my_bar3_diff.patch

--- my_bar3_org.m
+++ my_bar3_new.m
@@ -1,4 +1,4 @@
-function pp = my_bar3(M, width)
+function pp = my_bar3(M, width, C)
     % MY_BAR3  3D bar graph.
     %
     % M     - 2D matrix
@@ -33,6 +33,25 @@
     v = bsxfun(@plus, v, permute(offset,[3 2 1]));
     v = reshape(permute(v,[2 1 3]), 3,[]).';

+    % parse color argument
+    if nargin<3 || isempty(C)
+        % default solid color for all bars
+        color_args = {'FaceColor',[0.75 0.85 0.95]};
+    elseif ismatrix(C) && isequal(size(C),size(M))
+        % gradient colors, specified using indexed color mapping
+        fvcd = v(:,3) .* kron(C(:), ones(8,1));
+        color_args = {'FaceVertexCData',fvcd, 'FaceColor','interp'};
+    elseif ismatrix(C) && isequal(size(C),[numel(M) 3])
+        % matrix of flat true-colors, one per bar
+        fvcd = kron(C, ones(6,1));
+        color_args = {'FaceVertexCData',fvcd, 'FaceColor','flat'};
+    elseif (isvector(C) && numel(C)==3) || ischar(C)
+        % user-supplied solid color (accepts [0.1 0.1 0.1] or 'red')
+        color_args = {'FaceColor',C};
+    else
+        error('could not parse paramter C');
+    end
+
     % adjust bar heights to be equal to matrix values
     v(:,3) = v(:,3) .* kron(M(:), ones(8,1));

@@ -56,7 +75,7 @@
     % draw patch specified by faces/vertices
     % (we use a solid color for all faces)
     p = patch('Faces',f, 'Vertices',v, ...
-        'FaceColor',[0.75 0.85 0.95], 'EdgeColor','k', 'Parent',hax);
+        'EdgeColor','k', 'Parent',hax, color_args{:});
     view(hax,3); grid(hax,'on');
     set(hax, 'XTick',1:nx, 'YTick',1:ny, 'Box','off', 'YDir','reverse', ...
         'PlotBoxAspectRatio',[1 1 (sqrt(5)-1)/2]) % 1/GR (GR: golden ratio)