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DX11 A few questions about DX10 and other items

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Well today GL died and DX won the battle most are saying now. So, I am now looking at maybe moving to DX10 or DX11, and I have heard that DX11 SDK will be out in Nov? Will the SDK run on DX10/10.1 hardware accelerated or in software mode? If I move to DX should I wait till DX11 comes out? Is DX10 coding going to carry over into DX11, or will DX11 be a complete overhaul like 9 to 10 was? What about a GUI library for DX10? What about Physx libs? I want something that is native to DX10, basically drop in and play? What about model loading or rendering? Does DX10 have a decent model loader like .x files under DX10? Is the DXUT or math libs still in DX10? I need some of these questions answered so I can make my decision soon, and what about ATI/Nvidia drivers for DX10 are all the features included as of now on both? Meaning if I code DX10 will it run on both without a headache? Thanks

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Original post by MARS_999So, I am now looking at maybe moving to DX10 or DX11, and I have heard that DX11 SDK will be out in Nov? Will the SDK run on DX10/10.1 hardware accelerated or in software mode?


A techpreview will be out in November. Since D3D10 it has become a tradition to show the developers a techpreview first. While it will be mostly complete some minor changes can still happen. Direct3D 11 will run with Direct3D 10/10.1 in hardware mode you just can't use the new D3D11 features like the compute shaders.

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Original post by MARS_999If I move to DX should I wait till DX11 comes out? Is DX10 coding going to carry over into DX11, or will DX11 be a complete overhaul like 9 to 10 was?


It will be mostly the same. Porting from 10 to 11 should be just a matter of some hours. Most of this could be done with a simple find/replace.

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Original post by MARS_999What about a GUI library for DX10? What about Physx libs? I want something that is native to DX10, basically drop in and play?


I am not aware of a GUI lib but I am never actively searched for any as we use our own. I am not sure where you see problem with PhysX. The PhysX SDK may not contain a sample for Direct3D 10 but it is mostly the same workflow as with Direct3D 9

Quote:
Original post by MARS_999What about model loading or rendering? Does DX10 have a decent model loader like .x files under DX10?


X Files are considered as dead. They have some loader code for their new SDK asset format. But in general writing an asset loader is very straight forward.

Quote:
Original post by MARS_999Is the DXUT or math libs still in DX10?


Yes the DXUT is still part of the SDK and D3DX contains still the math libraries.

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Original post by MARS_999I need some of these questions answered so I can make my decision soon, and what about ATI/Nvidia drivers for DX10 are all the features included as of now on both? Meaning if I code DX10 will it run on both without a headache?


Direct3D 10 requires that the hardware and the driver support the full techlevel. There are only some optional features left. In our case we run the exact same code on every Direct3D 10 hardware.

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Well today GL died
I briefly discussed OpenGL with Rob at GameFest last week and he mentioned there was an announcement due that week. I'm a bit out of the loop - what came up and why do you declare GL dead?

Ralf's covered your questions, but just to throw my 2-pence in... Go with D3D 10.0 and be happy, it can be stated that simply.

The only case I'd suggest you hold off for D3D11 is if you want to go for a massively parallel architecture or want to port some old X360 native code over. The architectural changes with 11 allow for a very different design that can be quite tricky to implement on 10.x and older API's. The stuff for free-threaded resource creation and immediate/deferred display lists is powerful.

As an aside, I was also discussing with Rob and Richard last week about my thoughts that traditional frame-based designs will be rapidly going the way of the dodo in this multi-threaded world. But thats a whole other discussion [grin]

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Does DX10 have a decent model loader like .x files under DX10?
There are ID3DX10Mesh objects that map reasonably well to legacy formats but there is no .X support nor any mesh manipulation functions. However you can still do all your mesh work with D3DX9 and a NULLREF device then just copy the ID3DXMesh to a ID3DX10Mesh for rendering. I've posted the code for this a few times but its not too hard to figure out for yourself [wink]

hth
Jack

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Original post by jollyjeffers
Quote:
Well today GL died
I briefly discussed OpenGL with Rob at GameFest last week and he mentioned there was an announcement due that week. I'm a bit out of the loop - what came up and why do you declare GL dead?
Ok, I shouldn't be so lazy!

