是否有适用于 iPhone SDK 的体面的 OpenGL 文本绘制库? [英] Is there a decent OpenGL text drawing library for the iPhone SDK?
问题描述
我试图找出一个简单的方法来在 OpenGL 中绘制一些文本.我的研究表明这是一项相当复杂的任务.它涉及创建(或在运行时生成)字体图集纹理，然后为每个字母创建一个四边形，并使用正确的位置和纹理坐标.
I'm trying to figure out a simple to draw some text in OpenGL. My research has shown its a fairly complex task. It involves creating (or generating at runtime) a font atlas texture, and then creating a quad for each letter with just the right placement and texture coordinates.
我听说过一些关于 freetype 的好消息，但对如何让它在 iPhone 上运行却知之甚少，而且看起来相当复杂.
I've heard some good things about freetype, but have found very little about how to get it running on the iPhone, and it appears to be pretty complex.
那么是否有任何 Objective-C 封装的 OpenGL 文本库可以与人们一直在使用的 iPhone SDK 配合使用?还是我只是想多了，我错过了更简单的方法?
So is there any Objective-C wrapped OpenGL text library that works with the iPhone SDK that people have been using? Or am I just over thinking this and there is an easier approach that I am missing?
推荐答案
您对使用 freetype 创建纹理图集以及所有字形信息的描述正是我在当前 iPhone 项目中所做的.
Your description of using freetype to create a texture atlas along with all the glyph information is exactly what I'm doing in my current iPhone project.
我在预处理步骤中完成了字体的所有解析(所有在 Windows 上的 C# 中都发生了).地图集本身被生成并且只包含所需的字符 - 为了减少空间，我有时最终也会生成多个地图集以保持纹理大小 pow2 和合理的分辨率.
I do all the parsing of the font in a pre-process step (All in C# on Windows as it happens). The atlas itself gets generated and contains only the characters needed - to cut down on space, I also sometimes end up generating more than a single atlas to keep textures sizes pow2 and of a sensible resolution.
您可以轻松地从 freetype 中提取字形信息.在运行时将它与纹理一起传递给您的应用程序，然后根据需要更改纹理的 UV 坐标就相当简单了.
You can easily pull out the glyph information from freetype. Pass that along to your app along with the textures at runtime and then it's fairly trivial to just alter the UV coords of the texture as required.
就其价值而言，这就是我在我的小引擎中定义字形字符的方式:
For what it's worth, this is how I define a glyph character inside my little engine:
struct FontGlyph
{
u32 char_code;
u32 m_x; // base x position on tpage
u32 m_y; // base y position on tpage
u32 m_width; // glyph width
u32 m_height; // glyph height
i32 m_horiBearingX; // Distance to X shift
i32 m_horiBearingY; // Distance to Y shift
u32 m_horiAdvance; // Total Horizontal advance this character requires
u32 m__tpage_index; // Which tpage does this glyph use?
};
然后我有一个SpriteString"对象，它的行为与任何其他字符串非常相似，除了我可以使用精灵绘制它....
I then have a 'SpriteString' object, which behaves pretty much like any other string, apart from I can draw it using sprites....
我同意这对于一个相当微不足道的问题来说似乎是一项艰巨的工作，但我发现它给了我很大的灵活性，而且当我开始着手实施时并没有花那么长时间.
I agree this all might seem like a big job for a fairly trivial problem, but I've found it's given me plenty of flexibility and really didn't take that long to implement when I got down to it.
如果您需要任何其他详细信息，请随时回复或发表评论.(祝你好运:)
Feel free to reply or comment if you need any other details. (And good luck :)
当我在评论部分的空间不足时回复您的评论......
Reply to your comment as I ran out of room in the comment section...
查看 freetype 文档，它基本上为您提供字形数据而不会乱七八糟，它只是将其从字体中拉出来.至于纹理本身，您可以使用 freetype 来渲染每个字形，然后管理它以构建纹理.这是我作为一个完全独立于我的主应用程序的预处理.
Check out the freetype documentation, it basically gives you the glyph data without messing about, it just pulls it right out of the font. As for the textures themselves, you get freetype to render each glyph, and then manage that to build the texture. This I do as a pre-process entirely separate from my main app.
这是我执行此操作的工具代码的摘录:http://pastebin.com/md1c6354
Here's an excerpt of my tool code that does this: http://pastebin.com/md1c6354
不过请注意，这只是为了我的眼睛而不是公共消费，所以请原谅它像地狱一样凌乱:)
Please note though, this was only ever intended for my eyes and not for public consumption, so excuse the fact it's messy as hell :)
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