motion-engine

Core rendering framework for creating animations in pure Python. No browser, no Node.js — just PIL + numpy + OpenCV.

Installation

Already installed. Modules live at ~/.claude/skills/motion_engine/.

Add to Python path before importing:

import sys
sys.path.insert(0, os.path.expanduser("~/.claude/skills"))

Quick Start

import sys, os
sys.path.insert(0, os.path.expanduser("~/.claude/skills"))

from motion_engine.scene import Scene
from motion_engine.elements import Text, Rect, Circle, GradientRect, ImageElement
from motion_engine.easing import get_easing
from motion_engine.color import parse_color, lerp_color
from motion_engine.particles import ParticleSystem
from motion_engine.morph import interpolate_shapes, circle_points, star_points

# Create scene (vertical video: 1080x1920)
scene = Scene(1080, 1920, fps=30, bg="#0a0a12")

# Add elements with timeline
title = Text("Hello World", font_size=96, color="#7c6aff", pos=(540, 960))
scene.add(title, enter=0.0, dur=3.0, exit=4.0,
          enter_anim="fade_up", exit_anim="fade_out")

# Render to MP4
scene.render("output.mp4")

Elements

Text

Text(text, font_size=48, color="#fff", font=None, bold=False,
     align="center", max_width=None, line_height=1.3,
     pos=(x, y), anchor=(0.5, 0.5), opacity=1.0, scale=1.0, rotation=0.0)

Rect

Rect(width, height, color="#fff", border_radius=0,
     border_color=None, border_width=0,
     gradient_end=None, gradient_angle=0,
     pos=(x, y), ...)

GradientRect

GradientRect(width, height, start_color="#7c6aff", end_color="#ff6ab0",
             angle=45, border_radius=20, pos=(x, y))

Circle

Circle(radius, color="#fff", border_color=None, border_width=0, pos=(x, y))

Line

Line(start=(x1, y1), end=(x2, y2), color="#fff", width=2)

ImageElement

ImageElement(source="path.png", width=200, height=None, pos=(x, y))

Scene.add() Parameters

scene.add(element,
    enter=0.0,          # when element appears (seconds)
    dur=3.0,            # visible duration
    exit=None,          # when exit starts (default: enter + dur)
    enter_anim="fade_in",  # enter animation name
    exit_anim="fade_out",  # exit animation name
    enter_dur=0.4,      # enter animation duration
    exit_dur=0.4,       # exit animation duration
    enter_easing="ease_out_cubic",
    exit_easing="ease_in_cubic",
    z_index=0,          # layer ordering
)

Enter Animations

fade_in, fade_up, fade_down, fade_left, fade_right, scale_in, scale_up, bounce_in, slide_up, slide_down, slide_left, slide_right, none

Exit Animations

fade_out, scale_out, slide_up, slide_down, fade_up, fade_down, none

Easing Functions

All standard easings: linear, ease_in/out/in_out_ + sine, quad, cubic, quart, quint, expo, circ, back, elastic, bounce.

Custom: cubic_bezier(x1, y1, x2, y2) returns an easing function.

Particles

ps = ParticleSystem(
    max_particles=500, emit_rate=50,
    lifetime=2.0, speed=100, gravity=50,
    size_start=4, size_end=0,
    color_start="#7c6aff", color_end="#ff6ab0",
    fade_out=True
)
ps.emit_pos = (540, 960)

def on_frame(canvas, t, frame_num):
    ps.update(1/30)
    return ps.draw(canvas)

scene.on_frame(on_frame)

Shape Morphing

from motion_engine.morph import circle_points, star_points, interpolate_shapes, draw_shape

shape_a = circle_points(540, 960, 100)
shape_b = star_points(540, 960, 120, 50, tips=5)

# In a frame callback:
points = interpolate_shapes(shape_a, shape_b, t=0.5)
draw_shape(canvas, points, fill=(124, 106, 255, 200))

Per-Frame Callbacks

def custom_effect(canvas, t, frame_num):
    # t = time in seconds, frame_num = frame index
    # Modify canvas (PIL RGBA Image) and return it
    return canvas

scene.on_frame(custom_effect)

Color Utilities

from motion_engine.color import parse_color, lerp_color, gradient_colors, Color

c = parse_color("#7c6aff")    # Color object
c = parse_color((255, 0, 0))  # RGB tuple
c.rgba  # (124, 106, 255, 255)
c.hex   # "#7c6aff"

mid = lerp_color("#ff0000", "#0000ff", 0.5)  # purple
colors = gradient_colors("#000", "#fff", 10)  # 10-step gradient