能找到最好的解释来自：http://www.gamedev.net/topic/489879-glpushmatrixglpopmatrix--glloadmatrixf/
原理：
glPushMatrix didn't fail to push onto the stack; it's job is to push a copy of the current matrix onto a stack of matrices. Those matrices on the stack don't interact at all. You only manipulate the current, top-most, matrix at any given time.
Example 1:
command result glLoadMatrixf(A) stack = [A] glPushMatrix() stack = [A, A] glLoadMatrixf(B) stack = [B, A] glPopMatrix() stack = [A]
Example 2:
command result glLoadMatrixf(A) stack = [A] glPushMatrix() stack = [A, A] glMultMatrixf(B) stack = [AB, A] glPopMatrix() stack = [A]
注意：
glTranslate* 等都是实际调用的是glMultMatrixf
实例：
看下面的代码：
743 glPushMatrix();
744
745 // tramsform camera
746 matrixView.identity();
747 matrixView.rotate(cameraAngleY, 0, 1, 0);
748 matrixView.rotate(cameraAngleX, 1, 0, 0);
749 matrixView.translate(0, 0, -cameraDistance);
750 //@@ the equivalent code for using OpenGL routine is:
751 //@@ glTranslatef(0, 0, -cameraDistance);
752 //@@ glRotatef(cameraAngleX, 1, 0, 0); // pitch
753 //@@ glRotatef(cameraAngleY, 0, 1, 0); // heading
754
755 // copy view matrix to OpenGL
756 glLoadMatrixf(matrixView.getTranspose());
757
758 drawGrid(); // draw XZ-grid with default size
759
760 // compute model matrix
761 matrixModel.identity();
762 //matrixModel.rotateZ(45); // rotate 45 degree on Z-axis
763 matrixModel.rotateY(10); // rotate 45 degree on Y-axis
764 matrixModel.translate(0, 1, 0); // move 2 unit up
765
766 // compute modelview matrix
767 matrixModelView = matrixView * matrixModel;
768
769 // copy modelview matrix to OpenGL
770 glLoadMatrixf(matrixModelView.getTranspose());
771
772 drawAxis();
770 glLoadMatrixf(matrixModelView.getTranspose());
不能是glMultMatrixf