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OpenGL Efficient GUI rendering

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This has probably come up before here, so feel free to link me straight to a good source of info .. but ..

Anyway for various reasons I have written a little GUI system for a game I'm working on, and decided to have a go at fleshing it out to make it useful for writing tools or little apps, possibly cross platform. Oh gawd, yet another reinventing the wheel I hear you cringe, yes, well, can't say much on that ...

Here's a screeny showing I have it working ok, it didn't take too long:

[img]http://i49.tinypic.com/2mxgbnq.jpg[/img]

For the game I was using directx to do the actual GUI rendering, but I've swapped over to opengl for general use, and it's a long time since I did much opengl, I'm very out of date with it.

So my question is probably to people who have done this before, what did you find the most efficient way of rendering the GUI objects? I can see there's a few trade offs involved. I was until recently just doing everything in software, writing to one big software surface, then locking a big viewport size texture and copying the RGB data across. Not particularly elegant or fast, but simple and it works.

That is until I realised I wanted to have some opengl 3d viewports displaying 3d models inside the app, with GUI elements possibly overlayed (such as menus, or dialog boxes). And to future proof things it would be nice to not lock the entire viewport every time there is a little change, so it works at reasonable speed.

So my guesses for some alternative methods are:

1) As each 'widget' is changed, I render this to the big software texture, and lock and upload just a part of the texture (using glTexSubImage2D?). This isn't as simple as it could be though, because it appears the source data can't have a 'pitch' to jump across the x coord on each line (if the viewport is much wider than the 'dirty rectangle'), so I'd have to first convert the big software texture to a temporary smaller one before uploading to opengl.

I could also keep a list of dirty rectangles that need uploading to opengl to avoid uploading the same area more than once in a frame.

2) Same as above but keep a separate software surface for each 'widget'. That way it can be uploaded without fiddling. However it makes changing the size of widgets potentially more problematic (as the software surface size will change), and would be nicer to avoid all those unnecessary memory allocations (although I could use memory pools I spose).

3) Have a separate opengl texture for each widget. Probably faster for rendering but pretty ugly in terms of memory allocation / deletion.

4) Try and render everything directly on the 3d card, without using software textures.

So, anyone know is there a standard good way of doing this? Anyone know what CeGUI, MyGUI etc do?
Cheers [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]

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[quote name='lawnjelly' timestamp='1341420449' post='4955665']
what did you find the most efficient way of rendering the GUI objects?[/quote]The one that takes less work to implement. I've had quite some stir with GUI systems and I can tell for sure performance has never been a problem for me. Never. They just are not performance paths.
But, as a design rule, I'd try to minimize memory consumption rather than runtime performance.

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[quote name='Krohm' timestamp='1341424113' post='4955675']
[quote name='lawnjelly' timestamp='1341420449' post='4955665']
what did you find the most efficient way of rendering the GUI objects?[/quote]The one that takes less work to implement. I've had quite some stir with GUI systems and I can tell for sure performance has never been a problem for me. Never. They just are not performance paths.
But, as a design rule, I'd try to minimize memory consumption rather than runtime performance.
[/quote]
Well that sounds encouraging. :)

I'm beginning to think the idea of trying to render GUI items on top of the opengl 3d windows is overkill, and opening up a bag of worms. Instead I could just render the GUI in the background, then just update the 3d window on top and assume nothing is overlaying it. And in the case of where the user opens a menu or something, I could pause the 3d window, kind of avoiding the problem.

I kind of agree on the memory consumption and also simplicity versus performance, after all I don't want to spend that much time on it, and create the greatest kickass GUI known to man if I'm only going to use it for a couple of apps. Just didn't want to paint myself into a corner later on with early design decisions if it's not necessary.

At the moment I'm thinking in terms of keeping the current approach with one big software surface, then just optimizing the amount of locking / dirty rectangles uploaded to the opengl texture. It may well stall the 3d pipeline, but it shouldn't matter that much if I'm not doing it every frame, and it's just for tools.

