kc3-lang/angle/src/libANGLE/renderer/gl/BufferGL.cpp

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• Hash : f1150231
  Author :
  Date : 2024-01-16T16:28:36
  

  Track WebGL buffer type in gl::Buffer state.
  
  WebGL has special validation that disallows buffers from changing
  "WebGL buffer type". Once a buffer is marked as having index data it
  cannot be bound as any other type of buffer except the copy binding
  points to copy to other index buffers. This disallows any GPU writes
  to buffers used for index data.
  
  Use this rule to shadow index buffer data when the driver is unable
  to give us robust access. Index range computation can be done much
  faster when the buffer does not need to be read back.
  
  Bug: angleproject:8434
  Change-Id: I059eff732bb2f43234f61d9ef5528289f7698b38
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5200242
  Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
  Commit-Queue: Geoff Lang <geofflang@chromium.org>
  

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• src/libANGLE/renderer/gl/BufferGL.cpp

• //
  // Copyright 2015 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  // BufferGL.cpp: Implements the class methods for BufferGL.
  
  #include "libANGLE/renderer/gl/BufferGL.h"
  
  #include "common/debug.h"
  #include "common/utilities.h"
  #include "libANGLE/Context.h"
  #include "libANGLE/angletypes.h"
  #include "libANGLE/formatutils.h"
  #include "libANGLE/renderer/gl/ContextGL.h"
  #include "libANGLE/renderer/gl/FunctionsGL.h"
  #include "libANGLE/renderer/gl/StateManagerGL.h"
  #include "libANGLE/renderer/gl/renderergl_utils.h"
  
  namespace rx
  {
  
  namespace
  {
  
  bool KeepBufferShadowCopy(const gl::Context *context, gl::WebGLBufferType webglType)
  {
      // Always keep a shadow copy if the feature is enabled. This usually means there is no other way
      // to read back the data.
      const angle::FeaturesGL &features = GetFeaturesGL(context);
      if (features.keepBufferShadowCopy.enabled)
      {
          return true;
      }
  
      // Shadow WebGL index buffers when the driver is unable to provide robust access.
      // WebGL element array buffers cannot be bound to other binding points or written to on the GPU
      // so the shadowed data will never be invalidated.
      if (context->isWebGL() && context->isBufferAccessValidationEnabled() &&
          webglType == gl::WebGLBufferType::ElementArray)
      {
          return true;
      }
  
      return false;
  }
  
  }  // namespace
  
  // Use the GL_COPY_READ_BUFFER binding when two buffers need to be bound simultaneously.
  // GL_ELEMENT_ARRAY_BUFFER is supported on more versions but can modify the state of the currently
  // bound VAO.  Two simultaneous buffer bindings are only needed for glCopyBufferSubData which also
  // adds the GL_COPY_READ_BUFFER binding.
  static constexpr gl::BufferBinding SourceBufferOperationTarget = gl::BufferBinding::CopyRead;
  
  // Use the GL_ELEMENT_ARRAY_BUFFER binding for most operations since it's available on all
  // supported GL versions and doesn't affect any current state when it changes.
  static constexpr gl::BufferBinding DestBufferOperationTarget = gl::BufferBinding::Array;
  
  BufferGL::BufferGL(const gl::BufferState &state, GLuint buffer)
      : BufferImpl(state),
        mIsMapped(false),
        mMapOffset(0),
        mMapSize(0),
        mShadowCopy(),
        mBufferSize(0),
        mBufferID(buffer)
  {}
  
  BufferGL::~BufferGL()
  {
      ASSERT(mBufferID == 0);
  }
  
  void BufferGL::destroy(const gl::Context *context)
  {
      StateManagerGL *stateManager = GetStateManagerGL(context);
      stateManager->deleteBuffer(mBufferID);
      mBufferID = 0;
  }
  
  angle::Result BufferGL::setData(const gl::Context *context,
                                  gl::BufferBinding target,
                                  const void *data,
                                  size_t size,
                                  gl::BufferUsage usage)
  {
      ContextGL *contextGL         = GetImplAs<ContextGL>(context);
      const FunctionsGL *functions = GetFunctionsGL(context);
      StateManagerGL *stateManager = GetStateManagerGL(context);
  
      stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
      ANGLE_GL_TRY(context, functions->bufferData(gl::ToGLenum(DestBufferOperationTarget), size, data,
                                                  ToGLenum(usage)));
  
