Add ant brush element with keybinding and GUI entry

src/GUI.ts

@@ -73,6 +73,7 @@ class GUIController {
             "rock  (E)": MAT_ROCK,
             "food  (W)": MAT_FOOD,
             "home  (Q)": MAT_HOME,
+            "ants  (A)": 999,
         };
 
         // proxy object for lil-gui string dropdown — initialize from saved config

src/scenes/ScreenScene.ts

@@ -15,6 +15,8 @@ import fragmentShaderGround from "../shaders/screenWorld.frag";
 import vertexShaderGround from "../shaders/screenWorld.vert";
 import AbstractScene from "./AbstractScene";
 
+export const BRUSH_ANTS = 999;
+
 export default class ScreenScene extends AbstractScene {
     public readonly camera: THREE.OrthographicCamera;
     public readonly material: THREE.ShaderMaterial;
@@ -33,11 +35,21 @@ export default class ScreenScene extends AbstractScene {
 
     // resolves active draw mode: key-held takes priority, then GUI brush selection
     public get effectiveDrawMode(): number {
+        if (this.drawMode === BRUSH_ANTS) return -1;
         if (this.drawMode >= 0) return this.drawMode;
-        if (this.isPointerDown && Config.brushMaterial >= 0)
+        if (this.isPointerDown && Config.brushMaterial >= 0) {
+            if (Config.brushMaterial === BRUSH_ANTS) return -1;
             return Config.brushMaterial;
+        }
         return -1;
     }
+
+    public get isAntBrushActive(): boolean {
+        if (this.drawMode === BRUSH_ANTS) return true;
+        if (this.isPointerDown && Config.brushMaterial === BRUSH_ANTS)
+            return true;
+        return false;
+    }
     public renderWidth: number = 1;
     public renderHeight: number = 1;
 
@@ -188,6 +200,10 @@ export default class ScreenScene extends AbstractScene {
                     this.drawMode = MAT_DIRT;
                     break;
                 }
+                case "KeyA": {
+                    this.drawMode = BRUSH_ANTS;
+                    break;
+                }
                 case "KeyV": {
                     Config.viewMode =
                         Config.viewMode === "side" ? "top" : "side";
@@ -276,7 +292,16 @@ export default class ScreenScene extends AbstractScene {
         this.renderHeight = height;
     }
 
-    public update() {}
+    public update() {
+        if (this.isAntBrushActive && this.isPointerDown) {
+            this.antSpawnRequest.set(
+                this.pointerPosition.x,
+                this.pointerPosition.y,
+                Config.brushRadius,
+                1, // flag: spawn requested
+            );
+        }
+    }
 
     public applyCameraZoom() {
         this.updateCameraZoom();