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Add support for interfaces in scripting API (cross language support C++/C#/VS)

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This commit is contained in:
Wojtek Figat
2021-10-04 12:22:28 +02:00
parent 147e5ada46
commit c3c0a4ef0d
16 changed files with 1039 additions and 355 deletions
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47
Source/Engine/Content/Assets/VisualScript.cpp
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@@ -1263,8 +1263,7 @@ Asset::LoadResult VisualScript::load()
if (visualScriptType.Script.ScriptVTable)
{
// Override object vtable with hacked one that has Visual Script functions calls
ASSERT(visualScriptType.Script.VTable);
*(void**)object = visualScriptType.Script.VTable;
visualScriptType.HackObjectVTable(object, visualScriptType.BaseTypeHandle, 1);
}
}
const int32 oldCount = _oldParamsLayout.Count();
@@ -1407,17 +1406,7 @@ void VisualScript::CacheScriptingType()
type.ManagedClass = baseType.GetType().ManagedClass;
// Create custom vtable for this class (build out of the wrapper C++ methods that call Visual Script graph)
// Call setup for all class starting from the first native type (first that uses virtual calls will allocate table of a proper size, further base types will just add own methods)
for (ScriptingTypeHandle e = nativeType; e;)
{
const ScriptingType& eType = e.GetType();
if (eType.Script.SetupScriptVTable)
{
ASSERT(eType.ManagedClass);
eType.Script.SetupScriptVTable(eType.ManagedClass, type.Script.ScriptVTable, type.Script.ScriptVTableBase);
}
e = eType.GetBaseType();
}
type.SetupScriptVTable(nativeType);
MMethod** scriptVTable = (MMethod**)type.Script.ScriptVTable;
while (scriptVTable && *scriptVTable)
{
@@ -1484,37 +1473,7 @@ ScriptingObject* VisualScriptingBinaryModule::VisualScriptObjectSpawn(const Scri
}
// Beware! Hacking vtables incoming! Undefined behaviors exploits! Low-level programming!
// What's happening here?
// We create a custom vtable for the Visual Script objects that use a native class object with virtual functions overrides.
// To make it easy to use in C++ we inject custom wrapper methods into C++ object vtable to execute Visual Script graph from them.
// Because virtual member functions calls are C++ ABI and impl-defined this is quite hard. But works.
if (visualScriptType.Script.ScriptVTable)
{
if (!visualScriptType.Script.VTable)
{
// Duplicate vtable
void** vtable = *(void***)object;
const int32 prefixSize = GetVTablePrefix();
int32 entriesCount = 0;
while (vtable[entriesCount] && entriesCount < 200)
entriesCount++;
const int32 size = entriesCount * sizeof(void*);
visualScriptType.Script.VTable = (void**)((byte*)Platform::Allocate(prefixSize + size, 16) + prefixSize);
Platform::MemoryCopy((byte*)visualScriptType.Script.VTable - prefixSize, (byte*)vtable - prefixSize, prefixSize + size);
// Override vtable entries by the class
for (ScriptingTypeHandle e = baseTypeHandle; e;)
{
const ScriptingType& eType = e.GetType();
if (eType.Script.SetupScriptObjectVTable)
eType.Script.SetupScriptObjectVTable(visualScriptType.Script.ScriptVTable, visualScriptType.Script.ScriptVTableBase, visualScriptType.Script.VTable, entriesCount, 1);
e = eType.GetBaseType();
}
}
// Override object vtable with hacked one that has Visual Script functions calls
*(void**)object = visualScriptType.Script.VTable;
}
visualScriptType.HackObjectVTable(object, baseTypeHandle, 1);
// Mark as custom scripting type
object->Flags |= ObjectFlags::IsCustomScriptingType;