把箭頭放在顯示軸的方向的Matlab圖形中

Question

我在Matlab中使用從physionet下載的代碼和數據繪製了VCG曲線。現在，我需要在圖中顯示箭頭，以顯示X，Y和Z軸的方向。 完全如圖所示。我一直試圖谷歌一段時間，但沒有一個提示。 你能給我任何建議嗎？

這就是我想實現：

Answer 1

沒有爲一個解決方案，它是由Matlab提供。

您可以創建一個函數（mArrow3.m）如下：

mArrow3.m

function h = mArrow3(p1,p2,varargin) 
%mArrow3 - plot a 3D arrow as patch object (cylinder+cone) 
% 
% syntax: h = mArrow3(p1,p2) 
%   h = mArrow3(p1,p2,'propertyName',propertyValue,...) 
% 
% with:  p1:   starting point 
%   p2:   end point 
%   properties: 'color':  color according to MATLAB specification 
%          (see MATLAB help item 'ColorSpec') 
%      'stemWidth': width of the line 
%      'tipWidth': width of the cone      
% 
%   Additionally, you can specify any patch object properties. (For 
%   example, you can make the arrow semitransparent by using 
%   'facealpha'.) 
%      
% example1: h = mArrow3([0 0 0],[1 1 1]) 
%   (Draws an arrow from [0 0 0] to [1 1 1] with default properties.) 
% 
% example2: h = mArrow3([0 0 0],[1 1 1],'color','red','stemWidth',0.02,'facealpha',0.5) 
%   (Draws a red semitransparent arrow with a stem width of 0.02 units.) 
% 
% hint:  use light to achieve 3D impression 
% 

propertyNames = {'edgeColor'}; 
propertyValues = {'none'};  

%% evaluate property specifications 
for argno = 1:2:nargin-2 
    switch varargin{argno} 
     case 'color' 
      propertyNames = {propertyNames{:},'facecolor'}; 
      propertyValues = {propertyValues{:},varargin{argno+1}}; 
     case 'stemWidth' 
      if isreal(varargin{argno+1}) 
       stemWidth = varargin{argno+1}; 
      else 
       warning('mArrow3:stemWidth','stemWidth must be a real number'); 
      end 
     case 'tipWidth' 
      if isreal(varargin{argno+1}) 
       tipWidth = varargin{argno+1}; 
      else 
       warning('mArrow3:tipWidth','tipWidth must be a real number'); 
      end 
     otherwise 
      propertyNames = {propertyNames{:},varargin{argno}}; 
      propertyValues = {propertyValues{:},varargin{argno+1}}; 
    end 
end    

%% default parameters 
if ~exist('stemWidth','var') 
    ax = axis; 
    if numel(ax)==4 
     stemWidth = norm(ax([2 4])-ax([1 3]))/300; 
    elseif numel(ax)==6 
     stemWidth = norm(ax([2 4 6])-ax([1 3 5]))/300; 
    end 
end 
if ~exist('tipWidth','var') 
    tipWidth = 3*stemWidth; 
end 
tipAngle = 22.5/180*pi; 
tipLength = tipWidth/tan(tipAngle/2); 
ppsc = 50; % (points per small circle) 
ppbc = 250; % (points per big circle) 

%% ensure column vectors 
p1 = p1(:); 
p2 = p2(:); 

%% basic lengths and vectors 
x = (p2-p1)/norm(p2-p1); % (unit vector in arrow direction) 
y = cross(x,[0;0;1]); % (y and z are unit vectors orthogonal to arrow) 
if norm(y)<0.1 
    y = cross(x,[0;1;0]); 
end 
y = y/norm(y); 
z = cross(x,y); 
z = z/norm(z); 

%% basic angles 
theta = 0:2*pi/ppsc:2*pi; % (list of angles from 0 to 2*pi for small circle) 
sintheta = sin(theta); 
costheta = cos(theta); 
upsilon = 0:2*pi/ppbc:2*pi; % (list of angles from 0 to 2*pi for big circle) 
sinupsilon = sin(upsilon); 
cosupsilon = cos(upsilon); 

%% initialize face matrix 
f = NaN([ppsc+ppbc+2 ppbc+1]); 

%% normal arrow 
if norm(p2-p1)>tipLength 
    % vertices of the first stem circle 
    for idx = 1:ppsc+1 
     v(idx,:) = p1 + stemWidth*(sintheta(idx)*y + costheta(idx)*z); 
    end 
    % vertices of the second stem circle 
    p3 = p2-tipLength*x; 
    for idx = 1:ppsc+1 
     v(ppsc+1+idx,:) = p3 + stemWidth*(sintheta(idx)*y + costheta(idx)*z); 
    end 
    % vertices of the tip circle 
    for idx = 1:ppbc+1 
     v(2*ppsc+2+idx,:) = p3 + tipWidth*(sinupsilon(idx)*y + cosupsilon(idx)*z); 
    end 
    % vertex of the tiptip 
    v(2*ppsc+ppbc+4,:) = p2; 

    % face of the stem circle 
    f(1,1:ppsc+1) = 1:ppsc+1; 
    % faces of the stem cylinder 
    for idx = 1:ppsc 
     f(1+idx,1:4) = [idx idx+1 ppsc+1+idx+1 ppsc+1+idx]; 
    end 
    % face of the tip circle 
    f(ppsc+2,:) = 2*ppsc+3:(2*ppsc+3)+ppbc; 
    % faces of the tip cone 
    for idx = 1:ppbc 
     f(ppsc+2+idx,1:3) = [2*ppsc+2+idx 2*ppsc+2+idx+1 2*ppsc+ppbc+4]; 
    end 

%% only cone v 
else 
    tipWidth = 2*sin(tipAngle/2)*norm(p2-p1); 
    % vertices of the tip circle 
    for idx = 1:ppbc+1 
     v(idx,:) = p1 + tipWidth*(sinupsilon(idx)*y + cosupsilon(idx)*z); 
    end 
    % vertex of the tiptip 
    v(ppbc+2,:) = p2; 
    % face of the tip circle 
    f(1,:) = 1:ppbc+1; 
    % faces of the tip cone 
    for idx = 1:ppbc 
     f(1+idx,1:3) = [idx idx+1 ppbc+2]; 
    end 
end 

%% draw 
fv.faces = f; 
fv.vertices = v; 
h = patch(fv); 
for propno = 1:numel(propertyNames) 
    try 
     set(h,propertyNames{propno},propertyValues{propno}); 
    catch 
     disp(lasterr) 
    end 
end 

，並把它傳遞的參考點：

Plot3D.m

clc;clear;close; 

hold on; 
mArrow3([0 0 0],[1 0 0]); 
mArrow3([0 0 0],[0 1 0]); 
mArrow3([0 0 0],[0 0 1]); 
hold off 

所以輸出會是這樣：