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    • By kanageddaamen
      Hello all,
      I am currently working on a game engine for use with my game development that I would like to be as flexible as possible.  As such the exact requirements for how things should work can't be nailed down to a specific implementation and I am looking for, at least now, a default good average case scenario design.
      Here is what I have implemented:
      Deferred rendering using OpenGL Arbitrary number of lights and shadow mapping Each rendered object, as defined by a set of geometry, textures, animation data, and a model matrix is rendered with its own draw call Skeletal animations implemented on the GPU.   Model matrix transformation implemented on the GPU Frustum and octree culling for optimization Here are my questions and concerns:
      Doing the skeletal animation on the GPU, currently, requires doing the skinning for each object multiple times per frame: once for the initial geometry rendering and once for the shadow map rendering for each light for which it is not culled.  This seems very inefficient.  Is there a way to do skeletal animation on the GPU only once across these render calls? Without doing the model matrix transformation on the CPU, I fail to see how I can easily batch objects with the same textures and shaders in a single draw call without passing a ton of matrix data to the GPU (an array of model matrices then an index for each vertex into that array for transformation purposes?) If I do the matrix transformations on the CPU, It seems I can't really do the skinning on the GPU as the pre-transformed vertexes will wreck havoc with the calculations, so this seems not viable unless I am missing something Overall it seems like simplest solution is to just do all of the vertex manipulation on the CPU and pass the pre-transformed data to the GPU, using vertex shaders that do basically nothing.  This doesn't seem the most efficient use of the graphics hardware, but could potentially reduce the number of draw calls needed.

