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  • 11/23/17 11:41 PM

    Designing A Modern Cross-Platform Graphics Library

    Graphics and GPU Programming

    DiligentDev

    This article uses material originally posted on Diligent Graphics web site.

    Introduction

    Graphics APIs have come a long way from small set of basic commands allowing limited control of configurable stages of early 3D accelerators to very low-level programming interfaces exposing almost every aspect of the underlying graphics hardware. Next-generation APIs, Direct3D12 by Microsoft and Vulkan by Khronos are relatively new and have only started getting widespread adoption and support from hardware vendors, while Direct3D11 and OpenGL are still considered industry standard. New APIs can provide substantial performance and functional improvements, but may not be supported by older hardware. An application targeting wide range of platforms needs to support Direct3D11 and OpenGL. New APIs will not give any advantage when used with old paradigms. It is totally possible to add Direct3D12 support to an existing renderer by implementing Direct3D11 interface through Direct3D12, but this will give zero benefits. Instead, new approaches and rendering architectures that leverage flexibility provided by the next-generation APIs are expected to be developed.

    There are at least four APIs (Direct3D11, Direct3D12, OpenGL/GLES, Vulkan, plus Apple's Metal for iOS and osX platforms) that a cross-platform 3D application may need to support. Writing separate code paths for all APIs is clearly not an option for any real-world application and the need for a cross-platform graphics abstraction layer is evident. The following is the list of requirements that I believe such layer needs to satisfy:

    • Lightweight abstractions: the API should be as close to the underlying native APIs as possible to allow an application leverage all available low-level functionality. In many cases this requirement is difficult to achieve because specific features exposed by different APIs may vary considerably.
    • Low performance overhead: the abstraction layer needs to be efficient from performance point of view. If it introduces considerable amount of overhead, there is no point in using it.
    • Convenience: the API needs to be convenient to use. It needs to assist developers in achieving their goals not limiting their control of the graphics hardware.
    • Multithreading: ability to efficiently parallelize work is in the core of Direct3D12 and Vulkan and one of the main selling points of the new APIs. Support for multithreading in a cross-platform layer is a must.
    • Extensibility: no matter how well the API is designed, it still introduces some level of abstraction. In some cases the most efficient way to implement certain functionality is to directly use native API. The abstraction layer needs to provide seamless interoperability with the underlying native APIs to provide a way for the app to add features that may be missing.

    Diligent Engine is designed to solve these problems. Its main goal is to take advantages of the next-generation APIs such as Direct3D12 and Vulkan, but at the same time provide support for older platforms via Direct3D11, OpenGL and OpenGLES. Diligent Engine exposes common C++ front-end for all supported platforms and provides interoperability with underlying native APIs. It also supports integration with Unity and is designed to be used as graphics subsystem in a standalone game engine, Unity native plugin or any other 3D application. Full source code is available for download at GitHub and is free to use.

    Overview

    Diligent Engine API takes some features from Direct3D11 and Direct3D12 as well as introduces new concepts to hide certain platform-specific details and make the system easy to use. It contains the following main components:

    Render device (IRenderDevice  interface) is responsible for creating all other objects (textures, buffers, shaders, pipeline states, etc.).

    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 tutorials, sample applications, asteroids performance benchmark and an example Unity project that uses Diligent Engine in native plugin.

    Atmospheric scattering sample 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.
    Screenshot.png.60e5c89e52271788fcb83ef99d7141a5.png

    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.

    Screenshot.png.147c048ea41e8efa8d2575255e6ea2a4.png

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

    Screenshot.thumb.png.1a3de12a972f2efcb38a14f5bd9520e5.png

    Future Work

    The engine is under active development. It currently supports Windows desktop, Universal Windows, Linux, Android, MacOS, and iOS platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and Metal backend is in the plan.



