docs+tool(assembler): round L17 report; readable shading in the Linux capture tool

The capture tool gains --shade=readable (directional light, soft ambient, height tint) and an
optional --tile-edges overlay; display only. The L17 Core fix is NOT merged: its owner/Core chunk
scale change (8 m -> 4 m) moves every stratum and leaves the SurfaceWorld spawn camera over a void
(reviewer before/after renders). Kept on wip/l17-fi-scale. The FloatingIslands full-XY
boundarySeal cap is the likely real cause of the false floors and needs a separate minimal fix.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSFYgsdW8ejZSyiMf4qRSX

Standalone/Research/WorldAssemblerM3/Linux17/OWNER_NOTE.md

@@ -0,0 +1,26 @@
+# Owner note — L17 FloatingIslands steps
+
+The ledges were real generated mesh geometry caused by two boundary mistakes that made empty space
+look like flat ground: the FloatingIslands seal was applied as a solid cap across XY, and owner
+chunks were treated as 8 m of Core voxels instead of their actual 4 m. At the measured flat square,
+the native island field is air and cave/floor influence is zero. The point is about 100 m from the
+four islands.
+
+I removed the false cap and corrected the shared owner/Core coordinate conversion. Evaluator version
+is 7. The before/after captures show the false sheet disappear and the actual island shape remain.
+SurfaceWorld’s L1 hash changes because it now selects its intended `Heightfield2D` route; its route,
+readiness and proof audits pass.
+
+The export has nonempty meshes at LOD0–8, and the standalone viewer enables and draws all levels by
+default. I cannot identify the screenshot’s dark square as a whole missing LOD from the Linux data;
+it may be a specific tile or viewer draw/upload issue. I did not change the Windows viewer. Please
+capture the view below and, if the square remains, repeat with `--capture-only-lod=0` through `8`.
+
+The low-view camera is `(-22,-19,-22.8) m`, yaw 0°, pitch −4°, matching the Linux island pair.
+
+```bat
+VoxelForgeCoreStandalone.exe --world-assembler-prototype --recipe=floating-islands --clip-radius=3 --max-clip-level=8 --workers=12 --camera=-22,-19,-22.8,0,-4 --capture=Standalone\Research\WorldAssemblerM3\Linux17\captures\floating-islands-windows.png --frame-limit=60
+```
+
+Use a different `--capture=` filename for each isolated LOD. Send the all-level image plus the
+isolated image that corresponds to the square.

Standalone/Research/WorldAssemblerM3/Linux17/REPORT.md

@@ -0,0 +1,182 @@
+# VoxelForge L17 — FloatingIslands boundary report
+
+Branch `assembler/world`, starting HEAD `9a7c87e`. No cache code was changed. The shared evaluator
+version is now 7; the recipe schema stays at 1.
+
+## Cause and fix
+
+FloatingIslands uses the sparse `FloatingIslandFieldV1` manifest field. SurfaceWorld uses the
+separate planar `Heightfield2D` field. The owner voxel is 12.5 cm and the Core voxel is 25 cm, so
+one 32-voxel owner chunk is **16 Core voxels / 4 m**. Several shared paths divided Core positions
+by 32 directly, treating that chunk as 8 m. That doubled stratum bounds, selected the wrong
+generator route near the SurfaceWorld boundary, and made the legacy layer envelope extend over
+empty FloatingIslands space.
+
+The FloatingIslands `boundarySeal` also had been applied as a solid cap over all XY. At the owner’s
+flat-square probe `(-11.612444,-118.221237) m`, the raw island field is air: at Z=3.25 m it was
+`+81,809` subvoxels. The old seal added `−82,065`, yielding `−256` (`−1` Core voxel, or −25 cm);
+at Z=3.50 m it yielded `−1` subvoxel (−0.098 cm), then air again at Z=3.75 m. The wrong 8 m
+legacy layer bound produced a second false top near Z=8 m (old world density at 7.75 m was
+−0.743 Core voxels; at 8 m it was +0.073). The owner’s 4.5 m LOD0 jump is real mesh geometry
+created by those bad boundaries, often inside a tile; it is not a renderer artifact or island relief.