      Really, I am looking for some advice on how to proceed with this, how something like this is typically handled.  Are the multiple draw calls and skinning calculations not a huge deal?  I would LIKE to save as much of the CPU's time per frame so it can be tasked with other things, as to keep CPU resources open to the implementation of the engine.  However, that becomes a moot point if the GPU becomes a bottleneck.
    • By DiligentDev
      I would like to introduce Diligent Engine, a project that I've been recently working on. Diligent Engine is a light-weight cross-platform abstraction layer between the application and the platform-specific graphics API. 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 front-end for all supported platforms and provides interoperability with underlying native API. Shader source code converter allows shaders authored in HLSL to be translated to GLSL and used on all platforms. Diligent Engine supports integration with Unity and is designed to be used as a graphics subsystem in a standalone game engine, Unity native plugin or any other 3D application. It is distributed under Apache 2.0 license and is free to use. Full source code is available for download on GitHub.
      True cross-platform Exact same client code for all supported platforms and rendering backends No #if defined(_WIN32) ... #elif defined(LINUX) ... #elif defined(ANDROID) ... No #if defined(D3D11) ... #elif defined(D3D12) ... #elif defined(OPENGL) ... Exact same HLSL shaders run on all platforms and all backends Modular design Components are clearly separated logically and physically and can be used as needed Only take what you need for your project (do not want to keep samples and tutorials in your codebase? Simply remove Samples submodule. Only need core functionality? Use only Core submodule) No 15000 lines-of-code files Clear object-based interface No global states Key graphics features: Automatic shader resource binding designed to leverage the next-generation rendering APIs Multithreaded command buffer generation 50,000 draw calls at 300 fps with D3D12 backend Descriptor, memory and resource state management Modern c++ features to make code fast and reliable The following platforms and low-level APIs are currently supported:
      Windows Desktop: Direct3D11, Direct3D12, OpenGL Universal Windows: Direct3D11, Direct3D12 Linux: OpenGL Android: OpenGLES MacOS: OpenGL iOS: OpenGLES API Basics
      The engine can perform initialization of the API or attach to already existing D3D11/D3D12 device or OpenGL/GLES context. For instance, the following code shows how the engine can be initialized in D3D12 mode:
      #include "RenderDeviceFactoryD3D12.h" using namespace Diligent; // ...  GetEngineFactoryD3D12Type GetEngineFactoryD3D12 = nullptr; // Load the dll and import GetEngineFactoryD3D12() function LoadGraphicsEngineD3D12(GetEngineFactoryD3D12); auto *pFactoryD3D11 = GetEngineFactoryD3D12(); EngineD3D12Attribs EngD3D12Attribs; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[0] = 1024; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[1] = 32; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[2] = 16; EngD3D12Attribs.CPUDescriptorHeapAllocationSize[3] = 16; EngD3D12Attribs.NumCommandsToFlushCmdList = 64; RefCntAutoPtr<IRenderDevice> pRenderDevice; RefCntAutoPtr<IDeviceContext> pImmediateContext; SwapChainDesc SwapChainDesc; RefCntAutoPtr<ISwapChain> pSwapChain; pFactoryD3D11->CreateDeviceAndContextsD3D12( EngD3D12Attribs, &pRenderDevice, &pImmediateContext, 0 ); pFactoryD3D11->CreateSwapChainD3D12( pRenderDevice, pImmediateContext, SwapChainDesc, hWnd, &pSwapChain ); 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. To create a buffer, you need to populate BufferDesc structure and call IRenderDevice::CreateBuffer(). The following code creates a uniform (constant) buffer:
      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 ); Similar, to create a texture, populate TextureDesc structure and call IRenderDevice::CreateTexture() as in the following example:
      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 ); Initializing Pipeline State
      Diligent Engine follows Direct3D12 style 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.)
      Creating Shaders
      To create a shader, populate ShaderCreationAttribs structure. An important member is ShaderCreationAttribs::SourceLanguage. The following are valid values for this member:
      SHADER_SOURCE_LANGUAGE_DEFAULT  - The shader source format matches the underlying graphics API: HLSL for D3D11 or D3D12 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. See shader converter for details. SHADER_SOURCE_LANGUAGE_GLSL  - The shader source is in GLSL. There is currently no GLSL to HLSL converter. To allow grouping of resources based on the frequency of expected change, Diligent Engine introduces classification of shader variables:
      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. This post describes the resource binding model in Diligent Engine.
      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
      To create a pipeline state object, define instance of PipelineStateDesc structure. The structure defines the pipeline specifics such as if the pipeline is a compute pipeline, number and format of render targets as well as depth-stencil format:
      // This is a graphics pipeline PSODesc.IsComputePipeline = false; PSODesc.GraphicsPipeline.NumRenderTargets = 1; PSODesc.GraphicsPipeline.RTVFormats[0] = TEX_FORMAT_RGBA8_UNORM_SRGB; PSODesc.GraphicsPipeline.DSVFormat = TEX_FORMAT_D32_FLOAT; The structure also defines depth-stencil, rasterizer, blend state, input layout and other parameters. For instance, rasterizer state can be defined as in the code snippet below:
      // Init rasterizer state RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; //RSDesc.MultisampleEnable = false; // do not allow msaa (fonts would be degraded) RasterizerDesc.AntialiasedLineEnable = False; When all fields are populated, call IRenderDevice::CreatePipelineState() to create the PSO:
      m_pDev->CreatePipelineState(PSODesc, &m_pPSO); Binding Shader Resources
      Shader resource binding in Diligent Engine is based on grouping variables in 3 different groups (static, mutable and dynamic). Static variables 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. They are bound directly to the shader object:
      PixelShader->GetShaderVariable( "g_tex2DShadowMap" )->Set( pShadowMapSRV ); Mutable and dynamic variables are bound via a new object called Shader Resource Binding (SRB), which is created by the pipeline state:
      m_pPSO->CreateShaderResourceBinding(&m_pSRB); Dynamic and mutable resources are then bound through SRB object:
      m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "tex2DDiffuse")->Set(pDiffuseTexSRV); m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); The difference between mutable and dynamic resources is that mutable ones can only be set once for every instance of a shader resource binding. Dynamic resources can be set multiple times. It is important to properly set the variable type as this may affect performance. Static variables are generally most efficient, followed by mutable. Dynamic variables are most expensive from performance point of view. This post explains shader resource binding in more details.
      Setting the Pipeline State and Invoking Draw Command
      Before any draw command can be invoked, all required vertex and index buffers as well as the pipeline state should be bound to the device context:
      // Clear render target const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); // 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); m_pContext->SetPipelineState(m_pPSO); Also, all shader resources must be committed to the device context:
      m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); When all required states and resources are bound, IDeviceContext::Draw() can be used to execute draw command or IDeviceContext::DispatchCompute() can be used to execute compute command. Note that for a draw command, graphics pipeline must be bound, and for dispatch command, compute pipeline must be bound. Draw() 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); Tutorials and Samples
      The GitHub repository contains a number of tutorials and sample applications that demonstrate the API usage.
      Tutorial 01 - Hello Triangle This tutorial shows how to render a simple triangle using Diligent Engine API.   Tutorial 02 - Cube This tutorial demonstrates how to render an actual 3D object, a cube. It shows how to load shaders from files, create and use vertex, index and uniform buffers.   Tutorial 03 - Texturing This tutorial demonstrates how to apply a texture to a 3D object. It shows how to load a texture from file, create shader resource binding object and how to sample a texture in the shader.   Tutorial 04 - Instancing This tutorial demonstrates how to use instancing to render multiple copies of one object using unique transformation matrix for every copy.   Tutorial 05 - Texture Array This tutorial demonstrates how to combine instancing with texture arrays to use unique texture for every instance.   Tutorial 06 - Multithreading This tutorial shows how to generate command lists in parallel from multiple threads.   Tutorial 07 - Geometry Shader This tutorial shows how to use geometry shader to render smooth wireframe.   Tutorial 08 - Tessellation This tutorial shows how to use hardware tessellation to implement simple adaptive terrain rendering algorithm.   Tutorial_09 - Quads This tutorial shows how to render multiple 2D quads, frequently swithcing textures and blend modes.
      AntTweakBar sample demonstrates how to use AntTweakBar library to create simple user interface.

