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glTexImage2D: specify a two-dimensional texture image.
C Specification |
Parameters |
Description |
Notes |
Errors |
Associated Gets |
See Also
void glTexImage2D(
GLenum target,
GLint level,
GLint internalformat,
GLsizei width,
GLsizei height,
GLint border,
GLenum format,
GLenum type,
const GLvoid *pixels)
- 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. Additionally, if the
extension GL_EXT_shadow is supported, may be one of the
symbolic constants GL_DEPTH_COMPONENT,
GL_DEPTH_COMPONENT16_EXT,
GL_DEPTH_COMPONENT24_EXT, or
GL_DEPTH_COMPONENT32_EXT.
- 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.
- height
- Specifies the height of the texture image. Must be
2m + 2border 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_RGBA,
GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
If the extension GL_EXT_shadow is
supported, the symbolic value GL_DEPTH_COMPONENT is also
accepted.
- 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.
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 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 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 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).
- GL_DEPTH_COMPONENT
- Each element is a single depth component. It is
converted to floating-point, then multiplied by the signed scale factor
GL_DEPTH_SCALE, added to the signed bias
GL_DEPTH_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 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 above
representations.)
Use the GL_PROXY_TEXTURE_2D 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
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.
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.
The format value
GL_DEPTH_COMPONENT and internalformat values
GL_DEPTH_COMPONENT16_EXT,
GL_DEPTH_COMPONENT24_EXT, and
GL_DEPTH_COMPONENT32_EXT may only be used if the
GL_EXT_shadow extension is supported.
glTexImage2D and GL_PROXY_TEXTURE_2D 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, 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 initialize this texture memory. The image is
undefined if the user tries to apply an uninitialized portion of the texture
image to a primitive.
- 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 format constant. Format constants other than
GL_STENCIL_INDEX 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 log2max, 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 or
height is less than 0 or greater than 2 +
GL_MAX_TEXTURE_SIZE, or if either cannot be
represented as 2k + 2border 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.
glGetTexImage
glIsEnabled with argument
GL_TEXTURE_2D
glCopyPixels,
glCopyTexImage1D,
glCopyTexImage2D,
glCopyTexSubImage1D,
glCopyTexSubImage2D,
glDrawPixels,
glPixelStore,
glPixelTransfer,
glTexEnv,
glTexGen,
glTexImage1D,
glTexSubImage1D,
glTexSubImage2D,
glTexParameter
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C Specification