Interesting thread to read and Oluseyi's comments about GL having other huge markets to cater for is a good one. Leading the GL community on was bad form, but maybe games just aren't that important to them when compared with multi-billion dollar CAD industries...?

Jack

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Original post by jollyjeffers
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Original post by jollyjeffers
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Well today GL died
I briefly discussed OpenGL with Rob at GameFest last week and he mentioned there was an announcement due that week. I'm a bit out of the loop - what came up and why do you declare GL dead?
Ok, I shouldn't be so lazy!

Interesting thread to read and Oluseyi's comments about GL having other huge markets to cater for is a good one. Leading the GL community on was bad form, but maybe games just aren't that important to them when compared with multi-billion dollar CAD industries...?

Jack


Hi Jack, the multi-billion dollar industry is fine, but games as a whole is many many times larger than they are, if everyone used GL vs. DX for games CAD would be a very small part as a whole. GL probably isn't dead, but sure feels like it when most people are talking about leaving it...

What are you saying about DX11? Will DX11 be different to code for than Dx10?

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Original post by MARS_999
Hi Jack, the multi-billion dollar industry is fine, but games as a whole is many many times larger than they are, if everyone used GL vs. DX for games CAD would be a very small part as a whole. GL probably isn't dead, but sure feels like it when most people are talking about leaving it...
I'm not well versed on the size (customers/companies/revenue) of the CAD and dependent industries so I don't know how it compares. I was just commenting that Oluseyi seemed to have raised a good point that one distinct interpretation of this is that the ARB/Khronos group bent to keep certain camp(s) happy and that gaming may well not have been their interest.

Quote:
Original post by MARS_999
What are you saying about DX11? Will DX11 be different to code for than Dx10?
As Ralf commented the actual code changes for D3D11 are pretty reasonable from a 10.0/10.1 perspective and if you're familiar with 10 you'll be fine with 11.

What I was getting at is the architectural possibilities. A big part of the D3D11 design is to better support multi-threading, something that isn't such a great story under D3D10 or D3D9.

Designing a "traditonal" D3D9/D3D10 renderer and then porting it up to D3D11 is perfectly fine. But if you were to go straight for D3D11 (which can support down-level hardware) then you have more options w.r.t. the design and architecture of your code - you can do more interesting and more powerful things with multi-threading.

If you want to get rolling straight away then stick with the traditional approach and go for D3D10. I would imagine you need to be at the bleeding edge with a pretty large and complex engine (inc. non graphics parts) to really see any ROI on a massively multi-threaded next-gen engine right now [smile]

hth
Jack

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One last question, maybe Jack can answer it, with DX11 they are talking about Multi-core CPUs being utilized better, so what do they mean by this? Would I be better off with a quad core vs. a dual core for DX11? Thanks

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This depends on your software. The multi core support for Direct3D 11 is not a feature that works automatic without special code. Direct3D 11 allows you to fill multiple “display list” at the same time on different threads. Finely you can send all this lists in the right order to the GPU for rendering. The advantage by doing this is that most CPU work will be already done by the threads that fill the display list.

If your software can fill four list parallel you can be faster with a quad core. But you need to be CPU limited and not GPU limited.

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Right now, with D3D9 and 10, there is very limited support for mutlithreading and doing things like resource creation or issuing drawing commands.

You pretty much have two choices;
1) don't do it. All drawing and resource creation/uploads take place in the main rendering thread the device was created in (like how a GL context is dealt with), just using other threads to decompress the data.

2) create a multi-threaded device which lets you do things from multiple threads at once but involves all manner of criticalsection locks which hurt performance.

With DX11 the landscape changes in that you'll be able to create resources from any thread and there are 'deferred' contexts which are used for constructing display lists which can then be executed from the main context.

Jack, Superpig and myself go into various levels of detail about this in our XNA Gamefest write ups in the journal section.

As for performance, it's less about DX11 and your cores and more about how the games as a whole are designed, DX11 just removes the cluggyness from dealing with multithreading.

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So it is possible that if the games are designed correctly that with a quad core you could get some decent speed increases over a dual core, if I am understanding you correctly. But on the same token, the current crop of games aren't designed to well to work with quad cores, and maybe the next round of games or when the next console generation comes out, we will have better designed engines, that could in theory take and use a quad core system to it fullest potential... So for now I would be better off with a faster dual core rig, 3.33Ghz dual vs. a 2.83Ghz quad core? Reason I am asking is I am building a new rig soon, and can't decide between dual or quad and my problem is I upgrade every 12-18 months, and I am trying to get away from that and keep a rig for 2-3 years for once! ;)

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Even now a game could see significant gains over dual core if designed in such a way as to take advantage of the extra cores.

