Animato - Drivers with Multiple Targets:

Drivers now support multiple targets which act as 'variables'. The targets have a short 'name' (see later), and reference some property (in much the same way as F-Curves do, using RNA-Paths) which acts as the 'value'. 

These named variables can then be used in a Python Expression which relates them to each other for more fine-grained control over the result of the driver. By using only the names of these variables in the expressions, we are able to define expressions/relationships in a much more readable way, as data access is separated from data use. This makes the underlying relationships easier to understand.

By default, if no Python Expression is given, the variables are simply averaged together, so old files won't break. :)

For example, check the following diagram (thanks Cessen/Nathan V from Peach team):
http://download.blender.org/ftp/incoming/250_drivers_mockup_cessen.png


TODO List:
* Depsgraph building for new driver relationships doesn't work yet. This needs to be recoded again, but this new system makes this much easier, since the targets are clearly defined (i.e. no need to parse py expressions to get list of objects)
* Graph Editor interface for editing these needs to be rewritten
* Python function for evaluating these expressions is needed (Campbell?)

1 files changed, 29 insertions, 20 deletions

diff --git a/source/blender/blenkernel/intern/ipo.c b/source/blender/blenkernel/intern/ipo.c
index b9417ccb467..48ffdca3a83 100644
--- a/source/blender/blenkernel/intern/ipo.c
+++ b/source/blender/blenkernel/intern/ipo.c
@@ -950,6 +950,7 @@ char *get_rna_access (int blocktype, int adrcode, char actname[], char constname
 static ChannelDriver *idriver_to_cdriver (IpoDriver *idriver)
 {
 	ChannelDriver *cdriver;
+	DriverTarget *dtar=NULL, *dtar2=NULL;
 	
 	/* allocate memory for new driver */
 	cdriver= MEM_callocN(sizeof(ChannelDriver), "ChannelDriver");
@@ -957,6 +958,7 @@ static ChannelDriver *idriver_to_cdriver (IpoDriver *idriver)
 	/* if 'pydriver', just copy data across */
 	if (idriver->type == IPO_DRIVER_TYPE_PYTHON) {
 		/* PyDriver only requires the expression to be copied */
+		// TODO: but the expression will be useless...
 		cdriver->type = DRIVER_TYPE_PYTHON;
 		strcpy(cdriver->expression, idriver->name); // XXX is this safe? 
 	}
@@ -965,12 +967,15 @@ static ChannelDriver *idriver_to_cdriver (IpoDriver *idriver)
 		if (idriver->blocktype == ID_AR) {
 			/* ID_PO */
 			if (idriver->adrcode == OB_ROT_DIFF) {
-				if (G.f & G_DEBUG) printf("idriver_to_cdriver - rotdiff %p \n", idriver->ob);
 				/* Rotational Difference is a special type of driver now... */
 				cdriver->type= DRIVER_TYPE_ROTDIFF;
 				
+				/* make 2 driver targets */
+				dtar= driver_add_new_target(cdriver);
+				dtar2= driver_add_new_target(cdriver);
+				
 				/* driver must use bones from same armature... */
-				cdriver->id= cdriver->id2= (ID *)idriver->ob;
+				dtar->id= dtar2->id= (ID *)idriver->ob;
 				
 				/* paths for the two targets get the pointers to the relevant Pose-Channels 
 				 *	- return pointers to Pose-Channels not rotation channels, as calculation code is picky
@@ -979,34 +984,36 @@ static ChannelDriver *idriver_to_cdriver (IpoDriver *idriver)
 				 *	- we use several hacks here - blocktype == -1 specifies that no property needs to be found, and
 				 *	  providing a name for 'actname' will automatically imply Pose-Channel with name 'actname'
 				 */
-				cdriver->rna_path= get_rna_access(-1, -1, idriver->name, NULL, NULL);
-				cdriver->rna_path2= get_rna_access(-1, -1, idriver->name+DRIVER_NAME_OFFS, NULL, NULL);
+				dtar->rna_path= get_rna_access(-1, -1, idriver->name, NULL, NULL);
+				dtar2->rna_path= get_rna_access(-1, -1, idriver->name+DRIVER_NAME_OFFS, NULL, NULL);
 			}
 			else {
-				if (G.f & G_DEBUG) printf("idriver_to_cdriver - arm  %p \n", idriver->ob);
 				/* 'standard' driver */
-				cdriver->type= DRIVER_TYPE_CHANNEL;
-				cdriver->id= (ID *)idriver->ob;
+				cdriver->type= DRIVER_TYPE_AVERAGE;
+				
+				/* make 1 driver target */
+				dtar= driver_add_new_target(cdriver);
+				dtar->id= (ID *)idriver->ob;
 				
