src/dawn_native/opengl/TextureGL.cpp - dawn - Git at Google

 // Copyright 2017 The Dawn Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "dawn_native/opengl/TextureGL.h"

 #include "common/Assert.h"
 #include "common/Constants.h"
 #include "common/Math.h"
 #include "dawn_native/opengl/BufferGL.h"
 #include "dawn_native/opengl/DeviceGL.h"
 #include "dawn_native/opengl/UtilsGL.h"

 namespace dawn_native { namespace opengl {

     namespace {

         GLenum TargetForTexture(const TextureDescriptor* descriptor) {
             switch (descriptor->dimension) {
                 case dawn::TextureDimension::e2D:
                     if (descriptor->arrayLayerCount > 1) {
                         ASSERT(descriptor->sampleCount == 1);
                         return GL_TEXTURE_2D_ARRAY;
                     } else {
                         if (descriptor->sampleCount > 1) {
                             return GL_TEXTURE_2D_MULTISAMPLE;
                         } else {
                             return GL_TEXTURE_2D;
                         }
                     }

                 default:
                     UNREACHABLE();
                     return GL_TEXTURE_2D;
             }
         }

         GLenum TargetForTextureViewDimension(dawn::TextureViewDimension dimension,
                                              uint32_t sampleCount) {
             switch (dimension) {
                 case dawn::TextureViewDimension::e2D:
                     return (sampleCount > 1) ? GL_TEXTURE_2D_MULTISAMPLE : GL_TEXTURE_2D;
                 case dawn::TextureViewDimension::e2DArray:
                     ASSERT(sampleCount == 1);
                     return GL_TEXTURE_2D_ARRAY;
                 case dawn::TextureViewDimension::Cube:
                     return GL_TEXTURE_CUBE_MAP;
                 case dawn::TextureViewDimension::CubeArray:
                     return GL_TEXTURE_CUBE_MAP_ARRAY;
                 default:
                     UNREACHABLE();
                     return GL_TEXTURE_2D;
             }
         }

         GLuint GenTexture(const OpenGLFunctions& gl) {
             GLuint handle = 0;
             gl.GenTextures(1, &handle);
             return handle;
         }

         bool UsageNeedsTextureView(dawn::TextureUsage usage) {
             constexpr dawn::TextureUsage kUsageNeedingTextureView =
                 dawn::TextureUsage::Storage | dawn::TextureUsage::Sampled;
             return usage & kUsageNeedingTextureView;
         }

         bool RequiresCreatingNewTextureView(const TextureBase* texture,
                                             const TextureViewDescriptor* textureViewDescriptor) {
             if (texture->GetFormat().format != textureViewDescriptor->format) {
                 return true;
             }

             if (texture->GetArrayLayers() != textureViewDescriptor->arrayLayerCount) {
                 return true;
             }

             if (texture->GetNumMipLevels() != textureViewDescriptor->mipLevelCount) {
                 return true;
             }

             switch (textureViewDescriptor->dimension) {
                 case dawn::TextureViewDimension::Cube:
                 case dawn::TextureViewDimension::CubeArray:
                     return true;
                 default:
                     break;
             }

             return false;
         }

     }  // namespace

     // Texture

     Texture::Texture(Device* device, const TextureDescriptor* descriptor)
         : Texture(device, descriptor, GenTexture(device->gl), TextureState::OwnedInternal) {
         const OpenGLFunctions& gl = ToBackend(GetDevice())->gl;

         uint32_t width = GetSize().width;
         uint32_t height = GetSize().height;
         uint32_t levels = GetNumMipLevels();
         uint32_t arrayLayers = GetArrayLayers();
         uint32_t sampleCount = GetSampleCount();

         const GLFormat& glFormat = GetGLFormat();

         gl.BindTexture(mTarget, mHandle);

         // glTextureView() requires the value of GL_TEXTURE_IMMUTABLE_FORMAT for origtexture to be
         // GL_TRUE, so the storage of the texture must be allocated with glTexStorage*D.
         // https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glTextureView.xhtml
         switch (GetDimension()) {
             case dawn::TextureDimension::e2D:
                 if (arrayLayers > 1) {
                     ASSERT(!IsMultisampledTexture());
                     gl.TexStorage3D(mTarget, levels, glFormat.internalFormat, width, height,
                                     arrayLayers);
                 } else {
                     if (IsMultisampledTexture()) {
                         gl.TexStorage2DMultisample(mTarget, sampleCount, glFormat.internalFormat,
                                                    width, height, true);
                     } else {
                         gl.TexStorage2D(mTarget, levels, glFormat.internalFormat, width, height);
                     }
                 }
                 break;
             default:
                 UNREACHABLE();
         }

