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OpenGL Is Clustered Forward Shading worth implementing?

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This has been a fascinating topic, and I commend everyone contributing too it! Warning, what follows is a somewhat off topic rant

 

Since it wasn't clear, I was arguing for deferred simply to handle most worst case scenarios in games today, not that it was the most efficient always, and yes forward/hybrid/etc. may always have scenarios where X is faster than Y. This generation, now closing, has seen an extreme need for optimization of resources for each game. Programmer time and talent has been, and will always be another consideration, but pushing good visuals versus limited resources has eaten up more and more consideration as time has gone on. So optimizing what you are doing for each game has been a priority, including refactoring something like lighting each time if need be.

 

This next generation however, I believe, will be different. Certainly more compute power will always be usable, pretty much into infinity. But the biggest constraint I can see is artist time. It's already been a constraint with modern games, and can only get worse now that a thousand materials can be supported on models a hundred thousand faces and more in count, not too mention all the advanced animation rigging for things like cloth physics, hair physics, skin and muscle simulation and etc. that can be done.

 

Which is simply why I foresee less time spent on refactoring rendering and more time making better tools for artists. Certainly, there are going to be cases still where forward/deferred/hybrid approaches are better; and as MJP pointed out you can have a more generalized pipeline far more easily now, which is great! But anything that makes the job easier and faster for artists, at least in my view, should be given priority. Which is a reason why I've viewed the use of multiple BRDFs with skepticism. The less the artist has to learn, and thus the more time spent actually making things, the better. And while certainly better can be done than Blinn-Phong, I'd simply rather not even give most artists the opportunity to sit there and switch between Beckmann to GGX to Cook-Torrance to etc. just to see what each did to "Get it right."

 

And I know there are ways to mitigate that. Suggestions I've seen range from pre-defined materials with correct values to not let artists screw things up to. etc. etc. All take time, and I'm mostly thinking way too hard about efficiency I suppose. So in short I'd rather hope for, in general, far less refactoring each game, as little complexity (and thus time and effort) added to the artists pipeline as possible, and more effort on all those very neat tools and research into such this go around. After all, I enjoy playing games as well, and would love to see them be as good as possible. And it makes more sense to me to take the Hollywood/offline VFX path of late, which is trying to make making things faster and cheaper, rather than trying harder to make things look better. So I'd rather have a deferred render capable of handling the worst case gameplay scenarios with a generalized BDRF that's good enough at doing multiple materials. But that's a far away thought I suppose.

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I.E. Here's what I'm talking about, even Hollywood and Disney have this problem and are trying to solve it: http://disney-animation.s3.amazonaws.com/library/s2012_pbs_disney_brdf_slides_v2.pdf

 

In fact, their BDRF sounds pretty good! "As few parameters as possible, 0-1 range, all combinations of parameters plausible" Mmmm yeah that's the stuff. One BDRF to rule them all, one BDRF to find them, one deferred renderer to bring them all, and in screenspace bind them! laugh.png

Edited by Frenetic Pony

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Which is a reason why I've viewed the use of multiple BRDFs with skepticism. The less the artist has to learn, and thus the more time spent actually making things, the better. And while certainly better can be done than Blinn-Phong, I'd simply rather not even give most artists the opportunity to sit there and switch between Beckmann to GGX to Cook-Torrance to etc. just to see what each did to "Get it right."

 

This isn't the problem you think it is; the BRDF/shaders are set up by tech artists (in association with rendering programmers) which are not the same guys doing the models/animation/rigging which take the time. Those guys are handed shaders and told 'use these' so they won't be swapping from one function to another to 'get it right'.

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Which is a reason why I've viewed the use of multiple BRDFs with skepticism. The less the artist has to learn, and thus the more time spent actually making things, the better. And while certainly better can be done than Blinn-Phong, I'd simply rather not even give most artists the opportunity to sit there and switch between Beckmann to GGX to Cook-Torrance to etc. just to see what each did to "Get it right."

 

This isn't the problem you think it is; the BRDF/shaders are set up by tech artists (in association with rendering programmers) which are not the same guys doing the models/animation/rigging which take the time. Those guys are handed shaders and told 'use these' so they won't be swapping from one function to another to 'get it right'.

Yes, and setting up a thousand BDRF shaders doesn't take up their time? Of course it does, otherwise Disney wouldn't have gone to all that trouble to reduce their rendering down to a single BDRF.

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ah yes, the old reductio ad absurdum argument....

 

A game is NOT going to have thousands of BDRF setup for it, a few will be selected from a small batch and those will be used (and result in many INSTANCES of the materials with different parameters) but the BDRFs themselves will be quite a low count. Over time more BDRF might get added but you aren't going to say "we are going to make a game, quick make ALL the BDRF shaders!" - that would be so many shades of dumb even thinking it is possible is.. well.. dumb.

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ah yes, the old reductio ad absurdum argument....

 

A game is NOT going to have thousands of BDRF setup for it, a few will be selected from a small batch and those will be used (and result in many INSTANCES of the materials with different parameters) but the BDRFs themselves will be quite a low count. Over time more BDRF might get added but you aren't going to say "we are going to make a game, quick make ALL the BDRF shaders!" - that would be so many shades of dumb even thinking it is possible is.. well.. dumb.

 

Tri-Ace was developing several already, for a game that was supposed to be this generation. Next gen there won't be nearly as much restriction, if Hollywood sees it as a problem to solve why would games, unburdened by much in the way of hardware constraints (as far as BDRF goes) be any different? Budgets can certainly be similar, and games often have far, far more assets.

