You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: spm_surf.m
    path of file: ./repos/ExploreASL/External/SPMmodified
    
    the code of the file until where you have to start completion: function varargout = spm_surf(P,mode,thresh)
% Surface extraction
% FORMAT spm_surf(P,mode,thresh)
%
% P      - char array of filenames
%          Usually, this will be c1xxx.<ext> & c2xxx.<ext> - grey and white
%          matter segments created using the segmentation routine.
% mode   - operation mode [1: rendering, 2: surface, 3: both]
% thresh - vector or threshold values for extraction [default: 0.5]
%          This is only relevant for extracting surfaces, not rendering.
%
% Generated files (depending on 'mode'):
% A "render_xxx.mat" file can be produced that can be used for
% rendering activations on to, see spm_render.
    
function renviews(V,oname)
%==========================================================================
function renviews(V,oname)
% Produce images for rendering activations to
%
% FORMAT renviews(V,oname)
% V     - mapped image to render, or alternatively
%         a structure of:
%         V.dat - 3D array
%         V.dim - size of 3D array
%         V.mat - affine mapping from voxels to millimeters
% oname - the name of the render.mat file.
%__________________________________________________________________________
%
% Produces a matrix file "render_xxx.mat" which contains everything that
% "spm_render" is likely to need.
%
% Ideally, the input image should contain values in the range of zero
% and one, and be smoothed slightly.  A threshold of 0.5 is used to
% distinguish brain from non-brain.
%__________________________________________________________________________

fprintf('%-40s: ','Rendering...');                                      %-#
                                
rend{1} = make_struct(V,[pi 0 pi/2]);    % Transverse 1
rend