Hello everyone,

 

I'm trying to create an overlay mod. I'm pretty much at the beginning of it and I'm trying to understand how rendering and gui-classes works.

 

My goal is a pretty simple overlay that shows a current state of an item i already created. (goal -> somewhat like the energy level of the ultimate lappack from the GraviChestPlate MOD)

 

I'm trying to render a string onto the screen with the FontRenderer - drawString method. I pretty much copied it together from the GuiIngame class.

 

GUI class

@SideOnly(Side.CLIENT)
public class GuiMasterWrench extends Gui {
private final Minecraft mc;

public GuiMasterWrench(Minecraft minecraft) {
this.mc = minecraft;
}

public void renderWrenchState() {
FontRenderer fontRender = this.mc.fontRenderer;
ScaledResolution sclRes = new ScaledResolution(this.mc.gameSettings, this.mc.displayWidth, this.mc.displayHeight);
//GL11.glColor4f(1.0F, 1.0F, 1.0F, 1.0F);
fontRender.drawStringWithShadow("This is the test string!", 1, 1, 0xffffffff);
}
}

 

In the item class I'm trying to call the overlay with the onItemUseFirst method.

 

@Override
public boolean onItemUseFirst(ItemStack stack, EntityPlayer player, World world, int X, int Y, int Z, int side) {
if (world.isRemote)
return false;
if (Keyboard.isKeyDown(Keyboard.KEY_M)) {
wrenchState++;
if (wrenchState > 3) wrenchState = 0;
GuiMasterWrench mwGui = new GuiMasterWrench(Minecraft.getMinecraft());
mwGui.renderWrenchState();
player.addChatMessage("You've set the Master Wrench to state "+ wrenchState);
} else {
player.addChatMessage("You've used the Master Wrench!");
}
return false;
}

 

 

When i try to right-click my item ingame, i get the following error.

 

Error - Stack Trace

 

2012-08-31 11:24:54 [sEVERE] [ForgeModLoader] A critical server error occured handling a packet, kicking net.minecraft.src.NetServerHandler@109099d
java.lang.NullPointerException
at org.lwjgl.opengl.GL11.glColor4f(GL11.java:881)
at net.minecraft.src.FontRenderer.renderString(FontRenderer.java:606)
at net.minecraft.src.FontRenderer.drawStringWithShadow(FontRenderer.java:327)
at tay.mods.masterwrench.common.GuiMasterWrench.renderWrenchState(GuiMasterWrench.java:34)
at tay.mods.masterwrench.common.ItemMasterWrench.onItemUseFirst(ItemMasterWrench.java:35)
at net.minecraft.src.Item.onItemUseFirst(Item.java:692)
at net.minecraft.src.ItemInWorldManager.activateBlockOrUseItem(ItemInWorldManager.java:340)
at net.minecraft.src.NetServerHandler.handlePlace(NetServerHandler.java:500)
at net.minecraft.src.Packet15Place.processPacket(Packet15Place.java:78)
at net.minecraft.src.MemoryConnection.processReadPackets(MemoryConnection.java:75)
at net.minecraft.src.NetServerHandler.networkTick(NetServerHandler.java:72)
at net.minecraft.src.NetworkListenThread.networkTick(NetworkListenThread.java:55)
at net.minecraft.src.IntegratedServerListenThread.networkTick(IntegratedServerListenThread.java:132)
at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:630)
at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:547)
at net.minecraft.src.IntegratedServer.tick(IntegratedServer.java:105)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:453)
at net.minecraft.src.ThreadServerApplication.run(ThreadServerApplication.java:17)

 

 

I would appreciate any kind of help.

Is it attached to a container?

Is it a screen GUI?

If it is a container, have it extend GuiContainer, go from there.

If it's a screen GUI without a container, extend GuiScreen.