glPushMatrix, glPopMatrix

[New - Windows 95, OEM Service Release 2]

The glPushMatrix and glPopMatrix functions push and pop the current matrix stack.

void glPushMatrix(

void
);

void glPopMatrix(

void
);

Remarks

There is a stack of matrices for each of the matrix modes. In GL_MODELVIEW mode, the stack depth is at least 32. In the other two modes, GL_PROJECTION and GL_TEXTURE, the depth is at least 2. The current matrix in any mode is the matrix on the top of the stack for that mode.

The glPushMatrix function pushes the current matrix stack down by one, duplicating the current matrix. That is, after a glPushMatrix call, the matrix on the top of the stack is identical to the one below it. The glPushMatrix function pops the current matrix stack, replacing the current matrix with the one below it on the stack. Initially, each of the stacks contains one matrix, an identity matrix.

The following functions retrieve information related to glPushMatrix and glPopMatrix:

glGet8KNKTW with argument GL_MATRIX_MODE

glGet with argument GL_MODELVIEW_MATRIX

glGet with argument GL_PROJECTION_MATRIX

glGet with argument GL_TEXTURE_MATRIX

glGet with argument GL_MODELVIEW_STACK_DEPTH

glGet with argument GL_PROJECTION_STACK_DEPTH

glGet with argument GL_TEXTURE_STACK_DEPTH

glGet with argument GL_MAX_MODELVIEW_STACK_DEPTH

glGet with argument GL_MAX_PROJECTION_STACK_DEPTH

glGet with argument GL_MAX_TEXTURE_STACK_DEPTH

Error Codes

It is an error to push a full matrix stack, or to pop a matrix stack that contains only a single matrix. In either case, the error flag is set and no other change is made to the OpenGL state.

The following are the error codes generated and their conditions.

Error Code	Condition
GL_STACK_OVERFLOW	glPushMatrix was called while the current matrix stack was full.
GL_STACK_UNDERFLOW	glPopMatrix was called while the current matrix stack contained only a single matrix.
GL_INVALID_OPERATION	glPushMatrix was called between a call to glBegin and the corresponding call to glEnd.