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      Below, I'm going to show you step by step what I tried and what glitches are occurring, NOTICE that even if I'm creating more than one textures I ONLY render the first one a.jpg:
      First check out my texture code. As you can see I'm configuring glTexImage2D() to read pixel data based on how many channels they have (I'm only using textures with 3 and 4 channels) and I already made sure that the width * channels for each image is multiple of 4.
      #include "texture.h" #include "stb_image/stb_image.h" #include "glcall.h" #include "engine_error.h" #include <math.h> Texture::Texture(std::string path, bool trans, int unit) { //Reverse the pixels. stbi_set_flip_vertically_on_load(1); //Try to load the image. unsigned char *data = stbi_load(path.c_str(), &m_width, &m_height, &m_channels, 0); //Debug. float check = (m_width * m_channels) / 4.0f; printf("file: %20s \tchannels: %d, Divisible by 4: %s, width: %d, height: %d, widthXheight: %d\n", path.c_str(), m_channels, check == ceilf(check) ? "yes" : "no", m_width, m_height, m_width * m_height); /* //The length of the pixes row is multiple of 4. if ( check == ceilf(check) ) { GLCall(glPixelStorei(GL_UNPACK_ALIGNMENT, 4)); } //It's NOT!!!! else { GLCall(glPixelStorei(GL_UNPACK_ALIGNMENT, 1)); } */ //Image loaded successfully. if (data) { //Generate the texture and bind it. GLCall(glGenTextures(1, &m_id)); GLCall(glBindTexture(GL_TEXTURE_2D, m_id)); //Not Transparent texture. if (m_channels == 3) { GLCall(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, m_width, m_height, 0, GL_RGB, GL_UNSIGNED_BYTE, data)); } //Transparent texture. else if (m_channels == 4) { GLCall(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data)); } else { throw EngineError("Unsupported Channels!!!"); } //Texture Filters. GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)); GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)); GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST)); GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)); //Generate mipmaps. GLCall(glGenerateMipmap(GL_TEXTURE_2D)); } //Loading Failed. else throw EngineError("The was an error loading image: " + path); //Unbind the texture. GLCall(glBindTexture(GL_TEXTURE_2D, 0)); //Free the image data. stbi_image_free(data); } Texture::~Texture() { GLCall(glDeleteTextures(1, &m_id)); } void Texture::Bind(int unit) { GLCall(glActiveTexture(GL_TEXTURE0 + unit)); GLCall(glBindTexture(GL_TEXTURE_2D, m_id)); }  
      Now Check out the Main.cpp File
      #include "Renderer.h" #include "camera.h" Camera *camera; //Handle Key Input. void HandleInput(GLFWwindow *window) { //Exit the application with ESCAPE KEY. if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, 1); //Move Forward. if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS) camera->Move(true); //Move Backward. if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS) camera->Move(false, true); //Move left. if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS) camera->Move(false, false, true); //Move right. if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS) camera->Move(false, false, false, true); } //Mouse Input. void MouseInput(GLFWwindow *window, double x, double y) { camera->UpdateRotation(x, y); } //Mouse Zoom input. void MouseZoom(GLFWwindow *window, double x, double y) { camera->UpdateZoom(x, y); } int main(void) { GLFWwindow* window; /* Initialize the library */ if (!glfwInit()) return -1; //Use openGL version 3.3 Core Profile. glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); /* Create a windowed mode window and its OpenGL context */ window = glfwCreateWindow(800, 600, "Hello World", NULL, NULL); if (!window) { glfwTerminate(); return -1; } /* Make the window's context current */ glfwMakeContextCurrent(window); //Initialize GLEW. if (glewInit() != GLEW_OK) { glfwTerminate(); return -1; } //Set Callback functions. glfwSetCursorPosCallback(window, MouseInput); glfwSetScrollCallback(window, MouseZoom); //Disable the cursor. glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED); //Enable Depth Test. GLCall(glEnable(GL_DEPTH_TEST)); //Get the max texture size. GLint size; GLCall(glGetIntegerv(GL_MAX_TEXTURE_SIZE, &size)); std::cout << "Texture Max Size: "<< size << std::endl; camera = new Camera(glm::vec3(0.0f, 0.0f, 3.0f)); Renderer *renderer = new Renderer(); Shader *shader = new Shader("Shaders/basic_vertex.glsl", "Shaders/basic_fragment.glsl"); Texture *texture1 = new Texture("Resources/a.jpg", false); Texture *texture2 = new Texture("Resources/container.jpg", false); Texture *texture3 = new Texture("Resources/brick2.jpg", false); Texture *texture4 = new Texture("Resources/brick3.jpg", false); //Forget this texture. //Texture *texture5 = new Texture("Resources/brick4.jpg", false); Texture *texture6 = new Texture("Resources/container2.png", true); /* Loop until the user closes the window */ while (!glfwWindowShouldClose(window)) { //Handle input. HandleInput(window); //Clear the screen. renderer->ClearScreen(0.0f, 0.0f, 0.0f); //Render the cube. renderer->Render(texture1, shader, camera); //Update. renderer->Update(window); } //-------------Clean Up-------------// delete camera; delete renderer; delete shader; //forget about textures for now. //-------------Clean Up-------------// glfwTerminate(); return 0; }  
      I will put the code of the rest classes and the glsl shaders at the end if you want to check them out, but i assure you that they work just fine.
      Now if i run the code below I'm getting this:

