blitToVManip: Check out-of-bounds using node position not index (#8127)

Previously, when using 'place on vmanip' to add a schematic to a
lua voxelmanip, if part of the schematic was outside the voxelmanip
volume, the outside part would often appear in a strange place
elsewhere inside the voxelmanip instead of being trimmed off.
This was due to the out-of-bounds check checking the index.

A position outside the voxelmanip can have an index that satisfies
'0 <= index <= voxelmanip volume', causing the node to be placed
at a strange position inside the voxelmanip.

Use 'vm->m_area.contains(pos)' instead.
Move index calculation to later in the code to optimise.

diff --git a/src/mapgen/mg_schematic.cpp b/src/mapgen/mg_schematic.cpp
index ba619b2e00b965e86a4b3f2702c66bc596b5beb0..36f1dd76b3b6fe5aa63232aab3ac21c47d0b3d14 100644 (file)
--- a/src/mapgen/mg_schematic.cpp
+++ b/src/mapgen/mg_schematic.cpp
@@ -137,8 +137,8 @@ void Schematic::blitToVManip(MMVManip *vm, v3s16 p, Rotation rot, bool force_pla
                for (s16 z = 0; z != sz; z++) {
                        u32 i = z * i_step_z + y * ystride + i_start;
                        for (s16 x = 0; x != sx; x++, i += i_step_x) {
-                               u32 vi = vm->m_area.index(p.X + x, y_map, p.Z + z);
-                               if (!vm->m_area.contains(vi))
+                               v3s16 pos(p.X + x, y_map, p.Z + z);
+                               if (!vm->m_area.contains(pos))
                                        continue;
 
                                if (schemdata[i].getContent() == CONTENT_IGNORE)
@@ -150,6 +150,7 @@ void Schematic::blitToVManip(MMVManip *vm, v3s16 p, Rotation rot, bool force_pla
                                if (placement_prob == MTSCHEM_PROB_NEVER)
                                        continue;
 
+                               u32 vi = vm->m_area.index(pos);
                                if (!force_place && !force_place_node) {
                                        content_t c = vm->m_data[vi].getContent();
                                        if (c != CONTENT_AIR && c != CONTENT_IGNORE)