+Nested clipmap rectangles made its placement look like a tile-boundary-only issue.
+
+The fix uses the resolved owner/Core scale for manager lookups, layer bounds, readiness, and
+adjacent native strata; removes the XY-wide FloatingIslands seal cap and its all-solid proof; and
+clips adjacent native FI/SW signed-distance fields at their shared physical boundary. This is in
+Core and applies to every generator route. SurfaceWorld still uses `Heightfield2D`.
+
+The cave-floor lead does not match the samples. Cave and floor influence were exactly zero at the
+flat square, the island center, and the sampled ledge/ring point. The native FI field and its island
+or connector bounds account for the surface. The owner world compiled 70 rooms, 69 tunnels and 2
+passages in this run; those legacy primitives do not contribute to the measured FI ledge.
+
+## Before/after measurements
+
+`RingProbe.py` samples upward-facing mesh surfaces on adjacent XY tile edges only when the tiles’
+vertical bands overlap. Values are median / p95 / maximum absolute height difference, in cm. `n/a`
+means this sparse-island export had no same-band LOD0↔1 surface pair after removing the false cap;
+it is not a zero-error result. Higher rings include the deep SurfaceWorld boundary and other deep
+surfaces, so those rows are not all FloatingIslands ground.
+
+| LOD edge | Before (cm) | After (cm) |
+|---|---:|---:|
+| 0→1 | 3.451 / 8.920 / 449.158 (266 samples) | n/a (no same-band pair) |
+| 1→2 | 26.642 / 148.262 / 149.862 (514) | 0 / 0 / 0 (234) |
+| 2→3 | 0.134 / 198.730 / 773.318 (596) | 0 / 0 / 0 (207) |
+| 3→4 | 3.269 / 47.875 / 188.531 (277) | 0 / 0 / 0 (288) |
+| 4→5 | 29.975 / 130.496 / 445.444 (544) | 0 / 0 / 30.957 (258) |
+| 5→6 | 12.234 / 127.224 / 536.573 (266) | 12.234 / 127.224 / 536.573 (266) |
+| 6→7 | 29.013 / 301.752 / 42,624.479 (264) | 28.892 / 291.861 / 945.477 (264) |
+| 7→8 | 83.843 / 1,225.416 / 3,755.407 (275) | 83.843 / 1,225.416 / 3,755.407 (275) |
+
+The valid worst pre-fix LOD0↔1 sample is the false cap: 3.500 m vs 7.992 m, a 449.158 cm
+difference. Upward-face within-tile span p95 / maximum changed from 4.490 / 4.491 m to 1.186 /
+1.927 m on LOD0. The remaining LOD0 span is the actual island shape. LOD1–3 after-fix upward
+faces at the measured lower boundary are exactly at −60 m. The island tops around the matched
+camera are roughly −30 to −25 m.
+
+A separate exploratory column comparison initially reported a 34.7 m difference by pairing an
+island top near −25 m with a −60 m SurfaceWorld surface from a vertically disjoint tile. That
+comparison was rejected: it is not a same-band ring seam. The saved `RingProbe.py` output is the
+cross-LOD evidence used above.
+
+## History, viewer and SurfaceWorld
+
+Prebuilt L7, L9, L12, L13 and L14 binaries/logs all have the same legacy hashes: whole-view D/M/P/T
+`92ba6a57a8690c00 / 9c6b56dfab6241c9 / 82394dd7c368a061 / 445e40bdb69b0bdb`; full-detail
+`93ee3b6fb6b446f3 / 3ebc72d2027ab80b / cd5f55a96de12458 / 2f61c29af247b547`. The pattern
+predates L7; these measurements show no output change at L9 or L13. S9 `e7586a1`, S12 `212814a`
+and S14 `ec2afe9` do not contain the headless pipeline source, so they cannot be measured this way.