      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 textures, using compute shaders and unordered access views, etc. 

      The repository includes Asteroids performance benchmark based on this demo developed by Intel. It renders 50,000 unique textured asteroids and lets compare performance of D3D11 and D3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures. 

      Integration with Unity
      Diligent Engine supports integration with Unity through Unity low-level native plugin interface. The engine relies on Native API Interoperability to attach to the graphics API initialized by Unity. After Diligent Engine device and context are created, they can be used us usual to create resources and issue rendering commands. GhostCubePlugin shows an example how Diligent Engine can be used to render a ghost cube only visible as a reflection in a mirror.

    • By Yxjmir
      I'm trying to load data from a .gltf file into a struct to use to load a .bin file. I don't think there is a problem with how the vertex positions are loaded, but with the indices. This is what I get when drawing with glDrawArrays(GL_LINES, ...):

      Also, using glDrawElements gives a similar result. Since it looks like its drawing triangles using the wrong vertices for each face, I'm assuming it needs an index buffer/element buffer. (I'm not sure why there is a line going through part of it, it doesn't look like it belongs to a side, re-exported it without texture coordinates checked, and its not there)
      I'm using jsoncpp to load the GLTF file, its format is based on JSON. Here is the gltf struct I'm using, and how I parse the file:
      #define GLTF_TARGET_ARRAY_BUFFER (34962) #define GLTF_TARGET_ELEMENT_ARRAY_BUFFER (34963) #define GLTF_COMPONENT_TYPE_BYTE (5120) #define GLTF_COMPONENT_TYPE_UNSIGNED_BYTE (5121) #define GLTF_COMPONENT_TYPE_SHORT (5122) #define GLTF_COMPONENT_TYPE_UNSIGNED_SHORT (5123) #define GLTF_COMPONENT_TYPE_INT (5124) #define GLTF_COMPONENT_TYPE_UNSIGNED_INT (5125) #define GLTF_COMPONENT_TYPE_FLOAT (5126) #define GLTF_COMPONENT_TYPE_DOUBLE (5127) #define GLTF_PARAMETER_TYPE_BYTE (5120) #define GLTF_PARAMETER_TYPE_UNSIGNED_BYTE (5121) #define GLTF_PARAMETER_TYPE_SHORT (5122) #define GLTF_PARAMETER_TYPE_UNSIGNED_SHORT (5123) #define GLTF_PARAMETER_TYPE_INT (5124) #define GLTF_PARAMETER_TYPE_UNSIGNED_INT (5125) #define GLTF_PARAMETER_TYPE_FLOAT (5126) #define GLTF_PARAMETER_TYPE_FLOAT_VEC2 (35664) #define GLTF_PARAMETER_TYPE_FLOAT_VEC3 (35665) #define GLTF_PARAMETER_TYPE_FLOAT_VEC4 (35666) struct GLTF { struct Accessor { USHORT bufferView; USHORT componentType; UINT count; vector<INT> max; vector<INT> min; string type; }; vector<Accessor> m_accessors; struct Asset { string copyright; string generator; string version; }m_asset; struct BufferView { UINT buffer; UINT byteLength; UINT byteOffset; UINT target; }; vector<BufferView> m_bufferViews; struct Buffer { UINT byteLength; string uri; }; vector<Buffer> m_buffers; vector<string> m_Images; struct Material { string name; string alphaMode; Vec4 baseColorFactor; UINT baseColorTexture; UINT normalTexture; float metallicFactor; }; vector<Material> m_materials; struct Meshes { string name; struct Primitive { vector<UINT> attributes_indices; UINT indices; UINT material; }; vector<Primitive> primitives; }; vector<Meshes> m_meshes; struct Nodes { int mesh; string name; Vec3 translation; }; vector<Nodes> m_nodes; struct Scenes { UINT index; string name; vector<UINT> nodes; }; vector<Scenes> m_scenes; vector<UINT> samplers; struct Textures { UINT sampler; UINT source; }; vector<Textures> m_textures; map<UINT, string> attributes_map; map<UINT, string> textures_map; }; GLTF m_gltf; // This is actually in the Mesh class bool Mesh::Load(string sFilename) { string sFileAsString; stringstream sStream; ifstream