fix dithering bug

script.js

@@ -599,9 +599,11 @@
     const pCols = OUTPUT_SIZE;
     const pRows = OUTPUT_SIZE;
 
-    outputCanvas.width = pCols * currentPatternSize;
-    outputCanvas.height = pRows * currentPatternSize;
-    outputCtx.clearRect(0, 0, outputCanvas.width, outputCanvas.height);
+    const canvasWidth = pCols + currentPatternSize - 1;
+    const canvasHeight = pRows + currentPatternSize - 1;
+    outputCanvas.width = canvasWidth;
+    outputCanvas.height = canvasHeight;
+    outputCtx.clearRect(0, 0, canvasWidth, canvasHeight);
 
     stats.grid.pCols = pCols;
     stats.grid.pRows = pRows;
@@ -743,19 +745,34 @@
         Object.assign(stats.memory, payload.memory || {});
         break;
       case 'WFC_COMPLETE':
-        phase = 'done';
-        statusEl.textContent = 'WFC complete!';
-        stats.wfcRun.status = 'WFC Complete!';
-        if (payload.finalStats)
+      phase = 'done';
+      statusEl.textContent = 'WFC complete!';
+      stats.wfcRun.status = 'WFC Complete!';
+      if (payload.finalStats) {
           Object.assign(stats.wfcRun, payload.finalStats.wfcRun || {});
-        if (stats.wfcRun.startTime > 0 && stats.wfcRun.endTime === 0) {
+      }
+      if (stats.wfcRun.startTime > 0 && stats.wfcRun.endTime === 0) {
           stats.wfcRun.endTime = performance.now();
-          stats.wfcRun.durationMs =
-            stats.wfcRun.endTime - stats.wfcRun.startTime;
-        }
-        processAndDrawDirtyTiles();
-        if (solverWorker) solverWorker.terminate();
-        break;
+          stats.wfcRun.durationMs = stats.wfcRun.endTime - stats.wfcRun.startTime;
+      }
+
+      // Use the definitive final grid from the payload to force a full redraw.
+      if (payload.finalGrid) {
+          payload.finalGrid.forEach((row, r) => {
+              row.forEach((cellOptions, c) => {
+                  // We use addDirtyTile to update our internal state and queue the draw
+                  addDirtyTile(c, r, cellOptions);
+              });
+          });
+      }
+      
+      // Immediately draw all the tiles from the final grid.
+      processAndDrawDirtyTiles(); 
+
+      if (solverWorker) {
+          solverWorker.terminate();
+      }
+      break;
       case 'WFC_FAILED':
         phase = 'error';
         statusEl.textContent = payload.message || 'WFC failed.';
@@ -854,8 +871,8 @@
   function drawTile(c, r, cellOptions, patternArrayForDrawing, pSize) {
     if (!cellOptions || !patternArrayForDrawing) return;
     const numOptions = cellOptions.length;
-    const pixelX = c * pSize;
-    const pixelY = r * pSize;
+    const pixelX = c;
+    const pixelY = r;
 
     if (numOptions === 1) {
       drawCollapsedPatternForCell(

wfc_setup_worker.js

@@ -215,6 +215,9 @@ function extractPatterns() {
   });
 }
 
+// --- CORRECTED `buildAdjacency` for the OVERLAPPING MODEL ---
+// --- Paste this into wfc_setup_worker.js ---
+
 function buildAdjacency() {
   const t1 = performance.now();
   adjacency = {};
@@ -223,7 +226,6 @@ function buildAdjacency() {
   let ruleCount = 0;
 
   for (const pat of patterns) {
-    // patterns is an array of pattern objects
     adjacency[pat.id] = { up: [], down: [], left: [], right: [] };
   }
 