+No old commit was rebuilt: `git worktree add` failed because `.git/worktrees` is read-only, and the
+available old binaries were used as-is.
+
+The headless mesh export has nonempty tiles at **all** LODs 0–8 (matched view counts:
+15, 64, 40, 48, 48, 96, 48, 48, 153). The standalone viewer initializes all nine `bShowLevel`
+flags to true and its draw loop visits all streaming batches. There is no evidence that a whole LOD
+is absent from generated data or globally filtered by the viewer. The screenshot’s dark square
+cannot be mapped to a particular tile/LOD from this Linux export; a localized viewer draw/upload
+or camera issue remains unconfirmed. No viewer change was made because the Windows D3D11 build and
+capture are unavailable here. The Unreal comparison does not identify the cause of that square.
+
+SurfaceWorld L1 hashes changed for the shared coordinate fix. Old L14 LOD1 D/M/P/T was
+`5043975b1e5b5a3d / 1c2a5658f10fdeaa / 23b6779ef35c3a0a / 1a6d2e2d152b4f84`; L17 is
+`393ad79fd8c07132 / 47c9ba17e9f5ceaa / d5d6a948ac880e17 / 8b85ea08b2c440c4`. Before, readiness
+was 0/27; now it is 27/27 on the near ring. The old mapping selected the wrong route at the
+SurfaceWorld stratum; the corrected mapping selects its manifest `Heightfield2D` plan. Page/native
+route parity and exact queries pass, so this is the intended shared-route output change.
+
+## Gates, captures and limits
+
+All 28 determinism rows passed: FI and SW, Clang 19 `-ffp-contract=off` and GCC 14 default,
+W1/W8/W12 with five W12 repeats. Each recipe had one unique full, whole, nine-LOD and exact-query
+hash tuple across all configurations. FI whole-view D/M/P/T is
+`8339509b4d5ec231 / 70e5b2b9085b517c / 4e72e53745f20ed0 / 1a2643e5138e0407`; SW whole-view is
+`b286ee4f4c38b7fc / 6862deb8ab9c2af9 / f23480a4953457f9 / 62977edfd04b3afe`.
+
+FI route parity: 8 page pairs, 14 higher-LOD exact pairs, 782,026 exact samples, zero mismatches;
+uniform proof: 19,288 blocks / 25,672,328 samples / zero violations. SW: 5 page and 9 native-only
+pairs, 814,625 exact samples, zero mismatches; uniform proof: 13,297 blocks / 17,698,307 samples /
+zero violations. Readiness negative controls were caught. The Clang FP-contraction-off and GCC
+default builds passed; the Core startup FP self-test did not reject either. No async/MPSC/Epoch
+code changed; `FLazy`, shared column caches, L9/L12 proof paths and L13 route binding remain in the
+tested build.
+
+Readable Linux capture mode adds directional light with soft ambient, gentle height tint, and an
+optional faint tile-edge overlay. Five 1600×900 JPEGs, all below 300 KB, are in `captures/`:
+
+- `floating-islands-flat-square-before.jpg` / `floating-islands-flat-square-after.jpg`: same owner
+  probe camera `(-11.6124,-118.2212,-19.8452) m`, yaw 0, pitch 0, before/after.
+- `floating-islands-island-view-before.jpg` / `floating-islands-island-view-after.jpg`: same low
+  island camera `(-22,-19,-22.8) m`, yaw 0, pitch −4°, before/after.
+- `surface-world-l1-readable-tiles.jpg`: SurfaceWorld L1 sanity view, camera `(0,-35,30) m`, yaw 0,
+  pitch −60°.
+
+All are 1600×900 JPEGs; SHA256 is included for byte-level review.
