VariableChanged Struct Reference | C4D R23.110 C++ SDK - 中文文档编制,帮助,手册,教程

VariableChanged Struct Reference

#include <c4d_baselist.h>

详细描述

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.

范例： 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 向量 * points = op->GetPointW(); if (points) points[count] = 向量 (0, 0, 0); // Set data for the new point op->Message( MSG_UPDATE ); // Notify change to the object EventAdd (); }

范例： 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 向量 * points= op->GetPointW(); if (points) points[pos] = 向量 (0, 0, 0); // Set data for the new point op->Message( MSG_UPDATE ); // Notify change to the object EventAdd (); } DeleteMem (vc. map ); }