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OpenGL vs DirectX: Key Difference

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As a game developer, you may be wondering which API is better, OpenGL or DirectX. Both APIs are quite popular and are used extensively all over the world.

However, they differ in their functionality and compatibility significantly and you should know at least the basic difference between the two before choosing the right one for yourself. In this article, we will explain the two APIs and will provide differences between the two.


What is OpenGL?

OpenGL is an acronym for Open Graphics Library and was developed in 1992 by Silicon Graphics Inc. OpenGL is widely used in game development, computer-aided design (CAD), and virtual reality applications.

As OpenGL is a low-level API, developers have direct access to the hardware where they can then optimise the programming codes for hardware-specific requirements. It is thus more suited to experienced programmers and developers.

Another major feature of OpenGL is that it is a state-based API. This means that OpenGL maintains a pre-defined set of variables to help render the graphics. However, you can change these variables to suit your requirements. This feature also makes OpenGL a favourite among the pro developers.

Furthermore, you can run OpenGL on various platforms including Windows, Linux, macOS, Android and iOS. For the API to run, however, you will need additional libraries that support these platforms. There are chances that this might cause a few minor compatibility issues, but nothing major.

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What is DirectX?

DirectX was developed by Microsoft in 1995. You can use DirectX in gaming, audio, video and other multimedia applications.

DirectX is a high-level API and as such it takes away a few complications that a low-level API might possess. The interface is simple and consistent and as such DirectX is favoured by those who are beginners in game development.

Furthermore, DirectX is a component-based API as opposed to OpenGL which is a state-based API. A component-based API has several sub-APIs that handle different tasks seamlessly such as rendering, audio and input devices. For example, for rendering DirectX deploys Direct3D. Similarly, for audio output, it employs DirectSound and so on.

DirectX is not cross-platform and is only hardcoded in Microsoft products, that is, Windows and Xbox. However, it works well with these products.

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OpenGL vs DirectX: Key differences

In this section, we will understand the key differences between OpenGL and DirectX based on several parameters.

Specifications

OpenGL and DirectX have different versions and extensions that define their capabilities and functionalities. The latest version of OpenGL is 4.6, released in 2017, which supports features such as tessellation, compute shaders, indirect drawing, and enhanced debugging. However, not all devices and drivers support the latest version of OpenGL, and some features may require additional extensions that are not standardized or widely available.

The latest version of DirectX is 12, released in 2015, which supports features such as ray tracing, variable rate shading, mesh shaders, and sampler feedback. However, DirectX 12 is only available on Windows 10 and Xbox One, and some features may require specific hardware or software support. For older or less powerful devices, DirectX 11 is still a viable option, as it supports features such as tessellation, compute shaders, and multithreading.


Performance

OpenGL and DirectX have similar performance in most cases, as they both rely on the same underlying hardware and drivers. However, there are some factors that can affect the performance of each API, such as the quality of the implementation, the optimisation of the code, and the overhead of the API.

OpenGL is a low-level API, which means that it gives developers more control and flexibility over the hardware and the rendering pipeline. This can result in better performance, especially for complex or custom graphics effects, as developers can fine-tune their code for specific scenarios and platforms. However, OpenGL is also a state-based API, which means that it has a higher overhead and complexity, as developers have to manage and update the state variables and issue commands to OpenGL.

DirectX is a high-level API, which means that it simplifies and standardizes the interface and the rendering pipeline. This can result in better performance, especially for simple or common graphics effects, as developers can rely on the API and the drivers to handle the details and optimize the code. However, DirectX is also a component-based API, which means that it has a lower overhead and complexity, as developers can use the sub-APIs that suit their needs and avoid unnecessary commands and calculations.


Features

Both the APIs have different features and capabilities that can enhance the quality and functionality of graphics. Some features such as shaders, textures, lighting, and bending, among others, are common to both OpenGL and DirectX.

However, in other respects, one API may be more advantageous than another. For example, DirectX offers features such as ray tracing, variable rate shading, and sampler feedback, among others, which are not available in OpenGL. On the other hand, OpenGL provides features such as tessellation and enhanced debugging in its latest version.

Other than that, both APIs have specific tools in their arsenal that developers can use. For example, OpenGL provides tools such as BuGLe, gDEBugger, GL Intercept, and Night Visual Studio. While DirectX has tools such as HLSL, DirectXMath, DirectX Tool Kit, and PIX, among others.


Compatibility

OpenGL is a cross-platform API and with the help of third-party libraries, you can use it on any platform. However, this is not the case with DirectX as it is only for Microsoft Windows and Xbox.


Gaming

But how do these two APIs perform in gaming? MakeUseOf conducted a 3D and 2D performance test to assess which one performs better. In both the tests, DirectX outperformed OpenGL significantly.

However, these tests are not conclusive. Even MOU has this to say about the tests: “While many people say that OpenGL performs better than DirectX, the latter API achieved better results in both of our benchmarks. This is far from conclusive, with many factors playing a role in dictating a game’s performance, especially as they get more complex.”

Games such as Minecraft, Baldur’s Gate: Dark Alliance, and 7 Days to Die use OpenGL while Fortnite for Android uses both OpenGL and DirectX depending on the platform.

CategoryOpenGLDirectX
Development year19921995
DeveloperSilicon Graphics Inc.Microsoft
Primary usageGame development, CAD, virtual realityGaming, audio, video, multimedia applications
Level of APILow-levelHigh-level
Access to hardwareDirect access, optimized for hardware-specific requirementsSimplified interface, less control over hardware
State of APIState-basedComponent-based
Platform supportWindows, Linux, macOS, Android, iOSWindows, Xbox
Latest versions4.6 (2017)12 (2015)
Key featuresTessellation, compute shaders, indirect drawing, enhanced debuggingRay tracing, variable rate shading, mesh shaders, sampler feedback
Performance factorsControl and flexibility, potentially better for complex or custom graphics effectsPotentially better for simple or common graphics effects
Tools and librariesBuGLe, gDEBugger, GL Intercept, Night Visual StudioHLSL, DirectXMath, DirectX Tool Kit, PIX
CompatibilityCross-platform with additional librariesWindows and Xbox only
Performance testsDirectX outperformed OpenGL in 3D and 2D performance testsResults not conclusive, performance depends on various factors
Popular gamesMinecraft, Baldur’s Gate: Dark Alliance, 7 Days to DieVaries, Fortnite for Android uses both OpenGL and DirectX

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OpenGL vs DirectX: Which one is better for you?

Well, the answer to this question depends entirely on your preferences and requirements. Both have some key advantages over one other and offer incredible performance.

So, choose the right API depending on your project’s requirements and platform. We hope that this article has helped you understand the key differences between OpenGL and DirectX.

Also read: AMD Ryzen 3 vs Intel Core i5: Which one is better? 

Kumar Hemant

Deputy Editor at Candid.Technology. Hemant writes at the intersection of tech and culture and has a keen interest in science, social issues and international relations. You can contact him here: kumarhemant@pm.me

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