       
      Now lets see what happens if I'm loading the textures one by one starting from the first one which is the only one i render.
       
      Attempt 1:
      Texture *texture1 = new Texture("Resources/a.jpg", false); //Texture *texture2 = new Texture("Resources/container.jpg", false); //Texture *texture3 = new Texture("Resources/brick2.jpg", false); //Texture *texture4 = new Texture("Resources/brick3.jpg", false); //Forget this texture. //Texture *texture5 = new Texture("Resources/brick4.jpg", false); //Texture *texture6 = new Texture("Resources/container2.png", true);
       
      Attempt 2:
      Texture *texture1 = new Texture("Resources/a.jpg", false); Texture *texture2 = new Texture("Resources/container.jpg", false); //Texture *texture3 = new Texture("Resources/brick2.jpg", false); //Texture *texture4 = new Texture("Resources/brick3.jpg", false); //Forget this texture. //Texture *texture5 = new Texture("Resources/brick4.jpg", false); //Texture *texture6 = new Texture("Resources/container2.png", true);
       
      Attempt 3:
      Texture *texture1 = new Texture("Resources/a.jpg", false); Texture *texture2 = new Texture("Resources/container.jpg", false); Texture *texture3 = new Texture("Resources/brick2.jpg", false); //Texture *texture4 = new Texture("Resources/brick3.jpg", false); //Forget this texture. //Texture *texture5 = new Texture("Resources/brick4.jpg", false); //Texture *texture6 = new Texture("Resources/container2.png", true);
       
      Attempt 4 (Orange Glitch Appears)
      Texture *texture1 = new Texture("Resources/a.jpg", false); Texture *texture2 = new Texture("Resources/container.jpg", false); Texture *texture3 = new Texture("Resources/brick2.jpg", false); Texture *texture4 = new Texture("Resources/brick3.jpg", false); //Forget this texture. //Texture *texture5 = new Texture("Resources/brick4.jpg", false); //Texture *texture6 = new Texture("Resources/container2.png", true);
       
      Attempt 5 (Grey Glitch Appears)
      Texture *texture1 = new Texture("Resources/a.jpg", false); Texture *texture2 = new Texture("Resources/container.jpg", false); Texture *texture3 = new Texture("Resources/brick2.jpg", false); Texture *texture4 = new Texture("Resources/brick3.jpg", false); //Forget this texture. //Texture *texture5 = new Texture("Resources/brick4.jpg", false); Texture *texture6 = new Texture("Resources/container2.png", true);
       
      If you see it, they only texture which I'm rendering is the first one, so how can the loading of the rest textures affect the rendering, since I'm not using them? (I'm binding the first texture before every draw call, you can check it out in the renderer class). This is so weird I literally can't think anything that causes the problem.
       
