text: //
  // Copyright (c) 2008-2020 the Urho3D project.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  //
  
  #include "../../Precompiled.h"
  
  #include "../../Graphics/Graphics.h"
  #include "../../Graphics/GraphicsImpl.h"
  #include "../../Graphics/VertexBuffer.h"
  #include "../../IO/Log.h"
  
  #include "../../DebugNew.h"
  
  namespace Urho3D
  {
  
  void VertexBuffer::OnDeviceLost()
  {
      if (object_.name_ && !graphics_->IsDeviceLost())
          glDeleteBuffers(1, &object_.name_);
  
      GPUObject::OnDeviceLost();
  }
  
  void VertexBuffer::OnDeviceReset()
  {
      if (!object_.name_)
      {
          Create();
          dataLost_ = !UpdateToGPU();
      }
      else if (dataPending_)
          dataLost_ = !UpdateToGPU();
  
      dataPending_ = false;
  }
  
  void VertexBuffer::Release()
  {
      Unlock();
  
      if (object_.name_)
      {
          if (!graphics_)
              return;
  
          if (!graphics_->IsDeviceLost())
          {
              for (unsigned i = 0; i < MAX_VERTEX_STREAMS; ++i)
              {
                  if (graphics_->GetVertexBuffer(i) == this)
                      graphics_->SetVertexBuffer(nullptr);
              }
  
              graphics_->SetVBO(0);
              glDeleteBuffers(1, &object_.name_);
          }
  
          object_.name_ = 0;
      }
  }
  
  bool VertexBuffer::SetData(const void* data)
  {
      if (!data)
      {
          URHO3D_LOGERROR("Null pointer for vertex buffer data");
          return false;
      }
  
      if (!vertexSize_)
      {
          URHO3D_LOGERROR("Vertex elements not defined, can not set vertex buffer data");
          return false;
      }
  
      if (shadowData_ && data != shadowData_.get())
          memcpy(shadowData_.get(), data, vertexCount_ * (size_t)vertexSize_);
  
      if (object_.name_)
      {
          if (!graphics_->IsDeviceLost())
          {
              graphics_->SetVBO(object_.name_);
              glBufferData(GL_ARRAY_BUFFER, vertexCount_ * (size_t)vertexSize_, data, dynamic_ ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW);
          }
          else
          {
              URHO3D_LOGWARNING("Vertex buffer data assignment while device is lost");
              dataPending_ = true;
          }
      }
  
      dataLost_ = false;
      return true;
  }
  
  bool VertexBuffer::SetDataRange(const void* data, unsigned start, unsigned count, bool discard)
  {
      if (start == 0 && count == vertexCount_)
          return SetData(data);
  
      if (!data)
      {
          URHO3D_LOGERROR("Null pointer for vertex buffer data");
          return false;
      }
  
      if (!vertexSize_)
      {
          URHO3D_LOGERROR("Vertex elements not defined, can not set vertex buffer data");
          return false;
      }
  
      if (start + count > vertexCount_)
      {
          URHO3D_LOGERROR("Illegal range for setting new vertex buffer data");
          return false;
      }
  
      if (!count)
          return true;
  
      if (shadowData_ && shadowData_.get() + start * vertexSize_ != data)
          memcpy(shadowData_.get() + start * vertexSize_, data, count * (size_t)vertexSize_);
  
      if (object_.name_)
      {
          if (!graphics_->IsDeviceLost())
          {
              graphics_->SetVBO(object_.name_);
              if (!discard || start != 0)
                  glBufferSubData(GL_ARRAY_BUFFER, start * (size_t)vertexSize_, count * vertexSize_, data);
              else
                  glBufferData(GL_ARRAY_BUFFER, count * (size_t)vertexSize_, data, dynamic_ ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW);
          }
          else
          {
              URHO3D_LOGWARNING("Vertex buffer data assignment while device is lost");
              dataPending_ = true;
          }
      }
  
      return true;
  }
  
  void* VertexBuffer::Lock(unsigned start, unsigned count, bool discard)
  {
      if (lockState_ != LOCK_NONE)
      {
          URHO3D_LOGERROR("Vertex buffer already locked");
          return nullptr;
      }
  
      if (!vertexSize_)
      {
          URHO3D_LOGERROR("Vertex elements not defined, can not lock vertex buffer");
          return nullptr;
      }
  
      if (start + count > vertexCount_)
      {
          URHO3D_LOGERROR("Illegal range for locking vertex buffer");
          return nullptr;
      }
  
      if (!count)
          return nullptr;
  
      lockStart_ = start;
      lockCount_ = count;
      discardLock_ = discard;
  
      if (shadowData_)
      {
          lockState_ = LOCK_SHADOW;
          return shadowData_.get() + start * vertexSize_;
      }
      else if (graphics_)
      {
          lockState_ = LOCK_SCRATCH;
          lockScratchData_ = graphics_->ReserveScratchBuffer(count * vertexSize_);
          return lockScratchData_;
      }
      else
          return nullptr;
  }
  
  void VertexBuffer::Unlock()
  {
      switch (lockState_)
      {
      case LOCK_SHADOW:
          SetDataRange(shadowData_.get() + lockStart_ * vertexSize_, lockStart_, lockCount_, discardLock_);
          lockState_ = LOCK_NONE;
          break;
  
      case LOCK_SCRATCH:
          SetDataRange(lockScratchData_, lockStart_, lockCount_, discardLock_);
          if (graphics_)
              graphics_->FreeScratchBuffer(lockScratchData_);
          lockScratchData_ = nullptr;
          lockState_ = LOCK_NONE;
          break;
  
      default:
          break;
      }
  }
  
  bool VertexBuffer::Create()
  {
      if (!vertexCount_ || !elementMask_)
      {
          Release();
          return true;
      }
  
      if (graphics_)
      {
          if (graphics_->IsDeviceLost())
          {
              URHO3D_LOGWARNING("Vertex buffer creation while device is lost");
              return true;
          }
  
          if (!object_.name_)
              glGenBuffers(1, &object_.name_);
          if (!object_.name_)
          {
              URHO3D_LOGERROR("Failed to create vertex buffer");
              return false;
          }
  
          graphics_->SetVBO(object_.name_);
          glBufferData(GL_ARRAY_BUFFER, vertexCount_ * (size_t)vertexSize_, nullptr, dynamic_ ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW);
      }
  
      return true;
  }
  
  bool VertexBuffer::UpdateToGPU()
  {
      if (object_.name_ && shadowData_)
          return SetData(shadowData_.get());
      else
          return false;
  }
  
  void* VertexBuffer::MapBuffer(unsigned start, unsigned count, bool discard)
  {
      // Never called on OpenGL
      return nullptr;
  }
  
  void VertexBuffer::UnmapBuffer()
  {
      // Never called on OpenGL
  }
  
  }
  