glteximage1d - Man Page
glTexImage1D(3G) OpenGL Reference glTexImage1D(3G)
NAME
glTexImage1D - specify a one-dimensional texture image
C SPECIFICATION
void glTexImage1D( GLenum target,
GLint level,
GLint components,
GLsizei width,
GLint border,
GLenum format,
GLenum type,
const GLvoid *pixels )
PARAMETERS
target Specifies the target texture. Must be GL_TEXTURE_1D or
GL_PROXY_TEXTURE_1D_SGI.
level Specifies the level-of-detail number. Level 0 is the base
image level. Level n is the nth mipmap reduction image.
components is used to request the internal storage format of the texture
image. It must be 1, 2, 3, or 4, or one of the following
symbolic constants: GL_ALPHA, GL_ALPHA4_EXT, GL_ALPHA8_EXT,
GL_ALPHA12_EXT, GL_ALPHA16_EXT, GL_LUMINANCE,
GL_LUMINANCE4_EXT, GL_LUMINANCE8_EXT, GL_LUMINANCE12_EXT,
GL_LUMINANCE16_EXT, GL_LUMINANCE_ALPHA,
GL_LUMINANCE4_ALPHA4_EXT, GL_LUMINANCE6_ALPHA2_EXT,
GL_LUMINANCE8_ALPHA8_EXT, GL_LUMINANCE12_ALPHA4_EXT,
GL_LUMINANCE12_ALPHA12_EXT, GL_LUMINANCE16_ALPHA16_EXT,
GL_INTENSITY_EXT, GL_INTENSITY4_EXT, GL_INTENSITY8_EXT,
GL_INTENSITY12_EXT, GL_INTENSITY16_EXT, GL_RGB, GL_RGB2_EXT,
GL_RGB4_EXT, GL_RGB5_EXT, GL_RGB8_EXT, GL_RGB10_EXT,
GL_RGB12_EXT, GL_RGB16_EXT, GL_RGBA, GL_RGBA2_EXT,
GL_RGBA4_EXT, GL_RGB5_A1_EXT, GL_RGBA8_EXT, GL_RGB10_A2_EXT,
GL_RGBA12_EXT, GL_RGBA16_EXT, GL_DUAL_ALPHA4_SGIS,
GL_DUAL_ALPHA8_SGIS, GL_DUAL_ALPHA12_SGIS,
GL_DUAL_ALPHA16_SGIS, GL_DUAL_LUMINANCE4_SGIS,
GL_DUAL_LUMINANCE8_SGIS, GL_DUAL_LUMINANCE12_SGIS,
GL_DUAL_LUMINANCE16_SGIS, GL_DUAL_INTENSITY4_SGIS,
GL_DUAL_INTENSITY8_SGIS, GL_DUAL_INTENSITY12_SGIS,
GL_DUAL_INTENSITY16_SGIS, GL_DUAL_LUMINANCE_ALPHA4_SGIS,
GL_DUAL_LUMINANCE_ALPHA8_SGIS, GL_QUAD_ALPHA4_SGIS,
GL_QUAD_ALPHA8_SGIS, GL_QUAD_LUMINANCE4_SGIS,
GL_QUAD_LUMINANCE8_SGIS, GL_QUAD_INTENSITY4_SGIS, or
GL_QUAD_INTENSITY8_SGIS.
width Specifies the width of the texture image. Must be
2**n+2*border for some integer n. The height of the texture
image is 1.
Page 1
glTexImage1D(3G) OpenGL Reference glTexImage1D(3G)
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_ABGR_EXT,
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_EXT,
GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
GL_UNSIGNED_INT_8_8_8_8_EXT, and
GL_UNSIGNED_INT_10_10_10_2_EXT.
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. One-dimensional texturing is
enabled and disabled using glEnable and glDisable with argument
GL_TEXTURE_1D.
Texture images are defined with glTexImage1D. The arguments 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
the way the image is represented in memory, and they are identical to the
pixel formats used for glDrawPixels.
