wip: continuous backbone floor profile for the cave planner (L134 design 4, untested)

Written by Luna before the Codex usage limit cut the round: one shared distance/floor profile across backbone rooms
and edges, edge cubic floors derived from it, sloped route-room floors, lower-floor backing cap at overlaps, and
validator checks for joint height/slope continuity. Not yet built or audited.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Standalone/Core/include/VoxelForgeCore/VoxelForgeCore.h

@@ -497,8 +497,9 @@ namespace VoxelForgeCore
     // Version 226 unifies the passage influence reach in metres and converts it to core
     // voxels for every broadphase and proof bound. Version 227 uses the exact smooth-max
     // support width/6 when deriving that reach. Version 228 composes deterministic cave
-    // graphs from fixed passage mouths and the owner Tunnel Network settings.
-    inline constexpr std::uint32_t WorldAssemblyEvaluatorVersion = 229;
+    // graphs from fixed passage mouths and the owner Tunnel Network settings. Version 229
+    // budgets cave floor support; 230 records a shared backbone floor profile and joint cap.
+    inline constexpr std::uint32_t WorldAssemblyEvaluatorVersion = 230;
 
     enum class FieldChannel : std::uint32_t
     {
@@ -893,6 +894,7 @@ namespace VoxelForgeCore
     inline constexpr std::uint32_t ResolvedLayoutStampVocabularyVersionV2 = 2;
     inline constexpr std::uint32_t ResolvedLayoutStampVocabularyVersionV3 = 3;
     inline constexpr std::uint32_t ResolvedLayoutCavernGraphVocabularyVersionV1 = 1;
+    inline constexpr std::uint32_t ResolvedLayoutCavernGraphVocabularyVersionV2 = 2;
     inline constexpr std::uint32_t ResolvedLayoutOreVeinVocabularyVersionV1 = 1;
     enum class ResolvedLayoutValidationModeV3 : std::uint8_t { compatibility, strict };
 
@@ -957,6 +959,11 @@ namespace VoxelForgeCore
         std::array<std::int64_t, 3> centerMicrometres{};
         std::array<std::int64_t, 3> halfExtentsMicrometres{};
         std::int64_t floorMicrometres = 0;
+        // Optional shared backbone profile reference. The room floor plane is
+        // floorMicrometres plus this Q16 XY gradient from centerMicrometres.
+        std::string floorProfileStableId;
+        std::int64_t floorProfileDistanceMicrometres = -1;
+        std::array<std::int32_t, 2> floorGradientQ16{};
         std::int64_t smoothWidthMicrometres = 0;
         // Optional feature-to-feature union width. Zero preserves the historical
         // behavior where smoothWidthMicrometres also controls the graph union.
@@ -976,6 +983,11 @@ namespace VoxelForgeCore
         std::int32_t strateIndex = -1;
         // A single cubic Bezier in XY. Its four Z values are the cubic floor profile.
         std::array<std::array<std::int64_t, 3>, 4> controlPointsMicrometres{};
+        // Edges with the same profile ID are adjacent pieces of one shared h(s).
+        // Distances are signed along that profile, so a terminal edge may be reversed.
+        std::string floorProfileStableId;
+        std::int64_t floorProfileStartDistanceMicrometres = -1;
+        std::int64_t floorProfileEndDistanceMicrometres = -1;
         // Resolve-time, error-bounded approximation of the cubic centerline. Each
         // consecutive pair is a physical segment used by the native cave field.
