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<STRONG>NAME</STRONG>
<STRONG>glTexImage2D</STRONG> - specify a two-dimensional texture image
<STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>
void <STRONG>glTexImage2D</STRONG>( GLenum <EM>target</EM>,
GLint <EM>level</EM>,
GLint <EM>internalformat</EM>,
GLsizei <EM>width</EM>,
GLsizei <EM>height</EM>,
GLint <EM>border</EM>,
GLenum <EM>format</EM>,
GLenum <EM>type</EM>,
const GLvoid *<EM>pixels</EM> )
<STRONG>PARAMETERS</STRONG>
<EM>target</EM> Specifies the target texture. Must be
<STRONG>GL_TEXTURE_2D</STRONG> or <STRONG>GL_PROXY_TEXTURE_2D</STRONG>.
<EM>level</EM> Specifies the level-of-detail number. Level
0 is the base image level. Level <EM>n</EM> is the
<EM>n</EM>th mipmap reduction image.
<EM>internalformat</EM> Specifies the number of color components in
the texture. Must be 1, 2, 3, or 4, or one
of the following symbolic constants:
<STRONG>GL_ALPHA</STRONG>, <STRONG>GL_ALPHA4</STRONG>, <STRONG>GL_ALPHA8</STRONG>, <STRONG>GL_ALPHA12</STRONG>,
<STRONG>GL_ALPHA16</STRONG>, <STRONG>GL_LUMINANCE</STRONG>, <STRONG>GL_LUMINANCE4</STRONG>,
<STRONG>GL_LUMINANCE8</STRONG>, <STRONG>GL_LUMINANCE12</STRONG>,
<STRONG>GL_LUMINANCE16</STRONG>, <STRONG>GL_LUMINANCE_ALPHA</STRONG>,
<STRONG>GL_LUMINANCE4_ALPHA4</STRONG>, <STRONG>GL_LUMINANCE6_ALPHA2</STRONG>,
<STRONG>GL_LUMINANCE8_ALPHA8</STRONG>, <STRONG>GL_LUMINANCE12_ALPHA4</STRONG>,
<STRONG>GL_LUMINANCE12_ALPHA12</STRONG>,
<STRONG>GL_LUMINANCE16_ALPHA16</STRONG>, <STRONG>GL_INTENSITY</STRONG>,
<STRONG>GL_INTENSITY4</STRONG>, <STRONG>GL_INTENSITY8</STRONG>,
<STRONG>GL_INTENSITY12</STRONG>, <STRONG>GL_INTENSITY16</STRONG>, <STRONG>GL_R3_G3_B2</STRONG>,
<STRONG>GL_RGB</STRONG>, <STRONG>GL_RGB4</STRONG>, <STRONG>GL_RGB5</STRONG>, <STRONG>GL_RGB8</STRONG>, <STRONG>GL_RGB10</STRONG>,
<STRONG>GL_RGB12</STRONG>, <STRONG>GL_RGB16</STRONG>, <STRONG>GL_RGBA</STRONG>, <STRONG>GL_RGBA2</STRONG>,
<STRONG>GL_RGBA4</STRONG>, <STRONG>GL_RGB5_A1</STRONG>, <STRONG>GL_RGBA8</STRONG>, <STRONG>GL_RGB10_A2</STRONG>,
<STRONG>GL_RGBA12</STRONG>, or <STRONG>GL_RGBA16</STRONG>.
<EM>width</EM> 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.
<EM>height</EM> Specifies the height of the texture image.
Must be 2m+2(border) for some integer m. All
implementations support texture images that
are at least 64 texels high.
<EM>border</EM> Specifies the width of the border. Must be
either 0 or 1.
<EM>format</EM> Specifies the format of the pixel data. The
following symbolic values are accepted:
<STRONG>GL_COLOR_INDEX</STRONG>, <STRONG>GL_RED</STRONG>, <STRONG>GL_GREEN</STRONG>, <STRONG>GL_BLUE</STRONG>,
<STRONG>GL_ALPHA</STRONG>, <STRONG>GL_RGB</STRONG>, <STRONG>GL_RGBA</STRONG>, <STRONG>GL_LUMINANCE</STRONG>, and
<STRONG>GL_LUMINANCE_ALPHA</STRONG>.
<EM>type</EM> Specifies the data type of the pixel data.
The following symbolic values are accepted:
<STRONG>GL_UNSIGNED_BYTE</STRONG>, <STRONG>GL_BYTE</STRONG>, <STRONG>GL_BITMAP</STRONG>,
<STRONG>GL_UNSIGNED_SHORT</STRONG>, <STRONG>GL_SHORT</STRONG>,
<STRONG>GL_UNSIGNED_INT</STRONG>, <STRONG>GL_INT</STRONG>, and <STRONG>GL_FLOAT</STRONG>.
<EM>pixels</EM> Specifies a pointer to the image data in
memory.