If target is GL_PROXY_TEXTURE_1D_EXT 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
will set all of the texture image state to 0 (GL_TEXTURE_WIDTH,
GL_TEXTURE_HEIGHT, GL_TEXTURE_BORDER, GL_TEXTURE_COMPONENTS,
GL_TEXTURE_RED_SIZE_EXT, GL_TEXTURE_GREEN_SIZE_EXT,
GL_TEXTURE_BLUE_SIZE_EXT, GL_TEXTURE_ALPHA_SIZE_EXT,
GL_TEXTURE_LUMINANCE_SIZE_EXT, and GL_TEXTURE_INTENSITY_SIZE_EXT), but no
error will be generated.
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. (Note that if type is set to GL_UNSIGNED_BYTE_3_3_2_EXT,
GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
GL_UNSIGNED_INT_8_8_8_8_EXT, or GL_UNSIGNED_INT_10_10_10_2_EXT then it is
a special case in which all the elements of each group are packed into a
single unsigned byte, unsigned short, or unsigned int. This is described
in glDrawPixels.)
Page 2
glTexImage1D(3G) OpenGL Reference glTexImage1D(3G)
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 left end of the texture 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 pixels. It can
assume one of nine symbolic values:
GL_COLOR_INDEX
Each element is a single value, a color index. It is converted
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. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for green and blue, and 1.0 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. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for red and blue, and 1.0 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. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for red and green, and 1.0 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. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 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).
Page 3
glTexImage1D(3G) OpenGL Reference glTexImage1D(3G)
GL_RGB Each element is an RGB triple. It is converted to floating
point and assembled into an RGBA element by attaching 1.0 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_ABGR_EXT
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].
GL_ABGR_EXT may be faster or slower than GL_RGBA depending on
the internal ordering native to the GL. (see glPixelTransfer).
GL_LUMINANCE
Each element is a single luminance value. It is converted to
floating point, then assembled into an RGBA element by
replicating the luminance value three times for red, green, and
blue and attaching 1.0 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. It is converted to
floating point, then assembled 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).
An application may desire that the texture be stored at a certain
resolution, or that it be stored in a certain format. This resolution and
format can be requested by components. The GL will choose an internal
representation that closely approximates that requested by components,
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.) The GL_PROXY_TEXTURE_1D_EXT target can be used to try-
out a resolution and format, the implementation will update and recompute
it's best match for the requested storage resolution and format. This
state can then be queried using glGetTexLevelParameter. If the texture
cannot be accomodated texture state will be 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.
Page 4
glTexImage1D(3G) OpenGL Reference glTexImage1D(3G)
The mapping of components from the canonical RGBA to the internal storage
formats that begin with GL_DUAL_ and GL_QUAD_ needs to be clarified.
There are three cases. The first case is for the GL_DUAL_ formats that
are groups of GL_ALPHA, GL_LUMINANCE, and GL_INTENSITY. The R value goes
to the first group while the A value goes to the second group. The
second case is for the GL_DUAL_ formats that are groups of
GL_LUMINANCE_ALPHA. The R and G values go to the first group while the B
and A values go to the second group. The third case is for the GL_QUAD_
formats. The R value goes to the first group, the G value to the second
group, the B value to the third group, and the A value to the fourth
group.
NOTES
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 proxy textures and the internal format components values are part of
the EXT_texture extension, not part of the core GL command set. If
GL_EXT_texture is included in the string returned by glGetString, when
called with argument GL_EXTENSIONS, extension EXT_texture is supported by
the connection. Similarly, if the extensions string contains
GL_EXT_abgr, then EXT_abgr is supported.
If type is set to GL_UNSIGNED_BYTE_3_3_2_EXT,
GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
GL_UNSIGNED_INT_8_8_8_8_EXT, or GL_UNSIGNED_INT_10_10_10_2_EXT and the
EXT_packed_pixels extension is not supported then a GL_INVALID_ENUM error
is generated.