         std::vector<std::array<std::int64_t, 3>> polylineMicrometres;

Standalone/Core/src/ResolvedLayoutInternal.h

@@ -621,6 +621,10 @@ namespace
                     <<"],\"half_extents_um\":["<<room.halfExtentsMicrometres[0]<<','
                     <<room.halfExtentsMicrometres[1]<<','<<room.halfExtentsMicrometres[2]
                     <<"],\"floor_um\":"<<room.floorMicrometres
+                    <<",\"floor_profile_id\":"<<LayoutEscape(room.floorProfileStableId)
+                    <<",\"floor_profile_distance_um\":"<<room.floorProfileDistanceMicrometres
+                    <<",\"floor_gradient_q16\":["<<room.floorGradientQ16[0]<<','
+                    <<room.floorGradientQ16[1]<<']'
                     <<",\"smooth_width_um\":"<<room.smoothWidthMicrometres
                     ;
                 if(room.unionWidthMicrometres>0)
@@ -647,6 +651,11 @@ namespace
                     out<<'['<<p[0]<<','<<p[1]<<','<<p[2]<<']';
                 }
                 out<<']';
+                out<<",\"floor_profile_id\":"<<LayoutEscape(edge.floorProfileStableId)
+                    <<",\"floor_profile_start_distance_um\":"
+                    <<edge.floorProfileStartDistanceMicrometres
+                    <<",\"floor_profile_end_distance_um\":"
+                    <<edge.floorProfileEndDistanceMicrometres;
                 if(!edge.polylineMicrometres.empty())
                 {
                     out<<",\"polyline_um\":[";
@@ -1235,7 +1244,8 @@ bool ResolvedLayoutSnapshotV3::validate(ResolvedLayoutValidationModeV3 mode,
             add("cavern_graph_vocabulary_version",
                 "cavern graph vocabulary version is set without graph records");
     }
-    else if(cavernGraphVocabularyVersion!=ResolvedLayoutCavernGraphVocabularyVersionV1)
+    else if(cavernGraphVocabularyVersion!=ResolvedLayoutCavernGraphVocabularyVersionV1
+        &&cavernGraphVocabularyVersion!=ResolvedLayoutCavernGraphVocabularyVersionV2)
         add("cavern_graph_vocabulary_version",
             "cavern graph records require vocabulary version 1");
     if(cavernGraphVocabularyVersion!=0)
@@ -1268,6 +1278,16 @@ bool ResolvedLayoutSnapshotV3::validate(ResolvedLayoutValidationModeV3 mode,
                 ||(room.irregularityAmplitudeMicrometres>0
                     &&room.irregularityWavelengthMicrometres<=0))
                 add("cavern_room_parameters",room.stableId+" has invalid or unbounded parameters");
+            const std::int64_t gradientSquared=static_cast<std::int64_t>(room.floorGradientQ16[0])
+                *room.floorGradientQ16[0]+static_cast<std::int64_t>(room.floorGradientQ16[1])
+                *room.floorGradientQ16[1];
+            if((room.floorProfileStableId.empty()
+                    &&room.floorProfileDistanceMicrometres!=-1)
+                ||(!room.floorProfileStableId.empty()
+                    &&room.floorProfileDistanceMicrometres<0)
+                ||gradientSquared>static_cast<std::int64_t>(13108)*13108)
+                add("cavern_room_floor_profile",room.stableId+
+                    " has an invalid shared profile reference or floor grade");
             const std::int64_t pad=room.smoothWidthMicrometres
                 +room.unionWidthMicrometres+room.irregularityAmplitudeMicrometres;
             for(std::size_t axis=0;axis<3;++axis)
@@ -1308,6 +1328,15 @@ bool ResolvedLayoutSnapshotV3::validate(ResolvedLayoutValidationModeV3 mode,
                 ||(edge.irregularityAmplitudeMicrometres>0
                     &&edge.irregularityWavelengthMicrometres<=0))
                 add("cavern_edge_parameters",edge.stableId+" has invalid or unbounded parameters");
+            const bool hasFloorProfile=!edge.floorProfileStableId.empty();
+            if((hasFloorProfile&&(edge.floorProfileStartDistanceMicrometres<0
+                    ||edge.floorProfileEndDistanceMicrometres<0
+                    ||edge.floorProfileStartDistanceMicrometres
+                        ==edge.floorProfileEndDistanceMicrometres))
+                ||(!hasFloorProfile&&(edge.floorProfileStartDistanceMicrometres!=-1
+                    ||edge.floorProfileEndDistanceMicrometres!=-1)))
+                add("cavern_edge_floor_profile",edge.stableId+
+                    " has an invalid shared profile distance interval");
             std::array<std::int64_t,3> low=edge.controlPointsMicrometres[0];