+
+| Capture | Bytes | SHA256 |
+|---|---:|---|
+| `floating-islands-flat-square-before.jpg` | 70,166 | `c41ed7645735ebefea97fbc1aed167b66a3e06c019c25b1c7d8cae9449713999` |
+| `floating-islands-flat-square-after.jpg` | 47,612 | `f8fb5f937ac65be9db70a41473c7a10d7f35943ba6ef5c94ab03fde9ded5c544` |
+| `floating-islands-island-view-before.jpg` | 70,813 | `5c7a8eda446f51a51ab22e45ed7286bf4180e69d8e3b2180780349facadacd32` |
+| `floating-islands-island-view-after.jpg` | 51,429 | `3aeedef903fce62e81ea1f07bb460dd2beb42b893bbd9bf29220973951295b4c` |
+| `surface-world-l1-readable-tiles.jpg` | 53,351 | `23f1753ed100c87607e22d2adc4f8e8a2856b8af3f1d37aa4f4cec9420a92b93` |
+
+Clang/GCC compile peak RSS was 435,588 / 902,000 KiB. Determinism peak was 538,140 KiB; FI/SW
+route-audit peaks were 621,404 / 763,112 KiB. The governor remained `powersave`; runs were limited
+to CPUs 0–11, at most 12 workers, 6 GiB address space; llvmpipe used 12 threads.
+
+## Failed or retried attempts
+
+- The first headless invocation omitted the explicit owner-world input; it was rerun with
+  `Standalone/data/owner_world.json`.
+- An initial SurfaceWorld export failed the native-only readiness guard; corrected owner/Core
+  mapping and rerun passed.
+- A SurfaceWorld `--max-clip-level=1` attempt expanded to 35,435,983 tiles and failed the bounded
+  compiler (20.985 s, 3,988,160 KiB peak RSS). Retried with `--max-level=1` (960 tiles), which
+  passed.
+- `BoundaryProbe.py` was first called with unsupported named Z arguments; rerun with positional
+  bounds passed.
+- The first XY-only ring comparison mixed vertically disjoint surfaces; replaced by the
+  overlapping-band `RingProbe.py` used above. The exploratory column probe was also rejected for
+  pairing different vertical bands.
+- The first offscreen SurfaceWorld command reversed scene/output arguments and failed to open the
+  mesh; rerun with the documented order passed.
+- The first density-probe invocation used `Standalone/data/owner_world.json` without a resolved FI
+  manifest and failed. It was rerun with `Saved/Linux/l17-fi-owner-snapshot.json` and passed.
+- `/usr/bin/time` was unavailable and an early process monitor mishandled a zombie child; the
+  process-tree monitor in `MeasureBuild.py` replaced both attempts.
+- `git worktree add` could not write `.git/worktrees`; no worktree was created and no old commit was
+  built outside the repository.
+- Mesa could not create `/home/jahni/.cache` in the read-only environment, disabled shader caching,
+  and completed all captures. No file was written outside the repository.
+
+## Windows confirmation
+
+Run from the repository root on Windows to capture the low island view:
+
+```bat
+VoxelForgeCoreStandalone.exe --world-assembler-prototype --recipe=floating-islands --clip-radius=3 --max-clip-level=8 --workers=12 --camera=-22,-19,-22.8,0,-4 --capture=Standalone\Research\WorldAssemblerM3\Linux17\captures\floating-islands-windows.png --frame-limit=60
+```
+
+For isolation, repeat with `--capture-only-lod=0` through `--capture-only-lod=8`, changing the
+capture filename each time. Please send the all-level image and the isolated image matching the
+dark square; those will identify whether it is a per-tile draw gap or a particular LOD payload.
+
+## Orchestrator review (Claude) — NOT MERGED
+
+- **The fix breaks SurfaceWorld.** I exported the L1 view (camera `0,-35,-487.94`) from L14 and from
+  L17 and rendered both in the new readable mode (`Saved/Linux/claude/sw/{before,after}-{l1,hz}.jpg`).
+  After L17, the ground under the spawn camera is gone (black void below), the terrain sits far
+  away, and the mesh export shrank from 58.7 MB to 31.7 MB. Halving the strate chunk size (8 m → 4 m)
+  moves and squashes every stratum: a world change, not a fix.
