glTexImage1D

NAME

C SPECIFICATION

void glTexImage1D(GLenum target,
                  GLint level,
                  GLint internalformat,
                  GLsizei width,
                  GLint border,
                  GLenum format,
                  GLenum type,
                  const GLvoid *pixels)

PARAMETERS

DESCRIPTION

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 how the image is represented in memory; they are identical to the pixel formats used for glDrawPixels.

If target is GL_PROXY_TEXTURE_1D, 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_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. 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 image. Subsequent elements progress left-to- right through the remaining texels. The final element corresponds to the right end of the texture image.

The format parameter determines the composition of each element in pixels.

GL_COLOR_INDEX

Each element is a single value, a color index. The value 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_RGBA

Each pixel is a four-component group: for GL_RGBA, the red component is first, followed by green, followed by blue, followed by alpha. Floating-point values are converted directly to an internal floating-point format with unspecified precision. Signed integer values are mapped linearly to the internal floating-point format such that the most positive representable integer value maps to 1.0, and the most negative representable value maps to -1.0. (Note that this mapping does not convert 0 precisely to 0.0.) Unsigned integer data is mapped similarly: the largest integer value maps to 1.0, and 0 maps to 0.0. The resulting floating-point color values are then multiplied by GL_c_SCALE and added to GL_c_BIAS, where c is RED, GREEN, BLUE, and ALPHA for the respective color components.

If GL_MAP_COLOR is true, each color component is clamped to the range [0,1] and scaled by the size of lookup table GL_PIXEL_MAP_c_TO_c, then replaced by the value that it references in that table. c is R, G, B, or A respectively.

If GL_COLOR_TABLE_EXT is true, each color component is clamped to the range [0,1] and scaled by the size of the GL_COLOR_TABLE_EXT, then replaced by the value that it references in that table according to the format of the color table (see glColorTableEXT).

If GL_CONVOLUTION_1D_EXT is true one-dimensional convolution will be performed on each color component according to the format of the convolution filter (see glConvolutionFilter1DEXT). If the convolution border mode is such that the image is reduced, the resulting image must be a valid texture image size.

If GL_POST_CONVOLUTION_COLOR_TABLE_EXT is true, each color component is clamped to the range [0,1] and scaled by the size of the GL_POST_CONVOLUTION_COLOR_TABLE_EXT, then replaced by the value that it references in that table according to the format of the color table (see glColorTableEXT).

Each color is then transformed by the color matrix (see glMatrixMode).

If GL_POST_COLOR_MATRIX_COLOR_TABLE_EXT is true, each color component is clamped to the range [0,1] and scaled by the size of the GL_POST_COLOR_MATRIX_COLOR_TABLE_EXT, then replaced by the value that it references in that table according to the format of the color table (see glColorTableEXT).

Each color is then clamped to the color clamp values (see glPixelTransfer).

GL_RED

Each pixel is a single red component. This component is converted to the internal floating-point format in the same way the red component of an RGBA pixel is. It is then converted to an RGBA pixel with green and blue set to 0, and alpha set to 1. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_GREEN

Each pixel is a single green component. This component is converted to the internal floating-point format in the same way the green component of an RGBA pixel is. It is then converted to an RGBA pixel with red and blue set to 0, and alpha set to 1. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_BLUE

Each pixel is a single blue component. This component is converted to the internal floating-point format in the same way the blue component of an RGBA pixel is. It is then converted to an RGBA pixel with red and green set to 0, and alpha set to 1. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_ALPHA

Each pixel is a single alpha component. This component is converted to the internal floating-point format in the same way the alpha component of an RGBA pixel is. It is then converted to an RGBA pixel with red, green, and blue set to 0. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_LUMINANCE

Each pixel is a single luminance component. This component is converted to the internal floating-point format in the same way the red component of an RGBA pixel is. It is then converted to an RGBA pixel with red, green, and blue set to the converted luminance value, and alpha set to 1. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_LUMINANCE_ALPHA

Each pixel is a two-component group: luminance first, followed by alpha. The two components are converted to the internal floating-point format in the same way the red component of an RGBA pixel is. They are then converted to an RGBA pixel with red, green, and blue set to the converted luminance value, and alpha set to the converted alpha value. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_RGB

Each pixel is a three-component group: red first, followed by green, followed by blue. Each component is converted to the internal floating-point format in the same way the red, green, and blue components of an RGBA pixel are. The color triple is converted to an RGBA pixel with alpha set to 1. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_BGR_EXT

Each pixel is a three-component group: blue first, followed by green, followed by red. Each component is converted to the internal floating-point format in the same way the red, green, and blue components of an RGBA pixel are. The color triple is converted to an RGBA pixel with alpha set to 1. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_BGRA_EXT

Each pixel is a four-component group: blue first, followed by green, followed by red, followed by alpha. Each component is converted to the internal floating-point format in the same way the red, green, and blue components of an RGBA pixel are. The pixel is then treated as if it had been read as an RGBA pixel.

