diff options
| -rw-r--r-- | src/voxel.cpp | 49 |
1 files changed, 42 insertions, 7 deletions
diff --git a/src/voxel.cpp b/src/voxel.cpp index 13711d1a1..e6d4bdcd2 100644 --- a/src/voxel.cpp +++ b/src/voxel.cpp @@ -224,13 +224,48 @@ void VoxelManipulator::addArea(const VoxelArea &area) void VoxelManipulator::copyFrom(MapNode *src, const VoxelArea& src_area, v3s16 from_pos, v3s16 to_pos, v3s16 size) { - for(s16 z=0; z<size.Z; z++) - for(s16 y=0; y<size.Y; y++) - { - s32 i_src = src_area.index(from_pos.X, from_pos.Y+y, from_pos.Z+z); - s32 i_local = m_area.index(to_pos.X, to_pos.Y+y, to_pos.Z+z); - memcpy(&m_data[i_local], &src[i_src], size.X*sizeof(MapNode)); - memset(&m_flags[i_local], 0, size.X); + /* The reason for this optimised code is that we're a member function + * and the data type/layout of m_data is know to us: it's stored as + * [z*h*w + y*h + x]. Therefore we can take the calls to m_area index + * (which performs the preceding mapping/indexing of m_data) out of the + * inner loop and calculate the next index as we're iterating to gain + * performance. + * + * src_step and dest_step is the amount required to be added to our index + * every time y increments. Because the destination area may be larger + * than the source area we need one additional variable (otherwise we could + * just continue adding dest_step as is done for the source data): dest_mod. + * dest_mod is the difference in size between a "row" in the source data + * and a "row" in the destination data (I am using the term row loosely + * and for illustrative purposes). E.g. + * + * src <-------------------->|'''''' dest mod '''''''' + * dest <---------------------------------------------> + * + * dest_mod (it's essentially a modulus) is added to the destination index + * after every full iteration of the y span. + * + * This method falls under the category "linear array and incrementing + * index". + */ + + s32 src_step = src_area.getExtent().X; + s32 dest_step = m_area.getExtent().X; + s32 dest_mod = m_area.index(to_pos.X, to_pos.Y, to_pos.Z + 1) + - m_area.index(to_pos.X, to_pos.Y, to_pos.Z) + - dest_step * size.Y; + + s32 i_src = src_area.index(from_pos.X, from_pos.Y, from_pos.Z); + s32 i_local = m_area.index(to_pos.X, to_pos.Y, to_pos.Z); + + for (s16 z = 0; z < size.Z; z++) { + for (s16 y = 0; y < size.Y; y++) { + memcpy(&m_data[i_local], &src[i_src], size.X * sizeof(*m_data)); + memset(&m_flags[i_local], 0, size.X); + i_src += src_step; + i_local += dest_step; + } + i_local += dest_mod; } } |