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Good day ladies and gentlemen of the realm.

 

Towards the end of last year I decided graphics programming is something I really wanted to get into, so as part of the learning process I've been putting together a very basic OpenGL engine. One of the things I've been putting a fair bit of thought into is how to abstract OpenGL functionality, specifically OpenGL resources, in an object-oriented manner (using modern C++).

 

For me one of the main design considerations when abstracting resources is whether of not these abstractions should exhibit value or reference semantics, i.e. should they represent resource handles or the resources themselves.

 

It made sense to me, and suited my needs at the time, to follow reference semantics, so every copy of a resource object refers to the same underlying OpenGL resource. Implementation wise went I with smart pointers and custom deleters, with the approach being used for Shader, VAO, FBO and Texture objects.

Shader::Shader()
:
m_programID( new GLuint( glCreateProgram() ), [=]( GLuint* program ){ glDeleteProgram( *program ); } )
{
}

So why am I mentioning all this? Well I want to ask if there valid cases for choosing to go with value semantics, and how things might change if you had classes dedicated to managing resource pools. Also any tips anyone might have for managing OpenGL resources and creating meaningful abstractions.

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Sorry, I'm not gonna answer your question tongue.png

But can you point me to some books or articles about that 'value/reference semantics' stuff ?

Or maybe I do not understand you correctly. What is a recource handler in your situation and what it does ?

 

P.S.

Your constructor seems like  a useless lambda monstrocity. It makes eyes bleed.  You can't tell what it does at the first glance. Please, don't do like that :) C++ 11 is cool, but it's should be used not for the sake of the C++ 11 itself.

 

Also, if you're going to manage your RAM usage, I'd recommend to you not to use some automatics and smart/shared pointers at all, but to implement your own memory management mechanics, it will give you more flexibility and control over what's going on.

 

Do you really need to destroy your Shader object when it goes out of scope? Or it's more handy to load needed shaders, use them system-wise, and free memory manually after you're completely sure, that you'll not gonna use them at all ?

 

edit:

For resource pooling, I think, it's an effective approach to use your wrapper classes as the resources themselves + use standart containers with custom memory allocators and some memory counting structure for debugging.  Depends on what you've meant by 'classes dedicated to managing resource pools'.

 

edit2:

Hope this would be more constructive.

Edited by syskrank

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Your constructor seems like  a useless lambda monstrocity. It makes eyes bleed.  You can't tell what it does at the first glance. Please, don't do like that C++ 11 is cool, but it's should be used not for the sake of the C++ 11 itself.

 

Thanks for the reply but I think you'll find that is not quite as useless as you say. Using a custom deleter for a smart pointer is a fairly standard idiom for automatic lifetime management of non-memory resources.

 

See http://herbsutter.com/2013/05/29/gotw-89-solution-smart-pointers/

There are two main cases where you can’t use make_shared (or allocate_shared) to create an object that you know will be owned by shared_ptrs: (a) if you need a custom deleter, such as because of using shared_ptrs to manage a non-memory resource or an object allocated in a nonstandard memory area, you can’t use make_shared because it doesn’t support specifying a deleter; and (b) if you are adopting a raw pointer to an object being handed to you from other (usually legacy) code, you would construct a shared_ptr from that raw pointer directly.

 

 

 

Also, if you're going to manage your RAM usage, I'd recommend to you not to use some automatics and smart/shared pointers at all, but to implement your own memory management mechanics, it will give you more flexibility and control over what's going on.

 

Do you really need to destroy your Shader object when it goes out of scope? Or it's more handy to load needed shaders, use them system-wise, and free memory manually after you're completely sure, that you'll not gonna use them at all ?

 

I totally agree with that, if my ambitions were more grand and involved releasing an actual product then tighter, more manual control of resource lifetimes is definitely required for performance optimisations. That is sometimes I'll keep in the back of my mind and if my little project starts to get big enough I'll definitely look into it. As for now, resources being tied to scope seems to fit my relatively small bill. smile.png

 

 

But can you point me to some books or articles about that 'value/reference semantics' stuff ?

Or maybe I do not understand you correctly. What is a recource handler in your situation and what it does ?

