mc_Entity

in vec2 mc_Entity;

Valid Programs: gbuffers_terrain.vsh, gbuffers_water.vsh, shadow.vsh

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The x component stores the block ID which was assigned to the current block in block.properties. If an ID for the current block is not defined, a value of -1.0 is sent.

Note

OptiFine uses a signed short (16-bit two’s complement integer) for mc_Entity.x, meaning it can store IDs in the range [-32768, 32767]. This matches behavior in Iris [1.3, 1.8), while earlier Iris versions used a 16-bit unsigned integer with a range of [0, 65535] and its maximum value for blocks with unassigned IDs, instead of -1.0. Iris versions 1.8 and later use a 31-bit unsigned integer, offset by -1. This means that mc_Entity.x can store IDs in the range [-1, 2147483646], not accounting for IEEE-754 precision limitations.

Though the vertex attribute data for mc_Entity.x is stored as an integer in Iris 1.8+, it is always cast to a float before reading. This comes with significant precision issues at high values, >= 1.0 at values >= 16777217.0.

When block.properties isn’t present in the shader pack files, block IDs are assigned according to their pre-Minecraft 1.13 numerical values, as described in the Minecraft Wiki. This is intended for legacy purposes, and should not be used for new shader packs.

The y component stores the “render type”, which is 1.0 for fluids (water, lava, etc.) and -1.0 for all other blocks.

This attribute is only available for terrain. For other types of geometry, see entityid and blockentityid.