NAME
glTexImage1D - specify a one-dimensional texture image
C SPECIFICATION
void glTexImage1D( GLenum target,
GLint level,
GLint internalformat,
GLsizei width,
GLint border,
GLenum format,
GLenum type,
const GLvoid *pixels )
PARAMETERS
target Specifies the target texture. Must be
GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.
level Specifies the level-of-detail number. Level
0 is the base image level. Level n is the
nth mipmap reduction image.
internalformat Specifies the number of color components in
the texture. Must be 1, 2, 3, or 4, or one
of the following symbolic constants:
GL_ALPHA, GL_ALPHA4, GL_ALPHA8, GL_ALPHA12,
GL_ALPHA16, GL_LUMINANCE, GL_LUMINANCE4,
GL_LUMINANCE8, GL_LUMINANCE12,
GL_LUMINANCE16, GL_LUMINANCE_ALPHA,
GL_LUMINANCE4_ALPHA4, GL_LUMINANCE6_ALPHA2,
GL_LUMINANCE8_ALPHA8, GL_LUMINANCE12_ALPHA4,
GL_LUMINANCE12_ALPHA12,
GL_LUMINANCE16_ALPHA16, GL_INTENSITY,
GL_INTENSITY4, GL_INTENSITY8,
GL_INTENSITY12, GL_INTENSITY16, GL_RGB,
GL_R3_G3_B2, GL_RGB4, GL_RGB5, GL_RGB8,
GL_RGB10, GL_RGB12, GL_RGB16, GL_RGBA,
GL_RGBA2, GL_RGBA4, GL_RGB5_A1, GL_RGBA8,
GL_RGB10_A2, GL_RGBA12, or GL_RGBA16.
width Specifies the width of the texture image.
Must be 2n+2(border) for some integer n. All
implementations support texture images that
are at least 64 texels wide. The height of
the 1D texture image is 1.
border Specifies the width of the border. Must be
either 0 or 1.
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 and disable one-dimensional texturing, call glEnable
and glDisable with argument GL_TEXTURE_1D.
Texture images are defined with glTexImage1D. The arguments
describe the parameters of the texture image, such as width,
width of the border, level-of-detail number (see
glTexParameter), and the internal resolution and format used
to store the image. The last three arguments describe how
the image is represented in memory; they are identical to
the pixel formats used for glDrawPixels.
If target is GL_PROXY_TEXTURE_1D, no data is read from
pixels, but all of the texture image state is recalculated,
checked for consistency, and checked against the
implementation's capabilities. If the implementation cannot
handle a texture of the requested texture size, it sets all
of the image state to 0, but does not generate an error (see
glGetError). To query for an entire mipmap array, use an
image array level greater than or equal to 1.
If target is GL_TEXTURE_1D, data is read from pixels as a
sequence of signed or unsigned bytes, shorts, or longs, or
single-precision floating-point values, depending on type.
These values are grouped into sets of one, two, three, or
four values, depending on format, to form elements. If type
is GL_BITMAP, the data is considered as a string of unsigned
bytes (and format must be GL_COLOR_INDEX). Each data byte is
treated as eight 1-bit elements, with bit ordering
determined by GL_UNPACK_LSB_FIRST (see glPixelStore).
The first element corresponds to the left end of the texture
array. Subsequent elements progress left-to-right through
the remaining texels in the texture array. The final
element corresponds to the right end of the texture array.
format determines the composition of each element in pixels.
It can assume one of nine symbolic values:
GL_COLOR_INDEX
Each element is a single value, a color index. The
GL converts it to fixed point (with an unspecified
number of zero bits to the right of the binary
point), shifted left or right depending on the
value and sign of GL_INDEX_SHIFT, and added to
GL_INDEX_OFFSET (see glPixelTransfer). The
resulting index is converted to a set of color
components using the GL_PIXEL_MAP_I_TO_R,
GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B, and
GL_PIXEL_MAP_I_TO_A tables, and clamped to the
range [0,1].
GL_RED Each element is a single red component. The GL
converts it to floating point and assembles it
into an RGBA element by attaching 0 for green and
blue, and 1 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE,
added to the signed bias GL_c_BIAS, and clamped to
the range [0,1] (see glPixelTransfer).
GL_GREEN Each element is a single green component. The GL
converts it to floating point and assembles it
into an RGBA element by attaching 0 for red and
blue, and 1 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE,
added to the signed bias GL_c_BIAS, and clamped to
the range [0,1] (see glPixelTransfer).
GL_BLUE Each element is a single blue component. The GL
converts it to floating point and assembles it
into an RGBA element by attaching 0 for red and
green, and 1 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE,
added to the signed bias GL_c_BIAS, and clamped to
the range [0,1] (see glPixelTransfer).