 

The idea of values and references (to values) is a fairly fundamental topic in computer science and essentially what you are talking about is indirection. It's possible it is just the terminology that you aren't familiar with, in C++ references are implemented via pointer types and reference types, and in C# or Java the language explicitly categories types as being either "Reference Types" or "Value/Primitive Types".

 

See also:

http://en.wikipedia.org/wiki/Value_type

http://en.wikipedia.org/wiki/Reference_type

 

A succient summary from the wikipedia article "In computer science, the term value type is commonly used to refer to one of two kinds of data types: Types of values or Types of objects with deep copy semantics."

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If they're value types, it means they can be copied, and copied fairly easily by the user (as simply as a = b;). Copying a GPU resource can be quite an expensive operation, so I'd see value-references as quite a dangerous API. Also, there's no point in cloning some GPU resources -- e.g. in D3D a shader program is just code (no other state), so there's no need in ever having more than one instance of a particular program hanging around.

 

Regarding shaders specifically, I don't have functionality to load a single shader - I always load a "shader pack", which is a large file containing a huge collection of shader programs and all the associated reflection data and other structures needed to use them (e.g. default UBO data). Once a pack is loaded, the user can acquire references to individual items inside it... Actually, the user can acquire references to shaders ahead-of-time (e.g. at data-build time), because my references are actually a 32-bit pack name and 32-bit shader index into that pack -- these can exist on disk in other files, such as in a model or material file.

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Thanks for the reply but I think you'll find that is not quite as useless as you say.

 

I didn't say that it's useless, I said that its freaking hard to understand what it does, look : lambda list initializer + not-straightforward name 'm_programID' - clearly a mess at first sight. OR post more code so that everything would be clear :)

 


The idea of values and references (to values) is a fairly fundamental topic in computer science and essentially what you are talking about is indirection.

Your talks are obscure, as in the first post, which has confused me :) 

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If they're value types, it means they can be copied, and copied fairly easily by the user (as simply as a = b;). Copying a GPU resource can be quite an expensive operation, so I'd see value-references as quite a dangerous API.

 

This can't be highlighted enough; I've taken the liberty of underlining part of Hodgman's post above, because it needs to be heavily emphasised.

 

It's also the case that you need to destroy the copied resource when your function returns, by the way, which can also be an expensive operation.  So now you're creating new GPU resources, copying to them, then destroying them, and all for what may be a fairly trivial operation.  Expensive stuff.

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If they're value types, it means they can be copied, and copied fairly easily by the user (as simply as a = b;). Copying a GPU resource can be quite an expensive operation, so I'd see value-references as quite a dangerous API. Also, there's no point in cloning some GPU resources -- e.g. in D3D a shader program is just code (no other state), so there's no need in ever having more than one instance of a particular program hanging around.

 

This was my intuition of the situation, where for the most part you want shallow copies and reference semantics. If deep copies are required then that should be offered explicitly and cannot just happen 'by mistake'.

 

Your shader implementation sounds quite interesting, it's pretty cool what can be done when you're familiar with the domain, especially when it comes to performance optimisations. Considering how important resource management is, I definitely need to spend some more time researching the topic.

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Thanks for the reply but I think you'll find that is not quite as useless as you say.

 

I didn't say that it's useless, I said that its freaking hard to understand what it does, look : lambda list initializer + not-straightforward name 'm_programID' - clearly a mess at first sight. OR post more code so that everything would be clear smile.png

 

Here is an equivalent example of using a shared_ptr with a custom deleter to manage a D311Device and the same thing for automatically releasing an SDL_Surface. I'm not sure why programID would be a confusing name, it represents the unique ID assigned by OpenGL to that particular shader program. Sure I admit I'm not very good when it comes to naming things but that made sense in my head.

 

Edit:

Oh and another example for managing files.

Edited by Lantre

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I personally chose the reference way, specifically using shared_ptrs. A major reason being that OpenGL specification itself uses language that either directly talks about a reference count or otherwise mentions that deleted resources only actually die when nothing refers to them anymore. So when an index buffer is attached to an vertex array, my vertex array object is given a (wrapped) shared_ptr that points to the index buffer.

