Allow expression input

This affects the world height, the entity scale, and all view numeric inputs.
The fields are no longer of type 'number' so that text can be entered.

macrovision.html

@@ -95,7 +95,7 @@
           World height
         </div>
         <div class="options-row">
-          <input class="options-field-numeric" type="number" id="options-height-value" min="1" value="10" step="any">
+          <input class="options-field-numeric" id="options-height-value" value="10">
           <select class="options-field-unit" id="options-height-unit">
           </select>
         </div>

macrovision.js

@@ -1335,7 +1335,18 @@ function configEntityOptions(entity, view) {
     scaleInput.id = "options-entity-scale";
 
     scaleInput.addEventListener("change", e => {
-        entity.scale = e.target.value == 0 ? 1 : e.target.value;
+        try {
+            const newScale = e.target.value == 0 ? 1 : math.evaluate(e.target.value); 
+            if (typeof(newScale) !== "number") {
+                toast("Invalid input: scale can't have any units!")
+                return;
+            }
+            entity.scale = newScale;
+        } catch {
+            toast("Invalid input: could not parse " + e.target.value)
+        }
+
+
         entity.dirty = true;
         if (config.autoFit) {
             fitWorld();
@@ -1350,9 +1361,6 @@ function configEntityOptions(entity, view) {
         e.stopPropagation();
     })
 
-    scaleInput.setAttribute("min", 1);
-    scaleInput.setAttribute("type", "number");
-    scaleInput.setAttribute("step", "any");
     setNumericInput(scaleInput, entity.scale);
 
     scaleRow.appendChild(scaleInput);
@@ -1464,9 +1472,6 @@ function configViewOptions(entity, view) {
         const input = document.createElement("input");
         input.classList.add("options-field-numeric");
         input.id = "options-view-" + key + "-input";
-        input.setAttribute("type", "number");
-        input.setAttribute("step", "any");
-        input.setAttribute("min", 1);
 
         const select = document.createElement("select");
         select.classList.add("options-field-unit");
@@ -1488,7 +1493,26 @@ function configViewOptions(entity, view) {
 
 
         input.addEventListener("change", e => {
-            const value = input.value == 0 ? 1 : input.value;
+            const raw_value = input.value == 0 ? 1 : input.value;
+            let value
+            try {
+                value = math.evaluate(raw_value).toNumber(select.value);
+            } catch {
+                try {
+                    value = math.evaluate(input.value)
+                    if (typeof(value) !== "number") {
+                        toast("Invalid input: " + value.format() + " can't convert to " + select.value)
+                        value = undefined
+                    }
+                } catch {
+                    toast("Invalid input: could not parse: " + input.value)
+                    value = undefined
+                }
+            }
+            if (value === undefined) {
+                return;
+            }
+            input.value = value
             entity.views[view][key] = math.unit(value, select.value);
             entity.dirty = true;
             if (config.autoFit) {
@@ -4031,13 +4055,29 @@ function fitEntities(targetEntities, manual = false, factor = 1.1) {
     setWorldHeight(config.height, math.multiply(height, factor));
 }
 
-// TODO why am I doing this
 function updateWorldHeight() {
     const unit = document.querySelector("#options-height-unit").value;
-    const value = Math.max(0.000000001, document.querySelector("#options-height-value").value);
+    const rawValue = document.querySelector("#options-height-value").value;
+
+    var value
+    try {
+        value = math.evaluate(rawValue)
+        if (typeof(value) !== "number") {
+            try {
+                value = value.toNumber(unit)
+            } catch {
+                toast("Invalid input: " + rawValue + " can't be converted to " + unit)
+            }
+        }
+    } catch {
+        toast("Invalid input: could not parse " + rawValue)
+        return;
+    }
+
+    const newHeight = Math.max(0.000000001, value);
     const oldHeight = config.height;
 
-    setWorldHeight(oldHeight, math.unit(value, unit));
+    setWorldHeight(oldHeight, math.unit(newHeight, unit));
 }
 
 function setWorldHeight(oldHeight, newHeight) {