fin(sFilename); sStream << fin.rdbuf(); fin.close(); sFileAsString = sStream.str(); Json::Reader r; Json::Value root; if (!r.parse(sFileAsString, root)) { string errors = r.getFormatedErrorMessages(); if (errors != "") { // TODO: Log errors return false; } } if (root.isNull()) return false; Json::Value object; Json::Value value; // Load Accessors array, these are referenced by attributes with their index value object = root.get("accessors", Json::Value()); // store object with key "accessors", if not found it will default to Json::Value() if (!object.isNull()) { for (Json::ValueIterator it = object.begin(); it != object.end(); it++) { GLTF::Accessor accessor; value = (*it).get("bufferView", Json::Value()); if (!value.isNull()) accessor.bufferView = value.asUINT(); else return false; value = (*it).get("componentType", Json::Value()); if (!value.isNull()) accessor.componentType = value.asUINT(); else return false; value = (*it).get("count", Json::Value()); if (!value.isNull()) accessor.count = value.asUINT(); else return false; value = (*it).get("type", Json::Value()); if (!value.isNull()) accessor.type = value.asString(); else return false; m_gltf.accessors.push_back(accessor); } } else return false; object = root.get("bufferViews", Json::Value()); if(!object.isNull()) { for (Json::ValueIterator it = object.begin(); it != object.end(); it++) { GLTF::BufferView bufferView; value = (*it).get("buffer", Json::Value()); if(!value.isNull()) bufferView.buffer = value.asUInt(); else return false; value = (*it).get("byteLength", Json::Value()); if(!value.isNull()) bufferView.byteLength = value.asUInt(); else return false; value = (*it).get("byteOffset", Json::Value()); if(!value.isNull()) bufferView.byteOffset = value.asUInt(); else return false; value = (*it).get("target", Json::Value()); if(!value.isNull()) bufferView.target = value.asUInt(); else return false; m_gltf.m_bufferViews.push_back(bufferView); } } else return false; object = root.get("buffers", Json::Value()); if(!object.isNull()) { for (Json::ValueIterator it = object.begin(); it != object.end(); it++) { GLTF::Buffer buffer; value = (*it).get("byteLength", Json::Value()); if(!value.isNull()) buffer.byteLength = value.asUInt(); else return false; // Store the filename of the .bin file value = (*it).get("uri", Json::Value()); if(!value.isNull()) buffer.uri = value.asString(); else return false; } } else return false; object = root.get("meshes", Json::Value()); if(!object.isNull()) { for(Json::ValueIterator it = object.begin(); it != object.end(); it++) { GLTF::Meshes mesh; value = (*it).get("primitives", Json::Value()); for(Json::ValueIterator value_it = value.begin(); value_it != value.end(); value_it++) { GLTF::Meshes::Primitive primitive; Json::Value attributes; attributes = (*value_it).get("attributes", Json::Value()); vector<string> memberNames = attributes.getMemberNames(); for(size_t i = 0; i < memberNames.size(); i++) { Json::Value member; member = attributes.get(memeberNames[i], Json::Value()); if(!member.isNull()) { primitive.attributes_indices.push_back(member.asUInt()); m_gltf.attributes_map[member.asUInt()] = memberNames[i]; // Each of these referes to an accessor by indice, so each indice should be unique, and they are when loading a cube } else return false; } // Indice of the accessor used for indices Json::Value indices; indices = (*value_it).get("indices", Json::Value()); primitive.indices = indices.asUInt(); mesh.primitives.push_back(primitive); } m_gltf.m_meshes.push_back(mesh); } } vector<float> vertexData; vector<USHORT> indiceData; int vertexBufferSizeTotal = 0; int elementBufferSizeTotal = 0; GLTF::Meshes mesh = m_gltf.m_meshes[0]; vector<GLTF::Meshes::Primitive> primitives = mesh.primitives; // trying to make the code easier to read for (size_t p = 0; p < primitive.size(); p++) { vector<UINT> attributes = primitives[p].attributes_indices; for(size_t a = 0; a < attributes.size(); a++) { GLTF::Accessor accessor = m_gltf.m_accessors[attributes[a]]; GLTF::BufferView bufferView = m_gltf.m_bufferViews[accessor.bufferView]; UINT target = bufferView.target; if(target == GLTF_TARGET_ARRAY_BUFFER) vertexBufferSizeTotal += bufferView.byteLength; } UINT indice = primitives[p].indices; GLTF::BufferView bufferView = m_gltf.m_bufferViews[indice]; UINT target = bufferView.target; if(target == GLTF_TARGET_ELEMENT_ARRAY_BUFFER) elementBufferSizeTotal += bufferView.byteLength; } // These have already been generated glBindVertexArray(g_pGame->m_VAO); glBindBuffer(GL_ARRAY_BUFFER, g_pGame->m_VBO); glBufferData(GL_ARRAY_BUFFER, vertexBufferSizeTotal, nullptr, GL_STATIC_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_pGame->m_EBO); glBufferData(GL_ELEMENT_ARRAY_BUFFER, elementBufferSizeTotal, nullptr, GL_STATIC_DRAW); int offset = 0; int offset_indice = 0; for (size_t p = 0; p < primitive.size(); p++) { vector<UINT> attributes = primitives[p].attributes_indices; int pos = sFilename.find_last_of('\\') + 1; string sFolder = sFilename.substr(0, pos); for (size_t a = 0; a < attributes.size(); a++) { LoadBufferView(sFolder, attributes[a], data, offset); } UINT indice = primitives[p].indices; GLTF::BufferView bufferView_indice = m_gltf.m_bufferViews[indice]; UINT target_indice = bufferView_indice.target; bool result = LoadBufferView(sFolder, indice, data, offset_indice); if(!result) return false; } return true; } bool Mesh::LoadBufferView(string sFolder, UINT a, vector<float> &vertexData, vector<float> &indiceData, int &offset_indice) { ifstream fin; GLTF::Accessor accessor = m_gltf.m_accessors[a]; GLTF::BufferView bufferView = m_gltf.m_bufferViews[accessor.bufferView]; GLTF::Buffer buffer = m_gltf.m_buffers[bufferView.buffer]; const size_t count = accessor.count; UINT target = bufferView.target; int elementSize; int componentSize; int numComponents; string sFilename_bin = sFolder + buffer.uri; fin.open(sFilename_bin, ios::binary); if (fin.fail()) { return false; } fin.seekg(bufferView.byteOffset, ios::beg); switch (accessor.componentType) { case GLTF_COMPONENT_TYPE_BYTE: componentSize = sizeof(GLbyte); break; case GLTF_COMPONENT_TYPE_UNSIGNED_BYTE: componentSize = sizeof(GLubyte); break; case GLTF_COMPONENT_TYPE_SHORT: componentSize = sizeof(GLshort); break; case GLTF_COMPONENT_TYPE_UNSIGNED_SHORT: componentSize = sizeof(GLushort); break; case GLTF_COMPONENT_TYPE_INT: componentSize = sizeof(GLint); break; case GLTF_COMPONENT_TYPE_UNSIGNED_INT: componentSize = sizeof(GLuint); break; case GLTF_COMPONENT_TYPE_FLOAT: componentSize = sizeof(GLfloat); break; case GLTF_COMPONENT_TYPE_DOUBLE: componentSize = sizeof(GLfloat); break; default: componentSize = 0; break; } if (accessor.type == "SCALAR") numComponents = 1; else if (accessor.type == "VEC2") numComponents = 2; else if (accessor.type == "VEC3") numComponents = 3; else if (accessor.type == "VEC4") numComponents = 4; else if (accessor.type == "MAT2") numComponents = 4; else if (accessor.type == "MAT3") numComponents = 9; else if (accessor.type == "MAT4") numComponents = 16; else return false; vector<float> fSubdata; // I'm pretty sure this is one of the problems, or related to it. If I use vector<USHORT> only half of the vector if filled, if I use GLubyte, the entire vector is filled, but the data might not be right vector<GLubyte> nSubdata; elementSize = (componentSize) * (numComponents); // Only fill the vector I'm using if (accessor.type == "SCALAR") { nSubdata.resize(count * numComponents); fin.read(reinterpret_cast<char*>(&nSubdata[0]), count/* * elementSize*/); // I commented this out since I'm not sure which size the .bin is storing the indice values, and I kept getting runtime errors, no