ast+execute+js: compile sensing_distanceto

src/compiler/astgen.js

@@ -578,6 +578,11 @@ class ScriptTreeGenerator {
                 kind: 'constant',
                 value: block.fields.DISTANCETOMENU.value
             };
+        case 'sensing_distanceto':
+            return {
+                kind: 'sensing.distance',
+                target: this.descendInput(block, 'DISTANCETOMENU')
+            };
         case 'sensing_keyoptions':
             return {
                 kind: 'constant',

src/compiler/compat-blocks.js

@@ -49,7 +49,6 @@ const inputs = [
     'music_getTempo',
     'sensing_answer',
     'sensing_current',
-    'sensing_distanceto',
     'sensing_loud',
     'sensing_loudness',
     'sensing_of',

src/compiler/execute.js

@@ -289,7 +289,7 @@ const randomFloat = (low, high) => {
  * Perform an IO query
  * @param {string} device The name of the device to query
  * @param {string} func The function of the device to query
- * @param {*} args The arguments to pass to the device
+ * @param {*} [args] The arguments to pass to the device
  * @returns {*} The value returned by the IO device
  */
 const ioQuery = (device, func, args) => {
@@ -329,6 +329,31 @@ const daysSince2000 = () => {
     return mSecsSinceStart / (24 * 60 * 60 * 1000);
 };
 
+/**
+ * Determine distance to a sprite or point.
+ * @param {string} menu The name of the sprite or location to find.
+ * @returns {number} Distance to the point, or 10000 if it cannot be calculated.
+ */
+const distance = menu => {
+    if (thread.target.isStage) return 10000;
+
+    let targetX = 0;
+    let targetY = 0;
+    if (menu === '_mouse_') {
+        targetX = ioQuery('mouse', 'getScratchX');
+        targetY = ioQuery('mouse', 'getScratchY');
+    } else {
+        const distTarget = thread.target.runtime.getSpriteTargetByName(menu);
+        if (!distTarget) return 10000;
+        targetX = distTarget.x;
+        targetY = distTarget.y;
+    }
+
+    const dx = thread.target.x - targetX;
+    const dy = thread.target.y - targetY;
+    return Math.sqrt((dx * dx) + (dy * dy));
+};
+
 /**
  * Convert a Scratch list index to a JavaScript list index.
  * "all" is not considered as a list index.

src/compiler/jsgen.js

@@ -466,6 +466,9 @@ class JSGenerator {
             return new TypedInput(`target.colorIsTouchingColor(colorToList(${this.descendInput(node.target).asUnknown()}), colorToList(${this.descendInput(node.mask).asUnknown()}))`, TYPE_BOOLEAN);
         case 'sensing.daysSince2000':
             return new TypedInput('daysSince2000()', TYPE_NUMBER);
+        case 'sensing.distance':
+            // TODO: on stages, this can be computed at compile time
+            return new TypedInput(`distance(${this.descendInput(node.target).asString()})`, TYPE_NUMBER);
         case 'sensing.touching':
             return new TypedInput(`target.isTouchingObject(${this.descendInput(node.object).asUnknown()})`, TYPE_BOOLEAN);
         case 'sensing.touchingColor':