如何在Android OpenGL ES中实现立方体的颜色选择
我已经在 Android OpenGL ES 中实现了一个可以通过手势旋转的立方体。现在我想实现的是，当我点击立方体上的某个地方时，它可以知道哪个面被触摸并做出一些响应。
我在网上搜索了一下，发现颜色选择是一个好方法，这里有一些教程： http: //www.lighthouse3d.com/opengl/picking/index.php?color1
但我仍然觉得这对我来说很难。
如何为每个面分配不同的颜色？
如何从后台缓冲区读取鼠标单击的像素？
谁能告诉我更多详细信息？多谢！
如果您不介意，请给我留下一个电子邮件地址，我可以将我所做的工作发送给您。谢谢 ：）
I have already implemented a cube which can rotate by gestures in Android OpenGL ES. Now I want to implement that when I click somewhere on the cube, it can tell which face has been touched and make some response.
I searched the Internet and find color picking a good way, here are some tutorials: http://www.lighthouse3d.com/opengl/picking/index.php?color1
But I still find it difficult for me.
How to assigned each face a different color?
How to read the pixel where the mouse was clicked from the back buffer?
Can anyone show me some more details? Thanks a lot!
If you don't mind, leave me an email address and I can send you the work I have done. Thanks :)
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第一个评论是，通过分析向世界投射光线几乎总是更快。撇开评论不谈...
您可以为每个面指定不同的颜色以进行拾取，就像任何其他类型的渲染一样，无论是通过更改传递给
glColorPointer的内容（如果使用 ES 1）还是通过切换到单个像素、单色纹理或通过任何其他方式。如果您启用了照明，请务必将其禁用。您可以使用glReadPixels从帧缓冲区读回颜色。在触摸屏设备上，您可能想要抓取一个 20x20 像素区域并选择其中最常出现的颜色或类似的颜色，因为手指不是很精确。
The first comment is that it's almost always faster to do this analytically — by casting a ray into the world. That comment aside...
You'd assign each face a different colour for picking just like for any other sort of rendering, whether by changing what you pass to
glColorPointer(if using ES 1) or by switching to a single pixel, single coloured texture or by any other means. If you have lighting enabled, be sure to disable it.You can use
glReadPixelsto read a colour back from a frame buffer. On a touch-screen device you probably want to grab, say, a 20x20 pixel area and pick whichever colour appears most often in it, or something like, that because fingers aren't very precise.