Added a newFrame() method to UniformBindingManager

to signal the beginning of a frame.  Currently this
just grabs the time and tpf values once so as to avoid
per-material Float allocation and time drift within a
frame.
RenderManager now calls this at the beginning of the
root-level render() method.

jme3-core/src/main/java/com/jme3/renderer/RenderManager.java

@@ -1035,6 +1035,7 @@ public class RenderManager {
         }
 
         this.shader = renderer.getCaps().contains(Caps.GLSL100);
+        uniformBindingManager.newFrame();        
 
         for (int i = 0; i < preViewPorts.size(); i++) {
             ViewPort vp = preViewPorts.get(i);

jme3-core/src/main/java/com/jme3/shader/UniformBindingManager.java

@@ -51,7 +51,8 @@ import java.util.List;
 public class UniformBindingManager {
 
     private Timer timer;
-    private float near, far;
+    private Float near, far;
+    private Float time, tpf;
     private int viewX, viewY, viewWidth, viewHeight;
     private Vector3f camUp = new Vector3f(),
             camLeft = new Vector3f(),
@@ -196,10 +197,10 @@ public class UniformBindingManager {
                     u.setValue(VarType.Vector3, camUp);
                     break;
                 case Time:
-                    u.setValue(VarType.Float, timer.getTimeInSeconds());
+                    u.setValue(VarType.Float, time);
                     break;
                 case Tpf:
-                    u.setValue(VarType.Float, timer.getTimePerFrame());
+                    u.setValue(VarType.Float, tpf);
                     break;
                 case FrameRate:
                     u.setValue(VarType.Float, timer.getFrameRate());
@@ -251,4 +252,15 @@ public class UniformBindingManager {
         this.viewWidth = viewWidth;
         this.viewHeight = viewHeight;
     }
+ 
+    /**
+     *  Internal use only.  Called by the RenderManager at the beginning of a
+     *  new application frame.
+     */   
+    public void newFrame() {
+        // Avoid per-material Float allocations and lock in the
+        // time for this frame to avoid inter-frame drift.
+        time = timer.getTimeInSeconds();
+        tpf = timer.getTimePerFrame();
+    }
 }