Name

glCopyTexImage2D — copy pixels into a 2D texture image

C Specification

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

Parameters

target

Specifies the target texture of the active texture unit. Must be GL_TEXTURE_2D, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, or GL_TEXTURE_CUBE_MAP_NEGATIVE_Z.

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 internal format of the texture. Must be one of the following symbolic constants: GL_ALPHA, GL_LUMINANCE, GL_LUMINANCE_ALPHA, GL_RGB, or GL_RGBA.

x, y

Specify the window coordinates of the lower left corner of the rectangular region of pixels to be copied.

width

Specifies the width of the texture image. All implementations support 2D texture images that are at least 64 texels wide and cube-mapped texture images that are at least 16 texels wide.

height

Specifies the height of the texture image. All implementations support 2D texture images that are at least 64 texels high and cube-mapped texture images that are at least 16 texels high.

border

Specifies the width of the border. Must be 0.

Description

Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is active. Texturing is active when the current fragment shader or vertex shader makes use of built-in texture lookup functions.

glCopyTexImage2D defines a two-dimensional texture image or cube-map texture image with pixels from the current framebuffer (rather than from client memory, as is the case for glTexImage2D).

The screen-aligned pixel rectangle with lower left corner at (x, y) and with a width of width and a height of height defines the texture array at the mipmap level specified by level. internalformat specifies the internal format of the texture array.

The pixels in the rectangle are processed exactly as if glReadPixels had been called with format set to GL_RGBA, but the process stops just after conversion of RGBA values. Subsequent processing is identical to that described for glTexImage2D, beginning with the clamping of the R, G, B, and A values to the range 0 1 and then conversion to the texture's internal format for storage in the texel array.

The components required for internalformat must be a subset of those present in the framebuffer's format. For example, a GL_RGBA framebuffer can be used to supply components for any internalformat. However, a GL_RGB framebuffer can only be used to supply components for GL_RGB or GL_LUMINANCE base internal format textures, not GL_ALPHA, GL_LUMINANCE_ALPHA, or GL_RGBA textures.

Pixel ordering is such that lower x and y screen coordinates correspond to lower s and t texture coordinates.

If any of the pixels within the specified rectangle are outside the framebuffer associated with the current rendering context, then the values obtained for those pixels are undefined.

Notes

A GL implementation may choose to store the texture array at any internal resolution it chooses.

An image with height or width of 0 indicates a NULL texture.

glCopyTexImage2D specifies a two-dimensional or cube-map texture for the current texture unit, specified with glActiveTexture.

Errors

GL_INVALID_ENUM is generated if target is not GL_TEXTURE_2D, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, or GL_TEXTURE_CUBE_MAP_NEGATIVE_Z.

GL_INVALID_ENUM is generated if internalformat is not an accepted format.

GL_INVALID_VALUE is generated if target is one of the six cube map 2D image targets and the width and height parameters are not equal.

GL_INVALID_VALUE is generated if level is less than 0.

GL_INVALID_VALUE may be generated if level is greater than log 2 max , where max is the returned value of GL_MAX_TEXTURE_SIZE when target is GL_TEXTURE_2D or GL_MAX_CUBE_MAP_TEXTURE_SIZE when target is not GL_TEXTURE_2D.

GL_INVALID_VALUE is generated if width or height is less than 0 or greater than GL_MAX_TEXTURE_SIZE when target is GL_TEXTURE_2D or GL_MAX_CUBE_MAP_TEXTURE_SIZE when target is not GL_TEXTURE_2D.

GL_INVALID_VALUE is generated if border is not 0.

GL_INVALID_OPERATION is generated if the currently bound framebuffer's format does not contain a superset of the components required by the base format of internalformat.

GL_INVALID_FRAMEBUFFER_OPERATION is generated if the currently bound framebuffer is not framebuffer complete (i.e. the return value from glCheckFramebufferStatus is not GL_FRAMEBUFFER_COMPLETE).

Associated Gets

glGet with argument GL_MAX_TEXTURE_SIZE or GL_MAX_CUBE_MAP_TEXTURE_SIZE

See Also

glActiveTexture, glCheckFramebufferStatus, glCompressedTexImage2D, glCompressedTexSubImage2D, glCopyTexSubImage2D, glTexImage2D, glTexParameter, glTexSubImage2D

Copyright

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