@@ -240,15 +242,18 @@ function buildAdjacency() {
         ruleCount++;
         continue;
       }
+      
+      // Check if q can be to the RIGHT of p (OVERLAPPING MODEL)
+      // The right N-1 columns of p must match the left N-1 columns of q.
       let canSitRight = true;
       if (pSize > 1) {
-        for (let r = 0; r < pSize; r++) {
-          for (let c = 0; c < pSize - 1; c++) {
+        for (let r = 0; r < pSize; r++) {           // For each row
+          for (let c = 0; c < pSize - 1; c++) {   // For each overlapping column
             for (let ch = 0; ch < 4; ch++) {
-              if (
-                p.cells[(r * pSize + (c + 1)) * 4 + ch] !==
-                q.cells[(r * pSize + c) * 4 + ch]
-              ) {
+              // Compare p's pixel at [r][c+1] with q's pixel at [r][c]
+              const pPixel = p.cells[(r * pSize + (c + 1)) * 4 + ch];
+              const qPixel = q.cells[(r * pSize + c) * 4 + ch];
+              if (pPixel !== qPixel) {
                 canSitRight = false;
                 break;
               }
@@ -258,7 +263,7 @@ function buildAdjacency() {
           if (!canSitRight) break;
         }
       } else {
-        canSitRight = true;
+        canSitRight = true; // 1x1 patterns are always adjacent
       }
 
       if (canSitRight) {
@@ -268,15 +273,17 @@ function buildAdjacency() {
         ruleCount++;
       }
 
+      // Check if q can be DOWN from p (OVERLAPPING MODEL)
+      // The bottom N-1 rows of p must match the top N-1 rows of q.
       let canSitDown = true;
       if (pSize > 1) {
-        for (let c_col = 0; c_col < pSize; c_col++) {
-          for (let r_row = 0; r_row < pSize - 1; r_row++) {
+        for (let r = 0; r < pSize - 1; r++) {   // For each overlapping row
+          for (let c = 0; c < pSize; c++) {     // For each column in that row
             for (let ch = 0; ch < 4; ch++) {
-              if (
-                p.cells[((r_row + 1) * pSize + c_col) * 4 + ch] !==
-                q.cells[(r_row * pSize + c_col) * 4 + ch]
-              ) {
+              // Compare p's pixel at [r+1][c] with q's pixel at [r][c]
+              const pPixel = p.cells[((r + 1) * pSize + c) * 4 + ch];
+              const qPixel = q.cells[(r * pSize + c) * 4 + ch];
+              if (pPixel !== qPixel) {
                 canSitDown = false;
                 break;
               }
@@ -286,7 +293,7 @@ function buildAdjacency() {
           if (!canSitDown) break;
         }
       } else {
-        canSitDown = true;
+        canSitDown = true; // 1x1 patterns are always adjacent
       }
 
       if (canSitDown) {
@@ -395,4 +402,4 @@ self.onerror = function (message, source, lineno, colno, error) {
     );
   }
   return true; // Prevents default error handling if possible
-};
+};

wfc_solver_worker.js

@@ -372,112 +372,105 @@ function runStepInWorker() {
       payload: { wfcRun: { totalBacktracks: solverRunStats.totalBacktracks } },
     });
 
+    // THIS IS THE CORRECTED BACKTRACKING LOOP
     while (backtrackStack.length > 0) {
-      const lastDecision = backtrackStack.pop();
-      const {
-        gridBeforeChoice,
-        queueBeforeChoice,
-        queuedCoordinatesSetBeforeChoice,
-        cellCoords,
-        optionsAtCell,
-        lastTriedOptionIndexInList,
-      } = lastDecision;
+        const lastDecision = backtrackStack.pop();
+        const {
+            gridBeforeChoice,
+            queueBeforeChoice,
+            queuedCoordinatesSetBeforeChoice,
+            cellCoords,
+            optionsAtCell,
+            lastTriedOptionIndexInList,
+        } = lastDecision;
 
-      const [cc, cr] = cellCoords;
-      let nextOptionIndexToTryInList = lastTriedOptionIndexInList + 1;
+        const [cc, cr] = cellCoords;
+        let nextOptionIndexToTryInList = lastTriedOptionIndexInList + 1;
 
