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IPick Interface
IPick Interface
- GetItemAt
- GetItemAt3D
- GetItemAtDepth
- GetSurfacePointAt
IPick interface gives programmatic access to 3D selection The mechanism
provided by this interface is different from CurrentObjectChanged
event raised in Modify Mode.
IPick can be queried from the IView interface
Query path: KernelCAD > GetView
> IView > IPick
See also Pick Sample, Interface List
HRESULT GetItemAt( int xWnd, int yWnd, IItem** item )
Parameters
xWnd, int yWnd - [in] Window
coordinates in pixels measured from the top left corner
item - [out] The
returned IItem
interface.
Remarks:
The method detects whether there is an object at the specified window point
and returns IItem
interface implemented by the object. If there are several objects at the point
the top one (the visible one) is returned. See also the Advanced note
below, which applies to this method too.
HRESULT GetItemAt3D( int xWnd, int yWnd, DIPoint* point, IItem** item )
xWnd, int yWnd -[in] Window
coordinates in pixels measured from the top left corner.
point - [out] Returned global coordinates of 3D point on surface of the
object at the specified window point. Coordinates of the point are random if
there is no object at the window location.
item - [out] The
returned IItem
interface. The item rreference can be NULL if the
return is not required.
Remarks:
The method is an enhancement of the GetItemAt
above. It detects whether there is an object at the specified window point
and returns IItem
interface implemented by the object. If there are several objects at the point
the top one (the visible one) is returned.
The point is the 3D point on surface of the
object, if there is one. It is the intersection point of surface of the object
with 3D line orthogonal to the screen at the specified window point. Coordinates
of the point are relative to the global 3D axes.
Advanced:: As the method uses relatively complex computations for high
frequency programmatic usage it is recommended to experiment with graphic-only
algorithm. To change the algorithm set the
PrecisePointPicking property in context of the KernelCAD component to
false. In many situations the
graphic-only algorithm determines the point on the
surface with acceptable precision. An exception is the case when surface
approximation is very rough (See Geometric
Resolution) or the object consist only of few triangular simplexes. In the
later case z-coordinate of point relative to the Viewing
Frame is the maximum among all vertexes of the simplex.
HRESULT GetItemAtDepth( int xWnd, int yWnd, float* minZ, float* maxZ, IItem** item )
Parameters
xWnd, int yWnd - [in] Window
coordinates in pixels measured from the top left corner.
minZ, maxZ - [out]
Minimum and maximum of z coordinates in Viewing
Frame among all intersections of 3D line orthogonal to the screen at the specified window
point with the picked object
item - [out] The
returned IItem
interface. The item rreference can be NULL if the
return is not required.
Remarks:
The method is an enhancement of the GetItemAt
above. It detects whether there is an object at the specified window point
and returns IItem
interface implemented by the object. If there are several objects at the point
the top one (the visible one) is returned.
When the selected object is a closed surface, the 3D line orthogonal to the
screen at the specified point intersects it at least twice. The method returns
minimum and maximum of z coordinates in Viewing
Frame for those intersections.
See also note at the end of GetItemAt3D.
HRESULT GetSurfacePointAt( int xWnd, int yWnd,
ISurfacePointKC** surfPoint )
Parameters
xWnd, int yWnd - [in] Window
coordinates in pixels measured from the top left corner.
surfPoint - [out,retval]
The returned surface point
Remarks:
The method is an enhancement of the GetItemAt
above. It detects whether there is an object at the specified window point
and returns ISurfacePointKC interface implemented by the object.
Use ISurfacePointKC.GetItem()
> ISection to obtain information about the
object. Query ISurfacePointKC
>
IMeshPointKC for objects with meshed
surface to obtain extended information about simplex and other mesh elements
under the mouse.
Unless there was an error, the method always retuns a non-null surface point.
When there is no object at the screen location
ISurfacePointKC.GetPoint() returns the correspondent point at x and y plane
of eye frame and
ISurfacePointKC.GetItem() returns null
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