<STRONG>DESCRIPTION</STRONG>
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 <STRONG>glEnable</STRONG>
and <STRONG>glDisable</STRONG> with argument <STRONG>GL_TEXTURE_2D</STRONG>.
To define texture images, call <STRONG>glTexImage2D</STRONG>. The arguments
describe the parameters of the texture image, such as
height, width, width of the border, level-of-detail number
(see <STRONG>glTexParameter</STRONG>), and number of color components
provided. The last three arguments describe how the image
is represented in memory; they are identical to the pixel
formats used for <STRONG>glDrawPixels</STRONG>.
If <EM>target</EM> is <STRONG>GL_PROXY_TEXTURE_2D</STRONG>, no data is read from
<EM>pixels</EM>, 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
<STRONG>glGetError</STRONG>). To query for an entire mipmap array, use an
image array level greater than or equal to 1.
If <EM>target</EM> is <STRONG>GL_TEXTURE_2D</STRONG>, data is read from <EM>pixels</EM> as a
sequence of signed or unsigned bytes, shorts, or longs, or
single-precision floating-point values, depending on <EM>type</EM>.
These values are grouped into sets of one, two, three, or
four values, depending on <EM>format</EM>, to form elements. If <EM>type</EM>
is <STRONG>GL_BITMAP</STRONG>, the data is considered as a string of unsigned
bytes (and <EM>format</EM> must be <STRONG>GL_COLOR_INDEX</STRONG>). Each data byte is
treated as eight 1-bit elements, with bit ordering
determined by <STRONG>GL_UNPACK_LSB_FIRST</STRONG> (see <STRONG>glPixelStore</STRONG>).
The first element corresponds to the lower left corner of
the texture image. Subsequent elements progress left-to-
right through the remaining texels in the lowest row of the
texture image, and then in successively higher rows of the
texture image. The final element corresponds to the upper
right corner of the texture image.
<EM>format</EM> determines the composition of each element in <EM>pixels</EM>.
It can assume one of nine symbolic values:
<STRONG>GL_COLOR_INDEX</STRONG>
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 <STRONG>GL_INDEX_SHIFT</STRONG>, and added to
<STRONG>GL_INDEX_OFFSET</STRONG> (see
<STRONG>glPixelTransfer</STRONG>). The resulting index is converted
to a set of color components using the
<STRONG>GL_PIXEL_MAP_I_TO_R</STRONG>, <STRONG>GL_PIXEL_MAP_I_TO_G</STRONG>,
<STRONG>GL_PIXEL_MAP_I_TO_B</STRONG>, and <STRONG>GL_PIXEL_MAP_I_TO_A</STRONG>
tables, and clamped to the range [0,1].
<STRONG>GL_RED</STRONG> 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 <STRONG>GL_c_SCALE</STRONG>,
added to the signed bias <STRONG>GL_c_BIAS</STRONG>, and clamped to
the range [0,1] (see <STRONG>glPixelTransfer</STRONG>).
<STRONG>GL_GREEN</STRONG> 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 <STRONG>GL_c_SCALE</STRONG>,
added to the signed bias <STRONG>GL_c_BIAS</STRONG>, and clamped to
the range [0,1] (see <STRONG>glPixelTransfer</STRONG>).
<STRONG>GL_BLUE</STRONG> 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 <STRONG>GL_c_SCALE</STRONG>,
added to the signed bias <STRONG>GL_c_BIAS</STRONG>, and clamped to
the range [0,1] (see <STRONG>glPixelTransfer</STRONG>).
<STRONG>GL_ALPHA</STRONG> 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 <STRONG>GL_c_SCALE</STRONG>,
added to the signed bias <STRONG>GL_c_BIAS</STRONG>, and clamped to
the range [0,1] (see <STRONG>glPixelTransfer</STRONG>).
<STRONG>GL_RGB</STRONG> 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
<STRONG>GL_c_SCALE</STRONG>, added to the signed bias <STRONG>GL_c_BIAS</STRONG>,
and clamped to the range [0,1] (see
<STRONG>glPixelTransfer</STRONG>).
<STRONG>GL_RGBA</STRONG> Each element contains all four components. Each
component is multiplied by the signed scale factor
<STRONG>GL_c_SCALE</STRONG>, added to the signed bias <STRONG>GL_c_BIAS</STRONG>,
and clamped to the range [0,1] (see
<STRONG>glPixelTransfer</STRONG>).
<STRONG>GL_LUMINANCE</STRONG>
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 <STRONG>GL_c_SCALE</STRONG>,
added to the signed bias <STRONG>GL_c_BIAS</STRONG>, and clamped to
the range [0,1] (see <STRONG>glPixelTransfer</STRONG>).
<STRONG>GL_LUMINANCE_ALPHA</STRONG>
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 <STRONG>GL_c_SCALE</STRONG>, added to the signed bias
<STRONG>GL_c_BIAS</STRONG>, and clamped to the range [0,1] (see
<STRONG>glPixelTransfer</STRONG>).