DX11 just makes submitting data and streaming resources that much easier than before; granted, if you have secondary threads setting up display lists it could very well give you a boost but at the end of the day it all comes down to bottlenecks; if pixel rate is a bottle neck then throwing all the CPU resources in teh world at the problem won't increase the speed.

I've had my X2 2.2Ghz for the last 3years now, about the only thing i've upgraded has been the GPU because games outpace the GPU more than the CPU. However, if you are wanting to build a new rig I'd suggest holding off for a few months for Core i7's release as even if you don't get one it might well drop the price of the current Duo and Quad processors a little.
(my plans are to build a new machine around March next year, DoW2 has the power to adjust that build time however, closer or further away)

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So, whats going to be the standard in regards to models? What's the best format to be used in DX10+? I've used X files for some time, does DX10+ have a newer loader for any model types? 3ds? etc?

Thanks for any answers.

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Original post by QuinnJohns
So, whats going to be the standard in regards to models? What's the best format to be used in DX10+? I've used X files for some time, does DX10+ have a newer loader for any model types? 3ds? etc?

Thanks for any answers.


No. If you're not going to use X files, you're pretty much on your own. If you have a well-designed engine, writing model loaders is not hard really.

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Thanks, Phantom for the tip, so it looks like you are leaning towards a Quad core yourself, next build?

I thought about the i7, but problem is drivers, bugs, BIOS updates are going to be abundant at first and BSOD aren't in my best interest right now while working on my game. I want stable. Plus 32nm is coming in 2010, and I think I would rather have that version of i7, than the first rev, due to any bugs and possible more SSE extensions will be added by then... Not to mention the cost of i7 with DDR3 RAM and a X58 MB we are talking 400-500 above the cost of a 45nm Quad now with a P45 chipset. I pretty much have decided it will be a quad core probably 2.83ghz, next issue is GPU, I am not excited with the current latest generation GPUS, both run HOT, I would rather get a GF8800 GTS and wait till DX11 cards are out, and or Larrabee to see whats what, no sense in throwing away a few extra hundred dollars for nothing.

;)

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The 32nm will be a pin-compatible die strink so even if you did get a 45nm now the 32nm will work with the same equipment; I also don't see the 32nm going for faster than DDR3 ram either as that would require the memory controller to be updated, so that's a safe investment. SSE extensions are all well and good but unless you are planning to make a game only for that hardware you have to take into account everything else as well anyway; based on what I've read only some encryption functions are likely to be added.

Or to put all this another way; right now you are considering dropping a few 100 USD on a system you plan to upgrade in just over a year which was precisisely the situation you were trying to get out of as I recall [smile]

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Last system I had for 18 months, was a CD2 2.4Ghz, 6GB, 975X MB, 8800GTS 640MB, I sold that, and decided that I wanted to upgrade to quad, but you make a decent point, with the pin compatible 32nm from the 45nm Core i7. If you are sure of this? Plus DDR3 1333mhz will be the choice from what I hear, and if you can keep that with the X58MB I guess it would be just a CPU upgrade in 18-24 months to give it another speed boost. I think I will do that, and just maybe Nvidia will have their 55nm G200 series cards out by Oct also, and if not maybe ATI will have GL3 drivers and I can get an ATI card...

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I'm in the process of building a Q6600 Quad-Core Core2 box. I looked at the cutting edge stuff and that on the horizon but the Q6600 seems to have been well and truly tested by the enthusiast community and seems incredibly popular - figured that was a good trade off between fast (but not necessarily super fast) and stable [grin]


Anyway, on topic with D3D10/11... I've postulated that the "frame by frame" architecture of current games is probably going the way of the dodo. With a task-based multi-threaded architecture it's likely that all the overlapping and concurrent model updates are going to completely blur the line of what is/isn't in a given frame.

