[#19258] [patch] Adding drawing capabilities to BGE Python

patch from Mitchell Stokes (moguri)

simple use case
 scene.post_draw = [pyOpenGLFunc]

this only needs to be set once, then the funcion runs each redraw.

note, this patch also changes how python scripts run (not modules): Dont clear the namespace after running a script, since functions still use the namespace, BGE API is now better when dealing with stale data.

made some changes to this patch.
- assigning a list didnt decrement the existing list.
- initialize as NULL rather then a blank list
- dont use string comparisons for the callbacks, pass the python list to use instead.
- dont check the list items are callable. python will display an error if they are not.
- use python list macros that dont do any type checking sine blender does this when assigning the list

---- from tracker, edited since an updated patch changes some things.
Here is a patch to be able to draw to the screen with BGE Python. This will be very handy for GUI stuff. This patch
works by having the user register a callback in the scene. Two options are available KX_Scene.pre_draw
and KX_Scene.post_draw. The difference between these is when Python draws to the screen (before or after the BGE).
Each can take a list of functions. Here is an example that draws a blue semi-transparent

1 files changed, 14 insertions, 1 deletions

diff --git a/source/gameengine/Ketsji/KX_Scene.h b/source/gameengine/Ketsji/KX_Scene.h
index 4b01ab39d95..602e919b58d 100644
--- a/source/gameengine/Ketsji/KX_Scene.h
+++ b/source/gameengine/Ketsji/KX_Scene.h
@@ -95,6 +95,8 @@ class KX_Scene : public PyObjectPlus, public SCA_IScene
 
 #ifndef DISABLE_PYTHON
 	PyObject*	m_attr_dict;
+	PyObject*	m_draw_call_pre;
+	PyObject*	m_draw_call_post;
 #endif
 
 	struct CullingInfo {
@@ -102,7 +104,6 @@ class KX_Scene : public PyObjectPlus, public SCA_IScene
 		CullingInfo(int layer) : m_layer(layer) {}
 	};
 
-
 protected:
 	RAS_BucketManager*	m_bucketmanager;
 	CListValue*			m_tempObjectList;
@@ -287,6 +288,12 @@ public:
 	void RenderBuckets(const MT_Transform& cameratransform,
 						RAS_IRasterizer* rasty,
 						RAS_IRenderTools* rendertools);
+
+	/**
+	 * Run the registered python drawing functions.
+	 */
+	void RunDrawingCallbacks(PyObject* cb_list);
+
 	/**
 	 * Update all transforms according to the scenegraph.
 	 */
@@ -544,6 +551,10 @@ public:
 	static PyObject*	pyattr_get_cameras(void* self_v, const KX_PYATTRIBUTE_DEF *attrdef);
 	static PyObject*	pyattr_get_active_camera(void* self_v, const KX_PYATTRIBUTE_DEF *attrdef);
 	static int			pyattr_set_active_camera(void *self_v, const KX_PYATTRIBUTE_DEF *attrdef, PyObject *value);
+	static PyObject*	pyattr_get_drawing_callback_pre(void *self_v, const KX_PYATTRIBUTE_DEF *attrdef);
+	static int			pyattr_set_drawing_callback_pre(void *selv_v, const KX_PYATTRIBUTE_DEF *attrdef, PyObject *value);
+	static PyObject*	pyattr_get_drawing_callback_post(void *self_v, const KX_PYATTRIBUTE_DEF *attrdef);
+	static int			pyattr_set_drawing_callback_post(void *selv_v, const KX_PYATTRIBUTE_DEF *attrdef, PyObject *value);
 
 	virtual PyObject* py_repr(void) { return PyUnicode_FromString(GetName().ReadPtr()); }
 	
@@ -551,6 +562,8 @@ public:
 	static PyMappingMethods	Mapping;
 	static PySequenceMethods	Sequence;
 
+	PyObject* GetPreDrawCB() { return m_draw_call_pre; };
+	PyObject* GetPostDrawCB() { return m_draw_call_post; };
 #endif
 
 	/**