Selection Operation - Manual implementation¶
__TOC__
Selection Operation items can be automatically generated directly from an ILxSelectionOperation interface, however in some cases, greater control over the item and evaluation is required. In these instances, the selection operation has to be implemented manually. A package and modifier need to be created along with a selection operation interface, enabling the modifier to write the selection operation object to a channel on the item.
The package/item should be of the type LXsITYPE_SELOP, and the modifier should read the inputs it requires, and output the ILxSelectionOperation COM object to the LXsICHAN_SELOP_OBJ channel. The LXsSELOP_PMODEL server tag should not be present on the ILxSelectionOperation spawned by this modifier.
Sample Code¶
The following sample code implements a very basic selection operation, item type and modifier that selects all elements within a particular index range.
C++¶
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* The Package and PackageInstance define the item that the user can
* connect to a mesh operation to control the selection.
*/
class Instance : public CLxImpl_PackageInstance
{
public:
static void initialize ()
{
CLxGenericPolymorph *srv = NULL;
srv = new CLxPolymorph <Instance>;
srv->AddInterface (new CLxIfc_PackageInstance <Instance>);
lx::AddSpawner ("select.inRange.inst", srv);
}
};
class Package : public CLxImpl_Package
{
public:
static void initialize ()
{
CLxGenericPolymorph *srv = NULL;
srv = new CLxPolymorph <Package>;
srv->AddInterface (new CLxIfc_Package <Package>);
srv->AddInterface (new CLxIfc_StaticDesc <Package>);
lx::AddServer ("select.inRange", srv);
}
Package () : _inst_spawn ("select.inRange.inst") {}
LxResult
pkg_TestInterface (
const LXtGUID guid) LXx_OVERRIDE
{
_inst_spawn.TestInterfaceRC (guid);
}
LxResult
pkg_Attach (
void **ppvObj) LXx_OVERRIDE
{
_inst_spawn.Alloc (ppvObj);
return ppvObj[0] ? LXe_OK : LXe_FAILED;
}
LxResult
pkg_SetupChannels (
ILxUnknownID addChan_obj) LXx_OVERRIDE
{
CLxUser_AddChannel add_chan (addChan_obj);
if (add_chan.test ())
{
add_chan.NewChannel ("start", LXsTYPE_INTEGER);
add_chan.SetDefault (0.0, 0);
add_chan.NewChannel ("end", LXsTYPE_INTEGER);
add_chan.SetDefault (0.0, 100);
return LXe_OK;
}
return LXe_FAILED;
}
static LXtTagInfoDesc descInfo[];
private:
CLxSpawner <Instance> _inst_spawn;
};
LXtTagInfoDesc Package::descInfo[] =
{
{ LXsPKG_SUPERTYPE, LXsITYPE_SELOP },
{ 0 }
};
/*
* The Selection Operation is spawned by the modifier and selects all
* elements within the defined range.
*/
class SelOp : public CLxImpl_SelectionOperation
{
public:
static void initialize ()
{
CLxGenericPolymorph *srv = NULL;
srv = new CLxPolymorph <SelOp>;
srv->AddInterface (new CLxIfc_SelectionOperation <SelOp>);
lx::AddSpawner ("select.inRange.op", srv);
}
SelOp () : _start (0), _end (100) { }
LxResult
selop_SetMesh (
ILxUnknownID mesh) LXx_OVERRIDE
{
/*
* Cache the mesh COM object. This is need to spawn the accessors
* in the Test functions.
*/
return _mesh.set (mesh) ? LXe_OK : LXe_FAILED;
}
void
SetRange (
int start,
int end)
{
if (start > end)
{
_start = end;
_end = start;
}
else
{
_start = start;
_end = end;
}
}
LxResult
selop_TestPoint (
LXtPointID point) LXx_OVERRIDE
{
CLxUser_Point accessor;
unsigned int index = 0;
/*
* Select the provided point in the accessor and test it's index
* against the range.
