使用objective-c在iPhone openGL ES中绘制文本 [英] Draw text in iPhone openGL ES using just objective-c

问题描述

需要在openGL中绘制一些文本，然后对其进行旋转和翻译。需要只使用objective-c。有什么帮助？

A need to draw some text in openGL and then make rotations and translations over it. Need to use just objective-c. Any help?

推荐答案

使用Photoshop或其他东西创建如下的纹理文件。

Use Photoshop or something to create a texture file like below.

|ABCDEFGH|
|IJKLMNOP|
|QRSTU...|

sample.png

计算每个字符的UV位置。

Calculate UV position of each character.

float eachCharHeight = 0.125f;
float eachCharWidth = 0.125f;
char charToDraw = 'a';
int indexOfChar = charToDraw - 65; // 'a' = 65
float uValueForCharA = (float)(indexOfChar / 8) * eachCharHeight;
float vValueForCharA = (float)(indexOfChar % 8) * eachCharWidth;

设置texcoords并绘制。

Set texcoords and draw.

glPushMatrix();
glRotatef(...);  // or translate

glEnable(GL_TEXTURE_2D);
glBindTexture(texture);

float vertices[8] = {0.0f, 0.0f, 1.0f, 0.0f, ...};
float texcoords[8] = {uValueForCharA, vValueForCharA, 
                      uValueForCharA + eachCharWidth, ...};

...

glPopMatrix();

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