Basic Alembic support

All in all, this patch adds an Alembic importer, an Alembic exporter,
and a new CacheFile data block which, for now, wraps around an Alembic
archive. This data block is made available through a new modifier ("Mesh
Sequence Cache") as well as a new constraint ("Transform Cache") to
somewhat properly support respectively geometric and transformation data
streaming from alembic caches.

A more in-depth documentation is to be found on the wiki, as well as a
 guide to compile alembic: https://wiki.blender.org/index.php/
User:Kevindietrich/AlembicBasicIo.

Many thanks to everyone involved in this little project, and huge shout
out to "cgstrive" for the thorough testings with Maya, 3ds Max, Houdini
and Realflow as well as @fjuhec, @jensverwiebe and @jasperge for the
custom builds and compile fixes.

Reviewers: sergey, campbellbarton, mont29

Reviewed By: sergey, campbellbarton, mont29

Differential Revision: https://developer.blender.org/D2060

source/blender/python/intern/bpy_app_alembic.c

@@ -0,0 +1,113 @@
+/*
+ * ***** 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) 2016 Blender Foundation.
+ * All rights reserved.
+ *
+ * The Original Code is: all of this file.
+ *
+ * Contributor(s): Kevin Dietrich
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/python/intern/bpy_app_alembic.c
+ *  \ingroup pythonintern
+ */
+
+#include <Python.h>
+#include "BLI_utildefines.h"
+
+#include "bpy_app_alembic.h"
+
+#ifdef WITH_ALEMBIC
+#  include "ABC_alembic.h"
+#endif
+
+static PyTypeObject BlenderAppABCType;
+
+static PyStructSequence_Field app_alembic_info_fields[] = {
+	{(char *)"supported", (char *)"Boolean, True when Blender is built with Alembic support"},
+	{(char *)"version", (char *)"The Alembic version as a tuple of 3 numbers"},
+	{(char *)"version_string", (char *)"The Alembic version formatted as a string"},
+	{NULL}
+};
+
+static PyStructSequence_Desc app_alembic_info_desc = {
+	(char *)"bpy.app.alembic",     /* name */
+	(char *)"This module contains information about Alembic blender is linked against",  /* doc */
+	app_alembic_info_fields,    /* fields */
+	ARRAY_SIZE(app_alembic_info_fields) - 1
+};
+
+static PyObject *make_alembic_info(void)
+{
+	PyObject *alembic_info = PyStructSequence_New(&BlenderAppABCType);
+
+	if (alembic_info == NULL) {
+		return NULL;
+	}
+
+	int pos = 0;
+
+#ifndef WITH_ALEMBIC
+#	define SetStrItem(str) \
+	PyStructSequence_SET_ITEM(alembic_info, pos++, PyUnicode_FromString(str))
+#endif
+
+#define SetObjItem(obj) \
+	PyStructSequence_SET_ITEM(alembic_info, pos++, obj)
+
+#ifdef WITH_ALEMBIC
+	const int curversion = ABC_get_version();
+	const int major = curversion / 10000;
+	const int minor = (curversion / 100) - (major * 100);
+	const int patch = curversion - ((curversion / 100 ) * 100);
+
+	SetObjItem(PyBool_FromLong(1));
+	SetObjItem(Py_BuildValue("(iii)", major, minor, patch));
+	SetObjItem(PyUnicode_FromFormat("%2d, %2d, %2d", major, minor, patch));
+#else
+	SetObjItem(PyBool_FromLong(0));
+	SetObjItem(Py_BuildValue("(iii)", 0, 0, 0));
+	SetStrItem("Unknown");
+#endif
+
+	if (PyErr_Occurred()) {
+		Py_CLEAR(alembic_info);
+		return NULL;
+	}
+
+#undef SetStrItem
+#undef SetObjItem
+
+	return alembic_info;
+}
+
+PyObject *BPY_app_alembic_struct(void)
+{
+	PyStructSequence_InitType(&BlenderAppABCType, &app_alembic_info_desc);
+
+	PyObject *ret = make_alembic_info();
+
+	/* prevent user from creating new instances */
+	BlenderAppABCType.tp_init = NULL;
+	BlenderAppABCType.tp_new = NULL;
+	BlenderAppABCType.tp_hash = (hashfunc)_Py_HashPointer; /* without this we can't do set(sys.modules) [#29635] */
+
+	return ret;
+}