      // Initialize the shadow buffer if needed. Don't delete existing shadow data. WebGL allows users
      // to bind as an element array buffer first and then copy source/dest later (but not the other
      // way around).
      if (KeepBufferShadowCopy(context, mState.getWebGLType()) && !mShadowCopy.has_value())
      {
          mShadowCopy = angle::MemoryBuffer();
      }
  
      if (mShadowCopy.has_value())
      {
          ANGLE_CHECK_GL_ALLOC(contextGL, mShadowCopy->resize(size));
  
          if (size > 0 && data != nullptr)
          {
              memcpy(mShadowCopy->data(), data, size);
          }
      }
  
      mBufferSize = size;
  
      contextGL->markWorkSubmitted();
  
      return angle::Result::Continue;
  }
  
  angle::Result BufferGL::setSubData(const gl::Context *context,
                                     gl::BufferBinding target,
                                     const void *data,
                                     size_t size,
                                     size_t offset)
  {
      ContextGL *contextGL         = GetImplAs<ContextGL>(context);
      const FunctionsGL *functions = GetFunctionsGL(context);
      StateManagerGL *stateManager = GetStateManagerGL(context);
  
      stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
      ANGLE_GL_TRY(context, functions->bufferSubData(gl::ToGLenum(DestBufferOperationTarget), offset,
                                                     size, data));
  
      if (mShadowCopy.has_value() && size > 0)
      {
          memcpy(mShadowCopy->data() + offset, data, size);
      }
  
      contextGL->markWorkSubmitted();
  
      return angle::Result::Continue;
  }
  
  angle::Result BufferGL::copySubData(const gl::Context *context,
                                      BufferImpl *source,
                                      GLintptr sourceOffset,
                                      GLintptr destOffset,
                                      GLsizeiptr size)
  {
      ContextGL *contextGL         = GetImplAs<ContextGL>(context);
      const FunctionsGL *functions = GetFunctionsGL(context);
      StateManagerGL *stateManager = GetStateManagerGL(context);
  
      BufferGL *sourceGL = GetAs<BufferGL>(source);
  
      stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
      stateManager->bindBuffer(SourceBufferOperationTarget, sourceGL->getBufferID());
  
      ANGLE_GL_TRY(context, functions->copyBufferSubData(gl::ToGLenum(SourceBufferOperationTarget),
                                                         gl::ToGLenum(DestBufferOperationTarget),
                                                         sourceOffset, destOffset, size));
  
      if (mShadowCopy.has_value() && size > 0)
      {
          // WebGL only allows copying between buffers that are marked as the same type. Both buffers
          // would have to be element array buffers and have shadow data.
          ASSERT(sourceGL->mShadowCopy.has_value());
  
          ASSERT(sourceGL->mShadowCopy->size() >= static_cast<size_t>(sourceOffset + size));
          memcpy(mShadowCopy->data() + destOffset, sourceGL->mShadowCopy->data() + sourceOffset,
                 size);
      }
  
      contextGL->markWorkSubmitted();
  
      return angle::Result::Continue;
  }
  
  angle::Result BufferGL::map(const gl::Context *context, GLenum access, void **mapPtr)
  {
      ContextGL *contextGL         = GetImplAs<ContextGL>(context);
      const FunctionsGL *functions = GetFunctionsGL(context);
      StateManagerGL *stateManager = GetStateManagerGL(context);
  
      if (mShadowCopy.has_value())
      {
          *mapPtr = mShadowCopy->data();
      }
      else
      {
          stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
          if (functions->mapBuffer)
          {
              *mapPtr = ANGLE_GL_TRY(
                  context, functions->mapBuffer(gl::ToGLenum(DestBufferOperationTarget), access));
          }
          else
          {
              ASSERT(functions->mapBufferRange && access == GL_WRITE_ONLY_OES);
              *mapPtr = ANGLE_GL_TRY(
                  context, functions->mapBufferRange(gl::ToGLenum(DestBufferOperationTarget), 0,
                                                     mBufferSize, GL_MAP_WRITE_BIT));
          }
  