      Now check this out. I'm going to run Attempt 5 again but with these changes in the Texture class (I'm going to Force 4 channels no matter what the source file's channels😞
      #include "texture.h" #include "stb_image/stb_image.h" #include "glcall.h" #include "engine_error.h" #include <math.h> Texture::Texture(std::string path, bool trans, int unit) { //Reverse the pixels. stbi_set_flip_vertically_on_load(1); //Try to load the image. unsigned char *data = stbi_load(path.c_str(), &m_width, &m_height, &m_channels, 4); //FORCE 4 CHANNELS. //Debug. float check = (m_width * m_channels) / 4.0f; printf("file: %20s \tchannels: %d, Divisible by 4: %s, width: %d, height: %d, widthXheight: %d\n", path.c_str(), m_channels, check == ceilf(check) ? "yes" : "no", m_width, m_height, m_width * m_height); /* //The length of the pixes row is multiple of 4. if ( check == ceilf(check) ) { GLCall(glPixelStorei(GL_UNPACK_ALIGNMENT, 4)); } //It's NOT!!!! else { GLCall(glPixelStorei(GL_UNPACK_ALIGNMENT, 1)); } */ //Image loaded successfully. if (data) { //Generate the texture and bind it. GLCall(glGenTextures(1, &m_id)); GLCall(glBindTexture(GL_TEXTURE_2D, m_id)); /* //Not Transparent texture. if (m_channels == 3) { GLCall(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, m_width, m_height, 0, GL_RGB, GL_UNSIGNED_BYTE, data)); } //Transparent texture. else if (m_channels == 4) { GLCall(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data)); } else { throw EngineError("Unsupported Channels!!!"); } */ GLCall(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data)); //Texture Filters. GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)); GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)); GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST)); GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)); //Generate mipmaps. GLCall(glGenerateMipmap(GL_TEXTURE_2D)); } //Loading Failed. else throw EngineError("The was an error loading image: " + path); //Unbind the texture. GLCall(glBindTexture(GL_TEXTURE_2D, 0)); //Free the image data. stbi_image_free(data); } Texture::~Texture() { GLCall(glDeleteTextures(1, &m_id)); } void Texture::Bind(int unit) { GLCall(glActiveTexture(GL_TEXTURE0 + unit)); GLCall(glBindTexture(GL_TEXTURE_2D, m_id)); }
      Rendering is what I expected!
      But I still can't understand why this fixes it. In the first version of my texture class, which I don't force 4 channels but instead I'm using the default channels, I'm configuring glTexImage2D the right way based on the source files channels and also I'm SURE that the width * channels of each image file is multiple of 4.But again in the second version of my texture class, which solve's the problem my mind is thinking again that this might be an alignment problem but it's not, I made sure of that.
      So what else can cause such a problem? Does anybody knows the answer?
       
      Below you will find the rest of the code:
      Vertex Shader:
      #version 330 core layout(location = 0) in vec3 aPos; layout(location = 1) in vec3 aNormal; layout(location = 2) in vec2 aTexCoord; uniform mat4 model; uniform mat4 view; uniform mat4 proj; out vec2 TexCoord; void main() { gl_Position = proj * view * model * vec4(aPos, 1.0); TexCoord = aTexCoord; }  
      Fragment Shader:
      #version 330 core layout(location = 0) in vec3 aPos; layout(location = 1) in vec3 aNormal; layout(location = 2) in vec2 aTexCoord; uniform mat4 model; uniform mat4 view; uniform mat4 proj; out vec2 TexCoord; void main() { gl_Position = proj * view * model * vec4(aPos, 1.0); TexCoord = aTexCoord; }  
      Renderer Class:
      #include "Renderer.h" Renderer::Renderer() { //Vertex Data. float vertices[] = { // positions // normals // texture coords -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f, 0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f, 0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f, 0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f, -0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f, -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, -0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, -0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f, -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, -0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f, -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f, 0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f, -0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f, -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f, -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, -0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f }; //Generate a VAO and a VBO. GLCall(glGenVertexArrays(1, &m_VAO)); GLCall(glGenBuffers(1, &m_VBO)); //Bind VAO and VBO. GLCall(glBindVertexArray(m_VAO)); GLCall(glBindBuffer(GL_ARRAY_BUFFER, m_VBO)); //Transfer The Data. GLCall(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW)); //Positions. GLCall(glEnableVertexAttribArray(0)); GLCall(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 8, (void *)0)); //Normals. GLCall(glEnableVertexAttribArray(1)); GLCall(glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(float) * 8, (void *) 12)); //Texture Coordinates. GLCall(glEnableVertexAttribArray(2)); GLCall(glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 8, (void *) 24)); //Unbind The Buffers. GLCall(glBindVertexArray(0)); GLCall(glBindBuffer(GL_ARRAY_BUFFER, 0)); } Renderer::~Renderer() { } void Renderer::ClearScreen(float r, float g, float b) { GLCall(glClearColor(r, g, b, 1.0f)); GLCall(glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)); } void Renderer::Update(GLFWwindow * window) { glfwSwapBuffers(window); glfwPollEvents(); } void Renderer::Render(Texture *texture, Shader *program, Camera *camera) { //Bind VAO. GLCall(glBindVertexArray(m_VAO)); //Bind The Program. program->Bind(); //Set the unit to be used on the shader. program->SetUniform1i("diffuse", 0); //Bind the texture at unit zero. texture->Bind(0); glm::mat4 model = glm::mat4(1.0f); glm::mat4 view = glm::mat4(1.0f); glm::mat4 proj = glm::mat4(1.0f); //Get The View Matrix. view = camera->GetView(); //Create The Perspective Projection. proj = glm::perspective(glm::radians(camera->m_fov), 800.0f / 600, 0.1f, 100.0f); //Set the transformation uniforms. program->SetUniformMat4f("model", model); program->SetUniformMat4f("view", view); program->SetUniformMat4f("proj", proj); //Draw Call. GLCall(glDrawArrays(GL_TRIANGLES, 0, 36)); }  
       