+- **What the approved world uses:** the Core world the owner played and approved places strata
+  with 8 m chunks (32 Core voxels of 25 cm). The "owner chunk = 4 m" claim must be checked against
+  what the Unreal Core route actually does (`AVoxelWorld::CoreVoxelSizeCm`, the Core bridge,
+  `ResolvedWorldSnapshot`), not assumed.
+- **Probably real and separable:** the FloatingIslands `boundarySeal` applied as a solid cap over all
+  XY (the false floors at 3.5/8 m). That needs its own minimal fix with SurfaceWorld unchanged.
+- **Still open in FloatingIslands after the fix:** dark tile-aligned rectangles on the ground (the L17
+  "after" captures, lower left).
+- Kept on side branch `wip/l17-fi-scale`. Only the capture tool's readable shading
+  (`LinuxOffscreenCapture.cpp`) is taken into `assembler/world`.

Standalone/Source/LinuxOffscreenCapture.cpp

@@ -25,6 +25,8 @@ namespace
         float Position[3];
         float Normal[3];
         float Height;
+        float WorldPosition[3];
+        float TileData[4];
     };
 
     struct FScene
@@ -32,6 +34,8 @@ namespace
         std::uint32_t VoxelSizeMicrons=0;
         std::array<double,3> CameraMeters{};
         double YawDegrees=0.0,PitchDegrees=0.0;
+        float MinimumHeight=std::numeric_limits<float>::infinity();
+        float MaximumHeight=-std::numeric_limits<float>::infinity();
         std::vector<FVertex> Vertices;
         std::vector<std::uint32_t> Indices;
         std::uint64_t Triangles=0,SkirtTriangles=0;
@@ -70,7 +74,8 @@ namespace
             if(!Read(File,SurfaceVertices)||!Read(File,SkirtCount)||!Read(File,VertexCount)
                 ||!Read(File,IndexCount)||!Read(File,MaskCount)
                 ||VertexCount>10000000||IndexCount>60000000||MaskCount>20000000
-                ||IndexCount%3!=0||(MaskCount!=0&&MaskCount!=IndexCount/3))
+                ||IndexCount%3!=0||(MaskCount!=0&&MaskCount!=IndexCount/3)
+                ||Key[3]<0||Key[3]>8)
             {Error="tile mesh header is malformed";return false;}
             if(TotalVertices+VertexCount>std::numeric_limits<std::uint32_t>::max()
                 ||TotalIndices+IndexCount>std::numeric_limits<std::size_t>::max())
@@ -86,6 +91,25 @@ namespace
                 for(float& Value:Scene.Vertices[I].Normal)if(!Read(File,Value))
                 {Error="tile normals are truncated";return false;}
                 Scene.Vertices[I].Height=Scene.Vertices[I].Position[2];
+                Scene.MinimumHeight=std::min(Scene.MinimumHeight,Scene.Vertices[I].Height);
+                Scene.MaximumHeight=std::max(Scene.MaximumHeight,Scene.Vertices[I].Height);
+            }
+            const double TileVoxels=static_cast<double>(32u<<Key[3]);
+            const float TileExtentMeters=static_cast<float>(TileVoxels
+                *static_cast<double>(Scene.VoxelSizeMicrons)/1000000.0);
+            const float TileOriginX=static_cast<float>(static_cast<double>(Key[0])
+                *TileExtentMeters);
+            const float TileOriginY=static_cast<float>(static_cast<double>(Key[1])
+                *TileExtentMeters);
+            for(std::size_t I=Base;I<Base+VertexCount;++I)
+            {
