Uniforms

Uniforms are variables passed to core shaders that help determine their behavior.

GameTime

GameTime increments indefinitely in core shaders. It seems to be synchronized with the server and thus between players. This can be observed by lagging the server. It has been observed that fract(GameTime * 1200) loops around roughly each second.

Fog

FogColor

FogColor determines the color of the fog displayed usually at the edges of render distance or under lava. The alpha of FogColor determines the density of the fog.

FogStart

FogStart determines (presumably in blocks) where the start of the fog begins. It has been observed that the lower FogStart is the more tinted the screen becomes corresponding to FogColor.

FogEnd

FogEnd determines the end of the fog.

Position

for block shaders

Position is a vector representing the xyz coordinates relative to the southwest (needs confirming) chunk corner in world-space.

for entity shaders

Position is a vector representing the xyz coordinates in camera-space (ergo relative to the camera). In essence Position for entities is the same as Position + ChunkOffset, but in different coordinate systems

ChunkOffset

A vector representing the xyz coordinates relative the player for each chunk. Thus all blocks in the same chunk have the same ChunkOffset. ChunkOffset is in world-space (needs confirming).

ScreenSize

A vector representing the dimensions of the screen. If the resolution of Minecraft is 1920x1080, ScreenSize will be vec2(1920.0, 1080.0).

Light0_Direction

This uniform seems to be used for shading. It has been observed to always point in the same direction regardless of rotation.

Light1_Direction

This uniform seems to be used for shading. It has been observed to always point in the same direction regardless of rotation.