glCopyTexImage2D

  • Article

The glCopyTexImage2D function copies pixels from the framebuffer into a two-dimensional texture image.

void glCopyTexImage2D(
  GLenum target,  GLint level,  GLenum internalFormat,  GLint x,  GLint y,  GLsizei width,  GLsizei height,  GLint border);

Parameters

  • target
    The target to which the image data will be changed. Must have the value GL_TEXTURE_2D.

  • level
    The level-of-detail number. Level 0 is the base image. Level n is the nth mipmap reduction image.

  • internalFormat
    The internal format and resolution of the texture data. The values 1, 2, 3, and 4 are not accepted for internalFormat. The parameter can assume one of the following symbolic values:

    Constant R Bits G Bits B Bits A Bits L Bits I Bits
    GL_ALPHA
    GL_ALPHA4 4
    GL_ALPHA8 8
    GL_ALPHA12 12
    GL_ALPHA16 16
    GL_LUMINANCE
    GL_LUMINANCE4 4
    GL_LUMINANCE8 8
    GL_LUMINANCE12 12
    GL_LUMINANCE16 16
    GL_LUMINANCE_ALPHA
    GL_LUMINANCE4_ALPHA4 4 4
    GL_LUMINANCE6_ALPHA2 2 6
    GL_LUMINANCE8_ALPHA8 8 8
    GL_LUMINANCE12_ALPHA4 4 12
    GL_LUMINANCE12_ALPHA12 12 12
    GL_LUMINANCE16_ALPHA16 16 16
    GL_INTENSITY
    GL_INTENSITY4 4
    GL_INTENSITY8 8
    GL_INTENSITY12 12
    GL_INTENSITY16 16
    GL_RGB
    GL_R3_G3_B2 3 3 2
    GL_RGB4 4 4 4
    GL_RGB5 5 5 5
    GL_RGB8 8 8 8
    GL_RGB10 10 10 10
    GL_RGB12 12 12 12
    GL_RGB16 16 16 16
    GL_RGBA
    GL_RGBA2 2 2 2 2
    GL_RGBA4 4 4 4 4
    GL_RGB5_A1 5 5 5 1
    GL_RGBA8 8 8 8 8
    GL_RGB10_A2 10 10 10 2
    GL_RGBA12 12 12 12 12
    GL_RGBA16 16 16 16 16

  • x, y
    The window coordinates of the lower-left corner of the rectangular region of pixels to be copied.

  • width
    The width of the texture image. Must be 2*n* + 2 * border for some integer n.

  • height
    The height of the texture image. Must be 2*n* + 2 * border for some integer n.

  • border
    The width of the border. Must be either zero or 1.

Remarks

The glCopyTexImage2D function defines a two-dimensional texture image using pixels from the current framebuffer, rather than from main memory as is the case for glTexImage2D.

Using the mipmap level specified with level, texture arrays are defined as a rectangle of pixels with the lower-left corner located at the coordinates x and y, width equal to width + (2 * border), and a height equal to height + (2 * border). The internal format of the texture array is specified with the internalFormat parameter.

The glCopyTexImage2D function processes the pixels in a row in the same way as glCopyPixels except that before the final conversion of the pixels, all pixel component values are clamped to the range [0, 1] and converted to the texture's internal format for storage in the texture array. Pixel ordering is determined with lower x and y coordinates corresponding to lower s and t texture coordinates. If any of the pixels within a specified row of the current framebuffer are outside the window associated with the current rendering context, then their values are undefined.

You cannot include calls to glCopyTexImage2D in display lists.

Note  The glCopyTexImage2D function is only available in OpenGL version 1.1 or later.

Texturing has no effect in color-index mode. The glPixelStore and glPixelTransfer functions affect texture images in exactly the way they affect glDrawPixels.

The following function retrieves information related to glCopyTexImage2D:

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 an accepted value.
GL_INVALID_VALUE level was less than zero or greater than log sub 2(max), where max is the returned value of GL_MAX_TEXTURE_SIZE.
GL_INVALID_VALUE border was not zero or 1.
GL_INVALID_VALUE width was less than zero, greater than 2 + GL_MAX_TEXTURE_SIZE; or width cannot be represented as 2n + 2 * border for some integer n.
GL_INVALID_OPERATION glCopyTexImage2D was called between a call to glBegin and the corresponding call to glEnd.

Requirements

**  Windows NT/2000:** Requires Windows NT 4.0 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, glCopyTexImage1D, glDrawPixels, glEnd, glFog, glPixelStore, glPixelTransfer, glTexEnv, glTexGen, glTexImage1D, glTexImage2D, glTexParameter