Point

WLJS

Execution environment

Supports dynamics

wljs-graphics-d3

Package

Point[p_List | _Offload]

is a graphics and geometry primitive that represents a point at p,

Point[{p1_List, p2_List, ...}]

represents collection of points

Graphics[Point[Table[{t, Sin[t]}, {t, 0, 2 \[Pi], 2 \[Pi]/10}]]]

Graphics[
 Table[{Hue[RandomReal[],1,0.5], PointSize[RandomReal[{0, 0.1}]], 
   Point[RandomReal[1, {2}]]}, {200}]]

Parameters

RGBColor

specifies colors of a points

Opacity

specifies opacity

PointSize

absolute size of a point

Methods

EventHandler

One can listen to a several events produced by this primitive using EventHandler

EventHandler[t_Point, {event_ -> handler_, ...}]

where event can be

• "mousemove" detects and sends coordinates of a mouse, when it is over this element
• "drag" makes primitive draggable and emits coordinates
• "zoom" detects zoom / mouse-wheel
• "click" detects mouse clicks

tip

See more in Mouse and keyboard

Indexed geometry

Using it inside GraphicsComplex allows to specify only the indexes of vertices as arguments similar to faces like in Indexed geometry

Dynamics

Point primitive supports dynamic updates even if the number of points is not constant.

There is a famous example of 1000 particles "dancing" with each other

cell 1

n = 1000;
r := RandomInteger[{1, n}];
f := (#/(.01 + Sqrt[#.#])) & /@ (x[[#]] - x) &;
s := With[{r1 = r}, p[[r1]] = r; q[[r1]] = r];
x = RandomReal[{-1, 1}, {n, 2}];
{p, q} = RandomInteger[{1, n}, {2, n}];

cell 2

EventHandler["frame", Function[Null,
  (* all calculations *)
  x = 0.995 x + 0.02 f[p] - 0.01 f[q];
  If[r < 100, s];
]];

cell 3

Graphics[{
  PointSize[0.007], Point[x // Offload],
  AnimationFrameListener[x // Offload, "Event"->"frame"]
}, PlotRange -> {{-2,2}, {-2,2}}, "TransitionType"->"Linear", "TransitionDuration"->1]