Returns an OpenGL compatible data buffer. Also returns the correspondent pixel format. \n
* The memory allocated is stored in the attribute "GLDATA" with BYTE type. And it will exists while the image exists. \n
* It can be cleared by setting the attribute to NULL. \n
* MAP images are converted to RGB, and BINARY images are converted to GRAY.
* Alpha channel is considered and Transparency* attributes are converted to alpha channel.
* So calculate depth from glformat, not from image depth.
*
* \verbatim image:GetOpenGLData() -> gldata: userdata, glformat: number [in Lua 5] \endverbatim
* \ingroup convert
Returns an OpenGL compatible data buffer. Also returns the correspondent pixel format. \n * The memory allocated is stored in the attribute "GLDATA" with BYTE type. And it will exists while the image exists. \n * It can be cleared by setting the attribute to NULL. \n * MAP images are converted to RGB, and BINARY images are converted to GRAY. * Alpha channel is considered and Transparency* attributes are converted to alpha channel. * So calculate depth from glformat, not from image depth. * * \verbatim image:GetOpenGLData() -> gldata: userdata, glformat: number [in Lua 5] \endverbatim * \ingroup convert