matter what type I used for nSubdata } else { fSubdata.resize(count * numComponents); fin.read(reinterpret_cast<char*>(&fSubdata[0]), count * elementSize); } switch (target) { case GLTF_TARGET_ARRAY_BUFFER: { vertexData.insert(vertexData.end(), fSubdata.begin(), fSubdata.end()); glBindBuffer(GL_ARRAY_BUFFER, g_pGame->m_VBO); glBufferSubData(GL_ARRAY_BUFFER, offset, fSubdata.size() * componentSize, &fSubdata[0]); int attribute_index = 0; // I'm only loading vertex positions, the only attribute stored in the files for now glEnableVertexAttribArray(attribute_index); glVertexAttribPointer(0, numComponents, GL_FLOAT, GL_FALSE, componentSize * numComponents, (void*)(offset)); }break; case GLTF_TARGET_ELEMENT_ARRAY_BUFFER: { indiceData.insert(indiceData.end(), nSubdata.begin(), nSubdata.end()); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_pGame->m_EBO); // This is another area where I'm not sure of the correct values, but if componentSize is the correct size for the type being used it should be correct glBufferSubData is expecting the size in bytes, right? glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, offset, nSubdata.size() * componentSize, &nSubdata[0]); }break; default: return false; } if (accessor.type == "SCALAR") offset += nSubdata.size() * componentSize; else offset += fSubdata.size() * componentSize; fin.close(); return true; } these are the draw calls, I only use one at a time, but neither is currently display properly, g_pGame->m_indices is the same as indiceData vector, and vertexCount contains the correct vertex count, but I forgot to copy the lines of code containing where I set them, which is at the end of Mesh::Load(), I double checked the values to make sure.
      glDrawElements(GL_LINES, g_pGame->m_indices.size(), GL_UNSIGNED_BYTE, (void*)0); // Only shows with GL_UNSIGNED_BYTE
      glDrawArrays(GL_LINES, 0, g_pGame->m_vertexCount);
      So, I'm asking what type should I use for the indices? it doesn't seem to be unsigned short, which is what I selected with the Khronos Group Exporter for blender. Also, am I reading part or all of the .bin file wrong?
    • By ritzmax72
      That means how do I use base DirectX or OpenGL api's to make a physics based destruction simulation? 
      Will it be just smart rendering or something else is required?
    • By jsquare89
      I am somewhat new to game development and trying to create a basic 3d engine. I have managed to set up a first person camera and it seems to be working fine for the most part. While I am able to look up, down, left and right just fine the camera is constrained to the mouse movement in the window (i.e when the mouse reaches edges of the window it discontinues camera rotation and mouse is out of window bounds. I tried to use SDL_WarpMouseInWindow(window, center.x,center.y) but when I do this then it messes up the camera and the camera is stuck, even though there is some slight movement of the camera, it keeps going back to the center.
      void Camera::UpdateViewByMouse(SDL_Window &window, glm::vec2 mousePosition)
      float xDistanceFromWindowCenter = mousePosition.x - ((float)1024 / 2) ;
      float yDistanceFromWindowCenter = ((float)720 / 2) - mousePosition.y;
      yaw = xDistanceFromWindowCenter * cameraRotationSpeed;
      pitch = yDistanceFromWindowCenter * cameraRotationSpeed;
      SDL_WarpMouseInWindow(&window, 1024 / 2, 768 / 2); }
      i’ve been stuck on this for far too long. any help would be much appreciated
      i have also tried relative mouse movement,  and .xrel and .yrel to avail. polling mouse state with sdl_event. I do also know that SDL_WarpMouseInWindow makes change to event and have tried also ignore and reenabling to no avail
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OpenGL Beginner at OpenGL, 2D or 3D first?

