# Method GL.glTexSubImage2D()

Method glTexSubImage2D

  ``void` glTexSubImage2D(`int` `target`, `int` `level`, `int` `xoffset`, `int` `yoffset`, `object`|`mapping`(`string`:`object`) `width`, `object`|`mapping`(`string`:`object`) `height`, `object`|`mapping`(`string`:`object`) `format`, `object`|`mapping`(`string`:`object`) `type`, `array`(`object`|`mapping`(`string`:`object`)) `pixels`)`

Description

  Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is enabled. To enable and disable two-dimensional texturing, call glEnable and glDisable with argument GL_TEXTURE_2D.

  glTexSubImage2D redefines a contiguous subregion of an existing two-dimensional texture image. The texels referenced by pixels replace the portion of the existing texture array with x indices xoffset and "xoffset"~+~"width"~-~1, inclusive, and y indices yoffset and "yoffset"~+~"height"~-~1, inclusive. This region may not include any texels outside the range of the texture array as it was originally specified. It is not an error to specify a subtexture with zero width or height, but such a specification has no effect.

Parameter `target`

  Specifies the target texture. Must be GL_TEXTURE_2D.

Parameter `level`

  Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.

Parameter `xoffset`

  Specifies a texel offset in the x direction within the texture array.

Parameter `yoffset`

  Specifies a texel offset in the y direction within the texture array.

Parameter `width`

  Specifies the width of the texture subimage.

Parameter `height`

  Specifies the height of the texture subimage.

Parameter `format`

  Specifies the format of the pixel data. The following symbolic values are accepted: GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.

Parameter `type`

  Specifies the data type of the pixel data. The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT, and GL_FLOAT.

Parameter `pixels`

  Specifies a pointer to the image data in memory.

Throws

  GL_INVALID_ENUM is generated if target is not GL_TEXTURE_2D.

  GL_INVALID_OPERATION is generated if the texture array has not been defined by a previous glTexImage2D operation.

  GL_INVALID_VALUE is generated if level is less than 0. .P P GL_INVALID_VALUE may be generated if level is greater than log sub 2max, where max is the returned value of GL_MAX_TEXTURE_SIZE.

  GL_INVALID_VALUE is generated if "xoffset" ~<~ ~-b, ("xoffset"~+~"width") ~>~ (w~-~b), "yoffset" ~<~ ~-b, or ("yoffset" ~+~ "height") ~>~ (h~-~b). Where w is the GL_TEXTURE_WIDTH, h is the GL_TEXTURE_HEIGHT, and b is the border width of the texture image being modified. Note that w and h include twice the border width.

  GL_INVALID_VALUE is generated if width or height is less than 0.

  GL_INVALID_ENUM is generated if format is not an accepted format constant.

  GL_INVALID_ENUM is generated if type is not a type constant.

  GL_INVALID_ENUM is generated if type is GL_BITMAP and format is not GL_COLOR_INDEX.

  GL_INVALID_OPERATION is generated if glTexSubImage2D is executed between the execution of glBegin and the corresponding execution of glEnd.