       
      Shader Class:
      #include "shader.h" #include "glcall.h" #include "engine_error.h" #include <fstream> #include <string> #include <glm/gtc/matrix_transform.hpp> #include <glm/gtc/type_ptr.hpp> struct ShaderSource { std::string vertex_src; std::string fragment_src; }; static void ReadSources(std::string filename, bool is_vertex, struct ShaderSource *src) { //Create a file object. std::ifstream file; //Open the file. file.open(filename, std::ios::in); //If the file opened successfully read it. if (file.is_open()) { //Size of the file. file.seekg(0, std::ios::end); std::streampos size = file.tellg(); file.seekg(0, std::ios::beg); //Allocate memory to store the data. char *data = (char *)malloc(sizeof(char) * (size + (std::streampos)1) ); //Read the data from the file. file.read(data, size); //Close the string. data[file.gcount()] = '\0'; //Close the file. file.close(); //This was the vertex file. if (is_vertex) src->vertex_src = (const char *)data; //This was the fragment file. else src->fragment_src = (const char *)data; //Release the memory for the data since I coppied them into the ShaderSource structure. free(data); } //Problem opening the file. else throw EngineError("There was a problem opening the file: " + filename); } static unsigned int CompileShader(std::string source, GLenum type) { //__________Local Variables__________// int length, success; //__________Local Variables__________// //Create the shader object. GLCall(unsigned int shader = glCreateShader(type)); //std::string to const c string. const char *src = source.c_str(); //Copy the source code into the shader object. GLCall(glShaderSource(shader, 1, &src, NULL)); //Compile the shader. GLCall(glCompileShader(shader)); //Get the shader info length. GLCall(glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length)); //Get the shader compilations status. GLCall(glGetShaderiv(shader, GL_COMPILE_STATUS, &success)); //Compilation Failed. if (!success) { //Error string. std::string error; //Allocate memory for the info log. char *info = (char *)malloc(sizeof(char) * (length+1) ); //Get the info. GLCall(glGetShaderInfoLog(shader, length, NULL, info)); //Terminate the string. info[length] = '\0'; //Initialize the error message as vertex compilation error. if (type == GL_VERTEX_SHADER) error = "Vertex Shader compilations error: "; //Initialize the error message as fragment compilation error. else error = "Fragment Shader compilation error: "; //Add the info log to the message. error += info; //Free info. free(info); //Throw a message error. throw EngineError(error); } return shader; } static unsigned int CreateProgram(ShaderSource &src) { //__________Local Variables__________// int length, success; //__________Local Variables__________// unsigned int program = glCreateProgram(); unsigned int vertex_shader = CompileShader(src.vertex_src, GL_VERTEX_SHADER); unsigned int fragment_shader = CompileShader(src.fragment_src, GL_FRAGMENT_SHADER); GLCall(glAttachShader(program, vertex_shader)); GLCall(glAttachShader(program, fragment_shader)); GLCall(glLinkProgram(program)); GLCall(glValidateProgram(program)); //Get the shader info length. GLCall(glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length)); //Get the shader compilations status. GLCall(glGetProgramiv(program, GL_LINK_STATUS, &success)); //Linking Failed. if (!success) { //Error string. std::string error = "Linking Error: "; //Allocate memory for the info log. char *info = (char *)malloc(sizeof(char) * (length + 1)); //Get the info. GLCall(glGetProgramInfoLog(program, length, NULL, info)); //Terminate