SFML community forums
General => General discussions => Topic started by: Dolf on December 26, 2009, 01:08:32 pm
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Hello,
I'm having some issues with the sf::Matrix3 class. It might be that I am completely misunderstanding the class but I was just questioning some interface decisions here.
Why aren't there Get/Set functions for:
Scale()
Rotation()
Translation()
And why doesn't the header file say whether it's a row or column matrix? Or at least explain the lay-out so that I could create my own matrix class and create a conversion between mine and sf::Matrix3.
And even worse, why does it start counting from 1 instead of 0? If I create a matrix with an translation X and Y, this is how I managed to get those values back from the matrix:
float x = someMatrix( 3, 1 );
float y = someMatrix( 4, 1 ); // 4 should be outside the array in a 4x4 matrix ... another point: why aren't there bounds checking asserts in the operator () ?
Thank you so much for reading my moaning about the Matrix3 class,
Dolf
Edit: And why is it in graphics instead of system?
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Hi
There's a simple answer to all of your questions: sf::Matrix3 is designed and optimized for my own internal usage, you're not supposed to use it directly. Nothing in the public API of SFML deals with matrices.
If you need a matrix class in your code you should definitely not use SFML's one.
And why doesn't the header file say whether it's a row or column matrix? Or at least explain the lay-out so that I could create my own matrix class and create a conversion between mine and sf::Matrix3.
Like I said it's not meant for public usage, but you can look at the source code to find out which layout it uses. But there's no point converting from/to sf::Matrix3, it's only used internally. Just focus on your own matrix class.
And even worse, why does it start counting from 1 instead of 0? If I create a matrix with an translation X and Y, this is how I managed to get those values back from the matrix:
float x = someMatrix( 3, 1 );
float y = someMatrix( 4, 1 ); // 4 should be outside the array in a 4x4 matrix
It's counting from 0, and up to 2 (it's a 3x3 matrix). Actually your indexes are completely wrong ;)
Should be this way for translation:
float x = someMatrix(0, 2);
float y = someMatrix(1, 2);
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Ah ok thanks, so I guess I'll copy a matrix class from somewhere then.
Anyway, the next question would be: Why isn't there a matrix class? You do have a Vector2 class... Are you planning on adding that at any point?
About the indices, ye that was an awfull mistake :oops:
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Dolf
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Anyway, the next question would be: Why isn't there a matrix class?
For what? SFML aims at being simple, thus all matrix operations are hidden behind simpler concepts.
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Even in OpenGL, you normally use functions like glTranslatef() or glRotatef() to modify transformation matrices. SFML deals with the same abstraction.