Add argument to DM_to_mesh() function to take ownership over the DM

The idea is pretty simple: instead of making temporary copy of all the
related custom data layers just pass the ownership from the DM to the
mesh.

This is really handy in cases when you've got DM which you need to
convert to Mesh datablock and wouldn't need that DM after conversion
anyway.

Foe example, render database conversion, exporters and even Modifier
Apply will benefit from this option.

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D1127

1 files changed, 42 insertions, 13 deletions

diff --git a/source/blender/blenkernel/intern/DerivedMesh.c b/source/blender/blenkernel/intern/DerivedMesh.c
index 870b020c8de..0bfa3628967 100644
--- a/source/blender/blenkernel/intern/DerivedMesh.c
+++ b/source/blender/blenkernel/intern/DerivedMesh.c
@@ -531,13 +531,26 @@ MTFace *DM_paint_uvlayer_active_get(DerivedMesh *dm, int mat_nr)
 	return tf_base;
 }
 
-void DM_to_mesh(DerivedMesh *dm, Mesh *me, Object *ob, CustomDataMask mask)
+void DM_to_mesh(DerivedMesh *dm, Mesh *me, Object *ob, CustomDataMask mask, bool take_ownership)
 {
 	/* dm might depend on me, so we need to do everything with a local copy */
 	Mesh tmp = *me;
 	int totvert, totedge /*, totface */ /* UNUSED */, totloop, totpoly;
 	int did_shapekeys = 0;
-	
+	int alloctype = CD_DUPLICATE;
+
+	if (take_ownership && dm->type == DM_TYPE_CDDM && dm->needsFree) {
+		bool has_any_referenced_layers =
+		        CustomData_has_referenced(&dm->vertData) ||
+		        CustomData_has_referenced(&dm->edgeData) ||
+		        CustomData_has_referenced(&dm->loopData) ||
+		        CustomData_has_referenced(&dm->faceData) ||
+		        CustomData_has_referenced(&dm->polyData);
+		if (!has_any_referenced_layers) {
+			alloctype = CD_ASSIGN;
+		}
+	}
+
 	CustomData_reset(&tmp.vdata);
 	CustomData_reset(&tmp.edata);
 	CustomData_reset(&tmp.fdata);
@@ -552,10 +565,10 @@ void DM_to_mesh(DerivedMesh *dm, Mesh *me, Object *ob, CustomDataMask mask)
 	totpoly = tmp.totpoly = dm->getNumPolys(dm);
 	tmp.totface = 0;
 
-	CustomData_copy(&dm->vertData, &tmp.vdata, mask, CD_DUPLICATE, totvert);
-	CustomData_copy(&dm->edgeData, &tmp.edata, mask, CD_DUPLICATE, totedge);
-	CustomData_copy(&dm->loopData, &tmp.ldata, mask, CD_DUPLICATE, totloop);
-	CustomData_copy(&dm->polyData, &tmp.pdata, mask, CD_DUPLICATE, totpoly);
+	CustomData_copy(&dm->vertData, &tmp.vdata, mask, alloctype, totvert);
+	CustomData_copy(&dm->edgeData, &tmp.edata, mask, alloctype, totedge);
+	CustomData_copy(&dm->loopData, &tmp.ldata, mask, alloctype, totloop);
+	CustomData_copy(&dm->polyData, &tmp.pdata, mask, alloctype, totpoly);
 	tmp.cd_flag = dm->cd_flag;
 
 	if (CustomData_has_layer(&dm->vertData, CD_SHAPEKEY)) {
@@ -590,13 +603,19 @@ void DM_to_mesh(DerivedMesh *dm, Mesh *me, Object *ob, CustomDataMask mask)
 	
 	/* not all DerivedMeshes store their verts/edges/faces in CustomData, so
 	 * we set them here in case they are missing */
-	if (!CustomData_has_layer(&tmp.vdata, CD_MVERT))
-		CustomData_add_layer(&tmp.vdata, CD_MVERT, CD_ASSIGN, dm->dupVertArray(dm), totvert);
-	if (!CustomData_has_layer(&tmp.edata, CD_MEDGE))
-		CustomData_add_layer(&tmp.edata, CD_MEDGE, CD_ASSIGN, dm->dupEdgeArray(dm), totedge);
+	if (!CustomData_has_layer(&tmp.vdata, CD_MVERT)) {
+		CustomData_add_layer(&tmp.vdata, CD_MVERT, CD_ASSIGN,
+		                     (alloctype == CD_ASSIGN) ? dm->getVertArray(dm) : dm->dupVertArray(dm),
+		                     totvert);
+	}
+	if (!CustomData_has_layer(&tmp.edata, CD_MEDGE)) {
+		CustomData_add_layer(&tmp.edata, CD_MEDGE, CD_ASSIGN,
+		                     (alloctype == CD_ASSIGN) ? dm->getEdgeArray(dm) : dm->dupEdgeArray(dm),
+		                     totedge);
+	}
 	if (!CustomData_has_layer(&tmp.pdata, CD_MPOLY)) {
-		tmp.mloop = dm->dupLoopArray(dm);
-		tmp.mpoly = dm->dupPolyArray(dm);
+		tmp.mloop = (alloctype == CD_ASSIGN) ? dm->getLoopArray(dm) : dm->dupLoopArray(dm);
+		tmp.mpoly = (alloctype == CD_ASSIGN) ? dm->getPolyArray(dm) : dm->dupPolyArray(dm);
 
 		CustomData_add_layer(&tmp.ldata, CD_MLOOP, CD_ASSIGN, tmp.mloop, tmp.totloop);
 		CustomData_add_layer(&tmp.pdata, CD_MPOLY, CD_ASSIGN, tmp.mpoly, tmp.totpoly);
@@ -607,7 +626,7 @@ void DM_to_mesh(DerivedMesh *dm, Mesh *me, Object *ob, CustomDataMask mask)
 	if (CustomData_has_layer(&me->ldata, CD_MDISPS)) {
 		if (totloop == me->totloop) {
 			MDisps *mdisps = CustomData_get_layer(&me->ldata, CD_MDISPS);
-			CustomData_add_layer(&tmp.ldata, CD_MDISPS, CD_DUPLICATE, mdisps, totloop);
+			CustomData_add_layer(&tmp.ldata, CD_MDISPS, alloctype, mdisps, totloop);
 		}
 	}
 
@@ -641,6 +660,16 @@ void DM_to_mesh(DerivedMesh *dm, Mesh *me, Object *ob, CustomDataMask mask)
 
 	/* skip the listbase */
 	MEMCPY_STRUCT_OFS(me, &tmp, id.prev);
+
+	if (take_ownership) {
+		if (alloctype == CD_ASSIGN) {
+			CustomData_free_typemask(&dm->vertData, dm->numVertData, ~mask);
+			CustomData_free_typemask(&dm->edgeData, dm->numEdgeData, ~mask);
+			CustomData_free_typemask(&dm->loopData, dm->numLoopData, ~mask);
+			CustomData_free_typemask(&dm->polyData, dm->numPolyData, ~mask);
+		}
+		dm->release(dm);
+	}
 }
 
 void DM_to_meshkey(DerivedMesh *dm, Mesh *me, KeyBlock *kb)