hazy-frames 0.1.0

Hierarchical coordinate frames - crystal clear transforms

hazy-frames

Hierarchical coordinate frames - crystal clear transforms

A Python library for managing hierarchical reference frames and frame-aware geometric primitives with efficient transformation caching, inspired by optiland.

Features

• Hierarchical Frame System: Build complex frame hierarchies with parent-child relationships
• Frame-Aware Primitives: Point and Vector classes that carry frame information
• Automatic Transformations: Transform primitives between any frames in the hierarchy
• Efficient Caching: Transformation matrices are cached for performance
• Proper Geometric Semantics: Type-safe arithmetic operations (e.g., Point - Point = Vector)
• Flexible Transformations: Support for rotation (Euler angles, matrices), translation, and scaling
• Global Reference Frame: Singleton global frame for world coordinates

Installation

Install directly from GitHub:

pip install git+https://github.com/Littie28/hazy-frames.git

Or download the wheel from releases:

pip install hazy_frames-0.1.0-py3-none-any.whl

For development:

# Clone the repository
git clone https://github.com/Littie28/hazy-frames.git
cd hazy-frames

# Install with development dependencies
uv sync --group dev

Quick Start

from hazy import Frame, Point, Vector

# Create a frame hierarchy
world = Frame.get_global()
robot = Frame(parent=world, name="robot")
robot.translate(x=5, y=0, z=0).rotate_euler(z=90, degrees=True)

camera = robot.make_child(name="camera")  # different initialization methods
camera.translate(x=0, y=0, z=1)

# Create frame-aware primitives
point_in_camera = Point(1, 0, 0, frame=camera)

# Transform between frames
point_in_world = point_in_camera.to_frame(world)
point_in_robot = point_in_camera.to_frame(robot)

print(f"Camera: {point_in_camera}")
print(f"World: {point_in_world}")
print(f"Robot: {point_in_robot}")

Core Concepts

Frames

Frames represent coordinate systems and can be organized hierarchically:

# Create frames
root = Frame.make_root(name="root")
parent = root.make_child("parent")
child = Frame(parent=parent, name="child")

# Apply transformations (chainable)
child.translate(x=10, y=5, z=0)
child.rotate_euler(x=45, y=0, z=90, degrees=True)
child.scale(2.0)  # uniform scaling
child.scale((1.0, 2.0, 1.5))  # non-uniform scaling

# Freeze frames to prevent modifications
child.freeze()

Transformations are applied in S->R->T order (Scale, Rotation, Translation) when converting from local to parent coordinates.

Points and Vectors

Points represent positions, vectors represent directions/displacements:

# Create primitives
origin = Point(0, 0, 0, frame=child)
direction = Vector(1, 0, 0, frame=child)

# Proper geometric arithmetic
point_a = Point(1, 2, 3, frame=child)
point_b = Point(4, 5, 6, frame=child)

displacement = point_b - point_a  # Returns Vector
new_point = point_a + displacement  # Returns Point

# Vectors support additional operations
vec = Vector(1, 0, 0, frame=child)
vec.normalize()  # Normalize in-place
magnitude = vec.magnitude

# Cross product
vec1 = Vector(1, 0, 0, frame=child)
vec2 = Vector(0, 1, 0, frame=child)
perpendicular = vec1.cross(vec2)  # Vector(0, 0, 1)

Frame Transformations

# Get transformation matrices
T_to_parent = frame.transform_to_parent  # 4x4 matrix
T_from_parent = frame.transform_from_parent  # Inverse
T_to_global = frame.transform_to_global  # To world frame
T_to_target = frame.transform_to(target_frame)  # To any frame

# Transform primitives
point_global = point_local.to_global()
point_target = point_local.to_frame(target_frame)

# Batch transformations for efficiency
points_array = np.array([[1, 0, 0], [0, 1, 0], [0, 0, 1]])
transformed = frame.batch_transform_points_global(points_array)

Unit Vectors and Origin

Frames provide convenient accessors for unit vectors and origin:

# Unit vectors in frame's local coordinates
x_axis = frame.x_axis 
y_axis = frame.y_axis
z_axis = frame.z_axis

# Unit vectors in global coordinates
x_global = frame.x_axis_global
y_global = frame.y_axis_global
z_global = frame.z_axis_global

# Frame origin
origin_local = frame.origin  # Point(0, 0, 0) in frame
origin_global = frame.origin_global  # Origin in global coords

API Overview

Frame Class

Method/Property	Description
translate(x, y, z)	Add translation to frame
rotate_euler(x, y, z, seq, degrees)	Add Euler angle rotation
rotate(matrix)	Add rotation from 3x3 matrix
scale(factor)	Add scaling (uniform or non-uniform)
freeze()/unfreeze()	Prevent/allow modifications
transform_to_parent	4x4 transformation matrix to parent
transform_to_global	4x4 transformation matrix to global
transform_to(target)	4x4 transformation matrix to target frame
point(x, y, z)	Create Point in this frame
vector(x, y, z)	Create Vector in this frame

Point Class

Method/Property	Description
to_frame(target)	Transform to target frame
to_global()	Transform to global frame
x, y, z	Coordinate components
Point + Vector	Returns Point (displacement)
Point - Point	Returns Vector (difference)
Point - Vector	Returns Point (reverse displacement)

Vector Class

Method/Property	Description
to_frame(target)	Transform to target frame
to_global()	Transform to global frame
x, y, z	Vector components
magnitude	Vector length
normalize()	Normalize to unit length (in-place)
cross(other)	Cross product with another vector
Vector + Vector	Returns Vector (sum)
Vector - Vector	Returns Vector (difference)
Vector + Point	Returns Point (displacement)

Development

Running Tests

# Run all tests
pytest

# Run with coverage
pytest --cov=src/hazy --cov-report=html

# Run specific test markers
pytest -m unit
pytest -m integration

# Watch mode for development
pytest-watcher

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.