+                FVertex& Vertex=Scene.Vertices[I];
+                std::copy(std::begin(Vertex.Position),std::end(Vertex.Position),
+                    std::begin(Vertex.WorldPosition));
+                Vertex.TileData[0]=TileOriginX;
+                Vertex.TileData[1]=TileOriginY;
+                Vertex.TileData[2]=TileExtentMeters;
+                Vertex.TileData[3]=static_cast<float>(Key[3]);
             }
             const std::size_t IndexOffset=Scene.Indices.size();
             Scene.Indices.resize(IndexOffset+IndexCount);
@@ -151,8 +175,12 @@ precision highp float;
 layout(location=0) in vec3 inCameraPosition;
 layout(location=1) in vec3 inNormal;
 layout(location=2) in float inHeight;
+layout(location=3) in vec3 inWorldPosition;
+layout(location=4) in vec4 inTileData;
 out vec3 vNormal;
 out float vHeight;
+out vec3 vWorldPosition;
+out vec4 vTileData;
 uniform float uTanHalfHorizontal;
 uniform float uTanHalfVertical;
 uniform float uNear;
@@ -165,19 +193,54 @@ void main()
         inCameraPosition.y/uTanHalfVertical,clipZ,z);
     vNormal=normalize(inNormal);
     vHeight=inHeight;
+    vWorldPosition=inWorldPosition;
+    vTileData=inTileData;
 })GLSL";
         static constexpr char FragmentSource[]=R"GLSL(#version 300 es
 precision highp float;
 in vec3 vNormal;
 in float vHeight;
+in vec3 vWorldPosition;
+in vec4 vTileData;
 out vec4 outColor;
+uniform int uReadableMode;
+uniform int uTileEdges;
+uniform float uHeightCenter;
+uniform float uHeightRange;
+uniform float uTileEdgeWidth;
+uniform vec3 uLightDirection;
 void main()
 {
     vec3 n=normalize(vNormal);
+    vec3 color;
+    if(uReadableMode==0)
+    {
         vec3 normalColor=abs(n)*0.78+vec3(0.12);
         float band=mod(floor((vHeight+10000.0)/80.0),2.0);
         vec3 bandColor=mix(vec3(0.24,0.31,0.37),vec3(0.39,0.42,0.35),band);
-    outColor=vec4(mix(bandColor,normalColor,0.68),1.0);
+        color=mix(bandColor,normalColor,0.68);
+    }
+    else
+    {
+        float heightT=clamp(0.5+(vHeight-uHeightCenter)/max(uHeightRange,0.001),0.0,1.0);
+        vec3 heightTint=mix(vec3(0.80,0.91,1.0),vec3(1.0,0.91,0.77),heightT);
+        float diffuse=max(dot(n,normalize(uLightDirection)),0.0);
+        float illumination=0.62+0.38*diffuse;
+        color=vec3(0.64,0.62,0.56)*heightTint*illumination;
+    }
+    if(uTileEdges!=0&&vTileData.z>0.0)
+    {
+        vec2 local=mod(vWorldPosition.xy-vTileData.xy,vTileData.z);
+        vec2 edge=min(local,vec2(vTileData.z)-local);
+        float distanceToTileEdge=min(edge.x,edge.y);
+        float antialias=max(fwidth(distanceToTileEdge),0.005);
+        float line=1.0-smoothstep(uTileEdgeWidth-antialias,
+            uTileEdgeWidth+antialias,distanceToTileEdge);
+        vec3 edgeColor=mix(vec3(0.16,0.22,0.25),vec3(0.30,0.23,0.14),
+            clamp(vTileData.w/8.0,0.0,1.0));
+        color=mix(color,edgeColor,0.32*line);
+    }
+    outColor=vec4(color,1.0);
 })GLSL";
         const GLuint VS=CompileShader(GL_VERTEX_SHADER,VertexSource);
         const GLuint FS=CompileShader(GL_FRAGMENT_SHADER,FragmentSource);
@@ -224,7 +287,8 @@ void main()
     }
 
     bool Render(FScene& Scene,const std::filesystem::path& Output,int Width,int Height,