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A GUI rendering can be slow, because text rendering can be slow if there's a lot of text. So you can look into text rendering optimization.

I know you didn't ask for comments on the reinventing thing, but it's pretty strange that you are really reinventing the look of the standard win32 GUI.
If you want to release stuff with this GUI, it will kick your ass. And it will kick the users' ass. A GUI that just looks like the well known Windows GUI but doesn't work like it is a major user-anti-experience.

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[quote name='Krohm' timestamp='1341424113' post='4955675']
The one that takes less work to implement. I've had quite some stir with GUI systems and I can tell for sure performance has never been a problem for me. Never. They just are not performance paths.
But, as a design rule, I'd try to minimize memory consumption rather than runtime performance.
[/quote]

I'm guessing that you've never worked with Scaleform. [img]http://public.gamedev.net//public/style_emoticons/default/tongue.png[/img] Edited by MJP

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[quote name='szecs' timestamp='1341427663' post='4955689']
A GUI rendering can be slow, because text rendering can be slow if there's a lot of text. So you can look into text rendering optimization.

I know you didn't ask for comments on the reinventing thing, but it's pretty strange that you are really reinventing the look of the standard win32 GUI.
If you want to release stuff with this GUI, it will kick your ass. And it will kick the users' ass. A GUI that just looks like the well known Windows GUI but doesn't work like it is a major user-anti-experience.
[/quote]

I agree about the user experience, there are some well executed and user-friendly third party GUIs and some that just leaving you scratching your head.

In this case I'd already written the basics of the GUI for a light weight in-game menu system, so thought why not add regular application menus and try running with it for a simple app. It's all good experience. I'm just planning on using it for a simple internal 3d model editor for now, nothing fancy.

And of course not being tied to win32 leaves you more options, me and a couple of friends have just released an app on iOS that used a simplified version of this.

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[quote name='MJP' timestamp='1341427897' post='4955691'] that you've never worked with Scaleform. [img]http://public.gamedev.net//public/style_emoticons/default/tongue.png[/img][/quote]Of course not. I'm referring to the shitty systems I use here.

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Have you come across GWEN? Its a GUI system aimed at games.

It comes with renderers for GDI, Allegro, OpenGL, Direct2D, DirectX and SFML.

I've used it with SFML. I had to modify the SFML renderer slightly to suit my needs and because it's open source it was easy to do.

Heres the link:
[url="http://code.google.com/p/gwen/"]http://code.google.com/p/gwen/[/url]

From the website:

[quote]
[b] Facts[/b][list]
[*]Coded in C++
[*]Fully Namespaced
[*]All standard window controls
[*]Behaves like you'd expect
[*]Lightweight
[list]
[*]No XML readers, no font loaders/renderers, no texture loaders - your engine should be doing all this stuff!
[/list][*]Easy to integrate (comes with renderers for Windows GDI, Allegro, OpenGL, Direct2D, DirectX and SFML)
[*]Totally portable & cross platform
[*]Doesn't need RTTI
[/list]
Released under a "do whatever you want" MIT license.
[/quote]

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I've written this, but am not really sure it answers any questions, but perhaps you will find something useful here ;)

I would say that what you do would largely depend on your end goals (and those may change as time progresses). By this I mean if it's only ever going to be for use in your own projects, or if you intend a more general purpose library for use by the masses.

I guess some of what I put here is more aimed at a public lib and so it may not apply if what you're doing is only ever going to be for use in your own stuff.

It has to be said that to be completely general purpose and suitable for all possible scenarios is exceptionally difficult, if not impossible, to pull off. GUIs used for games and such may usually make assumptions and impose limitations that perhaps you can not if your GUI is to be used for non-game things. Editors and such can fall into either category, and which category any given tool falls into depends on many things IMO.