             std::array<std::int64_t,3> high=low;
             if(nativeLattice&&!edge.polylineMicrometres.empty())
@@ -1363,6 +1392,114 @@ bool ResolvedLayoutSnapshotV3::validate(ResolvedLayoutValidationModeV3 mode,
                 add("cavern_edge_polyline",edge.stableId+
                     " has no bounded resolve-time polyline with matching endpoints");
         }
+        std::vector<std::string> floorProfileIds;
+        for(const auto& edge:cavernEdges)
+            if(!edge.floorProfileStableId.empty()
+                &&std::find(floorProfileIds.begin(),floorProfileIds.end(),
+                    edge.floorProfileStableId)==floorProfileIds.end())
+                floorProfileIds.push_back(edge.floorProfileStableId);
+        for(const std::string& profileId:floorProfileIds)
+        {
+            std::vector<const ResolvedCavernEdgeV1*> profileEdges;
+            for(const auto& edge:cavernEdges)
+                if(edge.floorProfileStableId==profileId)profileEdges.push_back(&edge);
+            std::sort(profileEdges.begin(),profileEdges.end(),[](const auto* a,const auto* b)
+            {
+                return std::min(a->floorProfileStartDistanceMicrometres,
+                    a->floorProfileEndDistanceMicrometres)
+                    <std::min(b->floorProfileStartDistanceMicrometres,
+                        b->floorProfileEndDistanceMicrometres);
+            });
+            const auto endpointZ=[](const ResolvedCavernEdgeV1& edge,bool atMinimum)
+            {
+                const bool forward=edge.floorProfileStartDistanceMicrometres
+                    <edge.floorProfileEndDistanceMicrometres;
+                const std::size_t point=(atMinimum==forward)?0:3;
+                return edge.controlPointsMicrometres[point][2];
+            };
+            const auto endpointSlope=[](const ResolvedCavernEdgeV1& edge,bool atMinimum)
+            {
+                const double span=static_cast<double>(edge.floorProfileEndDistanceMicrometres
+                    -edge.floorProfileStartDistanceMicrometres);
+                if(span==0.0)return std::numeric_limits<double>::infinity();
+                const bool forward=edge.floorProfileStartDistanceMicrometres
+                    <edge.floorProfileEndDistanceMicrometres;
+                const std::size_t control=atMinimum==forward?0:2;
+                return 3.0*(edge.controlPointsMicrometres[control+1][2]
+                    -edge.controlPointsMicrometres[control][2])/span;
+            };
+            const ResolvedCavernEdgeV1* previous=nullptr;
+            for(const auto* edge:profileEdges)
+            {
+                const std::int64_t low=std::min(edge->floorProfileStartDistanceMicrometres,
+                    edge->floorProfileEndDistanceMicrometres);
+                const std::int64_t high=std::max(edge->floorProfileStartDistanceMicrometres,
+                    edge->floorProfileEndDistanceMicrometres);
+                const double slope0=endpointSlope(*edge,true);
+                const double slope1=endpointSlope(*edge,false);
+                if(std::max(std::abs(slope0),std::abs(slope1))>0.200001)
+                    add("cavern_floor_profile_grade",edge->stableId+
+                        " exceeds the shared backbone 1:5 grade limit");
+                if(previous)
+                {
+                    const std::int64_t previousHigh=std::max(
+                        previous->floorProfileStartDistanceMicrometres,
+                        previous->floorProfileEndDistanceMicrometres);
+                    if(low!=previousHigh
+                        ||std::abs(endpointZ(*previous,false)-endpointZ(*edge,true))>1000
+                        ||std::abs(endpointSlope(*previous,false)-slope0)>0.000001)
+                        add("cavern_floor_profile_joint",profileId+
+                            " has a gap, height step, or slope step between adjacent edges");
+                }
+                previous=edge;
+                (void)high;
+            }
+            for(const auto& room:cavernRooms)
+            {
+                if(room.floorProfileStableId!=profileId)continue;
+                const ResolvedCavernEdgeV1* containing=nullptr;
+                for(const auto* edge:profileEdges)
+                {
+                    const auto low=std::min(edge->floorProfileStartDistanceMicrometres,