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I've started learning OpenGL about a week ago. I've learned how to make 3D shapes, texture objects, do simple lighting, and tranlsate/rotate polygons. I'm using Beginning OpenGL Game Programming(great book for those of you that are new to this too!). Well, now I feel that I'd like to make a simple game with this. My problem is that I'm not sure whether learning to make a 2D game or 3D game would be more benificial to me at this point. I've made a number of other, simple 2D games before, so I have a fairly good understanding of this. I'm completely new to 3D. What suggestions do you guys have? Also, what would be a good starting 3D game to make? Thanks in advanced!

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I went straight to 3d. (Caveat: I was 90% done with a CS B.S. degree and had just taken a class in graphics)
So I think you should go straight to 3d too.
as far as openGl is concerned, the difference is just whether you add a nonZero Z-coordinate to your polygons

The main difficulty you're probably going to have is camera setup, lots of people starting out in 3d tend to have all kinds of camera rotation questions, usually because they have issues visualizing the matrix transforms and how to order them to get the effect they want. Lots of examples of people getting stuck with trying to make glLookAt work right....
you can avoid the whole issue of course, if you just pushmatrix your own camera matrix in there instead of messing with euler rotations.....

Why not make a 3d Pong or 3d BreakOut game? should be simple enough, fixed camera positions to keep it simple for now.
Easy physics; essentially the same as the physics for normal 2d pong/breakout, but with an additional copy of the same X/Y motion forumulas for Z position...

