Sculpt/Paint: Move Elastic Deform Kelvinlets to BKE

After this commit it should be possible to share the same deformation
formulas that are used in the Elastic Deform brush with other areas of
Blender such as Grease Pencil or proportional editing.

This also removes a lot of code from sculpt.c that is not direclty
related to sculpting.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D6281

1 files changed, 77 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_kelvinlet.h b/source/blender/blenkernel/BKE_kelvinlet.h
new file mode 100644
index 00000000000..fbf7d3ede1f
--- /dev/null
+++ b/source/blender/blenkernel/BKE_kelvinlet.h
@@ -0,0 +1,77 @@
+/*
+ * 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) Blender Foundation.
+ * All rights reserved.
+ */
+#ifndef __BKE_KELVINLET_H__
+#define __BKE_KELVINLET_H__
+
+/** \file
+ * \ingroup bke
+ */
+
+#include "BLI_math.h"
+
+/* Regularized Kelvinlets: Sculpting Brushes based on Fundamental Solutions of Elasticity
+ * Pixar Technical Memo #17-03 */
+
+#define KELVINLET_MAX_ITERATIONS 3
+
+typedef struct KelvinletParams {
+  float a;
+  float b;
+  float c;
+
+  float f;
+
+  float radius_scaled[KELVINLET_MAX_ITERATIONS];
+} KelvinletParams;
+
+/* Initialize KelvinletParams to store the parameters that will affect the deformation produced by
+ * a Kelvinlet */
+void BKE_kelvinlet_init_params(
+    KelvinletParams *params, float radius, float force, float shear_modulus, float poisson_ratio);
+
+/* Regularized Kelvinlets */
+/* All these functions output the displacement that should be applied to each element. */
+/* The initial coordinates of that element should not be modified during the transformation */
+void BKE_kelvinlet_grab(float r_elem_disp[3],
+                        const KelvinletParams *params,
+                        const float elem_orig_co[3],
+                        const float brush_location[3],
+                        const float brush_delta[3]);
+void BKE_kelvinlet_grab_biscale(float r_elem_disp[3],
+                                const KelvinletParams *params,
+                                const float elem_orig_co[3],
+                                const float brush_location[3],
+                                const float brush_delta[3]);
+void BKE_kelvinlet_grab_triscale(float r_elem_disp[3],
+                                 const KelvinletParams *params,
+                                 const float elem_orig_co[3],
+                                 const float brush_location[3],
+                                 const float brush_delta[3]);
+void BKE_kelvinlet_scale(float r_elem_disp[3],
+                         const KelvinletParams *params,
+                         const float elem_orig_co[3],
+                         const float brush_location[3],
+                         const float surface_normal[3]);
+void BKE_kelvinlet_twist(float r_elem_disp[3],
+                         const KelvinletParams *params,
+                         const float elem_orig_co[3],
+                         const float brush_location[3],
+                         const float surface_normal[3]);
+
+#endif