I suggest to create a brief “mission statement” that describes specific roles for your GUI and stick to that at all costs. Decide early on some limitations and stick to them rigidly. While “rigidity” sounds like bad advice, in the long run it will save you time, effort and keep your project lean, mean and on target at all times. Trying to be all things to all people is a slippery slope, and ultimately will split users into two camps – those that love the fact that you're willing to implement their feature request or modification, and those that think your lib sucks because it is complex or bloated – you cannot please all of the people, all of the time ;)

Current CEGUI performs rendering at various levels. The base level caches geometry for a window's rendering which remains unmodified and thus is reused until something changes on that window. By geometry, I do not mean four corners, 2 triangles or whatever, but geometry for all imagery drawn, so if the window has tiled a background and text, the geometry for drawing all those quads is stored.

In addition to this, we also support rendering the base level cached geometry back to a texture along with rendering for all attached child elements. This is generally used either for special effects or for optimisation purposes (if you have a page of text, rendering it to a texture first can be a massive performance boost – because drawing the two triangles needed to display the 'cache' texture is likely faster than drawing 20,000 triangles or more needed for a page of text). CEGUI makes this cache texture optional, and under the users control, since scenarios exist where always rendering to texture first will be slower – if we exclude special effects where it might always be needed, if some UI element is changing every frame, using a middle-man texture will slow things down instead of speeding them up.

We give access to the user to various parts of this pipeline so they can do their own thing, such as rendering 3D models. Having said that, it is also possible if the user renders the 3D model to texture, and then uses that texture to put the rendered model into a window. For our purposes that can be beneficial since it allows the user to cleanly update that model without having to hook into the CEGUI rendering process directly.

TL;DR: Keep it as simple as possible. Avoid mission creep. Don't let other people pull you off of your original vision. There is no one right answer and only you can decide what is best for your project!

CE

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Thanks for the advice guys, especially thanks to Eddie as you are probably one of the most qualified guys to give answers having done it all! [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]

Yes I am sure trying to make a GUI for others to use is a whole other kettle of fish. You can end up trying to be all things to all people, but it's difficult because there are always trade-offs, as you say adding all the features that users demand, versus bloating the code and making it more complex to maintain.

I expect like other aspects of games (3d rendering, physics etc) the 'best' solution for your particular constraints only becomes apparent after several entire redesigns.

After a little investigation it turns out there is a way to easily upload just part of a software surface (canvas I'm calling it) to opengl, using


[i]glPixelStorei(GL_UNPACK_ROW_LENGTH, uiWidth);[/i]
prior to calling
[i]glTexSubImage2D[/i]

which deals with the problem of the pitch of source surface, although it may not work on opengl ES (I'll cross that bridge when I come to it).

So I'll go with the keep it simple stupid approach for now and do it all in software, and just upload dirty rectangles where pixel data changes.

And render to texture does sound like it may add extra possibilities to any problems of integrating 3d windows with the rest of the GUI. Good points too about having a cached surface for things like text, but it not being faster in all cases.