But the key thing there, and has also been commented in this thread is that it isn't a free lunch and doesn't just automagically happen. Developers have to start designing and writing their code for it.


cheers,
Jack

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Original post by jollyjeffers
I'm in the process of building a Q6600 Quad-Core Core2 box. I looked at the cutting edge stuff and that on the horizon but the Q6600 seems to have been well and truly tested by the enthusiast community and seems incredibly popular - figured that was a good trade off between fast (but not necessarily super fast) and stable [grin]


Anyway, on topic with D3D10/11... I've postulated that the "frame by frame" architecture of current games is probably going the way of the dodo. With a task-based multi-threaded architecture it's likely that all the overlapping and concurrent model updates are going to completely blur the line of what is/isn't in a given frame.

But the key thing there, and has also been commented in this thread is that it isn't a free lunch and doesn't just automagically happen. Developers have to start designing and writing their code for it.


cheers,
Jack


Yes, I have heard the Q6600 is a nice CPU. I doubt you are going to overclock it, but if you did you can hit 3+Ghz easily I hear. I don't overclock. Anyway about the frame by frame idea, how is that going to work for stuff like physics, or shadowmapping passes, and other methods I haven't even thought of yet. Is the new model going to be based off time slices? Meaning you have so much time to do what you need to do and then you updated the buffer? This is all new to me. But then again, for the distance future frame by frame is going to be ok for small indie guys right?

