Matlab使用streamparticles绘制流粒子

今天，再给大家带来一篇关于Matlab流线图函数相关的一个streamparticles，该函数用于Matlab绘制流粒子，一个向量场的流粒子。流粒子通常由标记表示，可以显示流线图的位置和速度。本文主要讲解关于streamparticles函数的常见用法、语法说明、在不显示流线图的情况下生成流动画等用法。

下面，我们首先给出Matlab中关于streamparticles函数的帮助文档如下：

>> help streamparticles
 streamparticles  Display stream particles.
    streamparticles(VERTICES) draws stream particles of a vector
    field. Stream particles are usually represented by markers and
    can show the position and velocity of a streamline. VERTICES
    is a cell array of 2D or 3D vertices (as if produced by STREAM2
    or STREAM3).
 
    streamparticles(VERTICES, N) uses N to determine how many
    stream particles are drawn. The 'ParticleAlignment' property
    controls how N is interpreted. If 'ParticleAlignment' is 'off'
    (the default) and N is greater than 1, then approximately N
    particles are drawn evenly spaced over the streamline vertices;
    if N is less than or equal to 1, N is interpreted as a fraction
    of the original stream vertices; for example, if N is 0.2,
    approximately 20% of the vertices will be used.  N determines
    the upper bound for the number of particles drawn. Note that
    the actual number of particles may deviate from N by as much
    as a factor of 2. If 'ParticleAlignment' is 'on', N determines
    the number of particles on the streamline with the most
    vertices; the spacing on the other streamlines is set to this
    value. The default value is N=1.
 
    streamparticles(...,'NAME1',VALUE1,'NAME2',VALUE2,...) controls
    the stream particles by using named properties and specified
    values.  Any unspecified properties have default values.  Case
    is ignored for property names.
 
 streamparticles PROPERTIES
 
 Animate - Stream particles motion [ non-negative integer ]
    The number of times to animate the stream particles. The
    default is 0 which does not animate. Inf will animate until
    ctrl-c is hit.
 
 FrameRate - Animation frames per second [ non-negative integer ]
    The number of frames per second for the animation. Inf, the
    default will draw the animation as fast as possible. Note: the
    framerate can not speed up an animation.
 
 ParticleAlignment - Align particles with streamlines [ on | {off} ]
    Set this property to 'on' to force particles to be drawn at the
    beginning of the streamlines. This property controls how N is
    interpreted.
 
 Also, any line property/value pairs such as 'linestyle' or
    'marker' can be used.  The following is the default list of
    line properties set by streamparticles. These can be overridden
    by passing in property/value pairs.
 
    Property           Value
    --------           -----
    'LineStyle'        'none'
    'Marker'           'o'
    'MarkerEdgeColor'  'none'
    'MarkerFaceColor'  'red'
 
    streamparticles(H,...) uses the LINE object H to draw the
    stream particles.
 
    streamparticles(AX,...) plots into AX instead of GCA.  This option is
    ignored if you specify H as well.
 
    H = streamparticles(...) returns a vector of handles to LINE
    objects.
 
    Example 1:
       load wind
       [sx sy sz] = meshgrid(80, 20:1:55, 5);
       verts = stream3(x,y,z,u,v,w,sx,sy,sz);
       sl = streamline(verts);
       iverts = interpstreamspeed(x,y,z,u,v,w,verts,.025);
       axis tight; view(30,30); daspect([1 1 .125])
       haxes = gca;
       haxes.SortMethod = 'ChildOrder';
       camproj perspective; box on
       camva(44); camlookat; camdolly(0,0,.4, 'f');
       h = line;
       streamparticles(h, iverts, 35, 'animate', 10, ...
                       'ParticleAlignment', 'on');
 
    Example 2:
       load wind
       daspect([1 1 1]); view(2)
       [verts averts] = streamslice(x,y,z,u,v,w,[],[],[5]);
       sl = streamline([verts averts]);
       axis tight manual off;
       set(sl,'LineWidth',2);
       set(sl,'Color','r');
       set(sl,'Visible','off');
       iverts = interpstreamspeed(x,y,z,u,v,w,verts,.05);
       haxes = gca;
       haxes.SortMethod = 'ChildOrder';
       haxes.Position = [0 0 1 1];
       zlim([4.9 5.1]);
       hfig = gcf;
       hfig.Color = 'k';
       h = line;
       streamparticles(h, iverts, 200, ...
                       'animate', 100, 'framerate',40, ...
                       'markers', 10, 'markerf', 'y');

常见用法

streamparticles(vertices)
streamparticles(vertices,n)
streamparticles(...,'PropertyName',PropertyValue,...)
streamparticles(ax,...)
streamparticles(line_handle,...)
h = streamparticles(...)

