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

António
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2 Answers2

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

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

sample.png

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;

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();
fish potato
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AFAIK there are basically three ways to do it either you can render the text as a texture (see) or you can use the 2-d graphics library (Quartz) mixed with your opengl or finally you can use e.g. UILabel to display the text on top of your opengl output.

Community
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AndersK
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    The problem is that I need to draw text as an object and then rotate and translate it. 2D solutions are solutions. Thanks any way :) – António Jun 19 '10 at 19:10