Edit: I think some drivers were/are buggy specifically with the relation of index buffers and vertex arrays, that binding a vertex array doesn't cause the related index buffer being bound automatically. When the vertex array object in my code has a reference to the index buffer, it could work around that bug by explicitly binding the buffer. Edited by Ubik

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If they're value types, it means they can be copied, and copied fairly easily by the user (as simply as a = b;). Copying a GPU resource can be quite an expensive operation, so I'd see value-references as quite a dangerous API. Also, there's no point in cloning some GPU resources -- e.g. in D3D a shader program is just code (no other state), so there's no need in ever having more than one instance of a particular program hanging around.

 

This was my intuition of the situation, where for the most part you want shallow copies and reference semantics. If deep copies are required then that should be offered explicitly and cannot just happen 'by mistake'.

 

One option that hasn't been discussed is to use non-copyable values. This avoids the issue of expensive copies by out-right preventing them.

 

You might still use shared_ptrs to share access to these objects - but there is a big difference between "an object that moves with reference semantics" and "an object passed by reference". By still being a value it allows you to also pass them by the cheaper plain reference or raw pointer. It also allows them to be stored more efficiently in contiguous arrays.

 

The precise way in which access to the object is passed around is a choice for the client code, not enforced by the handle type itself.

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If they're value types, it means they can be copied, and copied fairly easily by the user (as simply as a = b;). Copying a GPU resource can be quite an expensive operation, so I'd see value-references as quite a dangerous API. Also, there's no point in cloning some GPU resources -- e.g. in D3D a shader program is just code (no other state), so there's no need in ever having more than one instance of a particular program hanging around.

 

This was my intuition of the situation, where for the most part you want shallow copies and reference semantics. If deep copies are required then that should be offered explicitly and cannot just happen 'by mistake'.

 

One option that hasn't been discussed is to use non-copyable values. This avoids the issue of expensive copies by out-right preventing them.

 

You might still use shared_ptrs to share access to these objects - but there is a big difference between "an object that moves with reference semantics" and "an object passed by reference". By still being a value it allows you to also pass them by the cheaper plain reference or raw pointer. It also allows them to be stored more efficiently in contiguous arrays.

 

The precise way in which access to the object is passed around is a choice for the client code, not enforced by the handle type itself.

 

 

This makes a lot of sense especially if you only have one point of control, e.g. a resource manager/resource cache, which owns the 'real' resource. Client code can then request weak/non-owning references to these resources.

 

This is something I'll probably be playing around with pretty soon for meshes and materials. At the moment I have each object naively loading (and owning) its own textures and meshes, which while convenient is not particularly clever.

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One option that hasn't been discussed is to use non-copyable values. This avoids the issue of expensive copies by out-right preventing them.

That's actually what I do for resources, but the value is only used inside the render-device implementation biggrin.png They're owned by an RAII value, and then references are given out to the user, e.g.

//hidden internally, not seen by the user
struct NativeBuffer : NonCopyable { /*GL, D3D, etc buffer handle member variable*/
  NativeBuffer( ... ) { /*acquire handle*/ }
  ~NativeBuffer() { /* release handle*/ }
};

//what the user gets:
typedef Pool<NativeBuffer>::Handle BufferHandle;

class Device
{
public:
  BufferHandle CreateBuffer(...);
  void         ReleaseBuffer( BufferHandle );
  ResourceLock MapBuffer( BufferHandle );
  void         UnmapBuffer( ResourceLock );
private:
  Pool<NativeBuffer> m_Buffers;
}

A system to allow shared ownership is implemented on top of this -- e.g. you might have a model-asset that owns some buffers, and then many model-instances that all share the one model-asset.

Edited by Hodgman

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One option that hasn't been discussed is to use non-copyable values. This avoids the issue of expensive copies by out-right preventing them.

That's actually what I do for resources, but the value is only used inside the render-device implementation biggrin.png They're owned by an RAII value, and then references are given out to the user, e.g.

