Texturing - Praise for OpenGL ES 30 Programming Guide - page 268

(continued)
target specifies the texture target, either GL_TEXTURE_3D or
GL_TEXTURE_2D_ARRAY
level specifies which mip level to update
xoffset the x index of the texel to start updating from
yoffset the y index of the texel to start updating from
zoffset the z index of the texel to start updating from
width the width of the subregion of the image to update
height the height of the subregion of the image to update
depth

the depth of the subregion of the image to update

the format of the incoming texture data; can be
GL_RED , GL_RED_INTEGER , GL_RG , GL_RG_INTEGER ,
GL_GL_RGB , GL_RGB_INTEGER , GL_RGBA ,
GL_RGBA_INTEGER , GL_DEPTH_COMPONENT ,
GL_DEPTH_STENCIL , GL_LUMINANCE_ALPHA ,
GL_LUMINANCE , or GL_ALPHA

format

the type of the incoming pixel data; can be
GL_UNSIGNED_BYTE , GL_BYTE , GL_UNSIGNED_SHORT ,
GL_SHORT , GL_UNSIGNED_INT , GL_INT , GL_HALF_FLOAT ,
GL_FLOAT , GL_UNSIGNED_SHORT_5_6_5 ,
GL_UNSIGNED_SHORT_4_4_4_4 , GL_UNSIGNED_SHORT_5_5_5_l ,
GL_UNSIGNED_INT_2_10_10_10_REV ,
GL_UNSIGNED_INT_10F_11F_11F_REV ,
GL_UNSIGNED_INT_5_9_9_9_REV ,
GL_UNSIGNED_INT_24_8 , or
GL_FLOAT_32_UNSIGNED_INT_24_8_REV

type

contains the actual pixel data for the subregion of the image

pixels

glTexSubImage3D behaves just like glTexSubImage2D , with the only
difference being that the subregion contains a zoffset and a depth
for specifying the subregion within the depth slices to update. For
compressed 2D texture arrays, it is also possible to update a subregion of
the texture using glCompressedTexSubImage3D . For 3D textures, this
function can be used only with vendor-specific 3D compressed texture
formats, because ETC2/EAC are supported only for 2D textures and 2D
texture arrays.