| Extracted from Pike v7.8 release 866 at 2018-02-09.

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GL

# 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 .