Last-minute GUI fixes to make music cross-fade when switching between tracks. Also made it switch back to the main theme on End Game.

This was SVN commit r1396.

binaries/data/mods/official/gui/test/2_mainmenu.xml

@@ -15,12 +15,6 @@
                 // Play main 0 A.D. theme when the main menu starts.
 		curr_music = newRandomSound("music", "theme");
 		curr_music.loop();
-//		curr_session_playlist_1 = newRandomSound("music", "peace");
-//		curr_session_playlist_1.play();
-//		curr_session_playlist_1.free();
-//		curr_session_playlist_2 = newRandomSound("music", "peace");
-//		curr_session_playlist_2.play();
-//		curr_session_playlist_2.free();
         ]]></action>
 
         <object type="image" name="pregame-mainmenu-background-image" sprite="pregame-mainmenu-background" size="0 0 100% 100%" z="100" hidden="false" />
@@ -32,9 +26,10 @@
                 GUIObjectUnhide("End_Game_Button");
                 GUIObjectHide("pregame_gui");
                 FlipGUI(GUIType);
-		curr_music.free(); // Close main theme when starting game session.
+		// Select session peace track.
 		curr_session_playlist_1 = newRandomSound("music", "peace");
-		curr_session_playlist_1.play();
+		// Fade out main theme and fade in session theme.
+		CrossFade(curr_music, curr_session_playlist_1, 0.0001);
             ]]></action>
             <action on="MouseEnter"><![CDATA[
                 tooltipObject = getGUIObjectByName("pregame-mainmenu-tooltip");

binaries/data/mods/official/gui/test/6_global.xml

@@ -18,7 +18,7 @@
                 <object type="button" name="exit_button" sprite="exit_sprite" sprite-over="exit_sprite-over" size="100%-18 2 100%-2 18" z="1000" hidden="false">
                         <action on="Press"><![CDATA[
                                 btCaptions = new Array("Yes, let me out!", "Nooooo!");
-                                btCode = new Array("curr_music.free();\nexit();", "");
+                                btCode = new Array("exit();", "");
                                 messageBox(400, 200, "Do you really want to quit [icon=0ad_icon] A.D.? This will cause a sudden return to reality.", "Confirmation", 0, btCaptions, btCode);
                         ]]></action>
 
@@ -39,9 +39,9 @@
 
                 <object type="button" name="End_Game_Button" sprite="message_box-button-normal" sprite-over="message_box-button-over" hotkey="endgame" text-align="center" text-valign="center" size="100%-200 2 100%-100 36" z="105" hidden="true">
                         <action on="Press"><![CDATA[
-                                btCaptions = new Array("Yepp, work's done!", "No, more slaughter!");
+                                btCaptions = new Array("Yep, work's done!", "No, more slaughter!");
                                 //btCode = new Array("endGame();", "GUIObjectHide('mb_main');");
-                                btCode = new Array("endGame();\nGUIObjectHide('session_gui');\nGUIObjectUnhide('pregame_gui');\nGUIObjectHide('End_Game_Button');", "");
+                                btCode = new Array("endGame();\ncurr_music = newRandomSound('music', 'theme');\nCrossFade(curr_session_playlist_1, curr_music, 0.0001);\nGUIObjectHide('session_gui');\nGUIObjectUnhide('pregame_gui');\nGUIObjectHide('End_Game_Button');", "");
                                 messageBox(600, 200, "Do you want to leave the current game? There might be more dudes to slaughter.", "Confirmation", 0, btCaptions, btCode);
                         ]]></action>
                         End Game

binaries/data/mods/official/gui/test/functions_utility_music.js

@@ -13,8 +13,15 @@
 // Close "s" and free it from memory (use in conjunction with loop()):
 // s.free();
 
+// Adjust the gain (volume) of a sound (floating point range between 0 (silent) and 1 (max volume)).
+// s.SetGain(value);
+
+// ====================================================================
+
 function newRandomSound(soundType, soundSubType, soundPrePath)
 {
+	// Return a random audio file by category, to be assigned to a handle.
+
 	switch (soundType)
 	{
 		case "music":
@@ -230,3 +237,48 @@ function newRandomSound(soundType, soundSubType, soundPrePath)
 
 	return new Sound(randomSoundPath);
 }
+
+// ====================================================================
+
+function FadeOut (soundHandle, Rate)
+{
+	// Adjust the gain of a sound until it is zero.
+
+	for (fadeLoop = 1; fadeLoop > 0; fadeLoop = fadeLoop - Rate)
+	{
+		soundHandle.setGain(fadeLoop);
+	}
+	
+	return true;
+}
+
+// ====================================================================
+
+function FadeIn (soundHandle, Gain, Rate)
+{
+	// Adjust the gain of a sound from zero up to the given value.
+
+	for (fadeLoop = 0; fadeLoop < Gain; fadeLoop = fadeLoop + Rate)
+	{
+		soundHandle.setGain(fadeLoop);
+	}
+	
+	return true;	
+}
+
+// ====================================================================
+
+function CrossFade (outHandle, inHandle, Rate)
+{
+	// Accepts two sound handles. Fades out the first and fades in the second at the specified rate.
+	// Note that it plays the in and frees the out while it's at it.
+
+	FadeOut(outHandle, Rate);
+	inHandle.play();
+	FadeIn(inHandle, 1, Rate);
+	outHandle.free();
+
+	return true;
+}
+
+// ====================================================================