Refer to the <STRONG>glDrawPixels</STRONG> reference page for a description
of the acceptable values for the <EM>type</EM> parameter.
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 <EM>internalformat</EM>. The GL will
choose an internal representation that closely approximates
that requested by <EM>internalformat</EM>, but it may not match
exactly. (The representations specified by <STRONG>GL_LUMINANCE</STRONG>,
<STRONG>GL_LUMINANCE_ALPHA</STRONG>, <STRONG>GL_RGB</STRONG>, and <STRONG>GL_RGBA</STRONG> must match exactly.
The numeric values 1, 2, 3, and 4 may also be used to
specify the above representations.)
Use the <STRONG>GL_PROXY_TEXTURE_2D</STRONG> 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 then query this state, call <STRONG>glGetTexLevelParameter</STRONG>. 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 <EM>pixels</EM>. 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.
<STRONG>NOTES</STRONG>
Texturing has no effect in color index mode.
The texture image can be represented by the same data
formats as the pixels in a <STRONG>glDrawPixels</STRONG> command, except that
<STRONG>GL_STENCIL_INDEX</STRONG> and <STRONG>GL_DEPTH_COMPONENT</STRONG> cannot be used.
<STRONG>glPixelStore</STRONG> and <STRONG>glPixelTransfer</STRONG> modes affect texture images
in exactly the way they affect <STRONG>glDrawPixels</STRONG>.
<STRONG>glTexImage2D</STRONG> and <STRONG>GL_PROXY_TEXTURE_2D</STRONG> are only available 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, <EM>pixels</EM> may be a null pointer.
In this case texture memory is allocated to accommodate a
texture of width <EM>width</EM> and height <EM>height</EM>. You can then
download subtextures to initialize this texture memory. The
image is undefined if the user tries to apply an
uninitialized portion of the texture image to a primitive.
<STRONG>ERRORS</STRONG>
<STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>target</EM> is not <STRONG>GL_TEXTURE_2D</STRONG>
or <STRONG>GL_PROXY_TEXTURE_2D</STRONG>.
<STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>format</EM> is not an accepted
format constant. Format constants other than
<STRONG>GL_STENCIL_INDEX</STRONG> and <STRONG>GL_DEPTH_COMPONENT</STRONG> are accepted.
<STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>type</EM> is not a type constant.
<STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>type</EM> is <STRONG>GL_BITMAP</STRONG> and <EM>format</EM>
is not <STRONG>GL_COLOR_INDEX</STRONG>.
<STRONG>GL_INVALID_VALUE</STRONG> is generated if <EM>level</EM> is less than 0.
<STRONG>GL_INVALID_VALUE</STRONG> may be generated if <EM>level</EM> is greater than
log <EM>max</EM>, where <EM>max</EM> is the returned value of
<STRONG>GL_MAX_TEXTURE_SIZE</STRONG>.
<STRONG>GL_INVALID_VALUE</STRONG> is generated if <EM>internalformat</EM> is not 1, 2,
3, 4, or one of the accepted resolution and format symbolic
constants.
<STRONG>GL_INVALID_VALUE</STRONG> is generated if <EM>width</EM> or <EM>height</EM> is less
than 0 or greater than 2 + <STRONG>GL_MAX_TEXTURE_SIZE</STRONG>, or if either
cannot be represented as 2k+2(border) for some integer value
of <EM>k</EM>.
<STRONG>GL_INVALID_VALUE</STRONG> is generated if <EM>border</EM> is not 0 or 1.
<STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>glTexImage2D</STRONG> is
executed between the execution of <STRONG>glBegin</STRONG> and the
corresponding execution of <STRONG>glEnd</STRONG>.
<STRONG>ASSOCIATED</STRONG> <STRONG>GETS</STRONG>
<STRONG>glGetTexImage</STRONG>
<STRONG>glIsEnabled</STRONG> with argument <STRONG>GL_TEXTURE_2D</STRONG>
<STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>
<STRONG>glCopyPixels</STRONG>, <STRONG>glCopyTexImage1D</STRONG>, <STRONG>glCopyTexImage2D</STRONG>,
<STRONG>glCopyTexSubImage1D</STRONG>, <STRONG>glCopyTexSubImage2D</STRONG>, <STRONG>glDrawPixels</STRONG>,
<STRONG>glPixelStore</STRONG>, <STRONG>glPixelTransfer</STRONG>, <STRONG>glTexEnv</STRONG>, <STRONG>glTexGen</STRONG>,
<STRONG>glTexImage1D</STRONG>, <STRONG>glTexSubImage1D</STRONG>, <STRONG>glTexSubImage2D</STRONG>,
<STRONG>glTexParameter</STRONG>
</PRE>
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