//hidden internally, not seen by the user
struct NativeBuffer : NonCopyable { /*GL, D3D, etc buffer handle member variable*/
  NativeBuffer( ... ) { /*acquire handle*/ }
  ~NativeBuffer() { /* release handle*/ }
};

//what the user gets:
typedef Pool<NativeBuffer>::Handle BufferHandle;

class Device
{
public:
  BufferHandle CreateBuffer(...);
  void         ReleaseBuffer( BufferHandle );
  ResourceLock MapBuffer( BufferHandle );
  void         UnmapBuffer( ResourceLock );
private:
  Pool<NativeBuffer> m_Buffers;
}

A system to allow shared ownership is implemented on top of this -- e.g. you might have a model-asset that owns some buffers, and then many model-instances that all share the one model-asset.

 

 

Once you give out references to their respective users what mechanism do you use to track usage in order to determine what should or shouldn't be cached? If that is even a relevant question for your framework.

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Once you give out references to their respective users what mechanism do you use to track usage in order to determine what should or shouldn't be cached? If that is even a relevant question for your framework.

Creating/destroying a GL buffer is equivalent to calling malloc/free, except that you're dealing with GPU-addressable RAM. So, at this level I don't do any advanced management or caching.
 
Instead, the next level of the architecture can do those things. You have objects that are composed of GL resources, such as buffers -- e.g. a model asset loaded from disk. The model asset can have one-to-one "value" ownership over the buffers/resources. When the asset is created/destroyed, the resources are created/destroyed.
 
A model instance can then have shared ownership (e.g. reference counting / shared_ptr / etc) of a model asset. A file system can deal with reading bytes from disk, and a model factory can deal with converting those streams of bytes into model assets. An asset cache can perform the caching, e.g. by having a map/dictionary member that associates asset names with model asset objects. When the reference count on a model asset is zero, it can be deleted from the asset cache (which will free up the GL resources). When creating a model instance, it can use the asset cache, file system and model factory to either fetch an existing model asset or create a new one.

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      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 reenigne
      For those that don't know me. I am the individual who's two videos are listed here under setup for https://wiki.libsdl.org/Tutorials
      I also run grhmedia.com where I host the projects and code for the tutorials I have online.
      Recently, I received a notice from youtube they will be implementing their new policy in protecting video content as of which I won't be monetized till I meat there required number of viewers and views each month.

      Frankly, I'm pretty sick of youtube. I put up a video and someone else learns from it and puts up another video and because of the way youtube does their placement they end up with more views.
      Even guys that clearly post false information such as one individual who said GLEW 2.0 was broken because he didn't know how to compile it. He in short didn't know how to modify the script he used because he didn't understand make files and how the requirements of the compiler and library changes needed some different flags.

      At the end of the month when they implement this I will take down the content and host on my own server purely and it will be a paid system and or patreon. 

      I get my videos may be a bit dry, I generally figure people are there to learn how to do something and I rather not waste their time. 
      I used to also help people for free even those coming from the other videos. That won't be the case any more. I used to just take anyone emails and work with them my email is posted on the site.

      I don't expect to get the required number of subscribers in that time or increased views. Even if I did well it wouldn't take care of each reoccurring month.
      I figure this is simpler and I don't plan on putting some sort of exorbitant fee for a monthly subscription or the like.
      I was thinking on the lines of a few dollars 1,2, and 3 and the larger subscription gets you assistance with the content in the tutorials if needed that month.
      Maybe another fee if it is related but not directly in the content. 
      The fees would serve to cut down on the number of people who ask for help and maybe encourage some of the people to actually pay attention to what is said rather than do their own thing. That actually turns out to be 90% of the issues. I spent 6 hours helping one individual last week I must have asked him 20 times did you do exactly like I said in the video even pointed directly to the section. When he finally sent me a copy of the what he entered I knew then and there he had not. I circled it and I pointed out that wasn't what I said to do in the video. I didn't tell him what was wrong and how I knew that way he would go back and actually follow what it said to do. He then reported it worked. Yea, no kidding following directions works. But hey isn't alone and well its part of the learning process.

      So the point of this isn't to be a gripe session. I'm just looking for a bit of feed back. Do you think the fees are unreasonable?
      Should I keep the youtube channel and do just the fees with patreon or do you think locking the content to my site and require a subscription is an idea.