 				switch (idriver->adrcode) {
 					case OB_LOC_X:	/* x,y,z location are quite straightforward */
-						cdriver->rna_path= get_rna_access(ID_PO, AC_LOC_X, idriver->name, NULL, &cdriver->array_index);
+						dtar->rna_path= get_rna_access(ID_PO, AC_LOC_X, idriver->name, NULL, &dtar->array_index);
 						break;
 					case OB_LOC_Y:
-						cdriver->rna_path= get_rna_access(ID_PO, AC_LOC_Y, idriver->name, NULL, &cdriver->array_index);
+						dtar->rna_path= get_rna_access(ID_PO, AC_LOC_Y, idriver->name, NULL, &dtar->array_index);
 						break;
 					case OB_LOC_Z:
-						cdriver->rna_path= get_rna_access(ID_PO, AC_LOC_Z, idriver->name, NULL, &cdriver->array_index);
+						dtar->rna_path= get_rna_access(ID_PO, AC_LOC_Z, idriver->name, NULL, &dtar->array_index);
 						break;
 						
 					case OB_SIZE_X:	/* x,y,z scaling are also quite straightforward */
-						cdriver->rna_path= get_rna_access(ID_PO, AC_SIZE_X, idriver->name, NULL, &cdriver->array_index);
+						dtar->rna_path= get_rna_access(ID_PO, AC_SIZE_X, idriver->name, NULL, &dtar->array_index);
 						break;
 					case OB_SIZE_Y:
-						cdriver->rna_path= get_rna_access(ID_PO, AC_SIZE_Y, idriver->name, NULL, &cdriver->array_index);
+						dtar->rna_path= get_rna_access(ID_PO, AC_SIZE_Y, idriver->name, NULL, &dtar->array_index);
 						break;
 					case OB_SIZE_Z:
-						cdriver->rna_path= get_rna_access(ID_PO, AC_SIZE_Z, idriver->name, NULL, &cdriver->array_index);
+						dtar->rna_path= get_rna_access(ID_PO, AC_SIZE_Z, idriver->name, NULL, &dtar->array_index);
 						break;	
 						
 					case OB_ROT_X:	/* rotation - we need to be careful with this... XXX (another reason why we need eulers) */	
@@ -1015,8 +1022,8 @@ static ChannelDriver *idriver_to_cdriver (IpoDriver *idriver)
 					{
 						// XXX this is not yet a 1:1 map, since we'd need euler rotations to make this work nicely (unless we make some hacks)
 						// XXX -1 here is a special hack...
-						cdriver->rna_path= get_rna_access(ID_PO, -1, idriver->name, NULL, NULL);
-						cdriver->array_index= idriver->adrcode - OB_ROT_X;
+						dtar->rna_path= get_rna_access(ID_PO, -1, idriver->name, NULL, NULL);
+						dtar->array_index= idriver->adrcode - OB_ROT_X;
 					}
 						break;
 				}
@@ -1024,14 +1031,16 @@ static ChannelDriver *idriver_to_cdriver (IpoDriver *idriver)
 		}
 		else {
 			/* ID_OB */
-			if (G.f & G_DEBUG) printf("idriver_to_cdriver  - ob %p \n", idriver->ob);
-			cdriver->type= DRIVER_TYPE_CHANNEL;
-			cdriver->id= (ID *)idriver->ob;
-			cdriver->rna_path= get_rna_access(ID_OB, idriver->adrcode, NULL, NULL, &cdriver->array_index);
+			cdriver->type= DRIVER_TYPE_AVERAGE;
+			
+			/* make 1 driver target */
+			dtar= driver_add_new_target(cdriver);
+			
+			dtar->id= (ID *)idriver->ob;
+			dtar->rna_path= get_rna_access(ID_OB, idriver->adrcode, NULL, NULL, &dtar->array_index);
 		}
 	}
 	
-	if (G.f & G_DEBUG) printf("\tcdriver -> id = %p \n", cdriver->id);
 	
 	/* free old driver */
 	MEM_freeN(idriver);