Add the mousex and mousey signal

packages/core/signal.mjs

@@ -86,6 +86,25 @@ export const tri2 = fastcat(isaw2, saw2);
 
 export const time = signal(id);
 
+
+/**
+ *  The mouse's x or y position value ranges from 0 to 1.
+ *
+ * @return {Pattern}
+ * @example
+ * n(mousex.segment(4).range(0,7)).scale("C:minor")
+ * n(mousey.segment(4).range(0,7)).scale("C:minor")
+ *
+ */
+let _mouseY=0,_mouseX=0
+document.onmousemove = (e) => {
+  _mouseY = e.clientY / document.body.clientHeight;
+  _mouseX = e.clientX / document.body.clientWidth;
+};
+
+export const mousey = signal(() => _mouseY);
+export const mousex = signal(() => _mouseX);
+
 // random signals
 
 const xorwise = (x) => {