*/
if (_mesh.test () && accessor.fromMesh (_mesh))
{
if (LXx_OK (accessor.Select (point)))
{
accessor.Index (&index);
if (IsIndexInRange (index))
return LXe_TRUE;
}
}
return LXe_FALSE;
}
LxResult
selop_TestEdge (
LXtEdgeID edge) LXx_OVERRIDE
{
CLxUser_Edge accessor;
unsigned int index = 0;
/*
* Select the provided point in the accessor and test it's index
* against the range.
*/
if (_mesh.test () && accessor.fromMesh (_mesh))
{
if (LXx_OK (accessor.Select (edge)))
{
accessor.Index (&index);
if (IsIndexInRange (index))
return LXe_TRUE;
}
}
return LXe_FALSE;
}
LxResult
selop_TestPolygon (
LXtPolygonID polygon) LXx_OVERRIDE
{
CLxUser_Polygon accessor;
unsigned int index = 0;
/*
* Select the provided point in the accessor and test it's index
* against the range.
*/
if (_mesh.test () && accessor.fromMesh (_mesh))
{
if (LXx_OK (accessor.Select (polygon)))
{
accessor.Index (&index);
if (IsIndexInRange (index))
return LXe_TRUE;
}
}
return LXe_FALSE;
}
private:
bool
IsIndexInRange (
unsigned int index)
{
/*
* Test if the provided index is within range.
*/
return (index <= _end && index >= _start);
}
CLxUser_Mesh _mesh;
int _start;
int _end;
};
/*
* The Modifier is associated with the all items of our type, and it reads
* the start and end channels as inputs, spawns the selection operation and
* writes it to the selection operation object channel.
*/
class ModifierElement : public CLxItemModifierElement
{
public:
ModifierElement (
CLxUser_Evaluation &eval,
ILxUnknownID item_obj)
{
CLxUser_Item item (item_obj);
_start_index = -1;
_end_index = -1;
_output_index = -1;
if (item.test ())
{
/*
* Allocate the start and end channels as
* inputs and the selection operation object
* as an output.
*/
_start_index = eval.AddChan (item, "start", LXfECHAN_READ);
_end_index = eval.AddChan (item, "end", LXfECHAN_READ);
_output_index = eval.AddChan (item, LXsICHAN_SELOP_OBJ, LXfECHAN_WRITE);
}
}
void
Eval (
CLxUser_Evaluation &eval,
CLxUser_Attributes &attr) LXx_OVERRIDE
{
CLxUser_ValueReference val_ref;
SelOp *selOp = NULL;
ILxUnknownID selOp_obj = NULL;
int start = 0, end = 100;
CLxSpawner <SelOp> spawner ("select.inRange.op");
if (_output_index < 0)
return;
if (_start_index >= 0)
start = attr.Int (_start_index);
if (_end_index >= 0)
end = attr.Int (_end_index);
/*
* Spawn the selection operation and set the start and end
* values.
*/
selOp = spawner.Alloc (selOp_obj);
if (selOp)
selOp->SetRange (start, end);
/*
* Write the selection operation into the selection operation
* item output channel.
*/
if (attr.ObjectRW (_output_index, val_ref))
val_ref.SetObject (selOp_obj);
/*
* Release the selection operation COM object, as we spawned
* the item directly.
*/
lx::UnkRelease (selOp_obj);
}
private:
int _output_index, _start_index, _end_index;
};
class ModifierServer : public CLxItemModifierServer
{
public:
static void initialize ()
{
CLxExport_ItemModifierServer <ModifierServer> ("select.inRange.mod");
}
const char *
ItemType () LXx_OVERRIDE
{
/*
* Associate the modifier with all items of our type.
*/
return "select.inRange";
}
CLxItemModifierElement *
Alloc (
CLxUser_Evaluation &eval,
ILxUnknownID item_obj) LXx_OVERRIDE
{
return new ModifierElement (eval, item_obj);
}
};
void initialize ()
{
Package::initialize ();
Instance::initialize ();
SelOp::initialize ();
ModifierServer::initialize ();
}
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