glCopyTexImage2D

glCopyTexImage2D: man2/glCopyTexImage2D.xml

glCopyTexImage2D defines a two-dimensional texture image, or cube-map texture image with pixels from the current GL_READ_BUFFER. The screen-aligned pixel rectangle with lower left corner at ( x, y ) and with a width of width + 2 ⁡ border and a height of height + 2 ⁡ border 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 glCopyPixels had been called, but the process stops just before final conversion. At this point all pixel component values are clamped to the range 0 1 and then converted to the texture's internal format for storage in the texel array. 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 of the current GL_READ_BUFFER are outside the window associated with the current rendering context, then the values obtained for those pixels are undefined. When internalformat is one of the sRGB types, the GL does not automatically convert the source pixels to the sRGB color space. In this case, the glPixelMap function can be used to accomplish the conversion.

glCopyTexImage2D is available only if the GL version is 1.1 or greater. Texturing has no effect in color index mode. 1, 2, 3, and 4 are not accepted values for internalformat. An image with height or width of 0 indicates a null texture. When the ARB_imaging extension is supported, the RGBA components read from the framebuffer may be processed by the imaging pipeline. See glTexImage1D for specific details. 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, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or GL_PROXY_TEXTURE_CUBE_MAP are available only if the GL version is 1.3 or greater. GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT16, GL_DEPTH_COMPONENT24, and GL_DEPTH_COMPONENT32 are available only if the GL version is 1.4 or greater. The GL_SRGB, GL_SRGB8, GL_SRGB_ALPHA, GL_SRGB8_ALPHA8, GL_SLUMINANCE, GL_SLUMINANCE8, GL_SLUMINANCE_ALPHA, and GL_SLUMINANCE8_ALPHA8 internal formats are only available if the GL version is 2.1 or greater. See glTexImage2D for specific details about sRGB conversion.