      I'm just looking at the fact it is unrealistic to think youtube/google will actually get stuff right or that youtube viewers will actually bother to start looking for more accurate videos. 
    • By Balma Alparisi
      i got error 1282 in my code.
      sf::ContextSettings settings; settings.majorVersion = 4; settings.minorVersion = 5; settings.attributeFlags = settings.Core; sf::Window window; window.create(sf::VideoMode(1600, 900), "Texture Unit Rectangle", sf::Style::Close, settings); window.setActive(true); window.setVerticalSyncEnabled(true); glewInit(); GLuint shaderProgram = createShaderProgram("FX/Rectangle.vss", "FX/Rectangle.fss"); float vertex[] = { -0.5f,0.5f,0.0f, 0.0f,0.0f, -0.5f,-0.5f,0.0f, 0.0f,1.0f, 0.5f,0.5f,0.0f, 1.0f,0.0f, 0.5,-0.5f,0.0f, 1.0f,1.0f, }; GLuint indices[] = { 0,1,2, 1,2,3, }; GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); GLuint vbo; glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(vertex), vertex, GL_STATIC_DRAW); GLuint ebo; glGenBuffers(1, &ebo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, false, sizeof(float) * 5, (void*)0); glEnableVertexAttribArray(0); glVertexAttribPointer(1, 2, GL_FLOAT, false, sizeof(float) * 5, (void*)(sizeof(float) * 3)); glEnableVertexAttribArray(1); GLuint texture[2]; glGenTextures(2, texture); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageOne = new sf::Image; bool isImageOneLoaded = imageOne->loadFromFile("Texture/container.jpg"); if (isImageOneLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageOne->getSize().x, imageOne->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageOne->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageOne; glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageTwo = new sf::Image; bool isImageTwoLoaded = imageTwo->loadFromFile("Texture/awesomeface.png"); if (isImageTwoLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageTwo->getSize().x, imageTwo->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageTwo->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageTwo; glUniform1i(glGetUniformLocation(shaderProgram, "inTextureOne"), 0); glUniform1i(glGetUniformLocation(shaderProgram, "inTextureTwo"), 1); GLenum error = glGetError(); std::cout << error << std::endl; sf::Event event; bool isRunning = true; while (isRunning) { while (window.pollEvent(event)) { if (event.type == event.Closed) { isRunning = false; } } glClear(GL_COLOR_BUFFER_BIT); if (isImageOneLoaded && isImageTwoLoaded) { glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glUseProgram(shaderProgram); } glBindVertexArray(vao); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr); glBindVertexArray(0); window.display(); } glDeleteVertexArrays(1, &vao); glDeleteBuffers(1, &vbo); glDeleteBuffers(1, &ebo); glDeleteProgram(shaderProgram); glDeleteTextures(2,texture); return 0; } and this is the vertex shader
      #version 450 core layout(location=0) in vec3 inPos; layout(location=1) in vec2 inTexCoord; out vec2 TexCoord; void main() { gl_Position=vec4(inPos,1.0); TexCoord=inTexCoord; } and the fragment shader
      #version 450 core in vec2 TexCoord; uniform sampler2D inTextureOne; uniform sampler2D inTextureTwo; out vec4 FragmentColor; void main() { FragmentColor=mix(texture(inTextureOne,TexCoord),texture(inTextureTwo,TexCoord),0.2); } I was expecting awesomeface.png on top of container.jpg

    • By khawk
      We've just released all of the source code for the NeHe OpenGL lessons on our Github page at https://github.com/gamedev-net/nehe-opengl. code - 43 total platforms, configurations, and languages are included.
      Now operated by GameDev.net, NeHe is located at http://nehe.gamedev.net where it has been a valuable resource for developers wanting to learn OpenGL and graphics programming.