-      if (nextOptionIndexToTryInList < optionsAtCell.length) {
-        grid = deepCopyGrid(gridBeforeChoice); // Restore state
-        queue = deepCopyQueue(queueBeforeChoice);
-        queuedCoordinatesSet = new Set(queuedCoordinatesSetBeforeChoice);
+        if (nextOptionIndexToTryInList < optionsAtCell.length) {
+            grid = deepCopyGrid(gridBeforeChoice); // Restore state
+            queue = deepCopyQueue(queueBeforeChoice);
+            queuedCoordinatesSet = new Set(queuedCoordinatesSetBeforeChoice);
 
-        const newChosenPatternIndex = optionsAtCell[nextOptionIndexToTryInList];
-        grid[cr][cc] = [newChosenPatternIndex];
-        // Post update for the cell being retried
-        self.postMessage({
-          type: 'TILE_UPDATE',
-          payload: { updates: [{ c: cc, r: cr, cellOptions: grid[cr][cc] }] },
-        });
+            const newChosenPatternIndex = optionsAtCell[nextOptionIndexToTryInList];
+            grid[cr][cc] = [newChosenPatternIndex];
+            // Post update for the cell being retried
+            self.postMessage({
+                type: 'TILE_UPDATE',
+                payload: { updates: [{ c: cc, r: cr, cellOptions: grid[cr][cc] }] },
+            });
 
