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OpenGL SM4.0 and OpenGL

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I seen now the info on the Geforce 8800 is out and I noticed that one can now have 128 textures per pass vs. 16? So I am assuming this would relieve the need for texture atlases? What is everyone elses thoughts on SM4.0 support and OpenGL... Let the ideas flow.

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I have a feeling that in the last months OpenGL isn't developing forward. Since Khronos took it in their hand, there are no life signs. So a forecast is a bit difficult.

And as someone on this forum said that glsl is further than DX9 HLSL(i can't deny nor i can agree, cause i have not enough knowledge of HLSL), cause smX.X is bound to DX. But if it so than we can only hope that the new references will come out as soon as possible.

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theres a thread at www.opengl.org about the new extensions coming to opengl stuff like geometry shaders + texture arrays, texture buffers etc. (no need to have vista to play with them as well :) )
though theres not gonna be much info out until the geforce8800 comes out (which is this month i believe, so info should be soon forthcoming)

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Quote:
Original post by MARS_999
I seen now the info on the Geforce 8800 is out and I noticed that one can now have 128 textures per pass vs. 16?

The G80 has 128 stream processors, which does not mean, you can use 128 textures. It has 64 texture units, which provide 32 pixels per clock 2xAF filtered. I am not sure, if that means you can use 32 textures now...

Quote:
So I am assuming this would relieve the need for texture atlases? What is everyone elses thoughts on SM4.0 support and OpenGL... Let the ideas flow.

NVidias launch demos are written in OpenGL, so we can expect the extensions are already done :)

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On of the beautiful things about OpenGL is that it can be extended by vendors and other parties directly, which allows them to expose new functionality at their whim, rather than with the next DirectX release.

As for the "no progress" comment someone made about GL now that Khronos has taken the reigns, I think thats to be expected. Khronos has already made public their general plans to alter the API pretty radically in GL 3.0. Their basic plan is to strip out all the unnecesary fluff from the hardware/runtime layer leaving only a very lightweight, do-it-the-fastest-way-only, aimed at modern 3D hardware core of OpenGL. They'll move a compatibility layer with old GL as more of a software library - entirely seperate from the core GL functionality. This is the same approach that the very successful OpenGL|ES has taken, and the same general approach that Microsoft has taken with Direct3D 10.

It'll take some time, but GL 3 will be worth the wait IMHO.

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Just confirmed these added ext to the 8800 drivers release 95

gl_ext_framebuffer_blit
gl_ext_framebuffer_multisample
gl_NV_framebuffer_multisample_coverage
wgl_nv_GPU_AFFINITY

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The following was posted on the OGL forum:

ttp://www.opengl.org/discussion_boards/ubb/ultimatebb.php?ubb=get_topic;f=3;t=014831


Quote:


GL_ES
GL_EXTX_framebuffer_mixed_formats
GL_EXT_Cg_shader
GL_EXT_bindable_uniform
GL_EXT_depth_buffer_float
GL_EXT_draw_buffers2
GL_EXT_draw_instanced
GL_EXT_framebuffer_sRGB
GL_EXT_geometry_shader4
GL_EXT_gpu_program_parameters
GL_EXT_gpu_shader4
GL_EXT_packed_float
GL_EXT_shadow_funcs
GL_EXT_texture_array
GL_EXT_texture_buffer_object
GL_EXT_texture_compression_latc
GL_EXT_texture_compression_s3tc
GL_EXT_texture_integer
GL_EXT_texture_sRGB
GL_EXT_texture_shared_exponent
GL_EXT_transform_feedback
GL_EXT_ycbcr_422
GL_NVX_conditional_render
GL_NV_depth_buffer_float
GL_NV_framebuffer_multisample_ex
GL_NV_geometry_shader4
GL_NV_gpu_program4
GL_NV_gpu_shader4
GL_NV_parameter_buffer_object
GL_NV_texture_compression_latc
GL_NV_texture_compression_vtc
GL_NV_transform_feedback
GL_OES_conditional_query
WGL_EXT_framebuffer_sRGB
WGL_EXT_pixel_format_packed_float
WGL_NV_gpu_affinity


And from 'cass' (Mgr. at Nvidia):
Quote:

One of the traditional NVIDIA OpenGL Extensions docs is being readied and should be on developer.nvidia.com Real Soon Now.

We'll be following up with Cg 2.0 support for the new programmability shortly thereafter.

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Quote:

One of the traditional NVIDIA OpenGL Extensions docs is being readied and should be on developer.nvidia.com Real Soon Now.

We'll be following up with Cg 2.0 support for the new programmability shortly thereafter.

