OpenGL Programming Guide

Appendix BOpenGL State Variables

Saving and Restoring Sets of State Variables

You can save and restore the values of a collection of state variables on an attribute stack with the commands glPushAttrib() and glPopAttrib(). The attribute stack has a depth of at least 16, and the actual depth can be obtained using GL_MAX_ATTRIB_STACK_DEPTH with glGetIntegerv(). Pushing a full stack or popping an empty one generates an error.

In general, it's faster to use glPushAttrib() and glPopAttrib() than to get and restore the values yourself. Some values might be pushed and popped in the hardware, and saving and restoring them might be expensive. Also, if you're operating on a remote client, all the attribute data has to be transferred across the network connection and back as it's saved and restored. However, your OpenGL implementation keeps the attribute stack on the server, avoiding unnecessary network delays. void glPushAttrib(GLbitfield mask);

Saves all the attributes indicated by bits in mask by pushing them onto the attribute stack. Table B-2 lists the possible mask bits that can be logically ORed together to save any combination of attributes. Each bit corresponds to a collection of individual state variables. For example, GL_LIGHTING_BIT refers to all the state variables related to lighting, which include the current material color, the ambient, diffuse, specular, and emitted light, a list of the lights that are enabled, and the directions of the spotlights. When glPopAttrib() is called, all those variables are restored. To find out exactly which attributes are saved for particular mask values, see the tables in "OpenGL State Variables."

Table B-2 : Attribute Groups

Mask Bit	Attribute Group
GL_ACCUM_BUFFER_BIT	accum-buffer
GL_ALL_ATTRIB_BITS	--
GL_COLOR_BUFFER_BIT	color-buffer
GL_CURRENT_BIT	current
GL_DEPTH_BUFFER_BIT	depth-buffer
GL_ENABLE_BIT	enable
GL_EVAL_BIT	eval
GL_FOG_BIT	fog
GL_HINT_BIT	hint
GL_LIGHTING_BIT	lighting
GL_LINE_BIT	line
GL_LIST_BIT	list
GL_PIXEL_MODE_BIT	pixel
GL_POINT_BIT	point
GL_POLYGON_BIT	polygon
GL_POLYGON_STIPPLE_BIT	polygon-stipple
GL_SCISSOR_BIT	scissor
GL_STENCIL_BUFFER_BIT	stencil-buffer
GL_TEXTURE_BIT	texture
GL_TRANSFORM_BIT	transform
GL_VIEWPORT_BIT	viewport

void glPopAttrib(void);

Restores the values of those state variables that were saved with the last glPushAttrib().

OpenGL Programming Guide