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      Device context (IDeviceContext interface) is the main interface for recording rendering commands. Similar to Direct3D11, there are immediate context and deferred contexts (which in Direct3D11 implementation map directly to the corresponding context types). Immediate context combines command queue and command list recording functionality. It records commands and submits the command list for execution when it contains sufficient number of commands. Deferred contexts are designed to only record command lists that can be submitted for execution through the immediate context.
      An alternative way to design the API would be to expose command queue and command lists directly. This approach however does not map well to Direct3D11 and OpenGL. Besides, some functionality (such as dynamic descriptor allocation) can be much more efficiently implemented when it is known that a command list is recorded by a certain deferred context from some thread.
      The approach taken in the engine does not limit scalability as the application is expected to create one deferred context per thread, and internally every deferred context records a command list in lock-free fashion. At the same time this approach maps well to older APIs.
      In current implementation, only one immediate context that uses default graphics command queue is created. To support multiple GPUs or multiple command queue types (compute, copy, etc.), it is natural to have one immediate contexts per queue. Cross-context synchronization utilities will be necessary.
      Swap Chain (ISwapChain interface). Swap chain interface represents a chain of back buffers and is responsible for showing the final rendered image on the screen.
      Render device, device contexts and swap chain are created during the engine initialization.
      Resources (ITexture and IBuffer interfaces). There are two types of resources - textures and buffers. There are many different texture types (2D textures, 3D textures, texture array, cubmepas, etc.) that can all be represented by ITexture interface.
      Resources Views (ITextureView and IBufferView interfaces). While textures and buffers are mere data containers, texture views and buffer views describe how the data should be interpreted. For instance, a 2D texture can be used as a render target for rendering commands or as a shader resource.
      Pipeline State (IPipelineState interface). GPU pipeline contains many configurable stages (depth-stencil, rasterizer and blend states, different shader stage, etc.). Direct3D11 uses coarse-grain objects to set all stage parameters at once (for instance, a rasterizer object encompasses all rasterizer attributes), while OpenGL contains myriad functions to fine-grain control every individual attribute of every stage. Both methods do not map very well to modern graphics hardware that combines all states into one monolithic state under the hood. Direct3D12 directly exposes pipeline state object in the API, and Diligent Engine uses the same approach.
      Shader Resource Binding (IShaderResourceBinding interface). Shaders are programs that run on the GPU. Shaders may access various resources (textures and buffers), and setting correspondence between shader variables and actual resources is called resource binding. Resource binding implementation varies considerably between different API. Diligent Engine introduces a new object called shader resource binding that encompasses all resources needed by all shaders in a certain pipeline state.
      API Basics
      Creating Resources
      Device resources are created by the render device. The two main resource types are buffers, which represent linear memory, and textures, which use memory layouts optimized for fast filtering. Graphics APIs usually have a native object that represents linear buffer. Diligent Engine uses IBuffer interface as an abstraction for a native buffer. To create a buffer, one needs to populate BufferDesc structure and call IRenderDevice::CreateBuffer() method as in the following example:
      BufferDesc BuffDesc; BufferDesc.Name = "Uniform buffer"; BuffDesc.BindFlags = BIND_UNIFORM_BUFFER; BuffDesc.Usage = USAGE_DYNAMIC; BuffDesc.uiSizeInBytes = sizeof(ShaderConstants); BuffDesc.CPUAccessFlags = CPU_ACCESS_WRITE; m_pDevice->CreateBuffer( BuffDesc, BufferData(), &m_pConstantBuffer ); While there is usually just one buffer object, different APIs use very different approaches to represent textures. For instance, in Direct3D11, there are ID3D11Texture1D, ID3D11Texture2D, and ID3D11Texture3D objects. In OpenGL, there is individual object for every texture dimension (1D, 2D, 3D, Cube), which may be a texture array, which may also be multisampled (i.e. GL_TEXTURE_2D_MULTISAMPLE_ARRAY). As a result there are nine different GL texture types that Diligent Engine may create under the hood. In Direct3D12, there is only one resource interface. Diligent Engine hides all these details in ITexture interface. There is only one  IRenderDevice::CreateTexture() method that is capable of creating all texture types. Dimension, format, array size and all other parameters are specified by the members of the TextureDesc structure:
      TextureDesc TexDesc; TexDesc.Name = "My texture 2D"; TexDesc.Type = TEXTURE_TYPE_2D; TexDesc.Width = 1024; TexDesc.Height = 1024; TexDesc.Format = TEX_FORMAT_RGBA8_UNORM; TexDesc.Usage = USAGE_DEFAULT; TexDesc.BindFlags = BIND_SHADER_RESOURCE | BIND_RENDER_TARGET | BIND_UNORDERED_ACCESS; TexDesc.Name = "Sample 2D Texture"; m_pRenderDevice->CreateTexture( TexDesc, TextureData(), &m_pTestTex ); If native API supports multithreaded resource creation, textures and buffers can be created by multiple threads simultaneously.
      Interoperability with native API provides access to the native buffer/texture objects and also allows creating Diligent Engine objects from native handles. It allows applications seamlessly integrate native API-specific code with Diligent Engine.
      Next-generation APIs allow fine level-control over how resources are allocated. Diligent Engine does not currently expose this functionality, but it can be added by implementing IResourceAllocator interface that encapsulates specifics of resource allocation and providing this interface to CreateBuffer() or CreateTexture() methods. If null is provided, default allocator should be used.
      Initializing the Pipeline State
      As it was mentioned earlier, Diligent Engine follows next-gen APIs to configure the graphics/compute pipeline. One big Pipelines State Object (PSO) encompasses all required states (all shader stages, input layout description, depth stencil, rasterizer and blend state descriptions etc.). This approach maps directly to Direct3D12/Vulkan, but is also beneficial for older APIs as it eliminates pipeline misconfiguration errors. With many individual calls tweaking various GPU pipeline settings it is very easy to forget to set one of the states or assume the stage is already properly configured when in fact it is not. Using pipeline state object helps avoid these problems as all stages are configured at once.
      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 noodleBowl
      I am currently working on my first iteration of my sprite renderer and I'm trying to draw 2 sprites. They both use the same texture and are placed into the same buffer, but unfortunately only the second sprite is shown on the the screen. I assume I messed something up when I place them into the buffer and that I am overwriting the data of the first sprite.

      So how should I be mapping my buffer with an offset?
      /* Code that sets up the sprite vertices and etc */ D3D11_MAPPED_SUBRESOURCE resource = vertexBuffer->map(vertexBufferMapType); memcpy(resource.pData, verts, sizeof(SpriteVertex) * VERTEX_PER_QUAD); vertexBuffer->unmap(); vertexCount += VERTEX_PER_QUAD; I feel like I should be doing something like:
      /* Code that sets up the sprite vertices and etc */ D3D11_MAPPED_SUBRESOURCE resource = vertexBuffer->map(vertexBufferMapType); //Place the sprite vertex data into the pData using the current vertex count as offset //The code resource.pData[vertexCount] is syntatically wrong though :( Not sure how it should look since pData is void pointer memcpy(resource.pData[vertexCount], verts, sizeof(SpriteVertex) * VERTEX_PER_QUAD); vertexBuffer->unmap(); vertexCount += VERTEX_PER_QUAD;  
      Also speaking of offsets can someone give an example of when the pOffsets param for the IASetVertexBuffers call would not be 0
       
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