补丁透明性问题(FaceAlpha) [英] Problem with patch transparency (FaceAlpha)

问题描述

我在使用Windows XP的Matlab 2010b中进行补丁绘图时遇到了一些奇怪的问题.
当我尝试绘制以下补丁时，我得到的补丁不是全部填充，但有一些空白部分.

I encountered some strange problem with patch ploting in Matlab 2010b with windows xp.
When I try to plot following patch, I get a patch which is not all-filled, but has some blank parts.

如果我将渲染器设置为"painters"(请参见下文)，可以解决此问题，
但是我不能更改补丁的透明度.
有人遇到过类似的问题吗?任何解决方法?

This can be solve if I set the renderer to 'painters' (see below),
but then I can't change the transparency of the patch.
Has anyone encountered similar problem before? any workaround?

x = [734608.791666667;734608.843750000;734609;734609.041666667;734609.086805556;734609.125000000;734609.250000000;734609.277777778;];
y = [85.7847149493030;95.4499999983124;96.4800000077516;112.549999984098;109.949999996456;118.299999970804;120.450000002981;112.600000008944;];

figure;
set(gcf, 'Renderer', 'opengl');
patch(x, y, 'r');
title('this plot is with wrong vertices positions');

figure;
set(gcf, 'Renderer', 'painters');
patch(x, y, 'r', 'FaceAlpha', 0.1);
title('this plot is OK, but renderer ignores the transparency');

figure;
set(gcf, 'Renderer', 'opengl');
patch(x, y, 'r', 'FaceAlpha', 0.1);
title('this plot is with wrong vertices positions, but with transparency');

推荐答案

问题似乎源自于MATLAB-> OpenGL渲染管道(我的猜测)中某个地方的浮点精度.

The problem seems to originate from the floating point accuracy somewhere the MATLAB -> OpenGL rendering pipeline (my guess).

如果您将x操纵为:

x = [734608.791666667;734608.843750000;734609;734609.041666667;734609.086805556;734609.125000000;734609.250000000;734609.277777778;];
x = (x - mean(x));

这些图似乎工作正常.

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