Hmmm, Cg is available from within DX as well as OGL, right? (Never really played with Cg, so not sure)

Does this mean we'll get geometry shaders and everything in DX9 by that route?

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yes u can use cg with directx
though as theres gonna be no more releases of directx for winXP, sm4.0 wont be available with winXP with directx (only opengl) unless MS have a change of heart + release d3d10 for winXP (not likely)

fear not, vista is coming out janurary30 + SM4.0 will available then under directx

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Quote:
Original post by griffin2000
...
GL_NVX_conditional_render ?
...
GL_OES_conditional_query ?


any information on those 2 available yet?
conditional_query sounds extremly interesting...

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These plus the GS are interesting to me

ext_texture_array
nv_depth_buffer_float

Now from the sounds of it with the texture array would this allow a simpler mosaic but instead you use 3D textures? And this will allow for mipmapping and higher quality of filtering?

And the depth buffer float, I am assuming this will allow for better quality shadows as the depth buffer doesn't clamp 0-1 now and should allow for a great precision? Would this get rid of jagged edges on shadows?

Looks like this card is here today already. :)

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Quote:
Original post by MARS_999
These plus the GS are interesting to me

ext_texture_array
nv_depth_buffer_float

Now from the sounds of it with the texture array would this allow a simpler mosaic but instead you use 3D textures? And this will allow for mipmapping and higher quality of filtering?

It allows to bind an array of textures to a sampler for a shader (mhm, is this confusing? :D )

Quote:
And the depth buffer float, I am assuming this will allow for better quality shadows as the depth buffer doesn't clamp 0-1 now and should allow for a great precision? Would this get rid of jagged edges on shadows?

This is a depth buffer with more precision than [0,1].

See the thread at opengl.org for more information about all the extensions. Mr. Cass from Nvidia has posted there, too ;)

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Quote:
Original post by Enrico
Quote:
Original post by MARS_999
These plus the GS are interesting to me

ext_texture_array
nv_depth_buffer_float

Now from the sounds of it with the texture array would this allow a simpler mosaic but instead you use 3D textures? And this will allow for mipmapping and higher quality of filtering?

It allows to bind an array of textures to a sampler for a shader (mhm, is this confusing? :D )

Quote:
And the depth buffer float, I am assuming this will allow for better quality shadows as the depth buffer doesn't clamp 0-1 now and should allow for a great precision? Would this get rid of jagged edges on shadows?

This is a depth buffer with more precision than [0,1].

See the thread at opengl.org for more information about all the extensions. Mr. Cass from Nvidia has posted there, too ;)


No the array idea isn't, but if I want to pack 32 2D textures into this 3D array and have it act like a 2d texture instead of texture atlases. I am doing this now and has its limits. I will check out opengl.org

The great thing about this for OpenGL is you can now have DX10 gfx on XP without the need for Vista! So if game developers want to have a large platform to keep developing on get in line. Once the 8600/8200 comes out more users will have this ability on XP. Really bright future for OpenGL IMO, now I can hold off getting Vista! :) Well until Gears of War is out, if Microsoft forces you to have Vista like Halo2...

[Edited by - MARS_999 on November 9, 2006 9:51:22 AM]

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Well the beast is here and here is what I have so far...

Cubemaps 8192x8192
3DTextures 2048x2048x2048

I posted the gl info to delphi3d so hopefully Tom updates it, for a full complete listing.

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Quote:
Original post by ze moo
Quote:
Original post by griffin2000
...
GL_NVX_conditional_render ?
...
GL_OES_conditional_query ?


any information on those 2 available yet?
conditional_query sounds extremly interesting...

/oops
looks like the GL_NVX_conditional_render extension's been in the drivers for quite
some time already (at least since 2004)

there's even a demo in the nvidia sdk ...

GL_OES_conditional_query seems to be the "approved" version of this extension
(pretty cool, since you can render based on an occlusion query result without
having to wait for the result in the client :)

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If anyone wants to try out the new features without spending alot of $$$ on a new card you can always download NVEmulate from http://developer.nvidia.com

Performance will be bad but atleast you'll be able to test things and even implement and verfiy your shaders without spending alot of money on new hardware.

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Guest Anonymous Poster
Quote:
Original post by MARS_999
3DTextures 2048x2048x2048


Can that be correct? It's over 8 gig, in what memory would such a beast be placed?

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Well, if you had the resources you could texture over the PCIe bus [grin]

However the point is these are just the limits of what the card can do based on the hardware, apart from custom things you simply wont use such resources.

Besides, give it a few years and 8gig on a gfx card won't seem that far fetched [wink] (ATI's high end R600 is rumored to have 1gig of GDDR4 ram on a 512bit bus)

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      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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