 

With a single generalized BDRF, such as the one Disney has developed and I linked too, you would need a fat G-Buffer to store enough parameters sure. But you can go deferred and avoid dynamic branching, and you do save time. I'm not saying it's going to be as huge a benefit as a movie CG might get. Obviously artists wouldn't have time to sit there and fiddle with materials ad nauseum. But if it saves time it saves time. Point is I don't see much reason NOT to have a single, highly artists friendly BDRF as opposed to multiple kinds.

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Point is I don't see much reason NOT to have a single, highly artists friendly BDRF as opposed to multiple kinds.

In theory, it is a great idea... but, perhaps you're over-estimating next-gen power. Disney can spend an hour per frame, using 100 GPUs, we need 33ms per frame on 1 GPU.

 

For realtime, you're not going to want to compute sub-surface-scattering, or anisotropic reflections, for every surface if you can avoid it, etc, etc...

Edited by Hodgman

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For realtime, you're not going to want to compute sub-surface-scattering, or anisotropic reflections, for every surface if you can avoid it, etc, etc...

 

Awwee... But I want anistropic-specularity on my cream cheese, the bagels upon which 'tis spread, and my hot cup O' goodness!

 

There's an obvious engineering solution to this... isn't there? Ha... I'm sorry but I think it's just too simple to explicitly indicate. It's a very elementary premise of tool making... You don't need to internally implement such an "artist friendly BDRF" ... Too many hints ...

 

So yeah.

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Note that Forward+ (aka Clustered Forward, Light Indexed Deferred) is a very new topic and there's a lot of research coming up this year.

Now, just because I'd hate for this to turn into another deferred lighting / shading terminology kerfuffle:

 

Tiled Forward <=> Forward+, these use 2D tiling (same as Tiled Deferred), with a pre-z pass (optional) + separate geometry pass for shading.

Light Indexed Deferred, Builds the lists per pixel, which can be viewed as a 1x1 tile, and then it is really the same as Tiled Forward. The practical difference is pretty big, though...

Clustered Forward, performs tiling in 3D (or higher). othwewise as above.

Tiled/Clustered Deferred Shading, do tiling as their forward counterparts, but start with a G-Buffer pass and end with a deferred shading pass.

 

Hope this clears up, and/or prevents, some confusion.

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There is a thing I don't understand.
It appears there's this thing still going on which plain forward can only do 8-10 lights per pass. How? In the past I've had quite some success encoding light data in textures and looping them on entry-level SM3 hardware. Perhaps I'm not seeing the whole picture but in SM4 with the much higher resource limits and the unlimited dynamic instruction count... shouldn't we go easily in the thousand range? Of course we'll neeed a z-only pass first.
So I guess there are additional practical reasons to stay in the 8-10 range.

 

At the top of page 2, I read about extra pressure and lower execution efficiency. I understand.

But, as much as I love lighting modularity coming from deferred, as a DDR3 card owner I still don't understand how the improved processing makes up for the bandwidth increase required. The trend on bandwidth is set. It looks to me we want to trash compute in the future.

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Hi Krohm,

 

In shader model 4.0 you can have up to 4096 entries in a constant buffer (which would limit lights to ~256 if they have position, direction diffuse, specular). Or you can use texture buffers and have near limitless lights.

Let's say you use the latter, so no worries about the light count. And today with SM 5.0 we really don't need to worry about loop count limits either. So we're good on that front

 

Indeed you can loop through a 1000 lights in SM4+ hardware. But let's say I'm running at 1920x1080 resolution and the whole screen is covered.

1920x1080 x 1000 lights = 2.073.600.000 light evaluations per frame.

Not to mention some BRDFs are expensive (i.e. Cook Torrance). Framerate would be sloooooooooow. So slow in fact, that it could trigger the Windows watchdog for believing the GPU is stalled and restart the driver.

 

The secret behind Deferred shaders (or Forward+) is that even though there are thousands of lights, they're not covering the whole screen at the same time.

In other words: many small lights = few big lights.

It's typical that a single region of the screen isn't lit by more than 4-20 lights, may be 5 on average. Let's be pessimistic and say 10.

1920x1080 x 10 lights = 20.736.000 light evaluations per frame

That's a lot more reasonable for a GPU to perform in real time. In such scenario every region of pixels (called tiles) would only have to loop through 10 lights (on average), not a 1000 and waste gpu time on 990 lights that aren't needed.

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But what if you would test whether a light actually should be covering the individual pixels inside this loop and skip all the lights, that shouldn't? The only difference to a tile-based deferred renderer would be, that the light culling is performed per pixel instead of per tile. But you wouldn't have all the BRDF, transparency, bandwidth and Anti-Aliasing issues. It would basically be a worse version of a light indexed deferred renderer, because the list of lights is not precomputed. Edited by CryZe

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Also with more traditional forward rendering you would typically have stage (performed either offline or online) where you determine which lights will affect a given mesh, so that you only apply those lights when rendering it. Once again the only major difference is your granularity, and when/where you cull your lights at your given level of granularity. Doing everything on the GPU lets you achieve very fine granularity (per-tile or per-pixel) with relatively simple code, which is the primary draw of deferred techniques.

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But what if you would test whether a light actually should be covering the individual pixels inside this loop and skip all the lights, that shouldn't? The only difference to a tile-based deferred renderer would be, that the light culling is performed per pixel instead of per tile. But you wouldn't have all the BRDF, transparency, bandwidth and Anti-Aliasing issues. It would basically be a worse version of a light indexed deferred renderer, because the list of lights is not precomputed.

You could do that, but GPUs suck at branch-heavy applications, specially if there's not good branch coherency within the tile block (pixel shaders are run in blocks)

 

And even if it did, a tile-based deferred renderer is MUCH more efficient in performing this culling.

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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.
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