如何在A帧中创建180度/半球/段/部分视频球？ [英] How to create a 180-degree/semisphere/segment/partial video sphere in A-Frame?

问题描述

< a-videosphere src = myvideo.mp4> 在整个360度范围内显示视频，但我想显示视频或图像，但仅在半球这样的球体的一部分上。

<sub>（来自MathWorld-Wolfram网络资源：

（来源： mediabox.fr ））</sub>

对于半球，我们可以这样做：

 < a-entity geometry = primitive：sphere; thetaLength：180; radius：5000; segmentWidth：64; segmentHeight：20 scale = 1 1 -1 material = src：#myVideo; shader：flat> ;< / a-entity> 
  

或：

 < a-sphere theta-length = 180> 
  

然后应用材料。

对于videosphere，我们可以对其进行更新：

 < a-videosphere src =＃myVideo geometry = thetaLength：180< //-videosphere> 
  

但是，视频不会像您期望的那样被裁剪。因此，您可能必须事先进行裁剪。如果您希望它像 background-size：cover 那样裁剪，我们可能需要做一些特别的事情，例如隐藏球体的一部分。

<a-videosphere src="myvideo.mp4"> displays a video on an entire 360-degree sphere, but I want to display a video or image, but only on a portion of a sphere like a hemisphere. Something like:

_{(from MathWorld - A Wolfram Web Resource: wolfram.com)}

How would I do this in A-Frame?

解决方案

You can use the sphere geometry (<a-entity geometry="primitive: sphere"> or <a-sphere>) and control the phiLength/thetaLength angles of the sphere to specify a segment. Theta length controls horizontal sweep angle and phi length controls vertical sweep angle:

_{(source: mediabox.fr)}

For a hemisphere, we would do:

<a-entity geometry="primitive: sphere; thetaLength: 180; radius: 5000; segmentsWidth: 64; segmentsHeight: 20" scale="1 1 -1" material="src: #myVideo; shader: flat"></a-entity>

Or:

<a-sphere theta-length="180">

And then apply the material.

For videosphere, we can update it:

<a-videosphere src="#myVideo" geometry="thetaLength: 180"></a-videosphere>

However, the video won't be cropped as you'd expect. So you might have to crop beforehand. If you want it to crop like background-size: cover, we might have to do something special like hide portions of the sphere.

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