VariableChanged Struct Reference

#include <c4d_baselist.h>

Detailed Description

The VariableChanged structure is essential for changing point/polygon counts in objects to allocate or remove multiple elements with a single C4DAtom::Message() call.
It can be used for example when sending MSG_POINTS_CHANGED and MSG_POLYGONS_CHANGED messages to objects, tags and keys.

The structure contains the number of elements (points or polygons) before and after the change, and optionally a translation map array.
Each element in the map represents an element before the change, and its value decides what element this corresponds to after the change. This is used to keep for example point selections and vertex maps valid.

Example: Adding a point to a point object.

VariableChanged vc;
 
Int32 count = op->GetPointCount(); // Get actual point count
vc.old_cnt = count;
vc.new_cnt = count+1; // Resize point count from count to count+1
 
// Just for adding a point at the end of the point list a map is not needed
 
// Send the message to all tags and keys and let them return a boolean, telling us if everything is alright
if (op->Message(MSG_POINTS_CHANGED, &vc))
{
  // Now all tags and structures have reacted and resized their memory part, so the new point can be accessed
  Vector* points = op->GetPointW();
  if (points)
    points[count] = Vector(0, 0, 0); // Set data for the new point
 
  op->Message(MSG_UPDATE); // Notify change to the object
  EventAdd();
}

Example: Inserting a point in a point object.

VariableChanged vc;
 
Int32 count = op->GetPointCount(); // Get actual point count
vc.old_cnt = count;
vc.new_cnt = count+1; // Resize point count from count to count+1
 
// Allocate a map
vc.map = NewMemClear(Int32, count);
if (vc.map != nullptr)
{
  Int32 i, pos = 5; // pos is the index to insert the point at
 
  // The points below pos stay at the same point number
  for (i = 0; i <= pos; i++)
    vc.map[i] = i;
 
  // The points above pos are shifted 1 step
  for (i = pos+1; i < count; i++)
    vc.map[i] = i+1;
 
  // Send the message to all tags and keys and let them return a boolean, telling us if everything is alright
  if (op->Message(MSG_POINTS_CHANGED, &vc))
  {
    // Now all tags and structures have reacted and resized their memory part, so the new point can be accessed
    Vector* points= op->GetPointW();
    if (points)
      points[pos] = Vector(0, 0, 0); // Set data for the new point
 
    op->Message(MSG_UPDATE); // Notify change to the object
    EventAdd();
  }
 
  DeleteMem(vc.map);
}

Public Member Functions
	VariableChanged ()

Public Attributes
Int32	old_cnt
Int32	new_cnt
Int32 *	map
Int32	vc_flags

Constructor & Destructor Documentation

VariableChanged()

VariableChanged

(

)

Default constructor.

Member Data Documentation

old_cnt

Int32 old_cnt

The number of elements before the change.

new_cnt

Int32 new_cnt

The new number of elements.

map

Int32 * map

The optional translation map.

Note

A map element can be NOTOK.

vc_flags

Int32 vc_flags

Flags: VC_FLAGS