+                        edge->floorProfileEndDistanceMicrometres);
+                    const auto high=std::max(edge->floorProfileStartDistanceMicrometres,
+                        edge->floorProfileEndDistanceMicrometres);
+                    if(room.floorProfileDistanceMicrometres>=low
+                        &&room.floorProfileDistanceMicrometres<=high)
+                    {containing=edge;break;}
+                }
+                if(!containing)
+                {
+                    add("cavern_room_floor_profile",room.stableId+
+                        " does not lie on its referenced continuous floor profile");
+                    continue;
+                }
+                const auto& edge=*containing;
+                const double t=static_cast<double>(room.floorProfileDistanceMicrometres
+                    -edge.floorProfileStartDistanceMicrometres)
+                    /(edge.floorProfileEndDistanceMicrometres
+                        -edge.floorProfileStartDistanceMicrometres);
+                const double one=1.0-t;
+                const double expected=one*one*one*edge.controlPointsMicrometres[0][2]
+                    +3.0*one*one*t*edge.controlPointsMicrometres[1][2]
+                    +3.0*one*t*t*edge.controlPointsMicrometres[2][2]
+                    +t*t*t*edge.controlPointsMicrometres[3][2];
+                std::array<double,2> routeXY{};
+                for(std::size_t axis=0;axis<2;++axis)
+                    routeXY[axis]=one*one*one*edge.controlPointsMicrometres[0][axis]
+                        +3.0*one*one*t*edge.controlPointsMicrometres[1][axis]
+                        +3.0*one*t*t*edge.controlPointsMicrometres[2][axis]
+                        +t*t*t*edge.controlPointsMicrometres[3][axis];
+                const double roomFloorAtProfile=room.floorMicrometres
+                    +room.floorGradientQ16[0]/65536.0
+                        *(routeXY[0]-room.centerMicrometres[0])
+                    +room.floorGradientQ16[1]/65536.0
+                        *(routeXY[1]-room.centerMicrometres[1]);
+                if(std::abs(expected-roomFloorAtProfile)>1000.0)
+                    add("cavern_room_floor_profile",room.stableId+
+                        " floor does not match its referenced h(s)");
+            }
+        }
     }
     if(oreVeins.empty())
     {
@@ -1526,6 +1663,12 @@ std::optional<ResolvedLayoutSnapshotV3> ResolvedLayoutSnapshotV3::FromJson(
         readTriplet("bounds_min_um",room.boundsMinimumMicrometres);
         readTriplet("bounds_max_um",room.boundsMaximumMicrometres);
         room.floorMicrometres=LayoutInt(v,"floor_um");
+        room.floorProfileStableId=LayoutString(v,"floor_profile_id");
+        if(v.Get("floor_profile_distance_um").IsNumber())
+            room.floorProfileDistanceMicrometres=LayoutInt(v,"floor_profile_distance_um");
+        const auto& floorGradient=v.Get("floor_gradient_q16").AsArray();
+        for(std::size_t axis=0;axis<2&&axis<floorGradient.size();++axis)
+            room.floorGradientQ16[axis]=static_cast<std::int32_t>(floorGradient[axis].Integer());
         room.smoothWidthMicrometres=LayoutInt(v,"smooth_width_um");
         room.unionWidthMicrometres=LayoutInt(v,"union_width_um");
         room.irregularityAmplitudeMicrometres=LayoutInt(v,"irregularity_amplitude_um");
@@ -1539,6 +1682,13 @@ std::optional<ResolvedLayoutSnapshotV3> ResolvedLayoutSnapshotV3::FromJson(
         edge.startAnchorStableId=LayoutString(v,"start_anchor_stable_id");
         edge.endRoomStableId=LayoutString(v,"end_room_stable_id");
         edge.strateIndex=static_cast<std::int32_t>(LayoutInt(v,"strate_index"));
+        edge.floorProfileStableId=LayoutString(v,"floor_profile_id");
+        if(v.Get("floor_profile_start_distance_um").IsNumber())
+            edge.floorProfileStartDistanceMicrometres=
+                LayoutInt(v,"floor_profile_start_distance_um");
+        if(v.Get("floor_profile_end_distance_um").IsNumber())
+            edge.floorProfileEndDistanceMicrometres=
+                LayoutInt(v,"floor_profile_end_distance_um");
         const auto& points=v.Get("control_points_um").AsArray();
         for(std::size_t i=0;i<edge.controlPointsMicrometres.size()&&i<points.size();++i)
         {
@@ -1879,7 +2029,7 @@ bool ResolveResolvedCavernGraphV1(ResolvedLayoutSnapshotV3& layout,std::int32_t
