Multires: Prepare for cached topology

Note that the actual caching is still disabled, since
more tests is needed with more production-looking files.

1 files changed, 28 insertions, 7 deletions

diff --git a/source/blender/modifiers/intern/MOD_multires.c b/source/blender/modifiers/intern/MOD_multires.c
index fc8a376d2d7..9775a536e99 100644
--- a/source/blender/modifiers/intern/MOD_multires.c
+++ b/source/blender/modifiers/intern/MOD_multires.c
@@ -67,6 +67,28 @@ static void initData(ModifierData *md)
 	mmd->quality = 3;
 }
 
+static void freeData(ModifierData *md)
+{
+	MultiresModifierData *mmd = (MultiresModifierData *) md;
+	if (mmd->subdiv != NULL) {
+		BKE_subdiv_free(mmd->subdiv);
+	}
+}
+
+/* Main goal of this function is to give usable subdivision surface descriptor
+ * which matches settings and topology. */
+static Subdiv *subdiv_descriptor_ensure(MultiresModifierData *mmd,
+                                        const SubdivSettings *subdiv_settings,
+                                        const Mesh *mesh)
+{
+	Subdiv *subdiv = BKE_subdiv_update_from_mesh(
+	        mmd->subdiv, subdiv_settings, mesh);
+	if (false) {
+		mmd->subdiv = subdiv;
+	}
+	return subdiv;
+}
+
 /* Subdivide into fully qualified mesh. */
 
 static Mesh *multires_as_mesh(MultiresModifierData *mmd,
@@ -137,16 +159,14 @@ static Mesh *applyModifier(ModifierData *md,
 	if (subdiv_settings.level == 0) {
 		return result;
 	}
-	/* TODO(sergey): Try to re-use subdiv when possible. */
-	Subdiv *subdiv = BKE_subdiv_new_from_mesh(&subdiv_settings, mesh);
+	Subdiv *subdiv = subdiv_descriptor_ensure(mmd, &subdiv_settings, mesh);
 	if (subdiv == NULL) {
 		/* Happens on bad topology, ut also on empty input mesh. */
 		return result;
 	}
 	/* NOTE: Orco needs final coordinates on CPU side, which are expected to be
 	 * accessible via MVert. For this reason we do not evaluate multires to
-	 * grids when orco is requested.
-	 */
+	 * grids when orco is requested. */
 	const bool for_orco = (ctx->flag & MOD_APPLY_ORCO) != 0;
 	if ((ctx->object->mode & OB_MODE_SCULPT) && !for_orco) {
 		/* NOTE: CCG takes ownership over Subdiv. */
@@ -156,9 +176,10 @@ static Mesh *applyModifier(ModifierData *md,
 	}
 	else {
 		result = multires_as_mesh(mmd, ctx, mesh, subdiv);
-		/* TODO(sergey): Cache subdiv somehow. */
 		// BKE_subdiv_stats_print(&subdiv->stats);
-		BKE_subdiv_free(subdiv);
+		if (subdiv != mmd->subdiv) {
+			BKE_subdiv_free(subdiv);
+		}
 	}
 	return result;
 }
@@ -188,7 +209,7 @@ ModifierTypeInfo modifierType_Multires = {
 
 	/* initData */          initData,
 	/* requiredDataMask */  NULL,
-	/* freeData */          NULL,
+	/* freeData */          freeData,
 	/* isDisabled */        NULL,
 	/* updateDepsgraph */   NULL,
 	/* dependsOnTime */     NULL,