I am trying to prevent a vanilla block from being placed under certain circumstances. I have used BlockEvent#PlaceEvent and PlayerInteractEvent#RightClickBlock successfully; however, a brief image of the block always appears on the screen, then quickly disappears. I would prefer to cancel the block placement without this brief image flashing on the screen. Is there a way to intercept the placement earlier? I've looked over the available events and didn't find anything else that seemed like it would work, but perhaps I'm missing something.

 

I have also noticed that when canceling the block placement, the ItemStack size decreases, yet if I move the stack to a different inventory slot or log out and back in, it magically jumps back up to the original size—or even reappears from nothing if the stack was completely depleted. Anyone know what's up with that? Do I need to, like, manually modify the ItemStack to prevent that before canceling the event? Seems weird.

It's...not complicated. Well, eventually I'll add more to check whatever conditions I'm interested in. For now I just wanted to make sure it would work at all, and I'm not happy with how the block appears briefly.

 

	@SubscribeEvent
	public void onBlockPlaced(BlockEvent.PlaceEvent event)
	{
	    if (!event.getWorld().isRemote)
	    {
	        if (event.getPlacedBlock().getBlock() == Blocks.DIRT)
	        {
	            event.setCanceled(true);
	        }
	    }
	}
	

Edited April 5, 20178 yr by Daeruin
Added more description.

You got an issue of brief Client-Server mis-match

 

Server: Didn't allow the thing. -Your code did this

Client: Allowed the thing. -Running as usual

Server: No you didn't. -Client updates with data from Server

 

Solution: Remove the World#isRemote check

18 minutes ago, Matryoshika said:

You got an issue of brief Client-Server mis-match

 

Server: Didn't allow the thing. -Your code did this

Client: Allowed the thing. -Running as usual

Server: No you didn't. -Client updates with data from Server

 

Solution: Remove the World#isRemote check

 

Interesting. That worked great in the PlayerInteractEvent, but not in BlockEvent#PlaceEvent. Perhaps PlaceEvent is only called on one side? There's nothing in the Javadoc about that, but it would make sense given the behavior. That's sad. I was excited to discover that event. It seemed like just what I needed.