GLTEXIMAGE2D(3G) GLTEXIMAGE2D(3G)
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 )
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 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_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^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^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 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_BGR GL_RGBA, GL_BGRA,
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, 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 graphical primitive for which textur-ing texturing
ing 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
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_2D, 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 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.
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 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 assem-bles assembles
bles it into an RGBA element by attaching 0 for red and blue, and 1 for alpha. Each compo-nent component
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 assem-bles assembles
bles it into an RGBA element by attaching 0 for red and green, and 1 for alpha. Each com-ponent component
ponent 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 assem-bles assembles
bles 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 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
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 assem-bles assembles
bles 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 processing with a
GL_CONVOLUTION_BORDER_MODE of GL_REDUCE, for example), the width must 2^n + 2(height), for some
integer n, and height must be 2^m +2 (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 com-mand, command,
mand, 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 version 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 ini-tialize initialize
tialize this texture memory. The image is undefined if the user tries to apply an uninitialized por-tion portion
tion 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 specifies the two-dimensional tex-ture texture
ture for the current texture unit, specified 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 log2(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 represented as 2^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 format 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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