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You say that that camera problems are common for beginners, do you have any tips/tutorials for it?

I'm presonally not into this whole Pong/Breakout/Tetris thing(Fun games, but I would never make them). Its just something about me. Space Invaders I could do. I was thinking of making a straight-forward racing game, similiar to the minigame in KOTOR, but with really bad graphics. So, no real physics, and no vertical movement. I could even keep the camera stationary and just move the objects in the gameworld to create the illusion of a moving camera(something I'm pretty sure I could do with relative ease). Would this make sense for a first game?

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The most difficult part about 3D in opengl is the math as its not difficult to understand the API. So the question is, are you comfortable with linear Algebra and solving quite complex math problems?

I started with 3D because most the books I have concentrated on that, but I quickly realised that I just wasn't getting the math part of it and so changed to 2D. Writting 2D for me is more rewarding because 2d uses trig quite a bit and is easy to understand, the development process is therefore much, much quicker.

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I think that I can do the math required for the game I have in mind. I really enjoy math, so I'm willing to put in the effort to figure out how to solve it if I don't get it to begin with.

I'll probably go for 3D, but I'll wait for another post or two just in case.

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It seems to me, that the main source of camera and rotation confusion is due to perception of Reference Frame.

Most people do an X,Y, and Z rotation (applied to all objects in the game, or to the camera - its all relative and equivalent) but they base them off some Absolute World Coordinate System X,Y and Z axis. Then get confused when their camera starts pointing strange directions due to a bad combo of rotations leading to a 'gimbal lock'.
It is important to realize that th
e order of rotations are important (imagine a tank turrent vs your shoulder(bad example...but all i can get now)) also, that once your camera has rotated, its axis for successive rotations do not necessarially match the World axis anymore... But people end up applying later rotations to those World axis instead of the Camera's Local axis and get results that don't match expectation.
So the key is to have a Local Coordinate System for your camera, that is separate from the Absolute World Coordinate System. And base your camera view changes off these.

I do this by having 3 vectors (a matrix) as part of my camera class, representing it's local X,Y, and Z axis, and whenever I want to rotate my camera, I change these. Then instead of messing with 3 succesive glRotate's(with the abovementioned issues) I directly plug the camera's x,y,z values into the opengl matrix stack. Once you have this kind of system working and get the idea, its a lot easier to use it everywhere (all my game objects have a similar local coord system and single matrix transform).

So it goes something like....
I want my camera aiming that direction, so set its Z to point that way.
and I want the camera's 'up' direction to point this way, so set its Y to point this way. Then I cross product the Z and Y to get the X ...normalize
Anyway, that kind of system lets you think of the camera as 'where do I want it pointed' rather than 'how many degrees does it need to rotate to point here'.

Ohwell, sorry if that was long and confusing. Been a while since I touched the basic stuff, I just wrote a good self contained camera class, and quit thinking about dealing with the internals afterwards.

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Original post by haphazardlynamed
Anyway, that kind of system lets you think of the camera as 'where do I want it pointed' rather than 'how many degrees does it need to rotate to point here'.

That's because people suffer from the hammer syndrome. "If all you have is a hammer, every problem will look like a nail". Most likely they simply don't know anything but glRotate/Translate and try to reduce every problem to this, resulting in horrible ideas like asking how to calculate Euler Angles to rotate by to make it look in some way instead of just _setting_ it to look that way.

And I further claim that this lack of knowledge about the available "tools" is the result of the annoyingly widespread "show me a tutorial"-mentality instead of a "know a good book covering the basics?"-mind set.

But as the original poster mentioned a book and said he likes math I just assume he is familiar with matrices or can quickly pick up the basics. Meaning he should be able to have box racing down a quad with other boxes as obstacles in pretty short time. It might even more more difficult to understand where the game logic ends and the actual graphics begin, ie. what OpenGL is responsible for and most of all, what not.

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