diff options
Diffstat (limited to 'source/blender/blenkernel/intern/mesh_evaluate.c')
| -rw-r--r-- | source/blender/blenkernel/intern/mesh_evaluate.c | 90 |
1 files changed, 82 insertions, 8 deletions
diff --git a/source/blender/blenkernel/intern/mesh_evaluate.c b/source/blender/blenkernel/intern/mesh_evaluate.c index 37f4477febf..643ca3ee536 100644 --- a/source/blender/blenkernel/intern/mesh_evaluate.c +++ b/source/blender/blenkernel/intern/mesh_evaluate.c @@ -1629,8 +1629,8 @@ void BKE_mesh_normals_loop_custom_from_vertices_set( /** * Computes average per-vertex normals from given custom loop normals. * - * @param clnors The computed custom loop normals. - * @param r_vert_clnors The (already allocated) array where to store averaged per-vertex normals. + * \param clnors: The computed custom loop normals. + * \param r_vert_clnors: The (already allocated) array where to store averaged per-vertex normals. */ void BKE_mesh_normals_loop_to_vertex( const int numVerts, const MLoop *mloops, const int numLoops, @@ -2002,11 +2002,14 @@ float BKE_mesh_calc_poly_area( * - http://forums.cgsociety.org/archive/index.php?t-756235.html * - http://www.globalspec.com/reference/52702/203279/4-8-the-centroid-of-a-tetrahedron * - * \note volume is 6x actual volume, and centroid is 4x actual volume-weighted centroid - * (so division can be done once at the end) - * \note results will have bias if polygon is non-planar. + * \note + * - Volume is 6x actual volume, and centroid is 4x actual volume-weighted centroid + * (so division can be done once at the end). + * - Results will have bias if polygon is non-planar. + * - The resulting volume will only be correct if the mesh is manifold and has consistent face winding + * (non-contiguous face normals or holes in the mesh surface). */ -static float mesh_calc_poly_volume_and_weighted_centroid( +static float mesh_calc_poly_volume_centroid( const MPoly *mpoly, const MLoop *loopstart, const MVert *mvarray, float r_cent[3]) { @@ -2043,6 +2046,43 @@ static float mesh_calc_poly_volume_and_weighted_centroid( return total_volume; } +/** + * \note + * - Results won't be correct if polygon is non-planar. + * - This has the advantage over #mesh_calc_poly_volume_centroid + * that it doesn't depend on solid geometry, instead it weights the surface by volume. + */ +static float mesh_calc_poly_area_centroid( + const MPoly *mpoly, const MLoop *loopstart, const MVert *mvarray, + float r_cent[3]) +{ + int i; + float tri_area; + float total_area = 0.0f; + float v1[3], v2[3], v3[3], normal[3], tri_cent[3]; + + BKE_mesh_calc_poly_normal(mpoly, loopstart, mvarray, normal); + copy_v3_v3(v1, mvarray[loopstart[0].v].co); + copy_v3_v3(v2, mvarray[loopstart[1].v].co); + zero_v3(r_cent); + + for (i = 2; i < mpoly->totloop; i++) { + copy_v3_v3(v3, mvarray[loopstart[i].v].co); + + tri_area = area_tri_signed_v3(v1, v2, v3, normal); + total_area += tri_area; + + mid_v3_v3v3v3(tri_cent, v1, v2, v3); + madd_v3_v3fl(r_cent, tri_cent, tri_area); + + copy_v3_v3(v2, v3); + } + + mul_v3_fl(r_cent, 1.0f / total_area); + + return total_area; +} + #if 0 /* slow version of the function below */ void BKE_mesh_calc_poly_angles(MPoly *mpoly, MLoop *loopstart, MVert *mvarray, float angles[]) @@ -2157,7 +2197,40 @@ bool BKE_mesh_center_bounds(const Mesh *me, float r_cent[3]) return false; } -bool BKE_mesh_center_centroid(const Mesh *me, float r_cent[3]) +bool BKE_mesh_center_of_surface(const Mesh *me, float r_cent[3]) +{ + int i = me->totpoly; + MPoly *mpoly; + float poly_area; + float total_area = 0.0f; + float poly_cent[3]; + + zero_v3(r_cent); + + /* calculate a weighted average of polygon centroids */ + for (mpoly = me->mpoly; i--; mpoly++) { + poly_area = mesh_calc_poly_area_centroid(mpoly, me->mloop + mpoly->loopstart, me->mvert, poly_cent); + + madd_v3_v3fl(r_cent, poly_cent, poly_area); + total_area += poly_area; + } + /* otherwise we get NAN for 0 polys */ + if (me->totpoly) { + mul_v3_fl(r_cent, 1.0f / total_area); + } + + /* zero area faces cause this, fallback to median */ + if (UNLIKELY(!is_finite_v3(r_cent))) { + return BKE_mesh_center_median(me, r_cent); + } + + return (me->totpoly != 0); +} + +/** + * \note Mesh must be manifold with consistent face-winding, see #mesh_calc_poly_volume_centroid for details. + */ +bool BKE_mesh_center_of_volume(const Mesh *me, float r_cent[3]) { int i = me->totpoly; MPoly *mpoly; @@ -2169,7 +2242,7 @@ bool BKE_mesh_center_centroid(const Mesh *me, float r_cent[3]) /* calculate a weighted average of polyhedron centroids */ for (mpoly = me->mpoly; i--; mpoly++) { - poly_volume = mesh_calc_poly_volume_and_weighted_centroid(mpoly, me->mloop + mpoly->loopstart, me->mvert, poly_cent); + poly_volume = mesh_calc_poly_volume_centroid(mpoly, me->mloop + mpoly->loopstart, me->mvert, poly_cent); /* poly_cent is already volume-weighted, so no need to multiply by the volume */ add_v3_v3(r_cent, poly_cent); @@ -2189,6 +2262,7 @@ bool BKE_mesh_center_centroid(const Mesh *me, float r_cent[3]) return (me->totpoly != 0); } + /** \} */ |