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glTexImage2D

The glTexImage2D function specifies a two-dimensional texture image.

void glTexImage2D(
  GLenum target,
  GLint level,
  GLint internalformat,
  GLsizei width,
  GLsizei height,
  GLint border,
  GLenum format,
  GLenum type,
  const GLvoid *pixels
);

Parameters

target
The target texture. Must be GL_TEXTURE_2D.
level
The level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
internalformat
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.
width
The width of the texture image. Must be 2n + 2(border) for some integer n.
height
The height of the texture image. Must be 2m + 2(border) for some integer m.
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:
Value Meaning
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 glTexImage2D function specifies a two-dimensional texture image. Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is enabled. Two-dimensional texturing is enabled and disabled using glEnable and glDisable with argument GL_TEXTURE_2D.

Texture images are defined with 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 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). Please see glDrawPixels for a description of the acceptable values for the type parameter.

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 height or 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 glTexImage2D:

glGetTexImage

glIsEnabled with argument GL_TEXTURE_2D

Error Codes

The following are the error codes generated and their conditions.

Error code Condition
GL_INVALID_ENUM target was not GL_TEXTURE_2D.
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 log2 max, where max was the returned value of GL_MAX_TEXTURE_SIZE.
GL_INVALID_VALUE internalformat was not 1, 2, 3, or 4.
GL_INVALID_VALUE width or height was less than zero or greater than 2 + GL_MAX_TEXTURE_SIZE, or if either could not be represented as 2k + 2(border) for some integer value of k.
GL_INVALID_VALUE border was not 0 or 1.
GL_INVALID_OPERATION glTexImage2D was called between a call to glBegin and the corresponding call to glEnd.

Requirements

  Windows NT/2000: Requires Windows NT 3.5 or later.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in Gl.h.
  Library: Use Opengl32.lib.

See Also

glBegin, glDrawPixels, glEnd, glFog, glIsEnabled, glPixelStore, glPixelTransfer, glTexEnv, glTexGen, glTexImage1D, glTexParameter


  

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