From 69a4f8f6dd638364ba8bf35dd70031148ac4b4ef Mon Sep 17 00:00:00 2001
From: Peter Wu <lekensteyn@gmail.com>
Date: Thu, 5 Dec 2013 12:24:22 +0100
Subject: Add FPS counter.

---
 src/RobotRace.java | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

(limited to 'src')

diff --git a/src/RobotRace.java b/src/RobotRace.java
index 5d5a99c..ba042af 100644
--- a/src/RobotRace.java
+++ b/src/RobotRace.java
@@ -4,15 +4,18 @@ import java.awt.Desktop;
 import java.awt.KeyEventDispatcher;
 import java.awt.KeyboardFocusManager;
 import java.awt.event.KeyEvent;
+import java.awt.Window;
 import java.io.IOException;
 import javax.media.opengl.GL;
 import static javax.media.opengl.GL2.*;
 import javax.swing.UIManager;
 import robotrace.Base;
+import robotrace.MainFrame;
 import robotrace.Vector;
 import static java.lang.Math.*;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.util.Locale;
 
 /**
  * Handles all of the RobotRace graphics functionality,
@@ -95,6 +98,21 @@ public class RobotRace extends Base {
      */
     private boolean lightingEnabled = true;
 
+    /**
+     * The main window for this program.
+     */
+    private MainFrame mainWindow;
+
+    /**
+     * Frames per second monitor: total frames in the past period.
+     */
+    private float frames;
+    /**
+     * Frames per second monitor: the timestamp in milliseconds for the begin of
+     * the previous period (or 0 if there is no previous period.)
+     */
+    private long last_frame_time;
+
     /**
      * Constructs this robot race by initializing robots, camera, track, and
      * terrain.
@@ -104,6 +122,16 @@ public class RobotRace extends Base {
         BetterBase.setGLU(glu);
         BetterBase.setGLUT(glut);
 
+        // find the MainFrame
+        for (Window w : Window.getWindows()) {
+            if (w instanceof MainFrame) {
+                mainWindow = (MainFrame) w;
+            }
+        }
+        if (mainWindow == null) {
+            System.err.println("No window found, FPS will be unavailable!");
+        }
+
         // Create a new array of four robots
         robots = new Robot[4];
 
@@ -186,11 +214,41 @@ public class RobotRace extends Base {
         gl.glEnable(GL_NORMALIZE);
     }
 
+    /**
+     * Updates the title with frames per second.
+     */
+    private void updateFPS() {
+        // just to be sure, avoid accessing the window if unavailable
+        if (mainWindow == null) {
+            return;
+        }
+
+        long now = System.currentTimeMillis();
+        float timediff = (now - last_frame_time) / 1000.0f;
+        frames++;
+        // periodically update the frame time
+        if (timediff >= 1.0f) {
+            // prevent inaccurate FPS on start
+            if (last_frame_time != 0) {
+                float fps = frames / timediff;
+                // display FPS with 2 decimals at most
+                mainWindow.setTitle(String.format(Locale.getDefault(), "RobotRace (FPS %.2f)", fps));
+            }
+            last_frame_time = now;
+            frames = 0;
+        }
+    }
+
     /**
      * Configures the viewing transform.
      */
     @Override
     public void setView() {
+        // due to limitations of the Base class (unable to override display
+        // function), the FPS update is done in the first accessible function
+        // (here, in setView)
+        updateFPS();
+
         // Select part of window.
         gl.glViewport(0, 0, gs.w, gs.h);
 
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