Debug screen



The debug screen is triggered when the key is pressed (+ on Macs [by default; the behavior of the F keys can be changed in Keyboard preferences] and some laptops). It shows the chunk cache, the memory usage, the map seed, 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 and monitoring performance. Pressing + (++ on Mac and some laptops) brings up the debug screen but without the graphs, as of 1.2.4.

Profiler graph
Pie charts in the lower right of the Shift+F3 debug screen display real time profiling information. More detailed information about one section can be displayed by using the keys 1-9. Press 0 to go back to the previous section.

History


In Indev, Infdev, and early Alpha versions, the debug screen only had what we recognize as "the top part with all the numbers". This debug screen was not activated with F3, but as a toggle in the options. In Alpha 1.1.0, the debug screen was no longer listed as an option and required F3 to be held down to activate. In Alpha 1.2.3, the coordinates were added.

In Beta 1.3, the debug screen, along with other F# controls, became a toggle. Also, between Beta 1.3 and Beta 1.7, when you activated the debug screen, it would show numbers above every mob; these numbers being the mob's Entity ID. These were visible through blocks, making F3 a very useful mob-finder. Some considered this cheating and felt that it took away from the game. Because of this, the Entity ID label was removed in Beta 1.8.

In Beta 1.7, the "f" coordinate was made visible in the debug screen (facing direction).

In Beta 1.8, the ability to see the level's seed was added.

In 1.2.1, information about the biome and light level of the player's location were added. The seed in multiplayer was made hidden, showing as "0".

In 1.3.1, information about the player's speed and whether the player is touching the ground were added. Information about the world's seed was also removed, seen instead by pressing the chat key and typing "/seed".

In 1.4.2, fl, x and z chunk coordinates, and more rotation (f) information were added. Shift+F3 now shows the profiler graph.

Trivia

 * Lc, Biome, and the lighting values do not display when you are in the void or above y = 255 (in the Overworld)


 * When triggered in the nether, the "B" (biome) displays the biome of "Hell". In The End, it will indicate the biome "Sky", likely because The End was originally going to be the Sky Dimension.