Draw 2D shape on HUD when key pressed

Roboguy99 · September 3, 2015

My question is firstly, how do I draw to the HUD and secondly, how can I only do this when a key is held down (I have a keyevent already set up).

Is it possible to do it using OpenGL directly or is there something else I should use?

Roboguy99 · September 3, 2015

To draw on the HUD you use RenderGameOverlayEvent (careful, choose one of the subevents and an event type, otherwise you draw multiple times per frame).

To draw shapes you can use standard OpenGL or the "Tessellator" (doesn't really have anything to do with tessellating, it is just an very thin abstraction over OpenGL calls that are then sent to teh GPU in a more compact format).

For the key: Just make a KeyBinding instance and register it (ClientRegistry.registerKeyBinding). It will then track the state of that key automatically and you can just check keybind.isKeyDown to check if the key is down wherever you want.

I'm going to need more help with this, my RenderGameOverlayEvent appears to be doing nothing (perhaps I needed to specify something extra?). Here is the code:

@SubscribeEvent(priority = EventPriority.NORMAL)
    public void renderOverlay(RenderGameOverlayEvent event)
    {
	System.out.println("fghgh");
	int x = Minecraft.getMinecraft().displayWidth/2;
	int y = Minecraft.getMinecraft().displayHeight/2;
	int r = 200;

	GL11.glBegin( GL11.GL_TRIANGLE_FAN );
        GL11.glVertex2f(x, y);
        for( int n = 0; n <= 18; n++ )
        {
            float t = 2 * 3.14152f * (float)n / (float)18;
            GL11.glVertex2d(x + Math.sin(t) * r, y + Math.cos(t) * r);
        }
        
        	GL11.glRectd(x, y, x+100, y+200);
        GL11.glEnd();
    }

Roboguy99 · September 3, 2015

Firstly:

[b[careful, choose one of the subevents and an event type, otherwise you draw multiple times per frame[/b]

Did you register your event handler?

I have this line in my main class:

FMLCommonHandler.instance().bus().register(new EventsHandler());

Is that correct? I've tried loading it at pre and post init stages with nothing happening.

Ernio · September 3, 2015

MinecraftForge.EVENT_BUS.register(new ForgeEvents());

Also - it should be in client proxy. (since it is rendering, you should separate common and client events)

There are Forge and FML events - 2 different buses.

Roboguy99 · September 3, 2015

MinecraftForge.EVENT_BUS.register(new ForgeEvents());

Also - it should be in client proxy. (since it is rendering, you should separate common and client events)

There are Forge and FML events - 2 different buses.

It's working now, thanks.

Roboguy99 · September 3, 2015

careful, choose one of the subevents and an event type, otherwise you draw multiple times per frame

How do I choose a subevent? My knowledge on Forge events is pretty limited.

Draco18s · September 3, 2015

EventName.SubEventName

Eg

EventChunkData.Load

Roboguy99 · September 3, 2015

EventName.SubEventName

Eg
EventChunkData.Load

Ok that makes sense. In terms of RenderGameOverlayEvent with a brand new HUD element, how would I implement that and what subevent should I use?

Draco18s · September 4, 2015

Pick one, it won't matter in 90% of cases.

Roboguy99 · September 4, 2015

Pick one, it won't matter in 90% of cases.

Ok at this point I'm just going to show you what I've done so far and hopefully you'll be able to help me better. Pressing the keybinding while holding the item brings up a 100% opaque circle in the middle of the screen, which occasionally changes from black to very dark brown when I change direction - it appears to be ignoring the Color4f line altogether.

EDIT: I have changed the class to extend Gui and checked to render after the experience bar. I now get the desired semi-transparent circle, but if I turn around it sometimes disappears.

Here is the updated code:

public class EventsHandler extends Gui
{
private static final float PI = 3.14152f;
private static final int RADIUS = 90;
private static final int SECTORS = 200;

@SideOnly(Side.CLIENT)
@SubscribeEvent(priority = EventPriority.NORMAL)
public void onRenderExperienceBar(RenderGameOverlayEvent event)
{
	if(event.isCancelable() || event.type != ElementType.EXPERIENCE)
    {      
      return;
    }

	Item holding;
	if (Minecraft.getMinecraft().thePlayer.getHeldItem() != null)
	{
		holding = Minecraft.getMinecraft().thePlayer.getHeldItem().getItem();
		if (holding instanceof ItemBag /*&& HotbarBag.bagHUD.getIsKeyPressed()*/)
		{
			BagInventory inventory = new BagInventory(Minecraft.getMinecraft().thePlayer.getHeldItem());

			int items = 0;
			for(int i = 0; i < inventory.getSizeInventory(); i++)
			{
				if (inventory.getStackInSlot(i) != null) items++;
			}

