Added example to create and update a custom mechanism

Author: RoboDK

Python/Examples/Scripts/MechanismArrayCustom.py

@@ -0,0 +1,81 @@
+# This example shows how to create and update a custom mechanism built from an array of objects using one API call
+# You can quickly update an array of objects in one shot without penalizing simulation performance
+import time
+import math
+from robodk import *    # RoboDK API
+from robolink import *    # Robot toolbox
+
+# Start the RoboDK API
+RDK = Robolink()
+
+# Number of elements
+x_count = 20
+y_count = 20
+
+# Spacing between elements
+x_spacing = 40
+y_spacing = 40
+
+# Length along X axis
+x_lenth = x_count * x_spacing
+
+# Retrieve the reference box (100x100x100 mm, centered)
+box_ref = RDK.Item("Reference Box", ITEM_TYPE_OBJECT)
+
+# Delete the previous array
+frame_old = RDK.Item("Mechanism Array", ITEM_TYPE_FRAME)
+if frame_old.Valid():
+    frame_old.Delete()
+
+# Frame to place the mechanism
+frame_ref = RDK.AddFrame("Mechanism Array")
+
+# Show as collapsed (less cluttered tree, faster rendering)
+frame_ref.setParam("Tree", "Collapse")
+
+# Create the array of objects based on the model object
+RDK.Render(False)
+box_ref.Copy()
+# Create the objects and scale them
+obj_array = RDK.Paste(frame_ref, x_count * y_count)
+idx = 0
+for i in range(x_count):
+    for j in range(y_count):
+        obj_array[idx].Scale([0.05, 0.05, 2])
+        obj_array[idx].setName("piston " + str(idx))
+        obj_array[idx].setVisible(True)
+        idx = idx + 1
+
+RDK.Render(True)
+
+# Random function to calculate a Z position based on X,Y and time
+def z_func(x,y, t):
+    """x and y are the coordinates on X and Y of the parent frame, in mm. t is time in seconds."""
+    z = 100 * math.sin(2 * math.pi * math.sqrt(x*x + y*y) * (1/x_lenth)  + t/6 )
+    return z
+
+def update_mechanism(t):
+    """Update the mechanism for the time t in seconds"""
+    obj_poses = []
+    for i in range(x_count):
+        x = i*x_spacing
+        for j in range(y_count):            
+            y = j*y_spacing
+            z = z_func(x, y, t)
+            pose = robomath.transl(x,y,z)
+            obj_poses.append(pose)
+
+    RDK.setPoses(obj_array, obj_poses)
+
+# Infinite loop to update the mechanism
+while True:
+    # Retrieve RoboDK simulation time:
+    t = RDK.SimulationTime()
+
+    # Update the mechanism
+    print("Updating mechanism at time frame: " + str(t))
+    update_mechanism(t)
+
+    # Wait a bit before running the next frame
+    time.sleep(0.05)
+