GLTEXIMAGE1D() MachTen Programmer’s Manual GLTEXIMAGE1D()

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 )

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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 $2 sup n + 2 ( "border" )$ for
some integer $n$. All implementations sup-
port 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 argu-
ments 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 recalcu-
lated, checked for consistency, and checked against the
implementation’s capabilities. If the implementation can-
not 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 glPixel-
Store).

The first element corresponds to the left end of the tex-
ture 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 pix-
els. 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 depend-
ing 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 glPixel-
Transfer).

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 glPixel-
Transfer).

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 glPixel-
Transfer).

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 multi-
plied 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 lumi-
nance 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 glPixel-
Transfer).

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 lumi-
nance 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 res-
olution 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 for-
mats 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 down-
load subtextures to initialize the texture memory. The
image is undefined if the program tries to apply an unini-
tialized 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 con-
stant.

GL_INVALID_ENUM is generated if type is GL_BITMAP and for-
mat 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
$log sub 2$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 sym-
bolic 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 $2 sup n + 2("border")$ 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 exe-
cuted between the execution of glBegin and the correspond-
ing execution of glEnd.

ASSOCIATED GETS
glGetTexImage glIsEnabled with argument GL_TEXTURE_1D

SEE ALSO
glCopyPixels, glCopyTexImage1D, glCopyTexImage2D, glCopy-
TexSubImage1D, glCopyTexSubImage2D, glDrawPixels, glPixel-
Store, glPixelTransfer, glTexEnv, glTexGen, glTexImage2D,
glTexSubImage1D, glTexSubImage2D, glTexParameter

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