Merge with trunk/2.5 at r25563

Most likely will not compile for others, I'd appreciate any build errors
and missing files reports (I can never seem to get everything committed
and all the build systems working without help).

Porting over the sculpt/multires tools was a breeze,
thanks goes to brecht for a design that didn't exclude
ngons and was easy to port.

Note that I've not tested externally-backed multires
file support yet.  Also, I still need to write version
patch code for some cases.

Some notes:

* Like trunk, topological changes don't update multires right,
  so e.g. subdivide will duplicate multires data on the new faces,
  instead of subdividing it.
* If you set the debug value (ctrl-alt-d) to 1 it'll turn on
  my experiments in speeding up sculpting on higher-res multires
  meshes (but note it makes partial redraw not completely accurate).
* There's a bug where you have to go through editmode to get out
  of sculpt mode, not sure if I inherited or created this myself.

1 files changed, 14 insertions, 5 deletions

diff --git a/source/blender/makesdna/DNA_customdata_types.h b/source/blender/makesdna/DNA_customdata_types.h
index b4feb3c4d16..f227e82fb44 100644
--- a/source/blender/makesdna/DNA_customdata_types.h
+++ b/source/blender/makesdna/DNA_customdata_types.h
@@ -44,15 +44,20 @@ typedef struct CustomDataLayer {
 	void *data;     /* layer data */
 } CustomDataLayer;
 
+typedef struct CustomDataExternal {
+	char filename[240]; /* FILE_MAX */
+} CustomDataExternal;
+
 /* structure which stores custom element data associated with mesh elements
  * (vertices, edges or faces). The custom data is organised into a series of
  * layers, each with a data type (e.g. MTFace, MDeformVert, etc.). */
 typedef struct CustomData {
-	CustomDataLayer *layers;  /* CustomDataLayers, ordered by type */
-	int typemap[100];         /* maps types to indices of first layer of that type */
-	int totlayer, maxlayer;   /* number of layers, size of layers array */
-	int totsize, pad;         /* in editmode, total size of all data layers */
-	void *pool;		  /* for Bmesh: Memory pool for allocation of blocks*/
+	CustomDataLayer *layers;      /* CustomDataLayers, ordered by type */
+	int typemap[100];             /* maps types to indices of first layer of that type */
+	int totlayer, maxlayer;       /* number of layers, size of layers array */
+	int totsize, pad;             /* in editmode, total size of all data layers */
+	void *pool;                   /* Bmesh: Memory pool for allocation of blocks */
+	CustomDataExternal *external; /* external file storing customdata layers */
 } CustomData;
 
 /* CustomData.type */
@@ -126,6 +131,10 @@ typedef struct CustomData {
 #define CD_FLAG_NOFREE    (1<<1)
 /* indicates the layer is only temporary, also implies no copy */
 #define CD_FLAG_TEMPORARY ((1<<2)|CD_FLAG_NOCOPY)
+/* indicates the layer is stored in an external file */
+#define CD_FLAG_EXTERNAL  (1<<3)
+/* indicates external data is read into memory */
+#define CD_FLAG_IN_MEMORY (1<<4)
 
 /* Limits */
 #define MAX_MTFACE 8