语法说明

streamparticles(vertices) 绘制一个向量场的流粒子。流粒子通常由标记表示，可以显示流线图的位置和速度。vertices 是一个二维或三维顶点元胞数组（就像由 stream2 或 stream3 生成一样）。

streamparticles(vertices,n) 使用 n 确定可以绘制多少流粒子。ParticleAlignment 属性控制如何解释 n。

如果 ParticleAlignment 设置为 off（默认值），并且 n 大于 1，则将在流线图顶点上等间距绘制大约 n 个粒子。如果 n 小于或等于 1，n 将解释为原始流线图顶点的一部分；例如，如果 n 是 0.2，则将使用大约 20% 的顶点。n 确定所绘制的粒子数的上限。实际粒子数与 n 的偏差最多可达 2n 倍。
如果 ParticleAlignment 是 on，n 确定具有最多顶点的流线上的粒子数，并按此值设置其他流线图上的间距。默认值为 n = 1。

streamparticles(…,’PropertyName’,PropertyValue,…) 使用所命名的属性和指定的值控制流粒子。任何未指定的属性都使用默认值。MATLAB^® 将忽略属性名称的大小写。

streamparticles(ax,…) 将在由 ax 指定的坐标区中，而不是在当前坐标区 (gca) 中创建流粒子。选项 ax 可以位于前面的语法中的任何输入参数组合之前。

流粒子属性

Animate – 流粒子运动 [非负整数]

设置流粒子动画运动的次数。默认值为 0，表示不做动画运动。Inf 表示一直做动画运动，直至您输入 Ctrl+C 为止。

FrameRate – 动画的每秒帧数 [非负整数]

此属性指定动画的每秒帧数。默认值 Inf 表示以尽可能快的速度绘制动画。请注意，动画速度可能会受到计算机速度的限制。在这种情况下，不一定能实现 FrameRate 的值。

ParticleAlignment – 使粒子与流线图对齐 [ on | {off} ]

将此属性设置为 on 可在每个流线图的开始位置绘制粒子。此属性控制 streamparticles 如何解释参数 n（流粒子数）。

流粒子为基本线条对象。除了流粒子属性，还可以指定任何线条属性，例如 Marker。调用 streamparticles 时会设置以下线条属性。

线条属性	streamparticles 设置值
LineStyle	‘none’
Marker	‘o’
MarkerEdgeColor	‘none’
MarkerFaceColor	‘red’

您可以将属性名称和值指定为 streamparticles 的参数来覆盖上述任何属性。例如，此语句使用 RGB 值将 MarkerFaceColor 设置为中度灰：

streamparticles(vertices,'MarkerFaceColor',[.5 .5 .5])

streamparticles(line_handle,…) 使用 line_handle 确定的线条对象来绘制流粒子。

h = streamparticles(…) 返回其创建的基本线条对象的句柄向量。

在不显示流线图的情况下生成流动画

此示例使用 z = 5 平面中的流线图通过流粒子来生成沿这些线条的流动画。

load wind
figure
daspect([1,1,1]); 
view(2)
[verts,averts] = streamslice(x,y,z,u,v,w,[],[],[5]); 
sl = streamline([verts averts]);
axis tight manual off;
set(sl,'Visible','off')
iverts = interpstreamspeed(x,y,z,u,v,w,verts,.05);
zlim([4.9,5.1]);
streamparticles(iverts, 200, ...
    'Animate',15,'FrameRate',40, ...
    'MarkerSize',10,'MarkerFaceColor',[0 .5 0])