C SPECIFICATION

void glTexImage1D(GLenum target, GLint level, GLint internalFormat, GLsizei width, GLint border, GLenum format, GLenum type, const GLvoid * data);

PARAMETERS

target

Specifies the target texture. Must be GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.

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 one of base internal formats given in Table 1, one of the sized internal formats given in Table 2, or one of the compressed internal formats given in Table 3, below.

width

Specifies the width of the texture image. All implementations support texture images that are at least 1024 texels wide. The height of the 1D texture image is 1.

border

This value must be 0.

format

Specifies the format of the pixel data. The following symbolic values are accepted: GL_RED, GL_RG, GL_RGB, GL_BGR, GL_RGBA, and GL_BGRA.

type

Specifies the data type of the pixel data. The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, 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.

data

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. To enable and disable one-dimensional texturing, call 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 how the image is represented in memory.

If target is GL_PROXY_TEXTURE_1D, no data is read from data, 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_1D, data is read from data 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. Each data byte is treated as eight 1-bit elements, with bit ordering determined by GL_UNPACK_LSB_FIRST (see glPixelStore()).

If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer()) while a texture image is specified, data is treated as a byte offset into the buffer object's data store.

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 data. It can assume one of these symbolic values:

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].

GL_RG

Each element is a single red/green double The GL converts it to floating point and assembles it into an RGBA element by attaching 0 for 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].

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].

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].

GL_DEPTH_COMPONENT

Each element is a single depth value. The GL converts it to floating point, multiplies by the signed scale factor GL_DEPTH_SCALE, adds the signed bias GL_DEPTH_BIAS, and clamps to the range [0,1].

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_RED, GL_RG, GL_RGB and GL_RGBA must match exactly.)

internalFormat may be one of the base internal formats shown in Table 1, below

Table 1. Base Internal Formats

internalFormat may also be one of the sized internal formats shown in Table 2, below

Table 2. Sized Internal Formats

Finally, internalFormat may also be one of the generic or compressed compressed texture formats shown in Table 3 below

Table 3. Compressed Internal Formats

If the internalFormat parameter is one of the generic compressed formats, GL_COMPRESSED_RED, GL_COMPRESSED_RG, GL_COMPRESSED_RGB, or GL_COMPRESSED_RGBA, the GL will replace the internal format with the symbolic constant for a specific internal format and compress the texture before storage. If no corresponding internal format is available, or the GL can not compress that image for any reason, the internal format is instead replaced with a corresponding base internal format.

If the internalFormat parameter is GL_SRGB, GL_SRGB8, GL_SRGB_ALPHAor GL_SRGB8_ALPHA8, the texture is treated as if the red, green, or blue components are encoded in the sRGB color space. Any alpha component is left unchanged. The conversion from the sRGB encoded component c s to a linear component c l is:

c l = { c s 12.92 if c s ≤ 0.04045 ( c s + 0.055 1.055 ) 2.4 if c s > 0.04045

Assume c s is the sRGB component in the range [0,1].

Use the GL_PROXY_TEXTURE_1D 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 from data. 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.

Image-based shadowing can be enabled by comparing texture r coordinates to depth texture values to generate a boolean result. See glTexParameter() for details on texture comparison.

NOTES

glPixelStore() modes affect texture images.

data may be a null pointer. In this case texture memory is allocated to accommodate a texture of width width. You can then download subtextures to initialize the texture memory. The image is undefined if the program tries to apply an uninitialized portion of the texture image to a primitive.

glTexImage1D specifies the one-dimensional texture for the current texture unit, specified with glActiveTexture().

ASSOCIATED GETS

glGetTexImage()

glGet() with argument GL_PIXEL_UNPACK_BUFFER_BINDING

COPYRIGHT

Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2011 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see m[blue]http://oss.sgi.com/projects/FreeB/m[].