I'm trying to figure out how to maintain TileEntity data when breaking and placing a block.  The OpenBlocks source code has some clues in it (spawning an EntityItem with the appropriate data stored in it), but when I place the block again, the data is lost.  I'm assuming that there's something I need to do with the item is placed, but I'm not sure what.  Any ideas?

Use the item values to change the tileentity state.

Something like:

onItemUse(world, itemstack,x,y,z...)
{
data = getData(itemstack.getTagCompound());
(MyTileEntity)world.getBlockTileEntity(x,y,z).changeState(data);
}

I'm still kind of in the dark here.  Block doesn't have an onItemUse function, so does that mean I need to create a custom Item class that, when placed, spawns the block and inserts the entity data?  I don't see any way to get the itemstack from inside the Block class when the block is placed.

I'm assuming that there's something I need to do with the item is placed

You said you had an item.

 

The easy way is certainly to use an item to place the block. Which means you want noone to get the actual block, only the item.

Then when block is broken, spawn an EntityItem which contains the item (again, not the block).

 

If I want the item to actually render like a block, is that going to be a huge ordeal of building a custom renderer or something, or is there some shortcut way to make it render the item as if it's an existing block?

 

You could use an IItemRenderer and use renderblocks i suppose...or use an ItemBlock.

Or you could just have the block... and the item... and the tileentity.

 

All you have to do is, in the method that returns what the block drops, you create a new Item and give it all the data it needs, and then spawn the EntityItem with that item you spawned. And that item is the item etc, that you create

 

 

*EDIT*

Just relized that it wouldn't look like a block though, it would be the 2D item. But hey, it would be easier

you could tottally use the same code for the IItemRenderer as the TileEntitySpecialRenderer, nothign is stopping you to do it