the initial implementation this is used for the case of an infinite prizm build
on a polygon in x and y axes, so z axis defines a positive direction
After the operation the resulting surface is often split into isolated pieces (A sphere clipped with a thin infinite
triangular prizm around the center). When the pieces have nonoverlapping distinct ranges they are arranged along z axis
In this situation if needTopLinkedComponentOnly is true only the one with max z will be the result of the operation.
Otherwise all components will be merged into the final object
HRESULT Clip2(IObjectOriented* objectClipper, IListT** listISection)
Parameters
objectClipper  [in] The object to be clipped with
listISection  [in] See remarks
Remarks
Calculates the result of cliping this object (the object, which implements this interface) with objectClipper
Does not modify this object. listISection contains linked pieces of the result. See also the previous method