GL_ARGB_I3D

Each pixel is a four-component group: alpha first, followed by red, followed by green, followed by blue. Each component is converted to the internal floating-point format in the same way the red, green, and blue components of an RGBA pixel are. The pixel is then treated as if it had been read as an RGBA pixel.

GL_422_EXT

Each pixel is a two-component group: chrominance first, followed by luminance. Only an even number of pixels are processed. Luminance is present on all pixels; a full chrominance value requires two pixels. Each component is converted to the internal floating-point format in the same way the red component of an RGBA pixel is. They are then converted to an RGBA pixel with red set to converted luminance value, green set to the even pixel's converted chrominance value, blue set to the odd pixel's converted chrominance value, and alpha set to 1. After this conversion, the pixel is treated as if it had been read as an RGBA pixel.

GL_422_REV_EXT

Each pixel is a two-component group: luminance first, followed by chrominance. Conversion to RGBA then follows the conversion of the GL_422_EXT format.

GL_422_AVERAGE_EXT

Each pixel is a two-component group: chrominance first, followed by luminance. Only an even number of pixels are processed. Luminance is present on all pixels; a full chrominance value requires two pixels. Each component is converted to the internal floating-point format in the same way the red component of an RGBA pixel is. They are then converted to an RGBA pixel according to the following.

For even pixels, red is set to converted luminance value, green is set to the even pixel's converted chrominance value, blue is set to the odd pixel's converted chrominance value, and alpha is set to 1.

For odd pixels, red is set to converted luminance value, green is set to the average of the even pixel's converted chrominance and the next even pixel's converted chrominance value, blue is set to the average of the odd pixel's converted chrominance and the next odd pixel's converted chrominance, and alpha is set to 1. If the next even or odd pixel does not exist, the behavior of the odd pixel is the same as the GL_422_EXT format.

GL_422_REV_AVERAGE_EXT

Each pixel is a two-component group: luminance first, followed by chrominance. Conversion to RGBA then follows the conversion of the GL_422_AVERAGE_EXT format.

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 (or GL_BGR_EXT), and GL_RGBA (or GL_BGRA_EXT or GL_ARGB_I3D) 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_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 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

A texture image with width specified as a value of 0 indicates the null texture. If the null texture is specified for level-of-detail 0, it is as if texturing were disabled.

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.

glTexImage1D and GL_PROXY_TEXTURE_1D 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. Subtextures can be used to initialize the texture memory. The image is undefined if the user tries to apply an uninitialized portion of the texture image to a primitive.

EXTENSIONS

GL_EXT_422_pixels

GL_422_EXT, GL_422_REV_EXT, GL_422_AVERAGE_EXT, and GL_422_REV_AVERAGE_EXT are part of the EXT_422_pixels extension.

GL_I3D_argb

GL_ARGB_I3D is part of the I3D_argb extension.

GL_EXT_bgra

GL_BGR_EXT and GL_BGRA_EXT are part of the EXT_bgra extension.

GL_I3D_color_clamp

The color clamp is part of the I3D_color_clamp extension.

GL_EXT_color_matrix

The color matrix is part of the EXT_color_matrix extension.

GL_EXT_color_table

GL_COLOR_TABLE_EXT, GL_POST_CONVOLUTION_COLOR_TABLE_EXT, and GL_POST_COLOR_MATRIX_COLOR_TABLE_EXT are part of the EXT_color_table extension.

GL_EXT_convolution

GL_CONVOLUTION_1D_EXT is part of the EXT_convolution extension.

GL_EXT_packed_pixels

GL_UNSIGNED_BYTE_3_3_2_EXT, GL_UNSIGNED_BYTE_2_3_3_REV_EXT, GL_UNSIGNED_SHORT_5_6_5_EXT, GL_UNSIGNED_SHORT_5_6_5_REV_EXT, GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_4_4_4_4_REV_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT, GL_UNSIGNED_SHORT_1_5_5_5_REV_EXT, GL_UNSIGNED_INT_8_8_8_8_EXT, GL_UNSIGNED_INT_8_8_8_8_REV_EXT, GL_UNSIGNED_INT_10_10_10_2_EXT, and GL_UNSIGNED_INT_2_10_10_10_REV_EXT are part of the EXT_packed_pixels extension.

ERRORS

GL_INVALID_ENUM is generated if 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 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 format symbolic constants.

GL_INVALID_VALUE is generated if width 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 glTexImage1D is executed between the execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS

SEE ALSO