the string. info[length] = '\0'; //Add the info log to the message. error += info; //Free info. free(info); //Throw a message error. throw EngineError(error); } return program; } Shader::Shader(std::string vertex_filename, std::string fragment_filename) { //Create a ShaderSource object. ShaderSource source; //Read the sources. ReadSources(vertex_filename, true, &source); ReadSources(fragment_filename, false, &source); //Create the program. m_id = CreateProgram(source); //And start using it. this->Bind(); } Shader::~Shader() { } void Shader::Bind() { GLCall(glUseProgram(m_id)); } void Shader::SetUniform1i(std::string name, int value) { //Bind the shader. this->Bind(); //Get uniform location. GLCall(int location = glGetUniformLocation(m_id, name.c_str())); //Set the value. GLCall(glUniform1i(location, value)); } void Shader::SetUniformMat4f(std::string name, glm::mat4 mat) { //Bind the shader. this->Bind(); //Get uniform location. GLCall(int location = glGetUniformLocation(m_id, name.c_str())); //Set the mat4. GLCall(glUniformMatrix4fv(location, 1, GL_FALSE, glm::value_ptr(mat))); } void Shader::SetUniformVec3(std::string name, glm::vec3 vec3) { //Bind the shader. this->Bind(); //Get uniform location. GLCall(int location = glGetUniformLocation(m_id, name.c_str())); //Set the Uniform. GLCall(glUniform3f(location, vec3.x, vec3.y, vec3.z)); } void Shader::SetUniform1f(std::string name, float value) { //Bind the shader. this->Bind(); //Get uniform location. GLCall(int location = glGetUniformLocation(m_id, name.c_str())); GLCall(glUniform1f(location, value)); }  
      Camera Class:
      #include "camera.h" #include <glm/gtc/matrix_transform.hpp> #include <iostream> Camera::Camera(glm::vec3 cam_pos) : m_cameraPos(cam_pos), m_pitch(0), m_yaw(-90), m_FirstTime(true), m_sensitivity(0.1), m_fov(45.0) { //Calculate last x and y. m_lastx = 800 / 2.0f; m_lasty = 600 / 2.0f; } Camera::~Camera() { } void Camera::Move(bool forward, bool backward, bool left, bool right) { //Move Forward. if (forward) m_cameraPos += m_cameraFront * m_speed; //Move Backwards. else if (backward) m_cameraPos -= m_cameraFront * m_speed; //Move Left. if (left) m_cameraPos += glm::normalize(glm::cross(m_cameraUp, m_cameraFront)) * m_speed; //Move Right. else if (right) m_cameraPos -= glm::normalize(glm::cross(m_cameraUp, m_cameraFront)) * m_speed; } glm::mat4 Camera::GetView() { return glm::lookAt(m_cameraPos, m_cameraPos + m_cameraFront, m_cameraUp); } void Camera::UpdateRotation(double xpos, double ypos) { //First time, don't do anything. if (m_FirstTime) { m_lastx = xpos; m_lasty = ypos; m_FirstTime = false; } //Get the offset for pitch and yaw. float xoffset = (xpos - m_lastx) * m_sensitivity; float yoffset = (m_lasty - ypos) * m_sensitivity; //Update lastX and lastY. m_lastx = xpos; m_lasty = ypos; //Add them to pitch and yaw. m_pitch += yoffset; m_yaw += xoffset; //Limits for pitch. if (m_pitch > 89.0f) m_pitch = 89.0f; if (m_pitch < -89.0f) m_pitch = -89.0f; //Calculate the new vector. glm::vec3 front = glm::vec3(1.0f); front.x = cos(glm::radians(m_pitch)) * cos(glm::radians(m_yaw)); front.y = sin(glm::radians(m_pitch)); front.z = cos(glm::radians(m_pitch)) * sin(glm::radians(m_yaw)); //Create the direction camera front vector. m_cameraFront = front; } void Camera::UpdateZoom(double x, double y) { m_fov -= y; if (m_fov <= 25) m_fov = 25; else if (m_fov > 45) m_fov = 45; std::cout << m_fov << std::endl; }  
    • By CGEngine
      Hi,
      I'm looking into how to manage state transitions of read only resources.
       
