glTexSubImage2D

glTexSubImage2D: specify a two-dimensional texture subimage.

C Specification

void glTexSubImage2D(
    GLenum	 target,
    GLint	 level,
    GLint	 xoffset,
    GLint	 yoffset,
    GLsizei	 width,
    GLsizei	 height,
    GLenum	 format,
    GLenum	 type,
    const GLvoid *pixels)

Parameters

target: Specifies the target texture. Must be GL_TEXTURE_2D.
level: Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
xoffset: Specifies a texel offset in the x direction within the texture array.
yoffset: Specifies a texel offset in the y direction within the texture array.
width: Specifies the width of the texture subimage.
height: Specifies the height of the texture subimage.
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. If the extension GL_EXT_shadow is supported, then the symbolic value GL_DEPTH_COMPONENT is also accepted.
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.
pixels: Specifies a pointer to the image data in memory.

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.

Notes

glTexSubImage2D is available only if the GL version is 1.1 or greater.

Texturing has no effect in color index mode.

The format GL_DEPTH_COMPONENT may only be used if the GL_EXT_shadow extension is supported.

glPixelStore and glPixelTransfer modes affect texture images in exactly the way they affect glDrawPixels.

Errors

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.
GL_INVALID_VALUE may be generated if level is greater than log₂ max, 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.

Associated Gets

glGetTexImage
glIsEnabled with argument GL_TEXTURE_2D