New python submodule `mathutils.interpolate` for various mesh interpolation and weighting methods.

This module will contain mirrored functions for calculating and applying
weights for points on a mesh. This includes barycentric and UV weighting
and possibly more advanced global weighting such as harmonic weights.

The naming should follow this scheme:
<type>_{2d,3d}_{calc,apply}

e.g.
poly_2d_calc
poly_2d_apply
uv_3d_calc
...

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D939

1 files changed, 137 insertions, 0 deletions

diff --git a/source/blender/python/mathutils/mathutils_interpolate.c b/source/blender/python/mathutils/mathutils_interpolate.c
new file mode 100644
index 00000000000..4d7841b906a
--- /dev/null
+++ b/source/blender/python/mathutils/mathutils_interpolate.c
@@ -0,0 +1,137 @@
+/*
+ * ***** 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.
+ *
+ * Contributor(s): Lukas Toenne
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/python/mathutils/mathutils_interpolate.c
+ *  \ingroup pymathutils
+ */
+
+
+#include <Python.h>
+
+#include "mathutils.h"
+#include "mathutils_interpolate.h"
+
+#include "BLI_math.h"
+#include "BLI_utildefines.h"
+
+#ifndef MATH_STANDALONE /* define when building outside blender */
+#  include "MEM_guardedalloc.h"
+#endif
+
+/*-------------------------DOC STRINGS ---------------------------*/
+PyDoc_STRVAR(M_Interpolate_doc,
+"The Blender interpolate module"
+);
+
+/* ---------------------------------WEIGHT CALCULATION ----------------------- */
+
+#ifndef MATH_STANDALONE
+
+PyDoc_STRVAR(M_Interpolate_poly_3d_calc_doc,
+".. function:: poly_3d_calc(veclist, pt)\n"
+"\n"
+"   Calculate barycentric weights for a point on a polygon.\n"
+"\n"
+"   :arg veclist: list of vectors\n"
+"   :arg pt: point"
+"   :rtype: list of per-vector weights\n"
+);
+static PyObject *M_Interpolate_poly_3d_calc(PyObject *UNUSED(self), PyObject *args)
+{
+	float fp[3];
+	float (*vecs)[3];
+	Py_ssize_t len;
+	
+	PyObject *point, *veclist, *ret;
+	int i;
+	
+	if (!PyArg_ParseTuple(args, "OO!:interpolation_weights",
+	                      &veclist,
+	                      &vector_Type, &point))
+	{
+		return NULL;
+	}
+	
+	if (BaseMath_ReadCallback((VectorObject *)point) == -1)
+		return NULL;
+	
+	fp[0] = ((VectorObject *)point)->vec[0];
+	fp[1] = ((VectorObject *)point)->vec[1];
+	if (((VectorObject *)point)->size > 2)
+		fp[2] = ((VectorObject *)point)->vec[2];
+	else
+		fp[2] = 0.0f;  /* if its a 2d vector then set the z to be zero */
+	
+	len = mathutils_array_parse_alloc_v(((float **)&vecs), 3, veclist, "interpolation_weights");
+	if (len == -1) {
+		return NULL;
+	}
+	
+	if (len) {
+		float *weights = MEM_mallocN(sizeof(float) * len, "interpolation weights");
+		
+		interp_weights_poly_v3(weights, vecs, len, fp);
+		
+		ret = PyList_New(len);
+		for (i = 0; i < len; i++) {
+			PyList_SET_ITEM(ret, i, PyFloat_FromDouble(weights[i]));
+		}
+
+		MEM_freeN(weights);
+
+		PyMem_Free(vecs);
+	}
+	else {
+		ret = PyList_New(0);
+	}
+
+	return ret;
+}
+
+#endif /* MATH_STANDALONE */
+
+
+static PyMethodDef M_Interpolate_methods[] = {
+#ifndef MATH_STANDALONE
+	{"poly_3d_calc", (PyCFunction) M_Interpolate_poly_3d_calc, METH_VARARGS, M_Interpolate_poly_3d_calc_doc},
+#endif
+	{NULL, NULL, 0, NULL}
+};
+
+static struct PyModuleDef M_Interpolate_module_def = {
+	PyModuleDef_HEAD_INIT,
+	"mathutils.interpolate",  /* m_name */
+	M_Interpolate_doc,  /* m_doc */
+	0,  /* m_size */
+	M_Interpolate_methods,  /* m_methods */
+	NULL,  /* m_reload */
+	NULL,  /* m_traverse */
+	NULL,  /* m_clear */
+	NULL,  /* m_free */
+};
+
+/*----------------------------MODULE INIT-------------------------*/
+PyMODINIT_FUNC PyInit_mathutils_interpolate(void)
+{
+	PyObject *submodule = PyModule_Create(&M_Interpolate_module_def);
+	return submodule;
+}