Line

This demo presents the line scene in 2D and shows how the animation state evolves over time with lib-anim. The script defines a canva, adds the corresponding items, and updates them frame by frame to produce the final motion.

Full Code

'''
2D line demo
'''

import numpy as np
import anim

# ═══ 2D Animation canva ═══════════════════════════════════════════════════

class Canva(anim.plane.canva):

  # ────────────────────────────────────────────────────────────────────────
  def __init__(self, window):

    super().__init__(window)

    # ─── Definitions

    # Number of lines
    self.N = 20

    # x-positions
    self.X = np.linspace(0.1, 0.9, self.N)

    # ─── Items

    Y = self.generate(0)

    for i in range(self.N):
      self.item[f'line_{i}'] = anim.plane.line(
        position = [self.X[i], 0.5-Y[i]/8],
        dimension = [0,  Y[i]],
        color = 'white'
      )

  # ────────────────────────────────────────────────────────────────────────
  def generate(self, t):

    return np.sin(self.X*10+ t/10)/4

  # ────────────────────────────────────────────────────────────────────────
  def update(self, t):

    Y = self.generate(t.step)
    for i in range(self.N):
      self.item[f'line_{i}'].position = [self.X[i], 0.5-Y[i]/8]
      self.item[f'line_{i}'].dimension = [0, Y[i]]
    
    # Confirm update
    super().update(t)

# ═══ Main ═════════════════════════════════════════════════════════════════

W = anim.window('Line animation')

# Add animation
W.add(Canva)

# Allow backward animation
W.allow_backward = True
W.allow_negative_time = True

W.show()