See glIntro for more information on using extensions.
ERRORS
GL_INVALID_ENUM is generated when target is not GL_TEXTURE_1D.
GL_INVALID_ENUM is generated when 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 when 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 zero.
GL_INVALID_VALUE is generated if components is not 1, 2, 3, or 4 or one
of the accepted resolution and format symbolic constants.
Page 5
glTexImage1D(3G) OpenGL Reference glTexImage1D(3G)
GL_INVALID_VALUE is generated if width is less than zero or greater than
2 + GL_MAX_TEXTURE_SIZE, or if it cannot be represented as 2**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 executed between the
execution of glBegin and the corresponding execution of glEnd.
GL_TEXTURE_TOO_LARGE_EXT is generated if the implementation cannot
accomodate a texture of the size requested.
ASSOCIATED GETS
glGetTexImage
glIsEnabled with argument GL_TEXTURE_1D
glGetTexLevelParameter with a first argument of GL_PROXY_TEXTURE_1D_EXT
and a third argument of GL_TEXTURE_RED_SIZE_EXT,
GL_TEXTURE_GREEN_SIZE_EXT, GL_TEXTURE_BLUE_SIZE_EXT,
GL_TEXTURE_ALPHA_SIZE_EXT, GL_TEXTURE_LUMINANCE_SIZE_EXT,
GL_TEXTURE_INTENSITY_SIZE_EXT, GL_TEXTURE_WIDTH, GL_TEXTURE_HEIGHT,
GL_TEXTURE_BORDER, or GL_TEXTURE_COMPONENTS.
MACHINE DEPENDENCIES
RealityEngine, RealityEngine2, and VTX systems do not support convolving
images as they are loaded into texture memory.
InfiniteReality systems have limited support for convolving images as
they are loaded into texture memory. The image resulting from
convolution must be a multiple of 8 in width.
RealityEngine, RealityEngine2, and VTX systems do not support histogram
or minmax operations on images as they are being loaded into texture
memory.
The EXT_packed_pixels extension is not supported on RealityEngine,
RealityEngine2, and VTX systems; it will be supported on High Impact and
Maximum Impact systems in a future release.
On RealityEngine, RealityEngine2, and VTX systems:
1. The texture environment must be defined and texturing must be
enabled before loading a texture.
2. Texture formats composed only of alpha are not supported.
3. Borders are not supported; hence the border width must be 0.
4. Proxy textures are not supported.
Page 6
glTexImage1D(3G) OpenGL Reference glTexImage1D(3G)
5. glTexImage2D with a NULL texture image may not be used inside a
display list.
6. GL_INTERLACE_SGIX is not supported (see glEnable).
High Impact and Maximum Impact systems do not support texture internal
formats of the type GL_INTENSITY or GL_ALPHA. Internally the number of
bits per component is the same for all components and will be 4, 8, or 12
bits per component. All specified internal formats will receive an equal
or greater representation in this scheme, up to the 12-bit limit.
High Impact and Maximum Impact systems without the TRAM option card
support 4 bits per component for GL_RGB and GL_RGBA, 4/8 bits per
component for GL_LUMINANCE_ALPHA, and 4/8/12 bits per component for
GL_RGBA.
Texture borders are not supported on InfiniteReality systems, so the
border width should always be zero. Borders will be supported in future
releases. However, borders use texture memory very inefficiently; up to
four times the memory required by the base texture may be needed to
support borders properly. Whenever possible, applications should use the
texture wrap mode GL_CLAMP_TO_EDGE_SGIS and borderless textures. This
might be essential for large textures, which otherwise won't fit in
texture memory because of the border overhead.
The SGIS_texture_select extension is supported only on InfiniteReality
systems and on High Impact and Maximum Impact systems with the TRAM
option card.
SEE ALSO
glDrawPixels, glFog, glPixelStore, glPixelTransfer, glTexEnv, glTexGen,
glTexImage2D, glTexParameter
Page 7