UPBGE: Implement BVH generation from KX_Mesh. (#736)

The python function KX_Mesh.constructBvh now returns a new BVH Tree
based on the mesh geometry where every indices elements of the tree
correspond to the polygons indices.

Author: panzergame

doc/python_api/rst/bge_types/bge.types.KX_Mesh.rst

@@ -154,3 +154,10 @@ base class --- :class:`EXP_Value`
 
       :return: a duplicated mesh of the current used.
       :rtype: :class:`KX_Mesh`.
+
+   .. method:: constructBvh()
+
+      Return a BVH tree based on mesh geometry. Indices of tree elements match polygons indices.
+
+      :return: A BVH tree based on mesh geometry.
+      :rtype: :class:`mathutils.bvhtree.BVHTree`

source/blender/python/mathutils/mathutils_bvhtree.c

@@ -117,7 +117,7 @@ typedef struct {
 /** \name Utility helper functions
  * \{ */
 
-static PyObject *bvhtree_CreatePyObject(
+PyObject *bvhtree_CreatePyObject(
         BVHTree *tree, float epsilon,
 
         float (*coords)[3], unsigned int coords_len,

source/blender/python/mathutils/mathutils_bvhtree.h

@@ -26,11 +26,22 @@
 #ifndef __MATHUTILS_BVHTREE_H__
 #define __MATHUTILS_BVHTREE_H__
 
+typedef struct BVHTree BVHTree;
+
 PyMODINIT_FUNC PyInit_mathutils_bvhtree(void);
 
 extern PyTypeObject PyBVHTree_Type;
 
 #define PyBVHTree_Check(v)  PyObject_TypeCheck((v), &PyBVHTree_Type)
 #define PyBVHTree_CheckExact(v)  (Py_TYPE(v) == &PyBVHTree_Type)
 
+PyObject *bvhtree_CreatePyObject(
+	BVHTree *tree, float epsilon,
+	
+	float (*coords)[3], unsigned int coords_len,
+	unsigned int (*tris)[3], unsigned int tris_len,
+
+	/* optional arrays */
+	int *orig_index, float (*orig_normal)[3]);
+
 #endif /* __MATHUTILS_BVHTREE_H__ */

source/gameengine/Ketsji/KX_Mesh.cpp

@@ -53,6 +53,14 @@
 #include "EXP_PyObjectPlus.h"
 #include "EXP_ListWrapper.h"
 
+#include "BLI_kdopbvh.h"
+
+#include "MEM_guardedalloc.h"
+
+extern "C" {
+#  include "mathutils_bvhtree.h"
+}
+
 KX_Mesh::KX_Mesh(KX_Scene *scene, Mesh *mesh, const RAS_Mesh::LayersInfo& layersInfo)
 	:RAS_Mesh(mesh, layersInfo),
 	m_scene(scene)
@@ -108,6 +116,7 @@ PyMethodDef KX_Mesh::Methods[] = {
 	{"transformUV", (PyCFunction)KX_Mesh::sPyTransformUV, METH_VARARGS},
 	{"replaceMaterial", (PyCFunction)KX_Mesh::sPyReplaceMaterial, METH_VARARGS},
 	{"copy", (PyCFunction)KX_Mesh::sPyCopy, METH_NOARGS},
+	{"constructBvh", (PyCFunction)KX_Mesh::sPyConstructBvh, METH_VARARGS},
 	{nullptr, nullptr} //Sentinel
 };
 
@@ -392,6 +401,70 @@ PyObject *KX_Mesh::PyCopy()
 	return dupli->GetProxy();
 }
 
+PyObject *KX_Mesh::PyConstructBvh(PyObject *args, PyObject *kwds)
+{
+	float epsilon = 0.0f;
+
+	if (!PyArg_ParseTuple(args, "|f:constructBvh", &epsilon)) {
+		return nullptr;
+	}
+
+	BVHTree *tree = BLI_bvhtree_new(m_numPolygons, epsilon, 4, 6);
+
+	unsigned int numVert = 0;
+	// Compute the totale number of vertices.
+	for (const PolygonRangeInfo& range : m_polygonRanges) {
+		numVert += range.array->GetVertexCount();
+	}
+
+	float (*coords)[3] = (float (*)[3])MEM_mallocN(sizeof(float[3]) * numVert, __func__);
+	// Convert the vertices.
+	{
+		unsigned vertBase = 0;
+		for (const PolygonRangeInfo& range : m_polygonRanges) {
+			RAS_DisplayArray *array = range.array;
+			for (unsigned int i = 0, size = array->GetVertexCount(); i < size; ++i) {
+				copy_v3_v3(coords[vertBase + i], array->GetPosition(i).data);
+			}
+			vertBase += array->GetVertexCount();
+		}
+	}
+
+	unsigned int *tris = (unsigned int *)MEM_mallocN(sizeof(unsigned int) * 3 * m_numPolygons, __func__);
+	// Convert the indices.
+	{
+		unsigned int index = 0;
+		unsigned int vertBase = 0;
+		for (const PolygonRangeInfo& range : m_polygonRanges) {
+			// Iterate by triangle (3 indices).
+			for (; index < range.endIndex; index += 3) {
+				// Get the relative triangle base index.
+				const unsigned int triBase = index - range.startIndex;
+				float co[3][3];
+
+				for (unsigned short i = 0; i < 3; ++i) {
+					// Get the absolute the vertex index.
+					const unsigned int vertIndex = vertBase + range.array->GetTriangleIndex(triBase + i);
+
+					tris[index + i] = vertIndex;
+					copy_v3_v3(co[i], coords[vertIndex]);
+				}
+
+				BLI_bvhtree_insert(tree, index / 3, co[0], 3);
+			}
+			vertBase += range.array->GetVertexCount();
+		}
+	}
+
+	BLI_bvhtree_balance(tree);
+
+	return bvhtree_CreatePyObject(
+		tree, epsilon,
+		coords, numVert,
+		(unsigned int (*)[3])tris, m_numPolygons * 3,
+		nullptr, nullptr);
+}
+
 PyObject *KX_Mesh::pyattr_get_materials(EXP_PyObjectPlus *self_v, const EXP_PYATTRIBUTE_DEF *attrdef)
 {
 	KX_Mesh *self = static_cast<KX_Mesh *>(self_v);

source/gameengine/Ketsji/KX_Mesh.h

@@ -76,6 +76,7 @@ class KX_Mesh : public EXP_Value, public RAS_Mesh
 	EXP_PYMETHOD(KX_Mesh, TransformUV);
 	EXP_PYMETHOD(KX_Mesh, ReplaceMaterial);
 	EXP_PYMETHOD_NOARGS(KX_Mesh, Copy);
+	EXP_PYMETHOD(KX_Mesh, ConstructBvh);
 
 	static PyObject *pyattr_get_materials(EXP_PyObjectPlus *self_v, const EXP_PYATTRIBUTE_DEF *attrdef);
 	static PyObject *pyattr_get_numMaterials(EXP_PyObjectPlus *self_v, const EXP_PYATTRIBUTE_DEF *attrdef);