问题描述
我一直工作在一个小应用程序为我的电话，我想补充一个
功能需求
一个圆圈被吸引到屏幕上。我不知道我怎么能做到这一点
使用OpenGL ES。谁能帮助？
I've been working on a small app for my phone, and I wanted to add afeature that needsa circle to be drawn to screen. I was wondering how I could do thisusing OpenGL ES. can anyone help?
推荐答案
基本上有三个选项画一个圆圈。你不指定是否要固/薄/厚等等看，所以不是所有的这些可能是appriopriate为您的情况：
Basically, there are three options for drawing a circle. You don't specify whether you want a solid/thin/thick etc look, so not all of these might be appriopriate for your case:
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产生在一个圆圈顶点和使用glDrawArray（GL_LINES，...）。根据你有多少个顶点生成，这将产生一个很好的和清晰的结果。
Generate vertices in a circle and use glDrawArray( GL_LINES, ... ). Depending on how many vertices you generate this will yield a nice and crisp result.
使用pgenerated圆（阿尔法透明度）的质地$ P $并将其映射在四。这将导致非常流畅的图形，并允许一个'thick'圈，但它不会像灵活：即使有纹理映射，你会希望你的纹理是关于你正在呈现四相同尺寸
Use a pregenerated texture of a circle (with alpha transparency) and map it on a quad. This will result in very smooth graphics and allow for a ´thick´ circle, but it will not be as flexible: even with mipmapping, you'll want your texture to be about the same size you are rendering the quad.
使用一个片段着色器。如的正常工作。
Use a fragment shader. Examples like this should work fine.
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