diff --git a/TODO b/TODO
index b0c6030..ace741a 100644
--- a/TODO
+++ b/TODO
@@ -20,6 +20,7 @@ Documentation
 
 Coding (Python editor)
 - Documentation panel?
+- Zoom in/out
 
 Coding (Robot configurator)
 - Help menu
@@ -36,6 +37,9 @@ Coding (Simulator)
   - touch sensor (simplified laser rangefinder with very short range)
 - Prevent jumping over wall when backing up. (Increasing wall friction doesn't work...)
 - Set duty_cycle_sp. Useful for aligning to wall.
+- Remote control
+- Buttons
+- Load zip file
 
 Coding (Sharing)
 - Remote coach view of student's work
diff --git a/public/js/babylon.js b/public/js/babylon.js
index 49ff294..100ded9 100644
--- a/public/js/babylon.js
+++ b/public/js/babylon.js
@@ -187,7 +187,7 @@ var babylon = new function() {
 
       // RTT test
       // var mat = new BABYLON.StandardMaterial("RTT mat", self.scene);
-      // mat.diffuseTexture = robot.getComponentByPort('in5').renderTarget;
+      // mat.diffuseTexture = robot.getComponentByPort('in1').renderTarget;
       // mat.emissiveColor = new BABYLON.Color3(1,1,1);
       // mat.disableLighting = true;
 
@@ -210,6 +210,9 @@ var babylon = new function() {
       self.scene.meshes.forEach(function(mesh) {
         mesh.origMaterial = mesh.material;
         if (mesh.material == null) {
+          if (mesh.visibility) {
+            console.log('WARNING: ' + mesh.id + ' does not have a material');
+          }
           mesh.rttMaterial == null;
         } else {
           let rttID = 'RTT_' + mesh.material.id;
@@ -224,6 +227,8 @@ var babylon = new function() {
               mesh.rttMaterial.emissiveColor = mesh.rttMaterial.diffuseColor;
             }
             mesh.rttMaterial.freeze();
+          } else {
+            mesh.rttMaterial = mat;
           }
         }
       });
diff --git a/public/js/world_Paintball.js b/public/js/world_Paintball.js
index cf0519b..4d4b54e 100644
--- a/public/js/world_Paintball.js
+++ b/public/js/world_Paintball.js
@@ -157,7 +157,7 @@ var world_Paintball = new function() {
   this.loadFindTarget = function(scene) {
     let ground = self.addCylinder(
       scene,
-      null,
+      babylon.getMaterial(scene, 'fff'),
       [10, 1000],
       [0,0,-10]
     );