glTexImage2D(3)
NAME
glTexImage2D - specify a two-dimensional texture image
C SPECIFICATION
void glTexImage2D( GLenum target,
GLint level,
GLint internalFormat,
GLsizei width,
GLsizei height,
GLint border,
GLenum format,
GLenum type,
const GLvoid *pixels )
delim $$
PARAMETERS
target Specifies the target texture. Must be GL_TEXTURE_2D or
GL_PROXY_TEXTURE_2D.
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 tex-
ture. 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_R3_G3_B2, GL_RGB, 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 support texture images that are at
least 64 texels wide.
height Specifies the height of the texture image. Must be $2
sup m ~+~ 2 ( "border" )$ for some integer $m$. All
implementations support texture images that are at
least 64 texels high.
border Specifies the width of the border. Must be either 0 or
1.
format Specifies the 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_BGR GL_RGBA,
GL_BGRA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
type Specifies the data type of the pixel data. The follow-
ing symbolic values are accepted: GL_UNSIGNED_BYTE,
GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT, GL_SHORT,
GL_UNSIGNED_INT, GL_INT, GL_FLOAT,
GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,
GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV,
GL_UNSIGNED_SHORT_4_4_4_4,
GL_UNSIGNED_SHORT_4_4_4_4_REV,
GL_UNSIGNED_SHORT_5_5_5_1,
GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8,
GL_UNSIGNED_INT_8_8_8_8_REV,
GL_UNSIGNED_INT_10_10_10_2, and
GL_UNSIGNED_INT_2_10_10_10_REV.
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.
To define texture images, call glTexImage2D. The arguments describe
the parameters of the texture image, such as height, width, width of
the border, level-of-detail number (see glTexParameter), 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 glDrawPixels.
If target is GL_PROXY_TEXTURE_2D, 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 implemen-
tation 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_2D, data is read from pixels as a sequence of
signed or unsigned bytes, shorts, or longs, or single-precision float-
ing-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 lower left corner of the texture
image. Subsequent elements progress left-to-right through the remain-
ing texels in the lowest row of the texture image, and then in succes-
sively higher rows of the texture image. The final element corresponds
to the upper right corner of the texture image.
format determines the composition of each element in pixels. It can
assume one of eleven symbolic values:
GL_COLOR_INDEX
Each element is a single value, a color index. The GL con-
verts 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 compo-
nent 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 compo-
nent 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 compo-
nent 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
GL_BGR Each element is an RGB triple. The GL converts it to float-
ing 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
GL_BGRA Each element contains all four components. Each component is
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).
Refer to the glDrawPixels reference page for a description of the
acceptable values for the type parameter.
If an application wants to store the texture at a certain resolution or
in a certain , it can request the resolution and 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 above representations.)
Use the GL_PROXY_TEXTURE_2D target to try out a resolution and update
and recompute its best match for the requested storage resolution and .
To then 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.
If the GL_ARB_imaging extension is supported, RGBA elements may also be
processed by the imaging pipeline. The following stages may be applied
to an RGBA color before color component clamping to the range [0, 1]:
1. Color component replacement by the color table specified for
GL_COLOR_TABLE, if enabled. See glColorTable.
2. Two-dimensional Convolution filtering, if enabled. See
glConvolutionFilter1D.
If a convolution filter changes the __width of the texture (by pro-
cessing with a GL_CONVOLUTION_BORDER_MODE of GL_REDUCE, for exam-
ple), the width must $2 sup n + 2 ( "height" )$, for some integer
$n$, and height must be $2 sup m + ( "border" )$, for some integer
$m$, after filtering.
3. RGBA components may be multiplied by GL_POST_CONVOLUTION_c_SCALE,
and added to GL_POST_CONVOLUTION_c_BIAS, if enabled. See
glPixelTransfer.
4. Color component replacement by the color table specified for
GL_POST_CONVOLUTION_COLOR_TABLE, if enabled. See glColorTable.
5. Transformation by the color matrix. See glMatrixMode.
6. RGBA components may be multiplied by GL_POST_COLOR_MATRIX_c_SCALE,
and added to GL_POST_COLOR_MATRIX_c_BIAS, if enabled. See
glPixelTransfer.
7. Color component replacement by the color table specified for
GL_POST_COLOR_MATRIX_COLOR_TABLE, if enabled. See glColorTable.
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.
glTexImage2D and GL_PROXY_TEXTURE_2D are available only if the GL ver-
sion is 1.1 or greater.
Internal formats other than 1, 2, 3, or 4 may be used only 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 and height height. You can then download subtextures to initial-
ize this texture memory. The image is undefined if the user tries to
apply an uninitialized portion of the texture image to a primitive.
Formats GL_BGR, and GL_BGRA and types GL_UNSIGNED_BYTE_3_3_2,
GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5,
GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4,
GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1,
GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8,
GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, and
GL_UNSIGNED_INT_2_10_10_10_REV are available only if the GL version is
1.2 or greater.
When the GL_ARB_multitexture extension is supported, glTexImage2D spec-
ifies the two-dimensional texture for the current texture unit, speci-
fied with glActiveTextureARB.
ERRORS
GL_INVALID_ENUM is generated if target is not GL_TEXTURE_2D or
GL_PROXY_TEXTURE_2D.
GL_INVALID_ENUM is generated if format is not an accepted
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 $log sub
2$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 symbolic constants.
GL_INVALID_VALUE is generated if width or height is less than 0 or
greater than 2 + GL_MAX_TEXTURE_SIZE, or if either cannot be repre-
sented as $2 sup k ~+~ 2("border")$ for some integer value of k.
GL_INVALID_VALUE is generated if border is not 0 or 1.
GL_INVALID_OPERATION is generated if glTexImage2D is executed between
the execution of glBegin and the corresponding execution of glEnd.
GL_INVALID_OPERATION is generated if type is one of
GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,
GL_UNSIGNED_SHORT_5_6_5, or GL_UNSIGNED_SHORT_5_6_5_REV and format is
not GL_RGB.
GL_INVALID_OPERATION is generated if type is one of
GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV,
GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV,
GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV,
GL_UNSIGNED_INT_10_10_10_2, or GL_UNSIGNED_INT_2_10_10_10_REV and for-
mat is neither GL_RGBA nor GL_BGRA.
ASSOCIATED GETS
glGetTexImage
glIsEnabled with argument GL_TEXTURE_2D
SEE ALSO
glColorTable(3G), glConvolutionFilter2D(3G), glCopyPixels(3G),
glCopyTexImage1D(3G), glCopyTexImage2D(3G), glCopyTexSubImage1D(3G),
glCopyTexSubImage2D(3G), glCopyTexSubImage3D(3G), glDrawPixels(3G),
glMatrixMode(3G), glPixelStore(3G), glPixelTransfer(3G),
glSeparableFilter2D(3G), glTexEnv(3G), glTexGen(3G), glTexImage1D(3G),
glTexImage3D(3G), glTexSubImage1D(3G), glTexSubImage2D(3G),
glTexSubImage3D(3G), glTexParameter(3G)
GLTEXIMAGE2D(3G)
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