float halfw = tan(params.fov/2.0f)*params.aspect;
frustum_skew = tan(Geometry::atan<float>(frustum_skew*halfw)+strabismus)/halfw;
left.setup_frame(base_camera, offset_axis*-eye_spacing, frustum_skew, params);
right.setup_frame(base_camera, offset_axis*eye_spacing, -frustum_skew, params);
float halfw = tan(params.fov/2.0f)*params.aspect;
frustum_skew = tan(Geometry::atan<float>(frustum_skew*halfw)+strabismus)/halfw;
left.setup_frame(base_camera, offset_axis*-eye_spacing, frustum_skew, params);
right.setup_frame(base_camera, offset_axis*eye_spacing, -frustum_skew, params);