Debug screen



The debug screen is a screen that is triggered when the F3 key is pressed. It shows the chunk cache, the memory usage, various parameters, the player's map coordinates and a graph that measures the game's current frame rate. It can be very useful for telling other players your map location, checking for mobs and various other purposes.

The world is rendered in multiple passes. The first pass draws normal, opaque blocks. The second pass draws water and ice. This makes sure water is always drawn on top of solid blocks without relying on depth sorting.

Legend:

The graph at the bottom screen is a graph displaying the current framerate the game is playing at. Green bars represent a frame rate higher than or equal to 60 frames per second, and red for less than 60. Once the graph has moved all the way to the right of the graph area, it will return to the left and begin to overwrite previous bars to show more recent frame rates. The speed at which the graph writes new bars also seems dependent on the current frame rate. When you activate the debug screen, it also shows numbers above every mob. This is useful for finding mobs to kill. Due to the high density of mobs in the small areas of dungeons, it is often used as a dungeon-finding tool.

In the 1.8 pre-release, the debug screen no longer shows the numbers above mobs. It is not known whether this is a pre-release bug, or if it will be implemented in the official 1.8 release.

Bugs

 * If you exit to the main menu with the debug screen open, it will stay on the screen.
 * Opening a chest or opening the Achievements screen with the debug screen on turns the debugging area grey. The text does not turn grey, however. This will not crash the game.