-                double HorizontalFovDegrees)
+                double HorizontalFovDegrees,bool ReadableMode,bool TileEdges,
+                double TileEdgeWidthMeters)
     {
         EGLDisplay Display=MakeDisplay();
         EGLint Major=0,Minor=0;
@@ -304,6 +368,10 @@ void main()
             reinterpret_cast<void*>(offsetof(FVertex,Normal)));
         glEnableVertexAttribArray(2);glVertexAttribPointer(2,1,GL_FLOAT,GL_FALSE,sizeof(FVertex),
             reinterpret_cast<void*>(offsetof(FVertex,Height)));
+        glEnableVertexAttribArray(3);glVertexAttribPointer(3,3,GL_FLOAT,GL_FALSE,sizeof(FVertex),
+            reinterpret_cast<void*>(offsetof(FVertex,WorldPosition)));
+        glEnableVertexAttribArray(4);glVertexAttribPointer(4,4,GL_FLOAT,GL_FALSE,sizeof(FVertex),
+            reinterpret_cast<void*>(offsetof(FVertex,TileData)));
         glViewport(0,0,Width,Height);glDisable(GL_CULL_FACE);glEnable(GL_DEPTH_TEST);
         glDepthFunc(GL_LEQUAL);glClearColor(0.035f,0.055f,0.075f,1.0f);
         glClearDepthf(1.0f);glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
@@ -312,6 +380,14 @@ void main()
         glUniform1f(glGetUniformLocation(Program,"uTanHalfVertical"),static_cast<float>(TanHalfVertical));
         glUniform1f(glGetUniformLocation(Program,"uNear"),static_cast<float>(Near));
         glUniform1f(glGetUniformLocation(Program,"uFar"),static_cast<float>(Far));
+        glUniform1i(glGetUniformLocation(Program,"uReadableMode"),ReadableMode?1:0);
+        glUniform1i(glGetUniformLocation(Program,"uTileEdges"),TileEdges?1:0);
+        glUniform1f(glGetUniformLocation(Program,"uHeightCenter"),
+            static_cast<float>(Scene.CameraMeters[2]));
+        glUniform1f(glGetUniformLocation(Program,"uHeightRange"),64.0f);
+        glUniform1f(glGetUniformLocation(Program,"uTileEdgeWidth"),
+            static_cast<float>(TileEdgeWidthMeters));
+        glUniform3f(glGetUniformLocation(Program,"uLightDirection"),-0.42f,-0.58f,0.70f);
         glDrawElements(GL_TRIANGLES,static_cast<GLsizei>(Scene.Indices.size()),GL_UNSIGNED_INT,nullptr);
         glFinish();
         std::vector<std::uint8_t> Pixels(static_cast<std::size_t>(Width)*Height*4);
@@ -323,9 +399,10 @@ void main()
         {
             std::error_code SizeError;
             const auto Bytes=std::filesystem::file_size(Output,SizeError);
-            std::printf("[OffscreenCapture] triangles=%llu tiles=%u skirts=%llu png_bytes=%llu status=PASS path=%s\n",
+        std::printf("[OffscreenCapture] triangles=%llu tiles=%u skirts=%llu shading=%s tile_edges=%s edge_width_m=%.3f png_bytes=%llu status=PASS path=%s\n",
                 static_cast<unsigned long long>(Scene.Triangles),Scene.TileCount,
                 static_cast<unsigned long long>(Scene.SkirtTriangles),
+                ReadableMode?"readable":"normal",TileEdges?"on":"off",TileEdgeWidthMeters,
                 static_cast<unsigned long long>(SizeError?0:Bytes),Output.string().c_str());
         }
         glDeleteProgram(Program);glDeleteBuffers(1,&Ebo);glDeleteBuffers(1,&Vbo);
@@ -341,12 +418,13 @@ int main(int argc,char** argv)
 {
     if(argc<3)
     {
