vaUV2

Danger

This attribute only works with the “core profile” in Minecraft 1.17 and newer. It is recommended to use the “compatibility profile” with Iris for better support.

in ivec2 vaUV2;

Valid Programs: all gbuffers/shadow

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The light value attribute, equivalent to gl_MultiTexCoord1 or gl_MultiTexCoord2 from the compatibility profile.

vaUV2 stores the block light level in the x component, and the sky light level in the y component. However, the exact range of the values is indeterminate (though it is currently 0-240). Therefore, it is recommended to use the following matrix (or gl_TextureMatrix[1] in the compatibility profile).

const mat4 TEXTURE_MATRIX_2 = mat4(vec4(0.00390625, 0.0, 0.0, 0.0), vec4(0.0, 0.00390625, 0.0, 0.0), vec4(0.0, 0.0, 0.00390625, 0.0), vec4(0.03125, 0.03125, 0.03125, 1.0));

vec2 lm_coord = (TEXTURE_MATRIX_2 * vec4(vaUV2, 0.0, 1.0)).xy;

vec2 lm_coord = (gl_TextureMatrix[1] * gl_MultiTexCoord1).xy;