-        const coordKeyBacktrack = `${cc},${cr}`;
-        if (!queuedCoordinatesSet.has(coordKeyBacktrack)) {
-          queue.push([cc, cr]);
-          queuedCoordinatesSet.add(coordKeyBacktrack);
-        }
-
-        // Push new decision point for this choice
-        if (backtrackStack.length < MAX_BACKTRACK_DEPTH_W) {
-          // Check before pushing
-          backtrackStack.push({
-            ...lastDecision, // Keep most of the old data
-            lastTriedOptionIndexInList: nextOptionIndexToTryInList, // Update the tried index
-          });
-          solverRunStats.maxBacktrackStackDepthReached = Math.max(
-            solverRunStats.maxBacktrackStackDepthReached,
-            backtrackStack.length
-          );
-          solverMemoryStats.backtrackStackPeakBytes = Math.max(
-            solverMemoryStats.backtrackStackPeakBytes,
-            backtrackStack.length * solverMemoryStats.estimatedGridSnapshotBytes
-          );
-          self.postMessage({
-            type: 'STATS_UPDATE',
-            payload: {
-              wfcRun: {
-                maxBacktrackStackDepthReached:
-                  solverRunStats.maxBacktrackStackDepthReached,
-              },
-              memory: {
-                backtrackStackPeakBytes:
-                  solverMemoryStats.backtrackStackPeakBytes,
-              },
-            },
-          });
-        } else {
-          // Cannot push new state if max depth would be exceeded by this push.
-          // This implies this new choice, if it leads to immediate contradiction, cannot be further backtracked from this exact point.
-          // This state is tricky; the original code had a check *before* collapse.
-          // For now, we just don't push if it would exceed.
-        }
-
-        self.postMessage({
-          type: 'STATUS_UPDATE',
-          payload: {
-            message: `Backtracked. Retrying option ${
-              nextOptionIndexToTryInList + 1
-            }/${optionsAtCell.length} at (${cc},${cr}). Stack: ${
-              backtrackStack.length
-            }`,
-          },
-        });
-        solverPhase = 'propagate';
-        backtrackedSuccessfully = true;
-
-        // When backtracking, the entire grid might have changed, so signal main to redraw all from current worker grid state.
-        // This is simpler than tracking all individual changes during backtrack restoration.
-        const allTilesUpdate = [];
-        for (let r_idx = 0; r_idx < pRows; r_idx++) {
-          for (let c_idx = 0; c_idx < pCols; c_idx++) {
-            if (grid[r_idx] && grid[r_idx][c_idx]) {
-              // Ensure cell exists
-              allTilesUpdate.push({
-                c: c_idx,
-                r: r_idx,
-                cellOptions: [...grid[r_idx][c_idx]],
-              });
+            const coordKeyBacktrack = `${cc},${cr}`;
+            if (!queuedCoordinatesSet.has(coordKeyBacktrack)) {
+                queue.push([cc, cr]);
+                queuedCoordinatesSet.add(coordKeyBacktrack);
             }
-          }
+
+            // THE FIX: Push the updated decision back onto the stack
+            if (backtrackStack.length < MAX_BACKTRACK_DEPTH_W) {
+                backtrackStack.push({
+                    ...lastDecision,
+                    lastTriedOptionIndexInList: nextOptionIndexToTryInList,
+                });
+                solverRunStats.maxBacktrackStackDepthReached = Math.max(
+                    solverRunStats.maxBacktrackStackDepthReached,
+                    backtrackStack.length
+                );
+                solverMemoryStats.backtrackStackPeakBytes = Math.max(
+                    solverMemoryStats.backtrackStackPeakBytes,
+                    backtrackStack.length * solverMemoryStats.estimatedGridSnapshotBytes
+                );
+                self.postMessage({
+                    type: 'STATS_UPDATE',
+                    payload: {
+                        wfcRun: {
+                            maxBacktrackStackDepthReached:
+                            solverRunStats.maxBacktrackStackDepthReached,
+                        },
+                        memory: {
+                            backtrackStackPeakBytes:
+                            solverMemoryStats.backtrackStackPeakBytes,
+                        },
+                    },
+                });
+            }
+
+            self.postMessage({
+                type: 'STATUS_UPDATE',
+                payload: {
+                message: `Backtracked. Retrying option ${
+                    nextOptionIndexToTryInList + 1
+                }/${optionsAtCell.length} at (${cc},${cr}). Stack: ${
+                    backtrackStack.length
+                }`,
+                },
+            });
+            solverPhase = 'propagate';
+            backtrackedSuccessfully = true;
+
+            const allTilesUpdate = [];
+            for (let r_idx = 0; r_idx < pRows; r_idx++) {
+                for (let c_idx = 0; c_idx < pCols; c_idx++) {
+                    if (grid[r_idx] && grid[r_idx][c_idx]) {
+                    allTilesUpdate.push({
+                        c: c_idx,
+                        r: r_idx,
+                        cellOptions: [...grid[r_idx][c_idx]],
+                    });
+                    }
+                }
+            }
+            if (allTilesUpdate.length > 0) {
+                self.postMessage({
+                    type: 'TILE_UPDATE',
+                    payload: { updates: allTilesUpdate },
+                });
+            }
+            break; // Exit backtrack loop
         }
-        if (allTilesUpdate.length > 0) {
-          self.postMessage({
-            type: 'TILE_UPDATE',
-            payload: { updates: allTilesUpdate },
-          });
-        }
-        break; // Exit backtrack loop
-      }
     }
 
+
     if (!backtrackedSuccessfully) {
       self.postMessage({
         type: 'REQUEST_RESTART_FROM_SOLVER',
@@ -493,14 +486,18 @@ function runStepInWorker() {
     }
   }
 
-  if (allCollapsed()) {
+if (allCollapsed()) {
     solverPhase = 'stop';
+    // Add the final grid to the payload. This is the definitive final state.
     self.postMessage({
       type: 'WFC_COMPLETE',
-      payload: { finalStats: { wfcRun: solverRunStats } },
+      payload: { 
+          finalStats: { wfcRun: solverRunStats },
+          finalGrid: grid 
+      },
     });
     return;
-  }
+}
 
   if (maxTriesInWorker-- <= 0 && solverPhase !== 'propagate') {
     self.postMessage({
@@ -638,4 +635,4 @@ self.onerror = function (message, source, lineno, colno, error) {
   });
   solverPhase = 'stop'; // Stop processing on unhandled error
   return true; // Prevents default error handling
-};
+};