Celstomp · Microck · Feb 21, 2026
diff --git a/celstomp/celstomp-app.js b/celstomp/celstomp-app.js
@@ -404,6 +404,9 @@
         function clearFx() {
             fxctx.setTransform(1, 0, 0, 1, 0, 0);
             fxctx.clearRect(0, 0, fxCanvas.width, fxCanvas.height);
+            setTransform(fxctx);
+            drawGrid(fxctx);
+            drawGuides(fxctx);
         }
 
         function wireBrushButtonRightClick() {
@@ -924,6 +927,48 @@
                 playSnapped = !!e.target.checked;
                 safeSetChecked(playSnappedChk, playSnapped);
             });
+
+            const gridBtn = $("toggleGridBtn");
+            const gridSizeInp = $("gridSizeInput");
+            const gridSnapBtn = $("toggleGridSnapBtn");
+            const guidesBtn = $("toggleGuidesBtn");
+            const guideSnapBtn = $("toggleGuideSnapBtn");
+            const addGuideHBtn = $("addGuideHBtn");
+            const addGuideVBtn = $("addGuideVBtn");
+            const clearGuidesBtn = $("clearGuidesBtn");
+            guideModeHint = $("guideModeHint");
+
+            gridBtn?.addEventListener("click", () => {
+                toggleGrid();
+                gridBtn.classList.toggle("active", gridEnabled);
+            });
+            gridSizeInp?.addEventListener("input", e => {
+                gridSize = Math.max(8, Math.min(128, parseInt(e.target.value, 10) || 32));
+                queueRenderAll();
+            });
+            gridSnapBtn?.addEventListener("click", () => {
+                toggleGridSnap();
+                gridSnapBtn.classList.toggle("active", gridSnap);
+            });
+            guidesBtn?.addEventListener("click", () => {
+                toggleGuides();
+                guidesBtn.classList.toggle("active", guidesEnabled);
+            });
+            guideSnapBtn?.addEventListener("click", () => {
+                toggleGuideSnap();
+                guideSnapBtn.classList.toggle("active", guideSnap);
+            });
+            addGuideHBtn?.addEventListener("click", () => {
+                setGuideMode(guideMode === 'h' ? null : 'h');
+                addGuideHBtn.classList.toggle("active", guideMode === 'h');
+                addGuideVBtn?.classList.remove("active");
+            });
+            addGuideVBtn?.addEventListener("click", () => {
+                setGuideMode(guideMode === 'v' ? null : 'v');
+                addGuideVBtn.classList.toggle("active", guideMode === 'v');
+                addGuideHBtn?.classList.remove("active");
+            });
+            clearGuidesBtn?.addEventListener("click", clearGuides);
         }
 
         function wirePanelToggles() {

diff --git a/celstomp/css/components/timeline.css b/celstomp/css/components/timeline.css
@@ -401,3 +401,29 @@ body.dragging-cel{ cursor: grabbing; user-select:none; }
     padding: 6px 8px;
   }
 }
+
+.gridGuideCtrls {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+}
+
+.gridGuideCtrls button.active {
+  background: rgba(0, 229, 255, 0.25);
+  border-color: rgba(0, 229, 255, 0.6);
+}
+
+.guideModeHint {
+  position: fixed;
+  bottom: calc(var(--timeline-h) + 8px);
+  left: 50%;
+  transform: translateX(-50%);
+  background: rgba(0, 229, 255, 0.18);
+  border: 1px solid rgba(0, 229, 255, 0.5);
+  color: #9fd5ff;
+  padding: 6px 12px;
+  border-radius: 8px;
+  font-size: 12px;
+  z-index: 100;
+  pointer-events: none;
+}
diff --git a/celstomp/js/input/pointer-events.js b/celstomp/js/input/pointer-events.js
@@ -11,6 +11,16 @@ let usePressureTilt = false;
 let brushSize = 3;
 let autofill = false;
 
+let gridEnabled = false;
+let gridSize = 32;
+let gridSnap = false;
+let guidesEnabled = false;
+let guideSnap = false;
+let guideHLines = [];
+let guideVLines = [];
+let guideMode = null;
+let guideModeHint = null;
+
 let trailPoints = [];
 
