Hi, I'm trying to make an item that can store "energy". I'd like the item to have a durability bar that displays how much energy it currently stores. I've tried to use showDurabilityBar() and getDurabilityForDisplay(), however it seems that the durability bar displays the opposite of what it should. (i.e. the bar is completely green when the item is empty and empty when the item is full)

Here is an example of what I mean:

http://i.imgur.com/U2byBbA.png

The item on the left is empty and the item on the right is full.

This is the code I have for the durability bar:

    @Override
    public boolean showDurabilityBar(ItemStack itemStack)
    {
        return true;
    }

    @Override
    public double getDurabilityForDisplay(ItemStack itemStack)
    {
        if (itemStack.getTagCompound() == null || !itemStack.getTagCompound().hasKey("Energy"))
        {
            itemStack.stackTagCompound = new NBTTagCompound();
            itemStack.getTagCompound().setInteger("Energy", 0);
        }

        return itemStack.getTagCompound().getInteger("Energy") / 80000;
    }

According to the documentation for getDurabilityForDisplay(), you are to pass 1 for 100% durability and 0 for 0%. I thought that this is what this would accomplish, but I must have done something wrong.

Thanks!

Yeah, sorry, I meant to say that. 80k should be a full item. I got the items from the creative menu. This is the code I used to add the full item to the menu, if it is relevant:

    @Override
    public void getSubItems(Item item, CreativeTabs creativeTabs, List list)
    {
            list.add(new ItemStack(this, 1));
            ItemStack fullEnergy = new ItemStack(this, 1);
            this.setEnergyStored(fullEnergy, 80000);
            list.add(fullEnergy);
    }

setEnergyStored() just manipulates the NBT value used to store the amount of energy.

It could be documented wrong.

Yes,

    /**
     * Queries the percentage of the 'Durability' bar that should be drawn.
     * 
     * @param stack The current ItemStack
     * @return 1.0 for 100% 0 for 0%
     */
    public double getDurabilityForDisplay(ItemStack stack)
    {
        return (double)stack.getItemDamageForDisplay() / (double)stack.getMaxDamage();
    }

  (default implementation of stack.getItemDamageForDisplay() just gives stack.itemDamage)

So this means that the javadoc is inverted.

 

And  how it is used:

                int j1 = (int)Math.round(13.0D - health * 13.0D);
                int k = (int)Math.round(255.0D - health * 255.0D);
                GL11.glDisable(GL11.GL_LIGHTING);
                GL11.glDisable(GL11.GL_DEPTH_TEST);
                GL11.glDisable(GL11.GL_TEXTURE_2D);
                GL11.glDisable(GL11.GL_ALPHA_TEST);
                GL11.glDisable(GL11.GL_BLEND);
                Tessellator tessellator = Tessellator.instance;
                int l = 255 - k << 16 | k << 8;
                int i1 = (255 - k) / 4 << 16 | 16128;
                this.renderQuad(tessellator, p_94148_4_ + 2, p_94148_5_ + 13, 13, 2, 0);
                this.renderQuad(tessellator, p_94148_4_ + 2, p_94148_5_ + 13, 12, 1, i1);
                this.renderQuad(tessellator, p_94148_4_ + 2, p_94148_5_ + 13, j1, 1, l);
                GL11.glEnable(GL11.GL_BLEND);
                GL11.glEnable(GL11.GL_ALPHA_TEST);
                GL11.glEnable(GL11.GL_TEXTURE_2D);
                GL11.glEnable(GL11.GL_LIGHTING);
                GL11.glEnable(GL11.GL_DEPTH_TEST);
                GL11.glColor4f(1.0F, 1.0F, 1.0F, 1.0F);

Thanks, it seems that's correct. I think the problem with the documentation is the difference between "Durability" and "Damage". The word could be switched and it would then make sense. Oh well, thanks again.