         if(!candidate.finalize(error))return false;
         layout=std::move(candidate);return true;
     }
-    candidate.cavernGraphVocabularyVersion=ResolvedLayoutCavernGraphVocabularyVersionV1;
+    candidate.cavernGraphVocabularyVersion=ResolvedLayoutCavernGraphVocabularyVersionV2;
     candidate.cavernRooms.assign(rooms.begin(),rooms.end());
     candidate.cavernEdges.assign(edges.begin(),edges.end());
     const auto isNativeCavesStrate=[&candidate](std::int32_t strateIndex)
@@ -2195,6 +2345,42 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
         cumulative[i]=cumulative[i-1]+distance2d(routePoints[i-1],routePoints[i]);
     if(cumulative.back()!=totalRouteLength)
     {error="cavern planner route length accounting failed";return false;}
+    const std::string backboneFloorProfileId="tunnel-network/strate-"
+        +std::to_string(strateIndex)+"/backbone-floor";
+    const auto routeFloorAt=[&](std::int64_t distance)
+    {
+        distance=std::clamp<std::int64_t>(distance,0,totalRouteLength);
+        return routeStart[2]+dz*distance/totalRouteLength;
+    };
+    const auto routeFloorGradientAt=[&](std::int64_t distance)
+    {
+        distance=std::clamp<std::int64_t>(distance,0,totalRouteLength);
+        std::size_t segment=1;
+        while(segment<cumulative.size()-1&&distance>cumulative[segment])++segment;
+        const auto unitTangent=[&](std::size_t index)
+        {
+            const double tx=static_cast<double>(routePoints[index][0]
+                -routePoints[index-1][0]);
+            const double ty=static_cast<double>(routePoints[index][1]
+                -routePoints[index-1][1]);
+            const double length=std::hypot(tx,ty);
+            return length>0.0?std::array<double,2>{tx/length,ty/length}
+                :std::array<double,2>{0.0,0.0};
+        };
+        auto tangent=unitTangent(segment);
+        if(segment+1<cumulative.size()&&distance==cumulative[segment])
+        {
+            const auto next=unitTangent(segment+1);
+            tangent[0]+=next[0];tangent[1]+=next[1];
+            const double length=std::hypot(tangent[0],tangent[1]);
+            if(length>1.0e-12){tangent[0]/=length;tangent[1]/=length;}
+        }
+        constexpr double Q16=65536.0;
+        const double profileSlope=static_cast<double>(dz)/totalRouteLength;
+        return std::array<std::int32_t,2>{
+            static_cast<std::int32_t>(std::llround(tangent[0]*profileSlope*Q16)),
+            static_cast<std::int32_t>(std::llround(tangent[1]*profileSlope*Q16))};
+    };
     const auto pointAt=[&](std::int64_t distance)
     {
         distance=std::clamp<std::int64_t>(distance,0,totalRouteLength);
@@ -2211,7 +2397,7 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
                 -routePoints[segment-1][axis];
             point[axis]=routePoints[segment-1][axis]+delta*local/segmentLength;
         }
-        point[2]=routeStart[2]+dz*distance/totalRouteLength;
+        point[2]=routeFloorAt(distance);
         return point;
     };
     std::int64_t spacing=std::min(std::max<std::int64_t>(settings.roomSpacingMicrometres,
@@ -2281,6 +2467,9 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
     {
         std::string id;
         FPoint point{};
+        std::string floorProfileStableId;
+        std::int64_t floorProfileDistanceMicrometres=-1;
+        std::array<std::int32_t,2> floorGradientQ16{};
         std::int64_t radiusMicrometres=0;
         bool destination=false;
     };
@@ -2298,6 +2487,9 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
     {
         const std::int64_t distance=nodeDistances[nodeIndex];
         FRoomNode node;node.point=pointAt(distance);
+        node.floorProfileStableId=backboneFloorProfileId;
+        node.floorProfileDistanceMicrometres=distance;
+        node.floorGradientQ16=routeFloorGradientAt(distance);
         node.destination=distance==mainRouteMidpoint;
         node.id="tunnel-network/strate-"+std::to_string(strateIndex)+"/room-"
             +std::to_string(nodeIndex);
@@ -2347,7 +2539,10 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
                     pathAxisX*pathAxisX+pathAxisY*pathAxisY))));
             const std::int64_t centerOffset=(component%2==0?1:-1)*offsetMagnitude;
             ResolvedCavernRoomV1 room;room.stableId=stableId;