GL_ALPHA Each element is a single alpha component. The GL
converts it to floating point and assembles it
into an RGBA element by attaching 0 for red,
green, and blue. Each component is then
multiplied by the signed scale factor GL_c_SCALE,
added to the signed bias GL_c_BIAS, and clamped to
the range [0,1] (see glPixelTransfer).
GL_RGB Each element is an RGB triple. The GL converts it
to floating point and assembles it into an RGBA
element by attaching 1 for alpha. Each component
is then multiplied by the signed scale factor
GL_c_SCALE, added to the signed bias GL_c_BIAS,
and clamped to the range [0,1] (see
glPixelTransfer).
GL_RGBA Each element contains all four components. Each
component is then multiplied by the signed scale
factor GL_c_SCALE, added to the signed bias
GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_LUMINANCE
Each element is a single luminance value. The GL
converts it to floating point, then assembles it
into an RGBA element by replicating the luminance
value three times for red, green, and blue and
attaching 1 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE,
added to the signed bias GL_c_BIAS, and clamped to
the range [0,1] (see glPixelTransfer).
GL_LUMINANCE_ALPHA
Each element is a luminance/alpha pair. The GL
converts it to floating point, then assembles it
into an RGBA element by replicating the luminance
value three times for red, green, and blue. Each
component is then multiplied by the signed scale
factor GL_c_SCALE, added to the signed bias
GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
If an application wants to store the texture at a certain
resolution or in a certain format, it can request the
resolution and format with internalformat. The GL will
choose an internal representation that closely approximates
that requested by internalformat, but it may not match
exactly. (The representations specified by GL_LUMINANCE,
GL_LUMINANCE_ALPHA, GL_RGB, and GL_RGBA must match exactly.
The numeric values 1, 2, 3, and 4 may also be used to
specify the preceding representations.)
Use the GL_PROXY_TEXTURE_1D target to try out a resolution
and format. The implementation will update and recompute its
best match for the requested storage resolution and format.
To query this state, call glGetTexLevelParameter. If the
texture cannot be accommodated, texture state is set to 0.
A one-component texture image uses only the red component of
the RGBA color extracted from pixels. A two-component image
uses the R and A values. A three-component image uses the
R, G, and B values. A four-component image uses all of the
RGBA components.
NOTES
Texturing has no effect in color index mode.
The texture image can be represented by the same data
formats as the pixels in a glDrawPixels command, except that
GL_STENCIL_INDEX and GL_DEPTH_COMPONENT cannot be used.
glPixelStore and glPixelTransfer modes affect texture images
in exactly the way they affect glDrawPixels.
GL_PROXY_TEXTURE_1D may only be used if the GL version is
1.1 or greater.
Internal formats other than 1, 2, 3, or 4 may only be used
if the GL version is 1.1 or greater.
In GL version 1.1 or greater, pixels may be a null pointer.
In this case texture memory is allocated to accommodate a
texture of width width. You can then download subtextures to
initialize the texture memory. The image is undefined if the
program tries to apply an uninitialized portion of the
texture image to a primitive.
ERRORS
GL_INVALID_ENUM is generated if target is not GL_TEXTURE_1D
or GL_PROXY_TEXTURE_1D.
GL_INVALID_ENUM is generated if format is not an accepted
format constant. Format constants other than
GL_STENCIL_INDEX and GL_DEPTH_COMPONENT are accepted.
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_VALUE is generated if level is less than 0.
GL_INVALID_VALUE may be generated if level is greater than
log max, where max is the returned value of
GL_MAX_TEXTURE_SIZE.
GL_INVALID_VALUE is generated if internalformat is not 1, 2,
3, 4, or one of the accepted resolution and format symbolic
constants.
GL_INVALID_VALUE is generated if width is less than 0 or
greater than 2 + GL_MAX_TEXTURE_SIZE, or if it cannot be
represented as 2n+2(border) for some integer value of n.
GL_INVALID_VALUE is generated if border is not 0 or 1.
GL_INVALID_OPERATION is generated if glTexImage1D is
executed between the execution of glBegin and the
corresponding execution of glEnd.
ASSOCIATED GETS
glGetTexImage glIsEnabled with argument GL_TEXTURE_1D
SEE ALSO
glCopyPixels, glCopyTexImage1D, glCopyTexImage2D,
glCopyTexSubImage1D, glCopyTexSubImage2D, glDrawPixels,
glPixelStore, glPixelTransfer, glTexEnv, glTexGen,
glTexImage2D, glTexSubImage1D, glTexSubImage2D,
glTexParameter