NodeData::GetDParameter() Manual

内容表

关于
用法
Further Examples
延伸阅读

关于

NodeData based classic plugin classes can implement NodeData::GetDParameter() . This allows to define the values of parameters accessed with C4DAtom::GetParameter() . This is done to handle data that is not stored in the object's BaseContainer . It is also used to create parameters that depend on the value of other parameters or element properties.

NodeData::GetDParameter() corresponds to C4DAtom::GetParameter() .

注意: In most cases, when implementing NodeData::GetDParameter() , one will also need to implement NodeData::SetDParameter() . For example, if the value is stored in a member variable.

用法

NodeData::GetDParameter() is called when the value of a parameter is accessed with C4DAtom::GetParameter() . It is possible to define or change the returned value.

Bool GetDParameter( GeListNode * node, const DescID & id , GeData & t_data, DESCFLAGS_GET & flags) { if (node == nullptr ) return false ;

// check parameter ID switch ( id [0]. id ) { // This parameter is not stored in the BaseContainer case EXAMPLE_GENERATOR_PARAMETER_NOT_BC: { // set the value from a member variable t_data. SetInt32 (_value);

// Parameter retrieved. flags |= DESCFLAGS_GET::PARAM_GET ;

return true ; } }

return SUPER::GetDParameter(node, id , t_data, flags); }

注意: Such member variables must also be handled in NodeData::Read() , NodeData::Write() , NodeData::CopyTo() and NodeData::SetDParameter() .

The arguments of the function are:

The node itself.
The parameter DescID in question.
A GeData object to return the read parameter value.
These flags:
- DESCFLAGS_GET::PARAM_GET : Parameter retrieved.
- DESCFLAGS_GET::NO_GEDATADEFAULTVALUE : If set, the GeData default type will not be initialized for C4DAtom::GetParameter .

Certain cases have to be handled with special functions:

The macro HandleDescGetVector has to be used to handle vector parameter values.
In nodes with a material preview description GetDParameterPreview() 可以使用。

Further Examples

// This example of a TagData plugin defines the value of the // Tag's parameter by calculating the volume of the host object. Bool GetDParameter( GeListNode * node, const DescID & id , GeData & t_data, DESCFLAGS_GET & flags) { if (node == nullptr ) return false ;

// check parameter ID switch ( id [0]. id ) { case EXAMPLE_TAG_VOLUME: { Float volume = 0.0; GeData data; BaseTag * const tag = static_cast< BaseTag * > (node); if (tag != nullptr ) { BaseObject * const hostObject = tag-> GetObject (); if (hostObject != nullptr ) { // check the object type switch (hostObject-> GetType ()) { // calculate volume of sphere primitive case Osphere : { hostObject-> GetParameter ( PRIM_SPHERE_RAD , data, DESCFLAGS_GET::NONE ); const Float radius = data. GetFloat (); volume = (4.0 / 3.0) * maxon::PI * radius * radius * radius; break ; } // calculate volume of cylinder primitive case Ocylinder : { hostObject-> GetParameter ( PRIM_CYLINDER_RADIUS , data, DESCFLAGS_GET::NONE ); const Float radius = data. GetFloat (); hostObject-> GetParameter ( PRIM_CYLINDER_HEIGHT , data, DESCFLAGS_GET::NONE ); const Float height = data. GetFloat (); volume = maxon::PI * radius * radius * height; break ; } // etc. default : break ; } } } t_data. SetFloat (volume); flags |= DESCFLAGS_GET::PARAM_GET ; // don't forget to set this flag

return true ; } } return SUPER::GetDParameter(node, id , t_data, flags); }

延伸阅读

PRIM_CYLINDER_HEIGHT

@ PRIM_CYLINDER_HEIGHT

定义： ocylinder.h:13

定义： c4d_baseobject.h:224

定义： lib_description.h:327

maxon::Float Float

定义： ge_sys_math.h:64

定义： c4d_basetag.h:46

#define Ocylinder

Cylinder.

定义： ge_prepass.h:1051

PRIM_SPHERE_RAD

@ PRIM_SPHERE_RAD

定义： osphere.h:6

static constexpr Float64 PI

floating point constant: PI

定义： apibasemath.h:139

DESCFLAGS_GET

定义： ge_prepass.h:3099

Represents a C4DAtom that resides in a 4D list.

定义： c4d_baselist.h:1767

#define Osphere

Sphere.

定义： ge_prepass.h:1041

GeData::SetFloat

void SetFloat(Float v)

定义： c4d_gedata.h:567

定义： c4d_gedata.h:82

GeData::SetInt32

void SetInt32(Int32 v)

定义： c4d_gedata.h:573

PRIM_CYLINDER_RADIUS

@ PRIM_CYLINDER_RADIUS

定义： ocylinder.h:8

DESCFLAGS_GET::NONE

@ NONE

None.

BaseTag::GetObject

BaseObject * GetObject(void)

定义： c4d_basetag.h:95

maxon::Bool Bool

定义： ge_sys_math.h:53

DESCFLAGS_GET::PARAM_GET

@ PARAM_GET

Parameter retrieved.

C4DAtom::GetType

Int32 GetType() const

定义： c4d_baselist.h:1348

C4DAtom::GetParameter

Bool GetParameter(const DescID &id, GeData &t_data, DESCFLAGS_GET flags)

GeData::GetFloat

Float GetFloat(void) const

定义： c4d_gedata.h:439