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      Creating Shaders
      While in earlier APIs shaders were bound separately, in the next-generation APIs as well as in Diligent Engine shaders are part of the pipeline state object. The biggest challenge when authoring shaders is that Direct3D and OpenGL/Vulkan use different shader languages (while Apple uses yet another language in their Metal API). Maintaining two versions of every shader is not an option for real applications and Diligent Engine implements shader source code converter that allows shaders authored in HLSL to be translated to GLSL. To create a shader, one needs to populate ShaderCreationAttribs structure. SourceLanguage member of this structure tells the system which language the shader is authored in:
      SHADER_SOURCE_LANGUAGE_DEFAULT - The shader source language matches the underlying graphics API: HLSL for Direct3D11/Direct3D12 mode, and GLSL for OpenGL and OpenGLES modes. SHADER_SOURCE_LANGUAGE_HLSL - The shader source is in HLSL. For OpenGL and OpenGLES modes, the source code will be converted to GLSL. SHADER_SOURCE_LANGUAGE_GLSL - The shader source is in GLSL. There is currently no GLSL to HLSL converter, so this value should only be used for OpenGL and OpenGLES modes. There are two ways to provide the shader source code. The first way is to use Source member. The second way is to provide a file path in FilePath member. Since the engine is entirely decoupled from the platform and the host file system is platform-dependent, the structure exposes pShaderSourceStreamFactory member that is intended to provide the engine access to the file system. If FilePath is provided, shader source factory must also be provided. If the shader source contains any #include directives, the source stream factory will also be used to load these files. The engine provides default implementation for every supported platform that should be sufficient in most cases. Custom implementation can be provided when needed.
      When sampling a texture in a shader, the texture sampler was traditionally specified as separate object that was bound to the pipeline at run time or set as part of the texture object itself. However, in most cases it is known beforehand what kind of sampler will be used in the shader. Next-generation APIs expose new type of sampler called static sampler that can be initialized directly in the pipeline state. Diligent Engine exposes this functionality: when creating a shader, textures can be assigned static samplers. If static sampler is assigned, it will always be used instead of the one initialized in the texture shader resource view. To initialize static samplers, prepare an array of StaticSamplerDesc structures and initialize StaticSamplers and NumStaticSamplers members. Static samplers are more efficient and it is highly recommended to use them whenever possible. On older APIs, static samplers are emulated via generic sampler objects.
      The following is an example of shader initialization:
      ShaderCreationAttribs Attrs; Attrs.Desc.Name = "MyPixelShader"; Attrs.FilePath = "MyShaderFile.fx"; Attrs.SearchDirectories = "shaders;shaders\\inc;"; Attrs.EntryPoint = "MyPixelShader"; Attrs.Desc.ShaderType = SHADER_TYPE_PIXEL; Attrs.SourceLanguage = SHADER_SOURCE_LANGUAGE_HLSL; BasicShaderSourceStreamFactory BasicSSSFactory(Attrs.SearchDirectories); Attrs.pShaderSourceStreamFactory = &BasicSSSFactory; ShaderVariableDesc ShaderVars[] = {     {"g_StaticTexture", SHADER_VARIABLE_TYPE_STATIC},     {"g_MutableTexture", SHADER_VARIABLE_TYPE_MUTABLE},     {"g_DynamicTexture", SHADER_VARIABLE_TYPE_DYNAMIC} }; Attrs.Desc.VariableDesc = ShaderVars; Attrs.Desc.NumVariables = _countof(ShaderVars); Attrs.Desc.DefaultVariableType = SHADER_VARIABLE_TYPE_STATIC; StaticSamplerDesc StaticSampler; StaticSampler.Desc.MinFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MagFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MipFilter = FILTER_TYPE_LINEAR; StaticSampler.TextureName = "g_MutableTexture"; Attrs.Desc.NumStaticSamplers = 1; Attrs.Desc.StaticSamplers = &StaticSampler; ShaderMacroHelper Macros; Macros.AddShaderMacro("USE_SHADOWS", 1); Macros.AddShaderMacro("NUM_SHADOW_SAMPLES", 4); Macros.Finalize(); Attrs.Macros = Macros; RefCntAutoPtr<IShader> pShader; m_pDevice->CreateShader( Attrs, &pShader );
      Creating the Pipeline State Object
      After all required shaders are created, the rest of the fields of the PipelineStateDesc structure provide depth-stencil, rasterizer, and blend state descriptions, the number and format of render targets, input layout format, etc. For instance, rasterizer state can be described as follows:
      PipelineStateDesc PSODesc; RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; RasterizerDesc.AntialiasedLineEnable = False; Depth-stencil and blend states are defined in a similar fashion.
      Another important thing that pipeline state object encompasses is the input layout description that defines how inputs to the vertex shader, which is the very first shader stage, should be read from the memory. Input layout may define several vertex streams that contain values of different formats and sizes:
