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moeen k

OpenGL glut glew freeglut, what is diffrence?

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hello my friends. 

 

im new on opengl and im working on some tutprial projects.

 

when i include headres like freeglut glew and glut the vs compiler says a bug that you have to include one above an other.

i think it is because some variables and functions are repeated in them and compiler doesnt know to use which one.

 

after that if i comment on of them, still program works and there will be no problem. i want to know what are the diffrences between them? are the compelete and if i use one of them there will be no need to others?

 

 

thank you for helping

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FreeGLUT is an open-source alternative to GLUT. As the latest version of GLUT was released in 1998 you should probably use FreeGLUT if you decide to use one of them. They provide functionality for window creation, input handling an some other things
GLEW on the other hand has a different functionality. It loads the function pointers that you need to write modern OpenGL code.
You should be able to use GLEW with FreeGLUT but you cannot use GLUT and FreeGLUT at the same time.

For more detailed information you should check the documentations of FreeGLUT and GLEW.

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I would just want to note that you could also choose a more modern and possibly better library for windowing, handling input etc. like GLFW, SDL or SFML.

Edited by ProtectedMode

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thank you my friends for your help. but there is a problem too.

i refrenced all include and lib files in a right place and gave it right addres to my compiler but there is still an error like below:

 

Error 2 error LNK2001: unresolved external symbol __imp___glewEnableVertexAttribArray D:\PROJECTS\opengl\training\t2\t2\main.obj t2
Error 1 error LNK2001: unresolved external symbol __imp___glewBindBuffer D:\PROJECTS\opengl\training\t2\t2\main.obj t2
Error 3 error LNK1120: 2 unresolved externals D:\PROJECTS\opengl\training\t2\x64\Debug\t2.exe 1 1 t2
 
now i read some articles that i have to add glew_static but i dont know what it is. can you please help me.
 
and plesae tell me what is opengl modern coding and old coding and can problem be from diffrent version of glew? in their website i found a lot od diffrent versions
thank you for helping
Edited by moeen k

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As a rule of thumb, when you want to use a static library you have to do three things:
1. Tell the compiler in which directory it can find the header files
2. Tell the linker in which directory it can find the library files
3. Tell the linker which library files to use.

Some tool chains allow 2+3 to be combined. Some allow the library files to be specified inside the header files via #pragma so that step 3 can be omitted. But again, as a rule of thumb, those are the three steps.

When the compiler complains that it can't find a header file you missed step 1. When the linker complains that it can't find a library file you either missed step 2 or messed up the library name. When the linker complains that it can't find certain symbols, as in your case, you probably missed part 3.

Looking at the current version of glew, the library files for VisualStudio are under lib/ in the glew-1.11.0-win32.zip file. There are different versions depending, amongst other things, on whether you are going for a 32-bit or 64-bit program.

Modern OpenGL refers to the newer versions of OpenGL. The newer versions have new API functions that you can call, but accessing them is a bit tricky and glew helps with that. Independent of which OpenGL version you are going for, using the newest version of glew is probably the best choice.

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3. Tell the linker which library files to use.

 

thank you for your answer Ohforf sake but i dont know last part.

what does it mean that to use which library? i pasted the library to programefiles86/ microsftsdks/windows/7.0/lib and include  

are there diffrent kind of files there with same name?

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now i read some articles that i have to add glew_static but i dont know what it is. can you please help me.


It's GLEW_STATIC (case is important) and you need to add it to your preprocessor definitins (Project Properties -> C/C++ -> Preprocessor -> Preprocessor Definitions), but only if you are linking against the static version of GLEW (i.e. one the glew32s.lib files).
 

what does it mean that to use which library? i pasted the library to programefiles86/ microsftsdks/windows/7.0/lib and include  
are there diffrent kind of files there with same name?


That directory is for Microsoft's Windows SDK. You don't want to put your files in there. You can place them wherever you want, but don't put them into into the folder of another SDK. You could for example create a dedicated SDK directory next to the projects folder you mentioned earlier. Then you add the directory where you placed your SDK to the linker directories (Project Properties -> Linker -> General -> Additional Library Directories) and the libary's name to the dependency list ((Project Properties -> Linker -> Input -> Additional Dependencies).

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sorry but i have more questions. you said modern coding is about using glew library but i have worked on some project that only used glut or freeglut.

and working on that was much easier. what i lose if i stop using glew.

is this about more features or quality? i could make objects particle and lightening only using glut.

 

next question is how can i make an update work once or for some special count of times or loop forever. i know glutIdleFunc(ddd) runs the ddd function for loop. and GlutDesplayfunc(ddd) runs just for one time but why we call them in on function. in most example i see they call same function ddd. but can i call that update for glutIdleFunction as diffrent?

thank you for helping.

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sorry but i have more questions. you said modern coding is about using glew library but i have worked on some project that only used glut or freeglut. and working on that was much easier. what i lose if i stop using glew.


Not using glew, or any other library/code that performs the same, you "just" loose every advance in computer graphics of the last 16 years.
Often times, if you just need a quick visualization of something with a couple of lines, points, and triangles, then the stuff from 16 years ago is completely sufficient.

I think whether or not you *need* the new stuff is irrelevant. Rendering has changed significantly since 16 years ago, and if you invest precious time into learning, you might just as well not waste it on s.th. that is dead and buried.

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