Zdog Backend¶

The zdog backend uses zdog to render shapes. Zdog is an HTML canvas-based engine that works best for simple, cartoon-style illustrations. Plato’s implementation works inside notebook environments and also supports rendering standalone HTML for inclusion in other pages.

class plato.draw.zdog.Scene(primitives=[], features={}, size=(40, 30), translation=(0, 0, -50), rotation=(1, 0, 0, 0), zoom=1, pixel_scale=20, **kwargs)[source]¶

A container to hold and display collections of primitives.

Scene keeps track of global information about a set of things to be rendered and handles configuration of optional (possibly backend-specific) rendering parameters.

Global information managed by a Scene includes the size of the viewing window, translation and rotation applied to the scene as a whole, and a zoom level.

Primitives can be added to a scene through the primitives argument of the constructor or the add_primitive method. Primitives can be retrieved by iterating over the scene:

for prim in scene:
    # (do something with prim)

Primitives can also be accessed in the order they were added to the scene using list-like syntax:

first_three_prims = scene[:3]
last_prim = scene[-1]

Optional rendering arguments are enabled as features, which are name-value pairs identifying a feature by name and any configuration of the feature in the value.

This Scene supports the following features:

ambient_light: Enable trivial ambient lighting. The given value indicates the magnitude of the light (in [0, 1]).
directional_light: Add directional lights. The given value indicates the magnitude*direction normal vector.
pan: Translate, rather than rotate, when dragging with the mouse

render()[source]¶

Render all the shapes in this scene.

Returns:	HTML string contents to be displayed

save(filename)[source]¶

Save the scene as an HTML file.

Parameters:	filename – target filename to save the result into

show()[source]¶: Render the scene to an image and display using ipython.

2D Graphics Primitives¶

class plato.draw.zdog.Arrows2D(*args, **kwargs)[source]¶

A collection of 2D arrows.

Each arrow has an independent position, orientation, color, and magnitude. The shape of arrows can be configured by changing its vertices attribute. The default orientation and scale of the vertices is an arrow centered at (0, 0), pointing in the (1, 0) direction, with length 1.

The origin of the arrows can be shifted to have the base lie on the given position by modifying vertices:

arrows.vertices = arrows.vertices + (0.5, 0)

This primitive has the following attributes:

positions: Position of each particle
orientations: Orientation quaternion of each particle
colors: Color, RGBA, [0, 1] for each particle
vertices: Vertices in local coordinates for the shape, to be replicated for each particle (CCW order)
outline: Outline width for all particles

class plato.draw.zdog.Disks(**kwargs)[source]¶

A collection of disks in 2D.

Each disk can have a different color and diameter.

This primitive has the following attributes:

positions: Position of each particle
colors: Color, RGBA, [0, 1] for each particle
radii: Radius of each particle
outline: Outline width for all particles

colors¶: Color, RGBA, [0, 1] for each particle

outline¶: Outline width for all particles

positions¶: Position of each particle

radii¶: Radius of each particle

class plato.draw.zdog.Polygons(**kwargs)[source]¶

A collection of polygons.

A Polygons object has a common shape for the whole collection. Each shape can have a different orientation and color. Vertices should be specified in counterclockwise order.

This primitive has the following attributes:

positions: Position of each particle
orientations: Orientation quaternion of each particle
colors: Color, RGBA, [0, 1] for each particle
vertices: Vertices in local coordinates for the shape, to be replicated for each particle (CCW order)
outline: Outline width for all particles

class plato.draw.zdog.Spheropolygons(**kwargs)[source]¶

A collection of rounded polygons.

A Spheropolygons object has a common shape and rounding radius for the whole collection. Each shape can have a different orientation and color. Vertices should be specified in counterclockwise order.

This primitive has the following attributes:

positions: Position of each particle
orientations: Orientation quaternion of each particle
colors: Color, RGBA, [0, 1] for each particle
vertices: Vertices in local coordinates for the interior (non-rounded) shape, to be replicated for each particle (CCW order)
outline: Outline width for all particles
radius: Rounding radius for all particles

3D Graphics Primitives¶

class plato.draw.zdog.Box(*args, **kwargs)[source]¶

A triclinic box frame.

This primitive draws a triclinic box centered at the origin. It is specified in terms of three lattice vector lengths Lx, Ly, Lz and tilt factors, defined using the hoomd-blue schema.

Rather than directly initializing via attributes, Box objects can also be automatically created from box-type objects using the from_box() method.

Examples:

Lx = Ly = Lz = 10
xy = xz = yz = 0
box_primitive = draw.Box(Lx=Lx, Ly=Ly, Lz=Lz, width=width, color=color)
box_tuple = (Lx, Ly, Lz, xy, xz, yz)
box_primitive = draw.Box.from_box(box_tuple)

This primitive has the following attributes:

start_points: Beginning coordinate for each line segment
end_points: Ending coordinate for each line segment
widths: Width of each line segment
colors: Color, RGBA, [0, 1] for each line segment
Lx: Length of first box vector
Ly: Length of second box vector
Lz: Length of third box vector
xy: Tilt factor between the first and second box vectors
xz: Tilt factor between the first and third box vectors
yz: Tilt factor between the second and third box vectors
width: Width of box line segments
color: Color, RGBA, [0, 1] for the box line segments

class plato.draw.zdog.ConvexPolyhedra(**kwargs)[source]¶

A collection of identically-shaped convex polyhedra.

Each shape can have its own position, orientation, and color.

This primitive has the following attributes:

positions: Position of each particle
orientations: Orientation quaternion of each particle
colors: Color, RGBA, [0, 1] for each particle
vertices: Vertices in local coordinates for the shape, to be replicated for each particle
outline: Outline width for all shapes

class plato.draw.zdog.ConvexSpheropolyhedra(**kwargs)[source]¶

A collection of identically-shaped convex spheropolyhedra.

Each shape can have its own position, orientation, and color. The rounding radius is shared over all shapes.

This primitive has the following attributes:

positions: Position of each particle
orientations: Orientation quaternion of each particle
colors: Color, RGBA, [0, 1] for each particle
vertices: Vertices in local coordinates for the interior (non-rounded) shape, to be replicated for each particle
radius: Rounding radius to be applied to all shapes

class plato.draw.zdog.Lines(**kwargs)[source]¶

A collection of line segments.

Each segment can have a different color and width. Lines can be used in both 2D and 3D scenes, but they are currently not shaded and may look out of place in 3D.

This primitive has the following attributes:

start_points: Beginning coordinate for each line segment
end_points: Ending coordinate for each line segment
widths: Width of each line segment
colors: Color, RGBA, [0, 1] for each line segment

class plato.draw.zdog.Spheres(**kwargs)[source]¶

A collection of spheres in 3D.

Each sphere can have a different color and diameter.

This primitive has the following attributes:

positions: Position of each particle
colors: Color, RGBA, [0, 1] for each particle
radii: Radius of each particle
light_levels: Number of quantized light levels to use

colors¶: Color, RGBA, [0, 1] for each particle

light_levels¶: Number of quantized light levels to use

positions¶: Position of each particle

radii¶: Radius of each particle