BGE Python API

This changes how the BGE classes and Python work together, which hasnt changed since blender went opensource.
The main difference is PyObjectPlus - the base class for most game engine classes, no longer inherit from PyObject, and cannot be cast to a PyObject.

This has the advantage that the BGE does not have to keep 2 reference counts valid for C++ and Python.

Previously C++ classes would never be freed while python held a reference, however this reference could be problematic eg: a GameObject that isnt in a scene anymore should not be used by python, doing so could even crash blender in some cases.

Instead PyObjectPlus has a member "PyObject *m_proxy" which is lazily initialized when python needs it. m_proxy reference counts are managed by python, though it should never be freed while the C++ class exists since it holds a reference to avoid making and freeing it all the time.
When the C++ class is free'd it sets the m_proxy reference to NULL, If python accesses this variable it will raise a RuntimeError, (check the isValid attribute to see if its valid without raising an error).
- This replaces the m_zombie bool and IsZombie() tests added recently.

In python return values that used to be..
 return value->AddRef();
Are now
 return value->GetProxy();
or...
 return value->NewProxy(true); // true means python owns this C++ value which will be deleted when the PyObject is freed

1 files changed, 4 insertions, 6 deletions

diff --git a/source/gameengine/Ketsji/KX_MeshProxy.cpp b/source/gameengine/Ketsji/KX_MeshProxy.cpp
index 93d92480b3d..09e19933dd9 100644
--- a/source/gameengine/Ketsji/KX_MeshProxy.cpp
+++ b/source/gameengine/Ketsji/KX_MeshProxy.cpp
@@ -232,7 +232,7 @@ PyObject* KX_MeshProxy::PyGetVertex(PyObject* self,
 		RAS_TexVert* vertex = m_meshobj->GetVertex(matindex,vertexindex);
 		if (vertex)
 		{
-			vertexob = new KX_VertexProxy(this, vertex);
+			vertexob = (new KX_VertexProxy(this, vertex))->NewProxy(true);
 		}
 	}
 	else {
@@ -263,7 +263,7 @@ PyObject* KX_MeshProxy::PyGetPolygon(PyObject* self,
 	RAS_Polygon* polygon = m_meshobj->GetPolygon(polyindex);
 	if (polygon)
 	{
-		polyob = new KX_PolyProxy(m_meshobj, polygon);
+		polyob = (new KX_PolyProxy(m_meshobj, polygon))->NewProxy(true);
 	}
 	else {
 		PyErr_SetString(PyExc_AttributeError, "polygon is NULL, unknown reason");
@@ -297,13 +297,11 @@ PyObject* KX_MeshProxy::pyattr_get_materials(void *self_v, const KX_PYATTRIBUTE_
 		if(polymat->GetFlag() & RAS_BLENDERMAT) 	 
 		{ 	 
 			KX_BlenderMaterial *mat = static_cast<KX_BlenderMaterial*>(polymat); 	 
-			PyList_SET_ITEM(materials, i, mat);
-			Py_INCREF(mat);
+			PyList_SET_ITEM(materials, i, mat->GetProxy());
 		}
 		else { 	
 			KX_PolygonMaterial *mat = static_cast<KX_PolygonMaterial*>(polymat);
-			PyList_SET_ITEM(materials, i, mat);
-			Py_INCREF(mat);
+			PyList_SET_ITEM(materials, i, mat->GetProxy());
 		}
 	}	
 	return materials;