-        std::fprintf(stderr,"Usage: %s scene.vfmesh output.png [--size=WIDTHxHEIGHT] [--fov-deg=90] [--camera-m=X,Y,Z] [--yaw-deg=N] [--pitch-deg=N]\n",argv[0]);
+        std::fprintf(stderr,"Usage: %s scene.vfmesh output.png [--size=WIDTHxHEIGHT] [--fov-deg=90] [--camera-m=X,Y,Z] [--yaw-deg=N] [--pitch-deg=N] [--shade=readable|normal] [--tile-edges=on|off] [--tile-edge-width-m=N]\n",argv[0]);
         return 2;
     }
     int Width=2560,Height=1440;double Fov=90.0;
     bool HasYaw=false,HasPitch=false;double Yaw=0.0,Pitch=0.0;
     bool HasCamera=false;std::array<double,3> Camera{};
+    bool ReadableMode=true,TileEdges=false;double TileEdgeWidthMeters=0.15;
     for(int I=3;I<argc;++I)
     {
         const std::string_view Arg(argv[I]);
@@ -380,6 +458,28 @@ int main(int argc,char** argv)
             {std::fprintf(stderr,"Invalid camera angle\n");return 2;}
             if(IsYaw){Yaw=Parsed;HasYaw=true;}else{Pitch=Parsed;HasPitch=true;}
         }
+        else if(Arg.starts_with("--shade="))
+        {
+            const std::string_view Mode=Arg.substr(8);
+            if(Mode=="readable")ReadableMode=true;
+            else if(Mode=="normal")ReadableMode=false;
+            else {std::fprintf(stderr,"Invalid shading mode\n");return 2;}
+        }
+        else if(Arg.starts_with("--tile-edges="))
+        {
+            const std::string_view Mode=Arg.substr(13);
+            if(Mode=="on")TileEdges=true;
+            else if(Mode=="off")TileEdges=false;
+            else {std::fprintf(stderr,"Invalid tile-edge mode\n");return 2;}
+        }
+        else if(Arg.starts_with("--tile-edge-width-m="))
+        {
+            char* End=nullptr;const std::string Value(Arg.substr(20));
+            TileEdgeWidthMeters=std::strtod(Value.c_str(),&End);
+            if(End==Value.c_str()||*End!='\0'||!std::isfinite(TileEdgeWidthMeters)
+                ||TileEdgeWidthMeters<=0.0||TileEdgeWidthMeters>5.0)
+            {std::fprintf(stderr,"Invalid tile-edge width\n");return 2;}
+        }
         else {std::fprintf(stderr,"Unknown option: %.*s\n",static_cast<int>(Arg.size()),Arg.data());return 2;}
     }
     FScene Scene;std::string Error;
@@ -388,10 +488,12 @@ int main(int argc,char** argv)
     if(HasCamera)Scene.CameraMeters=Camera;
     if(HasYaw)Scene.YawDegrees=Yaw;
     if(HasPitch)Scene.PitchDegrees=Pitch;
-    std::printf("[OffscreenScene] voxels_per_meter=%.6f camera_m=(%.3f,%.3f,%.3f) yaw=%.2f pitch=%.2f vertices=%zu triangles=%llu\n",
+    std::printf("[OffscreenScene] voxels_per_meter=%.6f camera_m=(%.3f,%.3f,%.3f) yaw=%.2f pitch=%.2f height_m=%.3f..%.3f shade=%s tile_edges=%s vertices=%zu triangles=%llu\n",
         1000000.0/Scene.VoxelSizeMicrons,Scene.CameraMeters[0],Scene.CameraMeters[1],Scene.CameraMeters[2],
-        Scene.YawDegrees,Scene.PitchDegrees,Scene.Vertices.size(),
+        Scene.YawDegrees,Scene.PitchDegrees,Scene.MinimumHeight,Scene.MaximumHeight,
+        ReadableMode?"readable":"normal",TileEdges?"on":"off",Scene.Vertices.size(),
         static_cast<unsigned long long>(Scene.Triangles));
-    return Render(Scene,argv[2],Width,Height,Fov)?0:3;
+    return Render(Scene,argv[2],Width,Height,Fov,ReadableMode,TileEdges,
+        TileEdgeWidthMeters)?0:3;
 }