          // Unbind the mapped buffer from the array buffer binding. Some drivers generate errors if
          // any mapped buffer is bound to array buffer bindings.
          // crbug.com/1345777
          stateManager->bindBuffer(DestBufferOperationTarget, 0);
      }
  
      mIsMapped  = true;
      mMapOffset = 0;
      mMapSize   = mBufferSize;
  
      contextGL->markWorkSubmitted();
  
      return angle::Result::Continue;
  }
  
  angle::Result BufferGL::mapRange(const gl::Context *context,
                                   size_t offset,
                                   size_t length,
                                   GLbitfield access,
                                   void **mapPtr)
  {
      ContextGL *contextGL         = GetImplAs<ContextGL>(context);
      const FunctionsGL *functions = GetFunctionsGL(context);
      StateManagerGL *stateManager = GetStateManagerGL(context);
  
      if (mShadowCopy.has_value())
      {
          *mapPtr = mShadowCopy->data() + offset;
      }
      else
      {
          stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
          *mapPtr =
              ANGLE_GL_TRY(context, functions->mapBufferRange(gl::ToGLenum(DestBufferOperationTarget),
                                                              offset, length, access));
  
          // Unbind the mapped buffer from the array buffer binding. Some drivers generate errors if
          // any mapped buffer is bound to array buffer bindings.
          // crbug.com/1345777
          stateManager->bindBuffer(DestBufferOperationTarget, 0);
      }
  
      mIsMapped  = true;
      mMapOffset = offset;
      mMapSize   = length;
  
      contextGL->markWorkSubmitted();
  
      return angle::Result::Continue;
  }
  
  angle::Result BufferGL::unmap(const gl::Context *context, GLboolean *result)
  {
      ContextGL *contextGL         = GetImplAs<ContextGL>(context);
      const FunctionsGL *functions = GetFunctionsGL(context);
      StateManagerGL *stateManager = GetStateManagerGL(context);
  
      ASSERT(result);
      ASSERT(mIsMapped);
  
      if (mShadowCopy.has_value())
      {
          stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
          ANGLE_GL_TRY(context,
                       functions->bufferSubData(gl::ToGLenum(DestBufferOperationTarget), mMapOffset,
                                                mMapSize, mShadowCopy->data() + mMapOffset));
          *result = GL_TRUE;
      }
      else
      {
          stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
          *result =
              ANGLE_GL_TRY(context, functions->unmapBuffer(gl::ToGLenum(DestBufferOperationTarget)));
      }
  
      mIsMapped = false;
  
      contextGL->markWorkSubmitted();
  
      return angle::Result::Continue;
  }
  
  angle::Result BufferGL::getIndexRange(const gl::Context *context,
                                        gl::DrawElementsType type,
                                        size_t offset,
                                        size_t count,
                                        bool primitiveRestartEnabled,
                                        gl::IndexRange *outRange)
  {
      ContextGL *contextGL         = GetImplAs<ContextGL>(context);
      const FunctionsGL *functions = GetFunctionsGL(context);
      StateManagerGL *stateManager = GetStateManagerGL(context);
  
      ASSERT(!mIsMapped);
  
      if (mShadowCopy.has_value())
      {
          *outRange = gl::ComputeIndexRange(type, mShadowCopy->data() + offset, count,
                                            primitiveRestartEnabled);
      }
      else
      {
          stateManager->bindBuffer(DestBufferOperationTarget, mBufferID);
  
          const GLuint typeBytes = gl::GetDrawElementsTypeSize(type);
          const uint8_t *bufferData =
              MapBufferRangeWithFallback(functions, gl::ToGLenum(DestBufferOperationTarget), offset,
                                         count * typeBytes, GL_MAP_READ_BIT);
          if (bufferData)
          {
              *outRange = gl::ComputeIndexRange(type, bufferData, count, primitiveRestartEnabled);
              ANGLE_GL_TRY(context, functions->unmapBuffer(gl::ToGLenum(DestBufferOperationTarget)));
          }
          else
          {
              // Workaround the null driver not having map support.
              *outRange = gl::IndexRange(0, 0, 1);
          }
      }
  
      contextGL->markWorkSubmitted();
  
      return angle::Result::Continue;
  }
  
  size_t BufferGL::getBufferSize() const
  {
      return mBufferSize;
  }
  
  GLuint BufferGL::getBufferID() const
  {
      return mBufferID;
  }
  }  // namespace rx
  

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