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Debug screen

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Screenshot showing the debug information

The debug screen is triggered when the F3 key is pressed (Fn+F3 on some laptops [by default; the behavior of the F keys can be changed in Keyboard preferences]). 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 and monitoring performance.

Legend[edit]

When displaying reduced debug info, only the starred items are included.

Name Description[1][2]
C* Number of chunk sections rendered over total number of chunks. Counts all render passes: if a chunk section is rendered twice (because it contains both water and normal blocks, for example) then it will be counted twice.
D* Client-side render distance
pC* Pending chunks to be batched
pU* Pending uploads to video card
aB* Available buffers to use in the batching process
F* Number of chunk sections loaded outside the viewing distance. Counts all render passes.
O* Number of chunk sections removed through occlusion culling. Counts all render passes.
E* Number of rendered entities over total entities
B* Unused, always 0. May previously have been the number of entities removed due to hidden chunks
I* Number of invisible entities
P* Number of particles on screen
T* Shows your max framerate (“inf" if Unlimited) and your Graphics type (“fast" if Fast and none if Fancy).
All* Displays total number of loaded entities (including mobs and dropped items)
MultiplayerChunkCache* The most chunks that will be loaded
XYZ X: Player's location in blocks East of 0,0 (negative values are to the West)

Y: Player's (feet) altitude in blocks (63 (62.9) is overworld sea level, 11 (10.9) is overworld lava flood level, 32 (31.9) is nether lava sea).
Z: Player's location in blocks South of 0,0 (negative values are to the North)

Block The co-ordinates of the block the player is on, in xyz format. Very similar to XYZ as above, excluding digits after the decimal point.
Chunk* The location of the player within a chunk, and the location of the chunk within the world. In reduced mode, only the location within the chunk is displayed.
Facing The direction in which a player is facing. Towards Positve X/Z indicates the player's alignment towards the x/z axis. The two numbers at the end indicate the player's horizontal (azimuthal) and vertical (altitudinal) rotation.
Biome Shows you what Biome you are in.
Light The first number is the total light level where your feet are. Note that there are a few caveats here due to the sky light level showing the light level the block would get from the sun in full daylight, but does not account for the lower light levels at night or during a storm.

The second number is the amount of light from the sky at the block your feet are in. Same caveat as above.
The third number is the amount of light from other blocks (e.g. torches) at the block your feet are in.

Local Difficulty Shows the difficulty of the chunk the player is in. See Difficulty on how this works. Followed by the amount of in-game days the player has been in the world, see Day-night cycle for more information.
Looking at Shows the co-ordinates of the block the player is looking at. If the player is not looking at any block, this entry does not appear.

Profiler graph[edit]

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.

More Debug-Keys[edit]

  • F3 + A : Reload all chunks
  • F3 + B : Toggle visibility of hitboxes of entities, and in 1.8 shows which direction entities are looking in using a blue line
  • F3 + C : Make a debug crash (press keys for 10 seconds)[3]
  • F3 + D : Clear chat history (including previously typed messages and commands)
  • F3 + H : Toggle IDs of items, the durability of tools, the armor color and the scale of maps
  • F3 + P : Toggle automatic pause when Minecraft loses focus on / off
  • F3 + T : Reload textures and models
  • F3 + S : Reload the sound engine and all resources

History[edit]

