Thread: What is DirectX and OpenGL ?

You might have come across these terms Directx and OpenGL terms . Like for Example the Nvidia GeForce 8600Gt is DirectX10 enabled

Directx
DirectX is a collection of API (Application program Interface) for handling Multimedia based tasks like Videos and gaming .Its made by Microsoft

Direct3D is widely used in the development of computer games for Microsoft Windows, Microsoft Xbox, and Microsoft Xbox 360. Direct3D is also used by other software applications for visualization and graphics tasks . As Direct3D is the most widely publicized component of DirectX, it is common to see the names "DirectX" and "Direct3D" used interchangeably.

Latest version of DirectX is the DirectX10.1 for Windows Vista

Versions of DirectX Currently Being used

DirectX 8.1 (xp)
DirectX 9a , 9b , 9c (xp)
Directx9L (Vista)
Directx10 , 10.1 (Vista)

OpenGL
OpenGL is slightly similar to DirectX . But it is Open Source

OpenGl is a standard specification defining a cross platform API for developing applications that produce 2d and 3d Graphics

Unlike DirectX it is not the API itself just the specification .

OpenGL is a specification, meaning it is simply a document that describes a set of functions and the precise behaviours that they must perform

Latest OpenGL version is OpenGL 3.0

Originally Posted by ShAdOwCoN

Directx9L (Vista)

Never heard of it.. i had to install DirectX 9c to play games in vista.

Good article. Repo!

Originally Posted by newprouser

Never heard of it.. i had to install DirectX 9c to play games in vista.

vista has directx 10 inbuild, so dont need to install.
i guess directx 10.1 is also released.
just check the microsoft website and update your vista.

Originally Posted by newprouser

Never heard of it.. i had to install DirectX 9c to play games in vista.

Dx9L was the first Vista version of Dx .....

Dx 9c is the last version of Dx for XP ... u can also use it for Vista obviously .... but for Vista its currently Dx10.1

Originally Posted by just4kix

Good article. Repo!

Thanks

hello shadow,
do you know anything about shader model.
does it affects the video playback and games too.
any idea.

Originally Posted by prasannaganesh

hello shadow,
do you know anything about shader model.
does it affects the video playback and games too.
any idea.

Yes definitely

Shader Model (SM) is primarily concerned with image rendering and so will effect both video and games ..
Puting it very simply [but not very accurately in the technical sense]
Shade=Color
Shader= ??
I hope you understood

Difference between shader models
How significant the effect will be will depend totally on the Shader Model ..... For example the difference between SM2 and SM3 is small when compared to difference between SM3 and SM4 .

Game devolopers include support for multiple shader models so it can be run on any card . But for advanced shader models more effects will be supported .And ofcourse your graphic card must have the capability of supporting the shader model .

Shader Model has many modules like Pixel Shader , Vertex Shader , geometry Shader etc

SM4 introduces a new shader that is the geometry shader hence the difference between SM3 and SM4 is great .

how does ur shader model version help in video ?? i did not understand

Originally Posted by rajan1311

how does ur shader model version help in video ?? i did not understand

pixel rendering .... Geometry rendering etc etc

For example
As i said before
SM4 introduces the geometry shader. A new module that provides instructions like 'triangleadj' (for getting adjacent triangles on the GPU) cannot be done on the GPU in SM2 or SM3.

So it effects the quality of image/graphics rendering

i'm a total n00b as far as graphics card are concerned so kindly explain to me the actual difference between the two terms i mean what actually does it mean in graphics cards terms and also how important is it ..........

What is the difference between DirectX and OpenGL ........ ??
what does these two actually refer to ...... ??

I' have noticed that most of the cards support DirectX 10.1 but while it comes to OpenGL 2.1 some do and some don't ........ why this is so ....... ??

from wikipedia

Direct3D is a proprietary API that provides functions to render three dimensional graphics, and uses hardware acceleration if it is available on the graphics card. It was designed by Microsoft Corporation for use on the Windows platform.

OpenGL is an open standard API that provides a number of functions for the rendering of 2D and 3D graphics and is available on most modern operating systems. If hardware 3D acceleration is present, OpenGL can use it.

OpenGL and Direct3D are both implemented in the display driver.

1. they both are drivers ~ they act like a translator between hardware and your game, and provide a variety of functions which can be used by game programmers.

