glTexSubImage1D(3G)

NAME
     glTexSubImage1D - specify a two-dimensional texture subimage


C SPECIFICATION
     void glTexSubImage1D( GLenum target,
                           GLint level,
                           GLint xoffset,
                           GLsizei width,
                           GLenum format,
                           GLenum type,
                           const GLvoid *pixels )


PARAMETERS
     target   Specifies the target texture.  Must be GL_TEXTURE_1D.

     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.

     width    Specifies the width 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.

     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.

DESCRIPTION
     Texturing maps a portion of a specified texture image onto each graphical
     primitive for which texturing is enabled.  To enable or disable one-
     dimensional texturing, call glEnable and glDisable with argument
     GL_TEXTURE_1D.

     glTexSubImage1D redefines a contiguous subregion of an existing one-
     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.  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 width of 0, but such a
     specification has no effect.

NOTES
     glTexSubImage1D 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.

ERRORS
     GL_INVALID_ENUM is generated if target is not one of the allowable
     values.

     GL_INVALID_OPERATION is generated if the texture array has not been
     defined by a previous glTexImage1D operation.

     GL_INVALID_VALUE is generated if level is less than 0.

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

     GL_INVALID_VALUE is generated if xoffset <  -b, or if
     (xoffset + width) > (w - b).  Where w is the GL_TEXTURE_WIDTH, and b is
     the width of the GL_TEXTURE_BORDER of the texture image being modified.
     Note that w includes twice the border width.

     GL_INVALID_VALUE is generated if width 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 glTexSubImage1D is executed between
     the execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS
     glGetTexImage
     glIsEnabled with argument GL_TEXTURE_1D


MACHINE DEPENDENCIES
     On InfiniteReality systems, there is a performance benefit when the width
     of the image to be transferred to texture memory is a multiple of 8.

     Texture borders are not supported on InfiniteReality systems.
     Applications should use borderless textures and GL_CLAMP_TO_EDGE_SGIS
     wrap mode.
     The EXT_packed_pixels extension is not supported on RealityEngine,
     RealityEngine2, and VTX systems.

     glTexSubImage1D and glTexSubImage1DEXT are not supported on
     RealityEngine, RealityEngine2, and VTX systems.

     On High Impact and Maximum Impact systems, if the right side of the image
     to be transferred to texture memory is not the right side of the texture,
     then its index must be a multiple of 32, where index = xoffset+width.
     Otherwise it will generate a GL_INVALID_VALUE error.


SEE ALSO
     glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D,
     glCopyTexSubImage2D, glDrawPixels, glPixelStore, glPixelTransfer,
     glTexEnv, glTexGen, glTexImage1D, glTexImage2D, glTexParameter,
     glTexSubImage2D