The debug information from Indev, Infdev, and early Alpha.
Indev
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.
Alpha
1.1.0 The debug screen was no longer listed as an option and required F3 to be held down to activate.
1.2.3 The coordinates were added to the debug screen.
Beta
1.3 The debug screen, along with other function key controls, became a toggle.
When the debug screen was open, 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.
1.7 The "f" coordinate was made visible in the debug screen (facing direction).
1.8 The ability to see the level's seed was added.
Removed entity numbers being shown above mob's head. Some players felt that it was cheating and that it took away from the game.
Official release
1.2.1 1.2-pre Information about the biome and light level of the player's location were added. The seed in multiplayer was made hidden, showing as "0".
1.2.4 Pressing F3 (Fn+F3 on Mac and some laptops) brings up the debug screen but without the graphs. The graph will appear on pressing ⇧ Shift+ F3 (Fn+ ⇧ Shift + F3 on Mac and some laptops).
1.3.1 12w18a Information about the player's speed and whether the player is touching the ground were added.
Coordinates are now rounded to 5 digits.
12w21a Information about the world's seed was removed, seen instead by pressing the chat key and typing "/seed".
1.4.2 12w39a Fl, x and z chunk coordinates, and more rotation (f) information were added.
12w41a Shift+F3 now shows the profiler graph.
1.8 14w02a Now shows which axis you are facing after the cardinal direction: "Towards positive/negative X/Z".
14w04a The crosshair will display 3 short colored lines to indicate the direction of each axis: x/red, y/green, z/blue.
The x coordinate line will now be bold when looking east/west, similarly the z coordinate line will now be bold when looking south/north.
14w05a Text now has a background.
Replaced x, y, z, b, bl and other labels with more understandable labels.
"Light" is now the light levels at feet, not eyes.
14w06a X, Y, and Z title has been changed from 'Feet' in the previous snapshot, to 'XYZ'.
Day counter added, which increases by 1 every dawn.
Now displays difficulty: Peaceful- 0.00, Easy- 0.75, Normal- 1.50, Hard 2.25 (but numbers slowly increase the longer you are in an area).
Now displays player rotation in degrees and quadrants.
14w11a On the right hand side, a display shows up if you are looking at a block, showing its ID and block states.
14w17a All blocks now have their info displayed on the right hand side of the F3 debug screen.
Removed the "Facing negative/positive x/z" from the F3 menu.
14w20a Readded "Facing negative/positive x/z".
14w25b F3 + B now also shows which direction entities are looking in using a blue line.
Removed the line on the right-hand side which had displayed the name of the block model the player was looking at.
14w29a A 'Reduced Debug Info' toggle now exists within multiplayer settings to enable/disable reduced information on the debug screen.
The reducedDebugInfo gamerule allows you to enable/disable reduced information on the debug screen. This overrides all 'reduced debug info' settings in clients.
14w30a Now displays how many chunk sections are being rendered currently and how many chunk sections are out of view in percent, the OpenGL version, display size, vendor and GPU.
"Vanilla" added to the version number.

Pre-1.8 Legend[edit]

Name Description[4][5]
C Number of chunk sections rendered over total number of chunks. Counts all render passes: if a chunk section is rendered twice (because it contains both water and normal blocks, for example) then it will be counted twice.
F Number of chunk sections loaded outside the viewing distance. Counts all render passes.
O Number of chunk sections removed through occlusion culling. Counts all render passes.
E (first row) Number of empty chunk sections. These sections are skipped for one of two reasons: Either the chunk has not yet been loaded and rendered into polygons, or the section has nothing to draw in the current render pass. Counts all render passes.
E (second row) Number of rendered entities over total entities
B Unused, always 0. May previously have been the number of entities removed due to hidden chunks
I Number of invisible entities
P Number of particles on screen
T Displays your max framerate
ALL Displays total number of loaded entities (including mobs and dropped items)
ServerChunkCache
ChunkCache
The most chunks that will be loaded
x Player's location in blocks East of 0,0 (negative values are to the West) and after the // is your chunk number with the block within the chunk in ()
y Player's altitude in blocks (63 (62.9) is overworld sea level, 11 (10.9) is overworld lava flood level, 32 (31.9) is nether lava sea).
z Player's location in blocks South of 0,0 (negative values are to the North) and after the // is your chunk number with the block within the chunk in ()
f The direction in which a player is facing (south=0, west=1, north=2, east=3) and if the player walks towards x or z respectively
lc Max section height for the chunk you are in (Uses cubic chunk sections, so heights will display in multiples of 16 minus 1.)
b Shows you what Biome you are in.
bl (for "block light") The amount of light from other blocks (e.g. torches) at the block your head is in. If you stand on top of a torch, this field will show a light level of 13 instead of the expected 14, due to your head being one block away from it.
sl (for sky light) The amount of light from the sky at the block your head is in. Note that the number shown here is only accurate during the day. It shows the light level the block would get from the sun in full daylight, but does not account for the lower light levels at night or during a storm.
rl (for raw light) The total light level where your head is, equal to max(bl,sl). Note that because the "sl" field is factored in here, this field has the same caveats as that one.
ws Walking speed.
fs Flying speed.
g On ground, Boolean value, true if the player touches the ground.
fl The y-coordinate of the highest block where the player is able to stand, rounded up when standing on half-blocks, such as slabs. When above the void (where there is no block), it will say 0.
shader The file path of the currently-active shader (within the "assets" directory of minecraft.jar). Only displayed if a shader is active.

Trivia[edit]

  • 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, until release 1.8 (snapshot 14w17a) it indicated the biome "Sky", likely because The End was originally going to be the Sky Dimension.
  • When used in a chunk that was created prior to Alpha 1.2 (when there were no biomes), the B field will read "Ocean".
  • Deeper into the profiler (Shift+F3), some tasks will have numbers higher than 9 and can't be accessed. Pressing the two keys simultaneously will not open the task.

References[edit]