2. usually all games support Dirext X.

3. as to why cards support direct x or open GL , it purely depends on manufacturer. I guess Direct X is more popular.


If you want further comparison , refer to wikipedia.

Comparison of OpenGL and Direct3D - Wikipedia, the free encyclopedia

i bet you will find every thing you need here:
http://www.indiabroadband.net/deskto...tx-opengl.html

thnxx a lot @newprouser and @rajan1311 ......... really useful links .......

thus it can be inferred that if the card is not OpenGL supported but the game is based on OpenGL instead of directX then it can't be played i guess ........ or is there something which i'm missing ...........

@rajan1311
well i had another querie about the version of OpenGL supported .While in most of the cards that i saw showed support for OpenGL 2.1 on the otherhand the thread link which you provided(@ShAdOwCoN) has reference that the latest OpenGL is 3.0 but i haven't seen even a single card supporting that version of openGL ............ why is it so ..... ?? i mean is it b'coz no new games are based on this version or something else ...........
while on the contrary DirectX latest version i.e. 10.1 is supported by almost every card type .

hmm, i m not too sure buddy, i never noticed it !
I think you should ask shadowcon. Btw, where is he ?? Is he even active now ?? He got promotion or what ? he seems to be too busy now.

Originally Posted by rajan1311

hmm, i m not too sure buddy, i never noticed it !
I think you should ask shadowcon. Btw, where is he ?? Is he even active now ?? He got promotion or what ? he seems to be too busy now.

ohk .........
anyways thnxx again ................
and yeah even i haven't noticed him online from a long time ...........

Originally Posted by eruptionjoojo

thnxx a lot @newprouser and @rajan1311 ......... really useful links .......

thus it can be inferred that if the card is not OpenGL supported but the game is based on OpenGL instead of directX then it can't be played i guess ........ or is there something which i'm missing ...........

@rajan1311
well i had another querie about the version of OpenGL supported .While in most of the cards that i saw showed support for OpenGL 2.1 on the otherhand the thread link which you provided(@ShAdOwCoN) has reference that the latest OpenGL is 3.0 but i haven't seen even a single card supporting that version of openGL ............ why is it so ..... ?? i mean is it b'coz no new games are based on this version or something else ...........
while on the contrary DirectX latest version i.e. 10.1 is supported by almost every card type .

As such the only explanation i can think of is that Direct X being made by M$ is not only the popular choice, its also a part of the system,so its more efficient , reliable etc.

Open GL on the other is made by a 3rd party. And probably because its not popular the hardware manufacturers may not have implemented it yet.

just like though modern hardware supports 64bit technoly not all software built for them !

Originally Posted by newprouser

As such the only explanation i can think of is that Direct X being made by M$ is not only the popular choice, its also a part of the system,so its more efficient , reliable etc.

Open GL on the other is made by a 3rd party. And probably because its not popular the hardware manufacturers may not have implemented it yet.

just like though modern hardware supports 64bit technoly not all software built for them !

thnxx for your useful input ................ +rep

and please clarify what i inferred was correct i.e.if the card is not OpenGL supported but the game is based on OpenGL instead of directX then it can't be played i guess ........ or is there something which i'm missing ...........

would still be waiting for some more confirmation from some other senior members ......

Well, if the game is purely base on OpenGL 3.0 and your card supports only 2.1, you can not play the game. But there could be softwares that can convert OpenGL instructions into DX.

Originally Posted by rajan1311

Well, if the game is purely base on OpenGL 3.0 and your card supports only 2.1, you can not play the game. But there could be softwares that can convert OpenGL instructions into DX.

interesting ................. maybe possible .....
and yeah thnxx mod's for merging this post ...........
let's see if some other senior members do reply ........

Originally Posted by eruptionjoojo

thnxx for your useful input ................ +rep

and please clarify what i inferred was correct i.e.if the card is not OpenGL supported but the game is based on OpenGL instead of directX then it can't be played i guess ........ or is there something which i'm missing ...........

would still be waiting for some more confirmation from some other senior members ......

please could somebody verify as to what i stated is correct ............

thnxx in advance.

whats the urgency ?? Are u making a game based on openGL 3 kya ??

Originally Posted by rajan1311

whats the urgency ?? Are u making a game based on openGL 3 kya ??

nothing like that bro .............. but just wanted to have an idea as to how the things actually work .