Multires: Initial groundwork to hook up displacement to new Subdiv object

Adds a displacement support for OpenSubdiov based subsurf object implemented
as a callback which gives vector displacement in object space. Currently is
implemented to calculate displacement based on myltires displacement grids,
but we can support things in the future if needed.

Submitting to review to see if there is something obviously wrong in the
direction (old multires code was sharing same displacement code to both
calculate final displaced mesh and reshape an existing one, which is rather
confusing and probably can be done more cleanly?).

Reviewers: brecht

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D3604

1 files changed, 46 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/subdiv_displacement.c b/source/blender/blenkernel/intern/subdiv_displacement.c
new file mode 100644
index 00000000000..a6af6f45e59
--- /dev/null
+++ b/source/blender/blenkernel/intern/subdiv_displacement.c
@@ -0,0 +1,46 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2018 by Blender Foundation.
+ * All rights reserved.
+ *
+ * Contributor(s): Sergey Sharybin.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenkernel/intern/subdiv_displacement.c
+ *  \ingroup bke
+ */
+
+#include "BKE_subdiv.h"
+
+#include "BLI_utildefines.h"
+
+#include "MEM_guardedalloc.h"
+
+void BKE_subdiv_displacement_detach(Subdiv *subdiv)
+{
+	if (subdiv->displacement_evaluator == NULL) {
+		return;
+	}
+	if (subdiv->displacement_evaluator->free != NULL) {
+		subdiv->displacement_evaluator->free(subdiv->displacement_evaluator);
+	}
+	MEM_freeN(subdiv->displacement_evaluator);
+	subdiv->displacement_evaluator = NULL;
+}