Does somebody know??

you need to use a raycast

You don't necessarily need to do it yourself though. It depends on the context.

 

onItemRichgtclick

I got some code nearly working, but it does strangely only work in x and y positive direction, and also upwards sight, I cant figure outr why, but I think its a problem with the world.getBlockState

 

if((player.rayTrace(200, 1.0F) != null)){
		int blockHitX = (int) player.rayTrace(200, 1.0F).hitVec.xCoord;
		int blockHitY = (int) player.rayTrace(200, 1.0F).hitVec.yCoord;
		int blockHitZ = (int) player.rayTrace(200, 1.0F).hitVec.zCoord;
		System.out.println(blockHitX + "	" + blockHitY + "\t"+ blockHitZ);
		BlockPos pos = new BlockPos(player.rayTrace(10, 1).hitVec);

		System.out.println(world.getBlockState(new BlockPos(player.posX, player.posY, player.posZ)));
		System.out.println(world.getBlockState(pos));

	}

dont know about that error, but why are u taytracing three times thats waste of processing time. raytrace once, save the result, read x/y/z from it

dont know about that error, but why are u taytracing three times thats waste of processing time. raytrace once, save the result, read x/y/z from it

Three times? He's doing it five times! @OP, as Failender said, raytrace once, save the result, then do stuff with that result instead of raytracin 5 times...