Fix track preview start marker alignment

RELEASE_MANIFEST.json

@@ -83,7 +83,7 @@
     "star_check.py": "5c17080957b81ffccf0de8314635b471562e55c92c97a1207d9034a99279b2c3",
     "steam_leaderboard.py": "d76397c39cae58f636ddf9a9be1a46ae3d77fefd6b7269feac73d34d97165481",
     "track-library.js": "351ec4c026b49420ce963f4310cb000d9e987fd28e6dac5ecd0176509340f6e6",
-    "track-map.js": "ab5374aa49c7ccec90a787ee8c56cd71beb56b903bf2bbc322783e6f43c009f0",
+    "track-map.js": "547b737d123d9479fc166ddc564568c0ff4b2099200c78e36bb46ec461bc754c",
     "training_config.py": "6eb7282bbee3b3a6273bddc29c949d9904067414c26e501d815012f033173a1c",
     "vendor/gradio-client/LICENSE": "c71d239df91726fc519c6eb72d318ec65820627232b2f796219e87dcf35d0ab4",
     "vendor/gradio-client/dist/index.min.js": "fdd776db8633354f118fe2908c980592283968737e6b91dc3aa86d648da5c3fd",

track-map.js

@@ -14,6 +14,25 @@
       throw Error('Track coordinates exceed preview bounds');
     return [x,y];
   }
+  function connection(value,message='Track has an invalid piece connection'){
+    if(!value||typeof value!=='object'||Array.isArray(value)||
+       !Number.isInteger(value.side)||value.side<0||value.side>3||
+       !Number.isInteger(value.index)||value.index<0||value.index>2||
+       !Number.isInteger(value.type)||value.type<0)throw Error(message);
+    return {side:value.side,index:value.index,type:value.type};
+  }
+  function connectionPoint(value,x,y,size){
+    const {side,index}=connection(value);
+    // Native Connection.position uses offsets 128,384,640 in a 768-unit tile.
+    // Shared boundaries keep adjacent path endpoints and the saved start aligned.
+    const offset=[128,384,640][index]/768*size;
+    switch(side){
+      case 0:return [x+offset,y];
+      case 1:return [x+offset,y+size];
+      case 2:return [x,y+offset];
+      case 3:return [x+size,y+offset];
+    }
+  }
   async function decode(file){
     if(!file||file.size<1||file.size>1048576)throw Error('Choose a .track file under 1 MB');
     if(typeof DecompressionStream!=='function')throw Error('This browser cannot preview gzip tracks');
@@ -39,14 +58,20 @@
       const id=item?.Block?.TileSetId;
       const block=atlas?.blocks?.[`${id?.AtlasId}:${id?.AlternativeId}`];
       if(!block||![0,1,2].includes(block.surface))throw Error('Track uses a piece not in the simulator atlas');
-      return {x,y,surface:block.surface,connections:block.connections};
+      if(!Array.isArray(block.connections)||block.connections.length!==2)throw Error('Track piece connections are unavailable');
+      return {x,y,surface:block.surface,connections:block.connections.map(value=>connection(value))};
     });
     if(new Set(tiles.map(t=>`${t.x},${t.y}`)).size!==tiles.length)throw Error('Duplicate track tile');
     const start=vector(saved.StartTileCoords);
+    const startTile=tiles.find(tile=>tile.x===start[0]&&tile.y===start[1]);
+    if(!startTile)throw Error('Start tile is not present in this track');
+    const startConnection=connection({side:saved.StartTileConnection?.Side,index:saved.StartTileConnection?.Index,type:saved.StartTileConnection?.Type},'Track has an invalid or missing start connection');
+    if(!startTile.connections.some(item=>item.side===startConnection.side&&item.index===startConnection.index&&item.type===startConnection.type))
+      throw Error('Saved start connection does not match the start tile');
     const minX=Math.min(...tiles.map(t=>t.x)),maxX=Math.max(...tiles.map(t=>t.x));
     const minY=Math.min(...tiles.map(t=>t.y)),maxY=Math.max(...tiles.map(t=>t.y));
     if(maxX-minX>30||maxY-minY>30)throw Error('Track preview is too large');
-    return {tiles,start,bounds:{minX,maxX,minY,maxY}};
+    return {tiles,start,startConnection,bounds:{minX,maxX,minY,maxY}};
   }
   function render(canvas,track){
     const context=canvas.getContext('2d');
@@ -63,25 +88,16 @@
       context.beginPath();context.roundRect(x+2,y+2,size-4,size-4,Math.max(4,size*.13));context.fill();
       context.strokeStyle='#d7e8f2';context.lineWidth=Math.max(1,size*.018);
       context.stroke();
-      const edge=connection=>{
-        const offset=(connection.index-1)*size*.16;
-        switch(connection.side){
-          case 0:return [x+size/2+offset,y+2];
-          case 1:return [x+size/2+offset,y+size-2];
-          case 2:return [x+2,y+size/2+offset];
-          case 3:return [x+size-2,y+size/2+offset];
-          default:return [x+size/2,y+size/2];
-        }
-      };
       if(Array.isArray(tile.connections)&&tile.connections.length>=2){
-        const a=edge(tile.connections[0]),z=edge(tile.connections[1]);
+        const a=connectionPoint(tile.connections[0],x,y,size),z=connectionPoint(tile.connections[1],x,y,size);
         context.beginPath();context.moveTo(...a);
         context.quadraticCurveTo(x+size/2,y+size/2,...z);
         context.strokeStyle='#f3a967';context.lineWidth=Math.max(3,size*.055);
         context.lineCap='round';context.stroke();
       }
     }
-    const sx=left+(track.start[0]-b.minX+.5)*size,sy=top+(track.start[1]-b.minY+.5)*size;
+    const startX=left+(track.start[0]-b.minX)*size,startY=top+(track.start[1]-b.minY)*size;
+    const [sx,sy]=connectionPoint(track.startConnection,startX,startY,size);
     context.beginPath();context.arc(sx,sy,Math.max(6,size*.105),0,Math.PI*2);
     context.fillStyle='#66e5aa';context.fill();context.strokeStyle='#0c1926';context.lineWidth=3;context.stroke();
   }
@@ -106,10 +122,10 @@
         if(current!==version)return;
         render(canvas,track);
         const counts=[0,0,0];track.tiles.forEach(tile=>counts[tile.surface]++);
-        status.textContent=source+' · '+track.tiles.length+' pieces · green dot marks the start';
+        status.textContent=source+' · '+track.tiles.length+' pieces · green dot marks the saved starting point';
         legend.textContent=NAMES.filter((_,i)=>counts[i]).map((name,index)=>{
           const i=NAMES.indexOf(name);return name+' '+counts[i];
-        }).join(' · ')+' · Piece and terrain preview; collision shapes are not shown.';
+        }).join(' · ')+' · Orange line shows the approximate route; collision shapes and car positions are not shown.';
       }catch(error){
         if(current!==version)return;
         renderEmpty();status.textContent='Map unavailable: '+error.message;legend.textContent='Training selection is unaffected.';