GLTEXSUBIMAGE2D(3gl)GLTEXSUBIMAGE2D(3gl)NAME
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 one of GL_TEXTURE_2D,
GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGA‐
TIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEX‐
TURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, or
GL_TEXTURE_CUBE_MAP_NEGATIVE_Z
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 sym‐
bolic values are accepted: GL_COLOR_INDEX, GL_RED, GL_GREEN,
GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA, GL_LUMINANCE, and GL_LUMI‐
NANCE_ALPHA.
type Specifies the data type of the pixel data. The following sym‐
bolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, GL_BIT‐
MAP, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT, and
GL_FLOAT.
pixels Specifies a pointer to the image data in memory.
DESCRIPTION
Texturing maps a portion of a specified texture image onto each graphi‐
cal 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 xoff‐
set+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 specifi‐
cation has no effect.
glTexSubImage2D is called on a existing constant data texture, the call
will always make a copy of the existing texture image before updating
the subimage except when the scenario given below is true.
If a glTexSubImage2D is called with pixel store pname GL_UNPACK_CON‐
STANT_DATA_SUNX set to GL_TRUE on a constant texture, then the address
of the start of the texture image is computed using the specified xoff‐
set, yoffset. If this computed address matches the start address of the
currently used constant texture then no action is taken. If the
addresses do not match then a copy is first made of the entire texture
and then the subimage is updated in this copy. A texture is a "constant
texture" if at the time of the specification of the texture no copy was
made. This attribute can be queried using glGetTexLevelParameter.
NOTES
glTexSubImage2D is available only if the GL version is 1.1 or greater.
Texturing has no effect in color index mode.
glPixelStore and glPixelTransfer modes affect texture images in exactly
the way they affect glDrawPixels.
If GL_UNPACK_CONSTANT_DATA_SUNX is set to GL_TRUE and application
wants to change part of the texture image that has been sent down, the
application should first call glFinishTextureSUNX before a part or all
of this texture image is changed.
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.
P GL_INVALID_VALUE may be generated if level is greater than log2max,
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_TEX‐
TURE_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 con‐
stant.
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.
GL_INVALID_OPERATION is generated if glTexSubImage2D is executed within
a display list with glPixelStore pname GL_UNPACK_CONTANT_DATA_SUNX set
to GL_TRUE.
ASSOCIATED GETS
glGetTexImage
glIsEnabled with argument GL_TEXTURE_2D
SEE ALSO
glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTex‐
SubImage2D, glDrawPixels, glPixelStore, glPixelTransfer, glTexEnv,
glTexGen, glTexImage1D, glTexImage2D, glTexSubImage1D, glTexParameter,
glGetTexLevelParameter, glFinishTextureSUNX
15 Mar 97 GLTEXSUBIMAGE2D(3gl)
