minor

Author: liminchen

0_getting_started/simulator0.py

@@ -8,7 +8,7 @@
 x = np.array([0.0, 0.0])    # position of particle
 v = np.array([0.0, 0.0])    # velocity of particle
 g = np.array([0.0, -10.0])  # gravitational acceleration
-h = 0.01                # time step size in seconds
+h = 0.01                    # time step size in seconds
 
 # visualization/rendering setup
 pygame.init()
@@ -39,13 +39,13 @@ def screen_projection(x):           # convert simulated coordinates to window co
         pygame.display.flip()   # flip the display
         pygame.time.wait(int(1000.0 / render_FPS))  # wait to render the next frame
 
-    # step forward the simulation by updating particle velocity and position
-    v += h * g
-    x += h * v
-
     # pause the simulation when the particle touches on the ground 
     if x[1] <= -1:
         input()
         break
 
+    # step forward the simulation by updating particle velocity and position
+    v += h * g
+    x += h * v
+
     time_step += 1  # update time step counter

0_getting_started/simulator1.py

@@ -6,7 +6,7 @@
 
 # simulation setup
 m = 1000                    # mass of particle
-x = np.array([0.3, 0.0])    # position of particle
+x = np.array([0.4, 0.0])    # position of particle
 v = np.array([0.0, 0.0])    # velocity of particle
 g = np.array([0.0, -10.0])  # gravitational acceleration
 spring_rest_len = 0.3       # rest length of the spring ###

0_getting_started/simulator2.py

@@ -6,9 +6,9 @@
 import square_mesh  # for generating a square mesh
 
 # simulation setup
-m = 1000                    # mass of each particle
 side_length = 1             # side length of the square
 n_seg = 4                   # number of springs per side of the square
+m = 1000                    # mass of each particle
 [x, e] = square_mesh.generate(side_length, n_seg)   # array of particle positions and springs   ###
 v = np.array([[0.0, 0.0]] * len(x))     # velocity array of particles ###
 g = np.array([0.0, -10.0])  # gravitational acceleration