			// Place circle slightly above centre of screen
			int x = event.resolution.getScaledWidth() / 2;
			int y = event.resolution.getScaledHeight() / 2 - 15;

			if (items != 0)
			{
				float multiplier = this.SECTORS / items;
				// System.out.println(multiplier);

				//GL11.glPushMatrix();
				GL11.glColor4f(0.6F, 0.6F, 0.6F, 0.3F);
				GL11.glBegin(GL11.GL_TRIANGLE_FAN);
				GL11.glVertex2f(x, y);
				for(int i = 0; i < items; i++)
				{
					for(float n = 0 + (i * multiplier); n <= (this.SECTORS / items) + (i * multiplier); n += 1)
					{
						float t = 2 * PI * (float) n / (float) this.SECTORS;
						GL11.glVertex2d(x + Math.sin(t) * this.RADIUS, y + Math.cos(t) * this.RADIUS);
					}
				}
				GL11.glEnd();

				ItemStack itemStack = inventory.getStackInSlot(1);
				//EntityItem entity = new EntityItem(Minecraft.getMinecraft().theWorld, 0, 0, 0, itemStack);
				//GL11.glPopMatrix();
			}
		}
	}
}
}

What I want is a semi-transparent grey circle. I assume it's just a few minor OpenGL things I'm not sure about causing this.

Ernio · September 4, 2015

Important thing - rendering phase (added) - always pick one. Same thing appears in TickEvents.

Also - never too many Push/Pops

public class EventsHandler extends Gui
{
private static final float PI = 3.14152f;
private static final int RADIUS = 90;
private static final int SECTORS = 200;

@SideOnly(Side.CLIENT)
@SubscribeEvent(priority = EventPriority.NORMAL)
public void onRenderExperienceBar(RenderGameOverlayEvent.Post event)
{
	Item holding;
	if (Minecraft.getMinecraft().thePlayer.getHeldItem() != null)
	{
		if (event.type == ElementType.ALL)
		{
		holding = Minecraft.getMinecraft().thePlayer.getHeldItem().getItem();
		if (holding instanceof ItemBag && HotbarBag.bagHUD.getIsKeyPressed())
		{
			BagInventory inventory = new BagInventory(Minecraft.getMinecraft().thePlayer.getHeldItem());

			int items = 0;
			for(int i = 0; i < inventory.getSizeInventory(); i++)
			{
				if (inventory.getStackInSlot(i) != null) items++;
			}

			int x = event.resolution.getScaledWidth() / 2;
			int y = event.resolution.getScaledHeight() / 2 - 15;

			if (items != 0)
			{
				float multiplier = this.SECTORS / items;

				GL11.glPushMatrix();
				GL11.glColor4f(0.6F, 0.6F, 0.6F, 0.3F);
				GL11.glBegin(GL11.GL_TRIANGLE_FAN);
				GL11.glVertex2f(x, y);
				for(int i = 0; i < items; i++)
				{
					for(float n = 0 + (i * multiplier); n <= (this.SECTORS / items) + (i * multiplier); n += 1)
					{
						float t = 2 * PI * (float) n / (float) this.SECTORS;
						GL11.glVertex2d(x + Math.sin(t) * this.RADIUS, y + Math.cos(t) * this.RADIUS);
					}
				}
				GL11.glEnd();

				ItemStack itemStack = inventory.getStackInSlot(1);
				EntityItem entity = new EntityItem(Minecraft.getMinecraft().theWorld, 0, 0, 0, itemStack);
				GL11.glPopMatrix();
			}
		}
		}
	}
}
}

Roboguy99 · September 4, 2015

Important thing - rendering phase (added) - always pick one. Same thing appears in TickEvents.

