fluid fixes

fluid.html

@@ -399,6 +399,9 @@
     let isDown = false;
     let running = true;
     let animId = null;
+    let idleFrames = 0;
+    const AUTO_BURST_INTERVAL = 600;
+    const IDLE_RESET_FRAMES = 120;
 
     function canvasCoords(e) {
       const rect = canvas.getBoundingClientRect();
@@ -686,6 +689,7 @@
       if (keyState['d']) fluidPanX -= 0.01 / fluidZoom;
 
       if (isDown && prevMouseX >= 0) {
+        idleFrames = 0;
         const mx = (mouseX - canvas.width / 2) / canvas.width / fluidZoom + fluidPanX + 0.5;
         const my = (mouseY - canvas.height / 2) / canvas.height / fluidZoom + fluidPanY + 0.5;
         const pmx = (prevMouseX - canvas.width / 2) / canvas.width / fluidZoom + fluidPanX + 0.5;
@@ -693,6 +697,15 @@
         const dx = mx - pmx;
         const dy = my - pmy;
         addForce(dx * 3, dy * 3, mx, my, 0.04 / fluidZoom);
+      } else {
+        idleFrames++;
+        if (idleFrames > IDLE_RESET_FRAMES && idleFrames % AUTO_BURST_INTERVAL === 0) {
+          let totalDye = 0;
+          for (let i = 0; i < d.length; i++) totalDye += d[i];
+          if (totalDye < 1) {
+            burstCenter();
+          }
+        }
       }
 
       step();
@@ -719,6 +732,7 @@
       mouseX = p.x; mouseY = p.y;
       prevMouseX = mouseX; prevMouseY = mouseY;
       isDown = true;
+      idleFrames = 0;
     }
 
     function mouseMove(e) {
@@ -743,6 +757,7 @@
       mouseX = p.x; mouseY = p.y;
       prevMouseX = mouseX; prevMouseY = mouseY;
       isDown = true;
+      idleFrames = 0;
     }
 
     function touchMove(e) {
@@ -770,6 +785,7 @@
 
     document.addEventListener('keydown', (e) => {
       if (e.key === 'Escape') window.location.href = 'index.html';
+      if (e.key.toLowerCase() === 'r') { resetFluid(); idleFrames = 0; }
     });
 
     window.addEventListener('resize', resizeFluid);