Added file to plot a Bezier curve and an example script

BezierExample.m

@@ -0,0 +1,95 @@
+% Bezier example
+
+% This goes in a file named BezierExample.m
+
+close all
+clear all
+
+x_nodes = [];
+y_nodes = [];
+
+% Initialize figure window
+
+figure
+hold on
+xlim([0 1])
+ylim([0 1])
+
+% Collect nodes
+
+disp('Click several points on curve. Hit enter to exit')
+index = 1;
+while(true)    
+    [x,y,button] = ginput(1);
+    
+    if (isempty(x))
+        break
+    end
+    
+    if (button ~= 1)
+        continue
+    end
+    
+    % Add the new point and plot the new line segment
+    
+    x_nodes(index) = x(1);
+    y_nodes(index) = y(1);
+    if (index > 1)
+        plot(x_nodes(index-1:index),y_nodes(index-1:index))
+    end
+    
+    index = index + 1;
+end
+
+% Points have been entered. Build the collection of nodes and control
+% points that define the curve
+
+number_curves = length(x_nodes) - 1;
+bezier_points = cell(number_curves,4);
+for k = 1:number_curves
+
+    % Insert the nodes
+    
+    bezier_points{k,1} = [x_nodes(k) y_nodes(k)];
+    bezier_points{k,4} = [x_nodes(k+1) y_nodes(k+1)];
+    
+    % Create the control points
+    
+    if (k == 1)
+        bezier_points{k,2} = [x_nodes(1) y_nodes(1)] + ([x_nodes(2) y_nodes(2)] - [x_nodes(1) y_nodes(1)])/3;
+    else
+        
+        % Compute positions for control points. Arbitrarily, they will be
+        % collinear with the node in between and 1/3 of the way to the next
+        % node
+        
+        vector_1 = [x_nodes(k) y_nodes(k)] - [x_nodes(k-1) y_nodes(k-1)];
+        length_1 = norm(vector_1);
+        vector_1 = vector_1/length_1;
+        
+        vector_2 = [x_nodes(k) y_nodes(k)] - [x_nodes(k+1) y_nodes(k+1)];
+        length_2 = norm(vector_2);
+        vector_2 = vector_2/length_2;
+        
+        vector_sum = vector_1 + vector_2;
+        n = vector_sum/norm(vector_sum);
+        
+        % If vector_1 X vector_2 is negative, reverse the direction of n
+        
+        if ((vector_1(1)*vector_2(2) - vector_2(1)*vector_1(2)) < 0)
+            n = -n;
+        end
+        n_p = [-n(2) n(1)];
+        
+        bezier_points{k-1,3} = [x_nodes(k) y_nodes(k)] + n_p*length_1/3;
+        bezier_points{k,2} = [x_nodes(k) y_nodes(k)] - n_p*length_2/3;
+        
+        if (k == (number_curves))
+            
+            bezier_points{k,3} = [x_nodes(number_curves+1) y_nodes(number_curves+1)] + ...
+                                 ([x_nodes(number_curves) y_nodes(number_curves)] - [x_nodes(number_curves+1) y_nodes(number_curves+1)])/3;
+        end
+    end 
+end
+
+PlotBezier(bezier_points)