glTexImage1D
[New
- Windows 95, OEM Service Release 2]
The glTexImage1D
function specifies a one-dimensional texture image.
void glTexImage1D(
|
GLenum target, |
|
|
GLint level, |
|
|
GLint components, |
|
|
GLsizei width, |
|
|
GLint border, |
|
|
GLenum format, |
|
|
GLenum type, |
|
|
const GLvoid *pixels |
|
|
); |
|
Parameters
target
The target
texture. Must be GL_TEXTURE_1D.
level
The
level-of-detail number. Level 0 is the base image level. Level n is the nth
mipmap reduction image.
components
The number of
color components in the texture. Must be 1, 2, 3, or 4.
width
The width of
the texture image. Must be 2^n + 2(border) for some integer n.
The height of the texture image is 1.
border
The width of
the border. Must be either 0 or 1.
format
The format of
the pixel data. 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 0 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 red 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).
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
Each element
is a complete RGBA element. It is converted to floating point. 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_BGR_EXT
Each pixel is
a group of three components in this order: blue, green, red.
GL_BGR_EXT
provides a format that matches the memory layout of Windows device-independent
bitmaps (DIBs). Thus your applications can use the same data with Win32
function calls and OpenGL pixel function calls.
GL_BGRA_EXT
Each pixel is
a group of four components in this order: blue, green, red, alpha.
GL_BGRA_EXT
provides a format that matches the memory layout of Windows device-independent
bitmaps (DIBs). Thus your applications can use the same data with Win32
function calls and OpenGL pixel function calls.
GL_LUMINANCE
Each element
is a single luminance value. It is converted to floating point, and 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, and 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).
type
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
A pointer to
the image data in memory.
Remarks
The glTexImage1D
function specifies a one-dimensional texture image. 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 number of color components provided. The
last three arguments describe the way the image is represented in memory. These
arguments are identical to the pixel formats used for glDrawPixels.
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).
A texture
image can have up to four components per texture element, depending on components.
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. The glPixelStore and glPixelTransfer modes affect texture
images in exactly the way they affect glDrawPixels.
A texture image
with zero width indicates the null texture. If the null texture is specified
for level-of-detail 0, it is as if texturing were disabled.
The following
functions retrieve information related to glTexImageID:
glGetTexImage
glIsEnabled with argument GL_TEXTURE_1D
Error Codes
The following
are the error codes generated and their conditions.
|
Error
Code |
Condition |
|
GL_INVALID_ENUM
|
target was not GL_TEXTURE_1D. |
|
GL_INVALID_ENUM
|
format was not an accepted format constant. Format
constants other than GL_STENCIL_INDEX and GL_DEPTH_COMPONENT were accepted. |
|
GL_INVALID_ENUM
|
type was not a type constant. |
|
GL_INVALID_ENUM
|
type was GL_BITMAP and format was not
GL_COLOR_INDEX. |
|
GL_INVALID_VALUE
|
level was less than zero or greater than log (2) max, where max was the returned value of
GL_MAX_TEXTURE_SIZE. |
|
GL_INVALID_VALUE
|
components was not 1, 2, 3, or 4. |
|
GL_INVALID_VALUE
|
width was less than zero or greater than 2 +
GL_MAX_TEXTURE_SIZE, or if it could not be represented as 2^n + 2(border)
for some integer value of n. |
|
GL_INVALID_VALUE
|
border was not 0 or 1. |
|
GL_INVALID_OPERATION
|
glTexImage1D was called between a call to glBegin and the
corresponding call to glEnd. |
See Also