BL_Shader.setUniformEyef(name)

defines a uniform that reflects the eye being rendered in stereo mode:
    0.0 for the left eye, 0.5 for the right eye.
    In non stereo mode, the value of the uniform is fixed to 0.0.
    The typical use of this uniform is in stereo mode to sample stereo textures
    containing the left and right eye images in a top-bottom order.

    python:
      shader = obj.meshes[0].materials[mat].getShader()
      shader.setUniformEyef("eye")

    shader:
      uniform float eye;
      uniform sampler2D tex;
      void main(void)
      {
         vec4 color;
         float ty, tx;
         tx = gl_TexCoord[0].x;
         ty = eye+gl_TexCoord[0].y*0.5;
         // ty will be between 0 and 0.5 for the left eye render
         // and 0.5 and 1.0 for the right eye render.
         color = texture(tex, vec2(tx, ty));
         ...
      }

doc/python_api/rst/bge_types/bge.types.BL_Shader.rst

@@ -214,6 +214,16 @@ base class --- :class:`PyObjectPlus`
       :arg iList: a list (2, 3 or 4 elements) of integer values
       :type iList: list[integer]
 
+   .. method:: setUniformEyef(name)
+
+      Set a uniform with a float value that reflects the eye being render in stereo mode: 
+      0.0 for the left eye, 0.5 for the right eye. In non stereo mode, the value of the uniform
+      is fixed to 0.0. The typical use of this uniform is in stereo mode to sample stereo textures
+      containing the left and right eye images in a top-bottom order. 
+
+      :arg name: the uniform name
+      :type name: string
+
    .. method:: validate()
 
       Validate the shader object.