         // The texture is not complete if it uses mipmapping and not all levels up to
         // MAX_LEVEL have been defined.
         gl.TexParameteri(mTarget, GL_TEXTURE_MAX_LEVEL, levels - 1);

         if (GetDevice()->IsToggleEnabled(Toggle::NonzeroClearResourcesOnCreationForTesting)) {
             GetDevice()->ConsumedError(ClearTexture(0, GetNumMipLevels(), 0, GetArrayLayers(),
                                                     TextureBase::ClearValue::NonZero));
         }
     }

     Texture::Texture(Device* device,
                      const TextureDescriptor* descriptor,
                      GLuint handle,
                      TextureState state)
         : TextureBase(device, descriptor, state), mHandle(handle) {
         mTarget = TargetForTexture(descriptor);
     }

     Texture::~Texture() {
         DestroyInternal();
     }

     void Texture::DestroyImpl() {
         ToBackend(GetDevice())->gl.DeleteTextures(1, &mHandle);
         mHandle = 0;
     }

     GLuint Texture::GetHandle() const {
         return mHandle;
     }

     GLenum Texture::GetGLTarget() const {
         return mTarget;
     }

     const GLFormat& Texture::GetGLFormat() const {
         return ToBackend(GetDevice())->GetGLFormat(GetFormat());
     }

     MaybeError Texture::ClearTexture(GLint baseMipLevel,
                                      GLint levelCount,
                                      GLint baseArrayLayer,
                                      uint32_t layerCount,
                                      TextureBase::ClearValue clearValue) {
         // TODO(jiawei.shao@intel.com): initialize the textures with compressed formats.
         if (GetFormat().isCompressed) {
             return {};
         }

         Device* device = ToBackend(GetDevice());
         const OpenGLFunctions& gl = device->gl;
         uint8_t clearColor = (clearValue == TextureBase::ClearValue::Zero) ? 0 : 1;
         if (GetFormat().isRenderable) {
             if (GetFormat().HasDepthOrStencil()) {
                 bool doDepthClear = GetFormat().HasDepth();
                 bool doStencilClear = GetFormat().HasStencil();
                 GLfloat depth = clearColor;
                 GLint stencil = clearColor;
                 if (doDepthClear) {
                     gl.DepthMask(GL_TRUE);
                 }
                 if (doStencilClear) {
                     gl.StencilMask(GetStencilMaskFromStencilFormat(GetFormat().format));
                 }

                 GLuint framebuffer = 0;
                 gl.GenFramebuffers(1, &framebuffer);
                 gl.BindFramebuffer(GL_DRAW_FRAMEBUFFER, framebuffer);
                 // TODO(natlee@microsoft.com): clear all mip levels and array layers.
                 gl.FramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
                                         GetGLTarget(), GetHandle(), 0);
                 if (doDepthClear && doStencilClear) {
                     gl.ClearBufferfi(GL_DEPTH_STENCIL, 0, depth, stencil);
                 } else if (doDepthClear) {
                     gl.ClearBufferfv(GL_DEPTH, 0, &depth);
                 } else if (doStencilClear) {
                     gl.ClearBufferiv(GL_STENCIL, 0, &stencil);
                 }
                 gl.DeleteFramebuffers(1, &framebuffer);
             } else {
                 static constexpr uint32_t MAX_TEXEL_SIZE = 16;
                 ASSERT(GetFormat().blockByteSize <= MAX_TEXEL_SIZE);
                 std::array<GLbyte, MAX_TEXEL_SIZE> clearColorData;
                 clearColor = (clearValue == TextureBase::ClearValue::Zero) ? 0 : 255;
                 clearColorData.fill(clearColor);

                 const GLFormat& glFormat = GetGLFormat();
                 for (GLint level = baseMipLevel; level < baseMipLevel + levelCount; ++level) {
                     Extent3D mipSize = GetMipLevelPhysicalSize(level);
                     gl.ClearTexSubImage(mHandle, level, 0, 0, baseArrayLayer, mipSize.width,
                                         mipSize.height, layerCount, glFormat.format, glFormat.type,
                                         clearColorData.data());
                 }
             }
         } else {
             // TODO(natlee@microsoft.com): test compressed textures are cleared
             // create temp buffer with clear color to copy to the texture image
             ASSERT(kTextureRowPitchAlignment % GetFormat().blockByteSize == 0);
             uint32_t rowPitch =
                 Align((GetSize().width / GetFormat().blockWidth) * GetFormat().blockByteSize,
                       kTextureRowPitchAlignment);