      Lets say I have the following scenario with buffer A:
      Draw Call #1 - Reads from buffer A in PS.
      Draw Call #2 - Reads from buffer A in VS.
       
      So the state will be:
      Initial - Common
      Draw Call #1 - Implicit transition to NON_PIXEL_SHADER_RESOURCE
      Draw Call #2 - Transition from NON_PIXEL_SHADER_RESOURCE to PIXEL_SHADER_RESOURCE.
      End of command list - Implicit decay to D3D12_RESOURCE_STATE_COMMON.
       
      Is this the optimal way to do it? Or should I do a single transition to NON_PIXEL_SHADER_RESOURCE | PIXEL_SHADER_RESOURCE at the beginning of every frame?
      Would it be more expensive to simply explicitly transition to GENERIC_READ at the beginning of every frame? This would make a lot easier to manage read only resources...
       
      Thanks!
    • By natte
      I am trying to understand skeletal animation in 3D.
      Somehow I am getting a stretched out model when I try to render it.
      I am unsure what is causing this.
      I have parsed the local bind transform from the COLLADA file for each bone I then transpose the matrix to shift the columns to rows, then multiply each bone with its parents local bind transform (recursivly starting at the parent bone (where I use identity matrix for the parent). After that I inverse the local bind transform for each bone and I then send it to the shader.
      I know I haven't applied a pose to it or anything but my understanding is that if I send the list of inverse matrices up to the shader it should render successfully in the initial pose.
      Do I have to do anything else to each bones matrix before I can send it to the shader?
       
    • By petya-kurochkin
      Hello everyone!
      I'm trying to create a window with SDL2. This code works perfectly:
      _window = SDL_CreateWindow("Hello", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, 0); However, this code already doesn't:
      _window = SDL_CreateWindow("Hello", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN); if (!_window){ throw SDLException("Can not create window!"); } I don't understand what's the problem: the exception is not thrown. I'm trying to get OpenGL 4.2, because glxinfo shows it's available:
      However the window is not shown. Here's the complete code:
      if (SDL_Init(SDL_INIT_VIDEO) < 0){ throw SDLException("Can not init SDL"); } SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1); SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4); SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2); SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE); SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1); _window = SDL_CreateWindow("Hello", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN); if (!_window) throw SDLException("Can not create window!"); SDL_ShowWindow(_window); _gl_context = SDL_GL_CreateContext(_window); if (!_gl_context) throw SDLException("Can not create an OpenGL context!"); SDL_GL_SetSwapInterval(1); However it's not crashing the app!!! I can also play some games on my laptop: MegaGlest, 0 A.D..They all work.
      I also tried to add: set (OpenGL_GL_PREFERENCE GLVND) in CMakeLists.txt, but it also didn't help.
      Great thanks for your attention. I tried to find the solution in the Internet first, but I've failed to find it. I hope, I'm not the only person with this problem.
       
      p.s. Just in case, I'm also attaching the project. I'm doing it under Ubuntu 18.04, but it shouldn't make too much sense, since it uses Qt Creator and CMake. To build the project you need to have a CMake or Qt Creator installed. If you have CMake you can download just 'client(light)' file.
      So, to build and run it:
      1. go to the client/build directory
      2. run: cmake ..&& make && ./Arena
      client(light).zip
      arena-shooter_(full).zip
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