Added usage of plasma ammo by the charger cannon.

This should add some much-needed depth to the tacticality of the
weapon. It's not much: it takes 5 plasma cells to fully charge the
cannon. But it does eliminate the previous effect where the charger
was always preferable over plasma bullets; it's still preferable in
a lot of circumstances, but for smaller ships, it's now typically
better to use plain old plasma ammo. It also limits the amount of
times the charger can be used.

src/game.cpp

@@ -1209,7 +1209,10 @@ static void game_doPlayer()
 						// With ammo cheat, cause the charge cannon to
 						// fire at full blast immediately.
 						if (engine.cheatAmmo)
+						{
+							player_chargerAlloc = 200;
 							player.ammo[1] = 200;
+						}
 
 						if (game.difficulty == DIFFICULTY_ORIGINAL)
 						{
@@ -1217,20 +1220,32 @@ static void game_doPlayer()
 						}
 						else
 						{
-							LIMIT_ADD(player.ammo[1], 1, 0, 150);
-							if (player.ammo[1] >= 150)
+							player.ammo[1] += 1;
+							if (player.ammo[1] > player_chargerAlloc)
 							{
+								if ((player_chargerAlloc < 150) &&
+										(player.ammo[0] > 0))
+								{
+									player.ammo[0] -= 1;
+									player_chargerAlloc += 30;
+								}
+								else
+								{
+									player.ammo[1] = player_chargerAlloc;
 									ship_fireBullet(&player, 1);
+									player_chargerAlloc = 0;
 									player.ammo[1] = 0;
 									player_chargerFired = true;
 								}
 							}
 						}
 					}
+				}
 				else
 				{
 					if (player.ammo[1] > 0)
 						ship_fireBullet(&player, 1);
+					player_chargerAlloc = 0;
 					player.ammo[1] = 0;
 					player_chargerFired = false;
 				}

src/player.cpp

@@ -20,6 +20,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "Starfighter.h"
 
 object player;
+int player_chargerAlloc = 0;
 bool player_chargerFired = false;
 
 /*
@@ -95,6 +96,7 @@ void player_checkShockDamage(float x, float y)
 
 void exitPlayer()
 {
+	player_chargerAlloc = 0;
 	player_chargerFired = false;
 
 	if ((player.weaponType[1] == W_CHARGER) || (player.weaponType[1] == W_LASER))

src/player.h

@@ -21,6 +21,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define PLAYER_H
 
 extern object player;
+extern int player_chargerAlloc;
 extern bool player_chargerFired;
 
 extern void initPlayer();