Also - never too many Push/Pops

public class EventsHandler extends Gui
{
private static final float PI = 3.14152f;
private static final int RADIUS = 90;
private static final int SECTORS = 200;

@SideOnly(Side.CLIENT)
@SubscribeEvent(priority = EventPriority.NORMAL)
public void onRenderExperienceBar(RenderGameOverlayEvent.Post event)
{
	Item holding;
	if (Minecraft.getMinecraft().thePlayer.getHeldItem() != null)
	{
		if (event.type == ElementType.ALL)
		{
		holding = Minecraft.getMinecraft().thePlayer.getHeldItem().getItem();
		if (holding instanceof ItemBag && HotbarBag.bagHUD.getIsKeyPressed())
		{
			BagInventory inventory = new BagInventory(Minecraft.getMinecraft().thePlayer.getHeldItem());

			int items = 0;
			for(int i = 0; i < inventory.getSizeInventory(); i++)
			{
				if (inventory.getStackInSlot(i) != null) items++;
			}

			int x = event.resolution.getScaledWidth() / 2;
			int y = event.resolution.getScaledHeight() / 2 - 15;

			if (items != 0)
			{
				float multiplier = this.SECTORS / items;

				GL11.glPushMatrix();
				GL11.glColor4f(0.6F, 0.6F, 0.6F, 0.3F);
				GL11.glBegin(GL11.GL_TRIANGLE_FAN);
				GL11.glVertex2f(x, y);
				for(int i = 0; i < items; i++)
				{
					for(float n = 0 + (i * multiplier); n <= (this.SECTORS / items) + (i * multiplier); n += 1)
					{
						float t = 2 * PI * (float) n / (float) this.SECTORS;
						GL11.glVertex2d(x + Math.sin(t) * this.RADIUS, y + Math.cos(t) * this.RADIUS);
					}
				}
				GL11.glEnd();

				ItemStack itemStack = inventory.getStackInSlot(1);
				EntityItem entity = new EntityItem(Minecraft.getMinecraft().theWorld, 0, 0, 0, itemStack);
				GL11.glPopMatrix();
			}
		}
		}
	}
}
}

For some odd reason it still stops/starts drawing as you change orientation. For some reason it seems to only work if you look south or east.

EDIT: It's not working at all now. I have changed nothing and the code is still being executed, but nothing is being drawn.

Roboguy99 · September 5, 2015

Bump. This is still broken and I'm not sure why. The code is being run, but nothing appears on the screen.

Here is the code, as far as I can see the same as when it was mostly working.

public class EventsHandler extends Gui
{
private static final int RADIUS = 90;
private static final int SECTORS = 200;

@SideOnly(Side.CLIENT)
@SubscribeEvent(priority = EventPriority.NORMAL)
public void onRenderExperienceBar(RenderGameOverlayEvent.Post event)
{
	Item holding;
	if (Minecraft.getMinecraft().thePlayer.getHeldItem() != null)
	{
		if (event.type == ElementType.ALL)
		{
			holding = Minecraft.getMinecraft().thePlayer.getHeldItem().getItem();
			if (holding instanceof ItemBag && HotbarBag.bagHUD.getIsKeyPressed())
			{
				BagInventory inventory = new BagInventory(Minecraft.getMinecraft().thePlayer.getHeldItem());

				int items = 0;
				for(int i = 0; i < inventory.getSizeInventory(); i++)
				{
					if (inventory.getStackInSlot(i) != null) items++;
				}

				int x = event.resolution.getScaledWidth() / 2;
				int y = event.resolution.getScaledHeight() / 2 - 15;

				if (items != 0)
				{
					float multiplier = this.SECTORS / items;

					GL11.glPushMatrix();
					GL11.glColor4f(0.6F, 0.6F, 0.6F, 0.3F);
					GL11.glBegin(GL11.GL_TRIANGLE_FAN);
					GL11.glVertex2f(x, y);
					for(int i = 0; i < items; i++)
					{
						for(float n = 0 + (i * multiplier); n <= (this.SECTORS / items) + (i * multiplier); n += 1)
						{
							double t = 2 * Math.PI * (float) n / (float) this.SECTORS;
							GL11.glVertex2d(x + Math.sin(t) * this.RADIUS, y + Math.cos(t) * this.RADIUS);
						}
					}
					GL11.glEnd();

					// ItemStack itemStack = inventory.getStackInSlot(1);
					// EntityItem entity = new
					// EntityItem(Minecraft.getMinecraft().theWorld, 0, 0,
					// 0, itemStack);
					GL11.glPopMatrix();

					float mouseX = Mouse.getX();
					float mouseY = Mouse.getY();
				}
			}
		}
	}
}
}

Roboguy99 · September 5, 2015

Since you are drawing without texture, you probably have to disable GL_TEXTURE_2D and re-enable it afterwards using glDisable / glEnable with GL_TEXTURE_2D as parameter.

That's fixed it, thanks!

We'll ignore the part where after doing what you said, I spent ages trying to fix the keybinding not working because I forgot I rebound the key.

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Draw 2D shape on HUD when key pressed

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