      // Define input layout InputLayoutDesc &Layout = PSODesc.GraphicsPipeline.InputLayout; LayoutElement TextLayoutElems[] = {     LayoutElement( 0, 0, 3, VT_FLOAT32, False ),     LayoutElement( 1, 0, 4, VT_UINT8, True ),     LayoutElement( 2, 0, 2, VT_FLOAT32, False ), }; Layout.LayoutElements = TextLayoutElems; Layout.NumElements = _countof( TextLayoutElems ); Finally, pipeline state defines primitive topology type. When all required members are initialized, a pipeline state object can be created by IRenderDevice::CreatePipelineState() method:
      // Define shader and primitive topology PSODesc.GraphicsPipeline.PrimitiveTopologyType = PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE; PSODesc.GraphicsPipeline.pVS = pVertexShader; PSODesc.GraphicsPipeline.pPS = pPixelShader; PSODesc.Name = "My pipeline state"; m_pDev->CreatePipelineState(PSODesc, &m_pPSO); When PSO object is bound to the pipeline, the engine invokes all API-specific commands to set all states specified by the object. In case of Direct3D12 this maps directly to setting the D3D12 PSO object. In case of Direct3D11, this involves setting individual state objects (such as rasterizer and blend states), shaders, input layout etc. In case of OpenGL, this requires a number of fine-grain state tweaking calls. Diligent Engine keeps track of currently bound states and only calls functions to update these states that have actually changed.
      Binding Shader Resources
      Direct3D11 and OpenGL utilize fine-grain resource binding models, where an application binds individual buffers and textures to certain shader or program resource binding slots. Direct3D12 uses a very different approach, where resource descriptors are grouped into tables, and an application can bind all resources in the table at once by setting the table in the command list. Resource binding model in Diligent Engine is designed to leverage this new method. It introduces a new object called shader resource binding that encapsulates all resource bindings required for all shaders in a certain pipeline state. It also introduces the classification of shader variables based on the frequency of expected change that helps the engine group them into tables under the hood:
      Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. Shader variable type must be specified during shader creation by populating an array of ShaderVariableDesc structures and initializing ShaderCreationAttribs::Desc::VariableDesc and ShaderCreationAttribs::Desc::NumVariables members (see example of shader creation above).
      Static variables cannot be changed once a resource is bound to the variable. They are bound directly to the shader object. For instance, a shadow map texture is not expected to change after it is created, so it can be bound directly to the shader:
      PixelShader->GetShaderVariable( "g_tex2DShadowMap" )->Set( pShadowMapSRV ); Mutable and dynamic variables are bound via a new Shader Resource Binding object (SRB) that is created by the pipeline state (IPipelineState::CreateShaderResourceBinding()):
      m_pPSO->CreateShaderResourceBinding(&m_pSRB); Note that an SRB is only compatible with the pipeline state it was created from. SRB object inherits all static bindings from shaders in the pipeline, but is not allowed to change them.
      Mutable resources can only be set once for every instance of a shader resource binding. Such resources are intended to define specific material properties. For instance, a diffuse texture for a specific material is not expected to change once the material is defined and can be set right after the SRB object has been created:
      m_pSRB->GetVariable(SHADER_TYPE_PIXEL, "tex2DDiffuse")->Set(pDiffuseTexSRV); In some cases it is necessary to bind a new resource to a variable every time a draw command is invoked. Such variables should be labeled as dynamic, which will allow setting them multiple times through the same SRB object:
      m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); Under the hood, the engine pre-allocates descriptor tables for static and mutable resources when an SRB objcet is created. Space for dynamic resources is dynamically allocated at run time. Static and mutable resources are thus more efficient and should be used whenever possible.
      As you can see, Diligent Engine does not expose low-level details of how resources are bound to shader variables. One reason for this is that these details are very different for various APIs. The other reason is that using low-level binding methods is extremely error-prone: it is very easy to forget to bind some resource, or bind incorrect resource such as bind a buffer to the variable that is in fact a texture, especially during shader development when everything changes fast. Diligent Engine instead relies on shader reflection system to automatically query the list of all shader variables. Grouping variables based on three types mentioned above allows the engine to create optimized layout and take heavy lifting of matching resources to API-specific resource location, register or descriptor in the table.