-            room.strateIndex=strateIndex;room.floorMicrometres=node.point[2];
+            room.strateIndex=strateIndex;
+            room.floorProfileStableId=node.floorProfileStableId;
+            room.floorProfileDistanceMicrometres=node.floorProfileDistanceMicrometres;
+            room.floorGradientQ16=node.floorGradientQ16;
             room.halfExtentsMicrometres={halfX,halfY,halfZ};
             room.centerMicrometres={node.point[0]+(-pathAxisY)*centerOffset/routeLengthXY,
                 node.point[1]+pathAxisX*centerOffset/routeLengthXY,
@@ -2362,6 +2557,11 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
                         %static_cast<std::uint64_t>(jitterRange+1)):0;
                 room.centerMicrometres[2]+=ceilingJitter;
             }
+            room.floorMicrometres=node.point[2]
+                -(static_cast<std::int64_t>(room.floorGradientQ16[0])
+                    *(room.centerMicrometres[0]-node.point[0])
+                    +static_cast<std::int64_t>(room.floorGradientQ16[1])
+                    *(room.centerMicrometres[1]-node.point[1]))/65536;
             room.smoothWidthMicrometres=smooth;
             room.irregularityAmplitudeMicrometres=irregularity;
             room.irregularityWavelengthMicrometres=settings.irregularityWavelengthMicrometres;
@@ -2374,7 +2574,8 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
     const auto componentRoomId=[](const FRoomNode& node)
     {return node.id+"/primitive-0";};
     const auto makeEdge=[&](std::string id,std::string startAnchor,
-        const FPoint& start,const FRoomNode& endNode,std::int64_t boreRadius)
+        const FPoint& start,const FRoomNode& endNode,std::int64_t boreRadius,
+        std::int64_t profileStartDistance,std::int64_t profileEndDistance)
     {
         ResolvedCavernEdgeV1 edge;edge.stableId=std::move(id);
         edge.startAnchorStableId=std::move(startAnchor);
@@ -2382,6 +2583,12 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
         edge.boreRadiusMicrometres=boreRadius;
         edge.boreHeightMicrometres=std::max(PlannedBoreHeight,MinimumBoreHeight);
         edge.floorSupportDepthMicrometres=settings.floorSupportDepthMicrometres;
+        if(profileStartDistance>=0&&profileEndDistance>=0)
+        {
+            edge.floorProfileStableId=backboneFloorProfileId;
+            edge.floorProfileStartDistanceMicrometres=profileStartDistance;
+            edge.floorProfileEndDistanceMicrometres=profileEndDistance;
+        }
         edge.smoothWidthMicrometres=smooth;
         edge.irregularityAmplitudeMicrometres=irregularity;
         edge.irregularityWavelengthMicrometres=settings.irregularityWavelengthMicrometres;
@@ -2394,10 +2601,21 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
             edge.controlPointsMicrometres[2][axis]=start[axis]+(delta*2)/3;
             edge.controlPointsMicrometres[3][axis]=end[axis];
         }
+        if(profileStartDistance>=0&&profileEndDistance>=0)
+        {
+            const std::int64_t floorStart=routeFloorAt(profileStartDistance);
+            const std::int64_t floorEnd=routeFloorAt(profileEndDistance);
+            const std::int64_t floorDelta=floorEnd-floorStart;
+            edge.controlPointsMicrometres[0][2]=floorStart;
+            edge.controlPointsMicrometres[1][2]=floorStart+floorDelta/3;
+            edge.controlPointsMicrometres[2][2]=floorStart+(floorDelta*2)/3;
+            edge.controlPointsMicrometres[3][2]=floorEnd;
+        }
         return edge;
     };
     const auto arrivalPoint=routeStart;
     FPoint previousPoint=arrivalPoint;
+    std::int64_t previousProfileDistance=0;
     std::string previousAnchor=arrivalPassage->stableId+"/lower-mouth";
     for(std::size_t nodeIndex=0;nodeIndex<nodes.size();++nodeIndex)
     {
@@ -2406,8 +2624,10 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
         const std::string edgeId="tunnel-network/strate-"+std::to_string(strateIndex)
             +"/route-edge-"+std::to_string(nodeIndex);
         edges.push_back(makeEdge(edgeId,previousAnchor,previousPoint,node,
-            portal?passageBoreRadius(*arrivalPassage,true):selectedBoreRadius(edgeId)));
+            portal?passageBoreRadius(*arrivalPassage,true):selectedBoreRadius(edgeId),
+            previousProfileDistance,node.floorProfileDistanceMicrometres));
