If you do not specify the CreateFcn property, then MATLAB executes a default creation function. MATLAB initializes all property values before executing the CreateFcn callback. This property specifies a callback function to execute when MATLAB creates the object. MATLAB evaluates this expression in the base workspace.įor more information about specifying a callback as a function handle, cell array, or character vector, see Create Callbacks for Graphics Objects. Subsequent elements in the cell array are the arguments to pass to the callback function.Ĭharacter vector containing a valid MATLAB expression (not recommended). % nested functions function can_branch = draw_branch_at (x, y, thickness, len, direction) % check length if len < min_branch_lengthĮnd function draw_leaves (leave_size, leave_size_randomness, alpha, alpha_randomness) for ii = 1:leaf_countĬur_alpha = alpha * ( 1.Cell array in which the first element is a function handle. Putting them together: function plot_tree % Plots a beautiful looking tree. 'EdgeColor', 'none', 'LineWidth', 1, 'Curvature', ) Rectangle( 'Position', rect, 'FaceColor', cur_color. Loc = leaf_locations(ii,:) - cur_size/ 2 % compute and add variance to the location of the current leaf % add randomness to size and transparencyĬur_size = leave_size * ( 1.0 + leave_size_randomness * max(min( randn(), 1), -1)) Ĭur_alpha = alpha * ( 1.0 + alpha_randomness * randn()) Straightforward: function draw_leaves (leave_size, leave_size_randomness, alpha, alpha_randomness) for ii = 1:leaf_count Otherwise we draw the current branch andĪdd two new branches by recursively calling draw_branch_at.Ĭompared with draw_branch_at, the implementation of draw_leaves is pretty We first check if the current branch length is less than min_branch_length. % we have already branched here, but cannot further branch % add a leaf at the starting location of the current branch ~draw_branch_at(new_x_2, new_y_2, new_thickness, new_length, new_dir_2) If ~draw_branch_at(new_x_1, new_y_1, new_thickness, new_length, new_dir_1) ||. 'LineWidth', thickness, 'Color', branch_color) ĭecay = branch_decay_factor * ( 1.0 + branch_decay_randomness * max(min( randn(), 1), -1)) % when drawing, draw a litte longer to make the junctions look better % compute end locations of the new branches
New_dir_2 = direction * ( cos(theta_2) + 1 j* sin(theta_2)) New_dir_1 = direction * ( cos(theta_1) + 1 j* sin(theta_1)) % we use a unit length complex number to represent the directional % vector here, and rotation is done via complex number multiplication Theta_2 = -branch_angle * ( 1.0 + branch_angle_randomness * max(min( randn(), 1), -1)) Theta_1 = branch_angle * ( 1.0 + branch_angle_randomness * max(min( randn(), 1), -1)) Let us first take a lookĪt draw_branch_at, which recursively calls itself to draw all the branches: function can_branch = draw_branch_at (x, y, thickness, len, direction) % check length if len < min_branch_length Now we need to implement the nested functions draw_branch_at and draw_leaves. The whole procedure can be visualized by the following four figures. Is called three times with different parameters to get a more interesting Tree trunk, the branches, and finally the leaves. Know how many leaves will be generated because of randomness). We first preallocate a matrix to store the leaf locations (actually we do not % draw three layers of leaves to get a nicer look Leaf_locations = leaf_locations( 1:leaf_count, :) 'LineWidth', base_thickness, 'Color', branch_color) īranch_decay_factor * base_thickness, branch_decay_factor * base_length, 1 j) % draw trunk, adding an extra y offset to make the junction look better Note that we added lots of randomness related parameters. % determines how far the leaves can deviate from the branch tips Min_branch_length = base_length * branch_decay_factor^ 7 % determines the randomness of branch_angle % determines the direction of the new branch, 0 = same direction % determines the randomness of branch_decay_factor % determines how fast the length and thickness of the branches decay Let us start by setting up the figure and defining the parameters: function plot_tree % Plots a beautiful looking tree. Now we know we need to use MATLAB 2014b or newer to get some good looking Since 2014b, alpha value can be specified in the color property. Does MATLAB support transparency (so I can get nicer looking leaves)? Yes.Major updates in its graphics engine, and the Does MATLAB support anti-aliasing? Yes.Use the rectangleįunction (yes, in MATLAB you use the rectangle function to draw circles). Can we draw circles (for the leaves) in MATLAB? Yes.Can we draw lines (for the trunk and branches) in MATLAB? Yes.Before jumping into the code, let us make a checklist about MATLAB's drawing
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