OpenGL ES iPhone - 绘制抗锯齿线条 [英] OpenGL ES iPhone - drawing anti aliased lines

问题描述

通常情况下，您会使用以下内容：

Normally, you'd use something like:

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
glEnable(GL_LINE_SMOOTH);

glLineWidth(2.0f);

glVertexPointer(2, GL_FLOAT, 0, points);
glEnableClientState(GL_VERTEX_ARRAY);

glDrawArrays(GL_LINE_STRIP, 0, num_points);

glDisableClientState(GL_VERTEX_ARRAY);

它在iPhone模拟器中看起来不错，但在iPhone上线条非常薄而且没有o / o任何抗锯齿。

It looks good in the iPhone simulator, but on the iPhone the lines get extremely thin and w/o any anti aliasing.

你如何在iPhone上获得AA？

How do you get AA on iPhone?

推荐答案

使用不透明度为0的顶点可以非常便宜地实现抗锯齿效果。
这是一个图像示例来解释：

One can achieve the effect of anti aliasing very cheaply using vertices with opacity 0. Here's an image example to explain:

与AA的比较：

你可以看一篇论文关于这个：

You can read a paper about this here:

http://research.microsoft.com/en-us/um/people/hoppe/overdraw.pdf

你可以做点什么这样：

// Colors is a pointer to unsigned bytes (4 per color).
// Should alternate in opacity.
glColorPointer(4, GL_UNSIGNED_BYTE, 0, colors);
glEnableClientState(GL_COLOR_ARRAY);

// points is a pointer to floats (2 per vertex)
glVertexPointer(2, GL_FLOAT, 0, points);
glEnableClientState(GL_VERTEX_ARRAY);

glDrawArrays(GL_TRIANGLE_STRIP, 0, points_count);

glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);

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