add some movement helpers

src/mesh/api.js

@@ -23,6 +23,7 @@ let groups = [];
 let api = mesh.api = {
 
     group: {
+        // @returns {MeshGroup[]}
         list() {
             return groups.slice();
         },
@@ -48,14 +49,49 @@ let api = mesh.api = {
     },
 
     model: {
+        // @returns {MeshModel[]}
         list() {
             return groups.map(g => g.models).flat();
         },
 
+        // @param group {MeshModel}
         remove: (model) => {
             model.group.remove(model);
         }
     }
 };
 
+let util = mesh.util = {
+
+    // @param object {THREE.Object3D}
+    // @returns bounds modified for moto.Space
+    bounds: (object) => {
+        let box = new THREE.Box3().setFromObject(object);
+        let bnd = {
+            min: {
+                x: box.min.x,
+                y: box.min.z,
+                z: box.min.y
+                },
+            max: {
+                x: box.max.x,
+                y: box.max.z,
+                z: box.max.y
+            }
+        };
+        bnd.size = {
+            x: bnd.max.x - bnd.min.x,
+            y: bnd.max.y - bnd.min.y,
+            z: bnd.max.z - bnd.min.z
+        };
+        bnd.center = {
+            x: (bnd.max.x + bnd.min.x) / 2,
+            y: (bnd.max.y + bnd.min.y) / 2,
+            z: (bnd.max.z + bnd.min.z) / 2
+        };
+        return bnd;
+    }
+
+};
+
 })();

src/mesh/group.js

@@ -26,7 +26,30 @@ mesh.group = class MeshGroup {
     }
 
     bounds() {
-        return new THREE.Box3().setFromObject(this.group);
+        return mesh.util.bounds(this.group);
+    }
+
+    floor() {
+        let b = this.bounds();
+        this.move(0, 0, -b.min.z);
+    }
+
+    centerXY() {
+        let b = this.bounds();
+        this.move(-b.center.x, -b.center.y, 0);
+    }
+
+    move(x = 0, y = 0, z = 0) {
+        let pos = this.position();
+        pos.set(pos.x + x, pos.y + y, pos.z + z);
+    }
+
+    position() {
+        let pos = this.group.position;
+        if (arguments.length === 0) {
+            return pos;
+        }
+        pos.set(...arguments);
     }
 
     // @param model {MeshModel}

src/mesh/model.js

@@ -39,7 +39,30 @@ mesh.model = class MeshModel {
     }
 
     bounds() {
-        return new THREE.Box3().setFromObject(this.mesh);
+        return mesh.util.bounds(this.mesh);
+    }
+
+    floor() {
+        let b = this.bounds();
+        this.move(0, 0, -b.min.z);
+    }
+
+    centerXY() {
+        let b = this.bounds();
+        this.move(-b.center.x, -b.center.y, 0);
+    }
+
+    move(x = 0, y = 0, z = 0) {
+        let pos = this.position();
+        pos.set(pos.x + x, pos.y + y, pos.z + z);
+    }
+
+    position() {
+        let pos = this.mesh.position;
+        if (arguments.length === 0) {
+            return pos;
+        }
+        pos.set(...this.arguments);
     }
 
     load(vertices, indices) {