      View full story
    • By TheChubu
      The Khronos™ Group, an open consortium of leading hardware and software companies, announces from the SIGGRAPH 2017 Conference the immediate public availability of the OpenGL® 4.6 specification. OpenGL 4.6 integrates the functionality of numerous ARB and EXT extensions created by Khronos members AMD, Intel, and NVIDIA into core, including the capability to ingest SPIR-V™ shaders.
      SPIR-V is a Khronos-defined standard intermediate language for parallel compute and graphics, which enables content creators to simplify their shader authoring and management pipelines while providing significant source shading language flexibility. OpenGL 4.6 adds support for ingesting SPIR-V shaders to the core specification, guaranteeing that SPIR-V shaders will be widely supported by OpenGL implementations.
      OpenGL 4.6 adds the functionality of these ARB extensions to OpenGL’s core specification:
      GL_ARB_gl_spirv and GL_ARB_spirv_extensions to standardize SPIR-V support for OpenGL GL_ARB_indirect_parameters and GL_ARB_shader_draw_parameters for reducing the CPU overhead associated with rendering batches of geometry GL_ARB_pipeline_statistics_query and GL_ARB_transform_feedback_overflow_querystandardize OpenGL support for features available in Direct3D GL_ARB_texture_filter_anisotropic (based on GL_EXT_texture_filter_anisotropic) brings previously IP encumbered functionality into OpenGL to improve the visual quality of textured scenes GL_ARB_polygon_offset_clamp (based on GL_EXT_polygon_offset_clamp) suppresses a common visual artifact known as a “light leak” associated with rendering shadows GL_ARB_shader_atomic_counter_ops and GL_ARB_shader_group_vote add shader intrinsics supported by all desktop vendors to improve functionality and performance GL_KHR_no_error reduces driver overhead by allowing the application to indicate that it expects error-free operation so errors need not be generated In addition to the above features being added to OpenGL 4.6, the following are being released as extensions:
      GL_KHR_parallel_shader_compile allows applications to launch multiple shader compile threads to improve shader compile throughput WGL_ARB_create_context_no_error and GXL_ARB_create_context_no_error allow no error contexts to be created with WGL or GLX that support the GL_KHR_no_error extension “I’m proud to announce OpenGL 4.6 as the most feature-rich version of OpenGL yet. We've brought together the most popular, widely-supported extensions into a new core specification to give OpenGL developers and end users an improved baseline feature set. This includes resolving previous intellectual property roadblocks to bringing anisotropic texture filtering and polygon offset clamping into the core specification to enable widespread implementation and usage,” said Piers Daniell, chair of the OpenGL Working Group at Khronos. “The OpenGL working group will continue to respond to market needs and work with GPU vendors to ensure OpenGL remains a viable and evolving graphics API for all its customers and users across many vital industries.“
      The OpenGL 4.6 specification can be found at https://khronos.org/registry/OpenGL/index_gl.php. The GLSL to SPIR-V compiler glslang has been updated with GLSL 4.60 support, and can be found at https://github.com/KhronosGroup/glslang.
      Sophisticated graphics applications will also benefit from a set of newly released extensions for both OpenGL and OpenGL ES to enable interoperability with Vulkan and Direct3D. These extensions are named:
      GL_EXT_memory_object GL_EXT_memory_object_fd GL_EXT_memory_object_win32 GL_EXT_semaphore GL_EXT_semaphore_fd GL_EXT_semaphore_win32 GL_EXT_win32_keyed_mutex They can be found at: https://khronos.org/registry/OpenGL/index_gl.php
      Industry Support for OpenGL 4.6
      “With OpenGL 4.6 our customers have an improved set of core features available on our full range of OpenGL 4.x capable GPUs. These features provide improved rendering quality, performance and functionality. As the graphics industry’s most popular API, we fully support OpenGL and will continue to work closely with the Khronos Group on the development of new OpenGL specifications and extensions for our customers. NVIDIA has released beta OpenGL 4.6 drivers today at https://developer.nvidia.com/opengl-driver so developers can use these new features right away,” said Bob Pette, vice president, Professional Graphics at NVIDIA.
      "OpenGL 4.6 will be the first OpenGL release where conformant open source implementations based on the Mesa project will be deliverable in a reasonable timeframe after release. The open sourcing of the OpenGL conformance test suite and ongoing work between Khronos and X.org will also allow for non-vendor led open source implementations to achieve conformance in the near future," said David Airlie, senior principal engineer at Red Hat, and developer on Mesa/X.org projects.

      View full story
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