 function pressure(e) {
@@ -47,6 +57,14 @@ function handlePointerDown(e) {
           return;
       }
   }
+  if (guideMode && e.button === 0) {
+      const pos = getCanvasPointer(e);
+      const pt = screenToContent(pos.x, pos.y);
+      if (handleGuideClick(pt.x, pt.y)) {
+          e.preventDefault();
+          return;
+      }
+  }
   try {
       drawCanvas.setPointerCapture(e.pointerId);
   } catch {}
@@ -1487,3 +1505,104 @@ function fillFromLineart(F) {
     updateTimelineHasContent(F);
     return true;
 }
+
+function drawGrid(ctx) {
+    if (!gridEnabled) return;
+    ctx.save();
+    ctx.strokeStyle = "rgba(255,255,255,0.12)";
+    ctx.lineWidth = 1 / Math.max(getZoom(), 1);
+    ctx.beginPath();
+    for (let x = 0; x <= contentW; x += gridSize) {
+        ctx.moveTo(x, 0);
+        ctx.lineTo(x, contentH);
+    }
+    for (let y = 0; y <= contentH; y += gridSize) {
+        ctx.moveTo(0, y);
+        ctx.lineTo(contentW, y);
+    }
+    ctx.stroke();
+    ctx.restore();
+}
+
+function drawGuides(ctx) {
+    if (!guidesEnabled) return;
+    ctx.save();
+    ctx.strokeStyle = "rgba(0,229,255,0.6)";
+    ctx.lineWidth = 1 / Math.max(getZoom(), 1);
+    ctx.setLineDash([4 / Math.max(getZoom(), 1), 2 / Math.max(getZoom(), 1)]);
+    ctx.beginPath();
+    for (const y of guideHLines) {
+        ctx.moveTo(0, y);
+        ctx.lineTo(contentW, y);
+    }
+    for (const x of guideVLines) {
+        ctx.moveTo(x, 0);
+        ctx.lineTo(x, contentH);
+    }
+    ctx.stroke();
+    ctx.restore();
+}
+
+function snapToGrid(x, y) {
+    if (!gridEnabled || !gridSnap) return { x, y };
+    return {
+        x: Math.round(x / gridSize) * gridSize,
+        y: Math.round(y / gridSize) * gridSize
+    };
+}
+
+function snapToGuides(x, y) {
+    if (!guidesEnabled || !guideSnap) return { x, y };
+    const threshold = 8;
+    let sx = x, sy = y;
+    for (const gy of guideHLines) {
+        if (Math.abs(y - gy) < threshold) sy = gy;
+    }
+    for (const gx of guideVLines) {
+        if (Math.abs(x - gx) < threshold) sx = gx;
+    }
+    return { x: sx, y: sy };
+}
+
+function toggleGrid() {
+    gridEnabled = !gridEnabled;
+    queueRenderAll();
+}
+
+function toggleGridSnap() {
+    gridSnap = !gridSnap;
+}
+
+function toggleGuides() {
+    guidesEnabled = !guidesEnabled;
+    queueRenderAll();
+}
+
+function toggleGuideSnap() {
+    guideSnap = !guideSnap;
+}
+
+function clearGuides() {
+    guideHLines = [];
+    guideVLines = [];
+    queueRenderAll();
+}
+
+function setGuideMode(mode) {
+    guideMode = mode;
+    if (guideModeHint) {
+        guideModeHint.textContent = mode ? `Click to place ${mode === 'h' ? 'horizontal' : 'vertical'} guide` : '';
+        guideModeHint.hidden = !mode;
+    }
+}
+
+function handleGuideClick(x, y) {
+    if (!guideMode) return false;
+    if (guideMode === 'h') {
+        guideHLines.push(Math.round(y));
+    } else if (guideMode === 'v') {
+        guideVLines.push(Math.round(x));
+    }
+    queueRenderAll();
+    return true;
+}
diff --git a/celstomp/js/ui/interaction-shortcuts.js b/celstomp/js/ui/interaction-shortcuts.js
@@ -491,6 +491,14 @@ function _wireExtraKeyboardShortcuts() {
           return;
       }
 
+      if (k === "g") {
+          e.preventDefault();
+          toggleGrid();
+          const gridBtn = document.getElementById("toggleGridBtn");
+          if (gridBtn) gridBtn.classList.toggle("active", gridEnabled);
+          return;
+      }
+
       if (k === "[") {
           e.preventDefault();
           brushSize = Math.max(1, brushSize - 5);

diff --git a/celstomp/parts/timeline.js b/celstomp/parts/timeline.js
@@ -48,6 +48,17 @@ document.getElementById('part-timeline').innerHTML = `
         <span class="timelineZoom">Zoom</span>
         <button id="zoomTimelineIn" class="miniBtn" title="Zoom In">+</button>
 
+        <div class="gridGuideCtrls">
+          <button id="toggleGridBtn" class="miniBtn" title="Toggle Grid (G)">Grid</button>
+          <input id="gridSizeInput" type="number" min="8" max="128" value="32" title="Grid Size" style="width:50px;" />
+          <button id="toggleGridSnapBtn" class="miniBtn" title="Toggle Grid Snap">Snap</button>
+          <button id="toggleGuidesBtn" class="miniBtn" title="Toggle Guides">Guides</button>
+          <button id="toggleGuideSnapBtn" class="miniBtn" title="Toggle Guide Snap">GSnap</button>
+          <button id="addGuideHBtn" class="miniBtn" title="Add Horizontal Guide">H Guide</button>
+          <button id="addGuideVBtn" class="miniBtn" title="Add Vertical Guide">V Guide</button>
+          <button id="clearGuidesBtn" class="miniBtn danger" title="Clear Guides">Clear</button>
+        </div>
+
         <button id="hideTimelineBtn">—</button>
       </div>
     </div>
@@ -60,6 +71,6 @@ document.getElementById('part-timeline').innerHTML = `
     </div>
   </section>
 
-
   <button id="showTimelineEdge" class="edge-btn">Show Timeline</button>
+  <div id="guideModeHint" class="guideModeHint" hidden></div>
 `;