MATLAB更新trisurf句柄

Question

我正在使用Delaunay三角化将散点图转换为曲面。要设置此绘图的动画，我希望更新trisurf控制柄，而不是创建新的trisurf绘图，以减少开销并提高绘图速度。

基本上，在for循环中，我想更新trisurf句柄h的属性，以获得与再次调用trisurf相同的绘图。

MWE

x = linspace(0,1,11); 
y = x;
[X,Y] = meshgrid(x,y);
mag = hypot(X(:),Y(:)); % exemplary magnitude
T = delaunay(X(:),Y(:));
z = 0
h = trisurf(T, X(:), Y(:), z*ones(size(X(:))), mag, 'FaceColor', 'interp'); view([-90 90]);
for i = 1:10
% Compute new values for X, Y, z, and mag
% -> Update properties of handle h to redraw the trisurf plot instead
%    of recalling the last line before the for loop again, e.g.,
% h.FaceVertexCData = ...
% h.Faces = ...
% h.XData = ...
end

Answer 1

您可以更改trisurf():返回的Patch对象的一些属性

for i = 1:9
% Compute new values for X, Y, z, and mag
% As an example:
x = linspace(0,1,11-i);
y = x;
[X,Y] = meshgrid(x,y);
mag = hypot(X(:),Y(:));
T = delaunay(X(:),Y(:));
z = i;
Z = z*ones(size(X)); %we could have just called `meshgrid()` with 3 arguments instead
% End recomputation
% Update trisurf() patch: option 1
set( h, 'Faces',T, 'XData',X(T).', 'YData',Y(T).', 'ZData',Z(T).', 'CData',mag(T).' );
pause(0.25); %just so we can see the result
% Update trisurf() patch: option 2
set( h, 'Faces',T, 'Vertices',[X(:) Y(:) Z(:)], 'FaceVertexCData',mag(:) );
pause(0.25); %just so we can see the result
end

其中z被假定为始终是标量，就像在对trisurf()的原始调用中一样。

• 问：这些选项同样快吗
• A： 我在我的计算机(R2019a，Linux(上运行了一些测试(见下面的代码(，发现当x/y位置的数量是2到20之间的随机数时，使用Vertices的多个set()调用可能比使用XData和相关属性的set()调用快20%，并且这些策略比多个trisurf()调用快大约一个数量级。然而，当x/y位置的数量允许在2到200之间变化时，三种方法的运行时间大致相同

Nruns=1e3;
Nxy_max=20;
for i=1:Nruns
if i==round(Nruns/10)
tic(); %discard first 10% of iterations
end
x = linspace(0,1,randi(Nxy_max-1)+1); %randi([2,Nxy_max]) can be a bit slower
[X,Y,Z] = meshgrid(x,x,randn());
mag = hypot(X(:),Y(:));
T = delaunay(X(:),Y(:));
trisurf(T, X(:), Y(:), Z(:), mag, 'FaceColor', 'interp');
view([-90 90]);
end
tmean_trisurf=1e3*toc()/(Nruns-round(Nruns/10)+1), %in [ms]
h=trisurf(T, X(:), Y(:), Z(:), mag, 'FaceColor', 'interp');
view([-90 90]);
for i=1:Nruns
if i==round(Nruns/10)
tic();
end
x = linspace(0,1,randi(Nxy_max-1)+1);
[X,Y,Z] = meshgrid(x,x,randn());
mag = hypot(X(:),Y(:));
T = delaunay(X(:),Y(:));
set( h, 'Faces',T, 'XData',X(T).', 'YData',Y(T).', 'ZData',Z(T).', 'CData',mag(T).' );
end
tmean_xyzdata=1e3*toc()/(Nruns-round(Nruns/10)+1), %in [ms]
for i=1:Nruns
if i==round(Nruns/10)
tic();
end
x = linspace(0,1,randi(Nxy_max-1)+1);
[X,Y,Z] = meshgrid(x,x,randn());
mag = hypot(X(:),Y(:));
T = delaunay(X(:),Y(:));
set( h, 'Faces',T, 'Vertices',[X(:) Y(:) Z(:)], 'FaceVertexCData',mag(:) );
end
tmean_vertices=1e3*toc()/(Nruns-round(Nruns/10)+1), %in [ms]