         previousPoint={node.point[0],node.point[1],node.point[2]};
+        previousProfileDistance=node.floorProfileDistanceMicrometres;
         previousAnchor=componentRoomId(node);
     }
     if(!nodes.empty())
@@ -2415,7 +2635,8 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
         const std::string departureEdgeId="tunnel-network/strate-"
             +std::to_string(strateIndex)+"/departure-edge";
         edges.push_back(makeEdge(departureEdgeId,departurePassage->stableId+"/upper-mouth",
-            routeEnd,nodes.back(),passageBoreRadius(*departurePassage,false)));
+            routeEnd,nodes.back(),passageBoreRadius(*departurePassage,false),
+            totalRouteLength,nodes.back().floorProfileDistanceMicrometres));
     }
 
     const std::int64_t roomDensity=clampQ16(settings.roomDensityQ16);
@@ -2444,16 +2665,19 @@ bool PlanResolvedCavernNetworkV1(const ResolvedLayoutSnapshotV3& layout,
         branch.point={parent.point[0]+(-pathAxisY)*branchLength/pathAxisLength*direction,
             parent.point[1]+pathAxisX*branchLength/pathAxisLength*direction,
             parent.point[2]};
+        branch.floorProfileStableId=parent.floorProfileStableId;
+        branch.floorProfileDistanceMicrometres=parent.floorProfileDistanceMicrometres;
+        branch.floorGradientQ16=parent.floorGradientQ16;
         makeCompound(branch,false,rooms);
         const std::string branchEdgeId="tunnel-network/strate-"
             +std::to_string(strateIndex)+"/side-edge-"+std::to_string(branchCount);
         ResolvedCavernEdgeV1 branchEdge;
         if(settings.tunnelsFlowTowardOrigin)
             branchEdge=makeEdge(branchEdgeId,componentRoomId(branch),
-                branch.point,parent,selectedBoreRadius(branchEdgeId));
+                branch.point,parent,selectedBoreRadius(branchEdgeId),-1,-1);
         else
             branchEdge=makeEdge(branchEdgeId,componentRoomId(parent),
-                parent.point,branch,selectedBoreRadius(branchEdgeId));
+                parent.point,branch,selectedBoreRadius(branchEdgeId),-1,-1);
         // Side branches retain their cave floor SDF, but they do not cap the
         // descending backbone when their tubes overlap it near a junction.
         branchEdge.floorSupportDepthMicrometres=0;

Standalone/Core/src/ShapeWorldInternal.h

@@ -3583,6 +3583,7 @@ private:
         double minimumFloorMetres=std::numeric_limits<double>::infinity();
         double maximumFloorMetres=-std::numeric_limits<double>::infinity();
         double maximumSegmentGrade=0.0;
+        std::array<double,2> floorGradient{};
         std::array<float,3> centerVoxels{},halfExtentsVoxels{};
         std::array<std::array<float,3>,4> controlPointsVoxels{};
         float floorVoxels=0.0f;
@@ -4011,8 +4012,10 @@ private:
     {
         CavernRuntime.clear();CavernSpatialNodes.clear();CavernSpatialOrder.clear();
         if(!ResolvedLayout||!Owner||Owner->CoreVoxelSizeMicrons==0
-            ||ResolvedLayout->cavernGraphVocabularyVersion
-                !=VoxelForgeCore::ResolvedLayoutCavernGraphVocabularyVersionV1)return;
+            ||(ResolvedLayout->cavernGraphVocabularyVersion
+                    !=VoxelForgeCore::ResolvedLayoutCavernGraphVocabularyVersionV1
+                &&ResolvedLayout->cavernGraphVocabularyVersion
+                    !=VoxelForgeCore::ResolvedLayoutCavernGraphVocabularyVersionV2))return;
         const auto isNativeGraphStrate=[this](std::int32_t strateIndex)
         {
             const auto found=std::find_if(ResolvedLayout->strates.begin(),
@@ -4042,6 +4045,8 @@ private:
             }
             runtime.floorVoxels=static_cast<float>(
                 static_cast<double>(room.floorMicrometres)/micronsPerVoxel);
+            runtime.floorGradient={room.floorGradientQ16[0]/65536.0,
+                room.floorGradientQ16[1]/65536.0};
             runtime.smoothWidthVoxels=static_cast<float>(
                 static_cast<double>(room.smoothWidthMicrometres)/micronsPerVoxel);
             runtime.irregularityAmplitudeVoxels=static_cast<float>(
@@ -5314,7 +5319,18 @@ public:
                     (std::sqrt(normalizedMinimumSquared)-1.0)*meanRadius,
                     (std::sqrt(normalizedMaximumSquared)-1.0)*meanRadius,true};
                 const double floorZ=feature.room->floorMicrometres/1000000.0;
-                const FMetricInterval floor={floorZ-hi[2],floorZ-lo[2],true};