      This post gives more details about the resource binding model in Diligent Engine.
      Setting the Pipeline State and Committing Shader Resources
      Before any draw or compute command can be invoked, the pipeline state needs to be bound to the context:
      m_pContext->SetPipelineState(m_pPSO); Under the hood, the engine sets the internal PSO object in the command list or calls all the required native API functions to properly configure all pipeline stages.
      The next step is to bind all required shader resources to the GPU pipeline, which is accomplished by IDeviceContext::CommitShaderResources() method:
      m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); The method takes a pointer to the shader resource binding object and makes all resources the object holds available for the shaders. In the case of D3D12, this only requires setting appropriate descriptor tables in the command list. For older APIs, this typically requires setting all resources individually.
      Next-generation APIs require the application to track the state of every resource and explicitly inform the system about all state transitions. For instance, if a texture was used as render target before, while the next draw command is going to use it as shader resource, a transition barrier needs to be executed. Diligent Engine does the heavy lifting of state tracking.  When CommitShaderResources() method is called with COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES flag, the engine commits and transitions resources to correct states at the same time. Note that transitioning resources does introduce some overhead. The engine tracks state of every resource and it will not issue the barrier if the state is already correct. But checking resource state is an overhead that can sometimes be avoided. The engine provides IDeviceContext::TransitionShaderResources() method that only transitions resources:
      m_pContext->TransitionShaderResources(m_pPSO, m_pSRB); In some scenarios it is more efficient to transition resources once and then only commit them.
      Invoking Draw Command
      The final step is to set states that are not part of the PSO, such as render targets, vertex and index buffers. Diligent Engine uses Direct3D11-syle API that is translated to other native API calls under the hood:
      ITextureView *pRTVs[] = {m_pRTV}; m_pContext->SetRenderTargets(_countof( pRTVs ), pRTVs, m_pDSV); // Clear render target and depth buffer const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); m_pContext->ClearDepthStencil(nullptr, CLEAR_DEPTH_FLAG, 1.f); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); Different native APIs use various set of function to execute draw commands depending on command details (if the command is indexed, instanced or both, what offsets in the source buffers are used etc.). For instance, there are 5 draw commands in Direct3D11 and more than 9 commands in OpenGL with something like glDrawElementsInstancedBaseVertexBaseInstance not uncommon. Diligent Engine hides all details with single IDeviceContext::Draw() method that takes takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
      DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); For compute commands, there is IDeviceContext::DispatchCompute() method that takes DispatchComputeAttribs structure that defines compute grid dimension.
      Source Code
      Full engine source code is available on GitHub and is free to use. The repository contains two samples, asteroids performance benchmark and example Unity project that uses Diligent Engine in native plugin.
      AntTweakBar sample is Diligent Engine’s “Hello World” example.

       
      Atmospheric scattering sample is a more advanced example. It demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to multiple render targets, using compute shaders and unordered access views, etc.

      Asteroids performance benchmark is based on this demo developed by Intel. It renders 50,000 unique textured asteroids and allows comparing performance of Direct3D11 and Direct3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

      Finally, there is an example project that shows how Diligent Engine can be integrated with Unity.

      Future Work
      The engine is under active development. It currently supports Windows desktop, Universal Windows and Android platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and support for more platforms is planned.
    • By michaeldodis
      I've started building a small library, that can render pie menu GUI in legacy opengl, planning to add some traditional elements of course.
      It's interface is similar to something you'd see in IMGUI. It's written in C.
      Early version of the library
      I'd really love to hear anyone's thoughts on this, any suggestions on what features you'd want to see in a library like this? 
      Thanks in advance!
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