+                const double centerX=feature.room->centerMicrometres[0]/1000000.0;
+                const double centerY=feature.room->centerMicrometres[1]/1000000.0;
+                const double gx=feature.room->floorGradientQ16[0]/65536.0;
+                const double gy=feature.room->floorGradientQ16[1]/65536.0;
+                const double x0=lo[0]-centerX,x1=hi[0]-centerX;
+                const double y0=lo[1]-centerY,y1=hi[1]-centerY;
+                const double gradientMinimum=(gx>=0.0?gx*x0:gx*x1)
+                    +(gy>=0.0?gy*y0:gy*y1);
+                const double gradientMaximum=(gx>=0.0?gx*x1:gx*x0)
+                    +(gy>=0.0?gy*y1:gy*y0);
+                const FMetricInterval floor={floorZ-hi[2]+gradientMinimum,
+                    floorZ-lo[2]+gradientMaximum,true};
                 const double width=feature.room->smoothWidthMicrometres/1000000.0;
                 featureVoid={SmoothMaxMetres(ellipsoid.minimum,floor.minimum,width),
                     SmoothMaxMetres(ellipsoid.maximum,floor.maximum,width),true};
@@ -7463,6 +7479,7 @@ private:
         double floorSupportScore=std::numeric_limits<double>::infinity();
         double floorSupportDepth=0.0,floorSupportFloor=0.0,floorSupportGrade=0.0;
         const std::string* floorSupportEdgeId=nullptr;
+        const std::string* floorSupportProfileId=nullptr;
         for(const std::uint32_t index:*candidates)
         {
             if(index>=CavernRuntime.size())continue;
@@ -7491,7 +7508,9 @@ private:
                         feature.irregularityWavelengthVoxels,feature.irregularitySeed)
                         *feature.irregularityAmplitudeVoxels*metresPerVoxel*fade;
                 }
-                const double floor=feature.room->floorMicrometres/1000000.0-point[2];
+                const double floor=feature.room->floorMicrometres/1000000.0-point[2]
+                    +feature.floorGradient[0]*(point[0]-feature.centerMetres[0])
+                    +feature.floorGradient[1]*(point[1]-feature.centerMetres[1]);
                 const double width=feature.room->smoothWidthMicrometres/1000000.0;
                 featureVoid=SmoothMaxMetres(ellipsoid,floor,width);
             }
@@ -7599,10 +7618,32 @@ private:
                 {
                     const double deltaZ=point[2]-nearestFloor;
                     const double candidateScore=nearestRadial*nearestRadial+deltaZ*deltaZ;
-                    if(candidateScore<floorSupportScore
+                    if(!feature.edge->floorProfileStableId.empty())
+                    {
+                        const bool sameProfile=floorSupportProfileId
+                            &&*floorSupportProfileId==feature.edge->floorProfileStableId;
+                        if(!floorSupportProfileId||sameProfile)
+                        {
+                            // Backbone edges share h(s). At a geometric joint their
+                            // cave volumes overlap, so the backing top is the lower
+                            // of the local floors, never the closer higher segment.
+                            if(!floorSupportProfileId||nearestFloor<floorSupportFloor
+                                ||(nearestFloor==floorSupportFloor
+                                    &&feature.edge->stableId<*floorSupportEdgeId))
+                            {
+                                floorSupportDepth=candidateSupportDepth;
+                                floorSupportFloor=nearestFloor;
+                                floorSupportGrade=nearestGrade;
+                                floorSupportEdgeId=&feature.edge->stableId;
+                            }
+                            floorSupportProfileId=&feature.edge->floorProfileStableId;
+                        }
+                    }
+                    else if(!floorSupportProfileId
+                        &&(candidateScore<floorSupportScore
                             ||(candidateScore==floorSupportScore
                                 &&(!floorSupportEdgeId
-                                ||feature.edge->stableId<*floorSupportEdgeId)))
+                                    ||feature.edge->stableId<*floorSupportEdgeId))))
                     {
                         floorSupportScore=candidateScore;
                         floorSupportDepth=candidateSupportDepth;