             // Make sure that we are not rounding
             ASSERT(rowPitch % GetFormat().blockByteSize == 0);
             ASSERT(GetSize().height % GetFormat().blockHeight == 0);

             dawn_native::BufferDescriptor descriptor;
             descriptor.size = rowPitch * (GetSize().height / GetFormat().blockHeight);
             if (descriptor.size > std::numeric_limits<uint32_t>::max()) {
                 return DAWN_OUT_OF_MEMORY_ERROR("Unable to allocate buffer.");
             }
             descriptor.nextInChain = nullptr;
             descriptor.usage = dawn::BufferUsage::CopySrc | dawn::BufferUsage::MapWrite;
             // TODO(natlee@microsoft.com): use Dynamic Uplaoder here for temp buffer
             Ref<Buffer> srcBuffer = ToBackend(device->CreateBuffer(&descriptor));
             // Call release here to prevent memory leak since CreateBuffer will up the ref count to
             // 1, then assigning to Ref<Buffer> ups the ref count to 2. Release will reduce the ref
             // count and ensure it to reach 0 when out of use.
             srcBuffer->Release();

             // Fill the buffer with clear color
             uint8_t* clearBuffer = nullptr;
             DAWN_TRY(srcBuffer->MapAtCreation(&clearBuffer));
             std::fill(reinterpret_cast<uint32_t*>(clearBuffer),
                       reinterpret_cast<uint32_t*>(clearBuffer + descriptor.size), clearColor);
             srcBuffer->Unmap();

             // Bind buffer and texture, and make the buffer to texture copy
             gl.PixelStorei(GL_UNPACK_ROW_LENGTH,
                            (rowPitch / GetFormat().blockByteSize) * GetFormat().blockWidth);
             gl.PixelStorei(GL_UNPACK_IMAGE_HEIGHT, 0);
             for (GLint level = baseMipLevel; level < baseMipLevel + levelCount; ++level) {
                 gl.BindBuffer(GL_PIXEL_UNPACK_BUFFER, srcBuffer->GetHandle());
                 gl.ActiveTexture(GL_TEXTURE0);
                 gl.BindTexture(GetGLTarget(), GetHandle());

                 Extent3D size = GetMipLevelPhysicalSize(level);
                 switch (GetDimension()) {
                     case dawn::TextureDimension::e2D:
                         // TODO(natlee@microsoft.com): This will break when layerCount is greater
                         // than 1, because the buffer is only sized for one layer.
                         ASSERT(layerCount == 1);
                         gl.TexSubImage2D(GetGLTarget(), level, 0, 0, size.width, size.height,
                                          GetGLFormat().format, GetGLFormat().type, 0);
                         break;

                     default:
                         UNREACHABLE();
                 }
                 gl.PixelStorei(GL_UNPACK_ROW_LENGTH, 0);
                 gl.PixelStorei(GL_UNPACK_IMAGE_HEIGHT, 0);

                 gl.BindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
             }
         }
         return {};
     }

     void Texture::EnsureSubresourceContentInitialized(uint32_t baseMipLevel,
                                                       uint32_t levelCount,
                                                       uint32_t baseArrayLayer,
                                                       uint32_t layerCount,
                                                       bool isLazyClear) {
         if (!GetDevice()->IsToggleEnabled(Toggle::LazyClearResourceOnFirstUse)) {
             return;
         }
         if (!IsSubresourceContentInitialized(baseMipLevel, levelCount, baseArrayLayer,
                                              layerCount)) {
             GetDevice()->ConsumedError(ClearTexture(baseMipLevel, levelCount, baseArrayLayer,
                                                     layerCount, TextureBase::ClearValue::Zero));
             if (isLazyClear) {
                 GetDevice()->IncrementLazyClearCountForTesting();
             }
             SetIsSubresourceContentInitialized(baseMipLevel, levelCount, baseArrayLayer,
                                                layerCount);
         }
     }

     // TextureView

     TextureView::TextureView(TextureBase* texture, const TextureViewDescriptor* descriptor)
         : TextureViewBase(texture, descriptor), mOwnsHandle(false) {
         mTarget = TargetForTextureViewDimension(descriptor->dimension, texture->GetSampleCount());

         if (!UsageNeedsTextureView(texture->GetUsage())) {
             mHandle = 0;
         } else if (!RequiresCreatingNewTextureView(texture, descriptor)) {
             mHandle = ToBackend(texture)->GetHandle();
         } else {
             // glTextureView() is supported on OpenGL version >= 4.3
             // TODO(jiawei.shao@intel.com): support texture view on OpenGL version <= 4.2
             const OpenGLFunctions& gl = ToBackend(GetDevice())->gl;
             mHandle = GenTexture(gl);
             const Texture* textureGL = ToBackend(texture);
             const GLFormat& glFormat = ToBackend(GetDevice())->GetGLFormat(GetFormat());
             gl.TextureView(mHandle, mTarget, textureGL->GetHandle(), glFormat.internalFormat,
                            descriptor->baseMipLevel, descriptor->mipLevelCount,
                            descriptor->baseArrayLayer, descriptor->arrayLayerCount);
             mOwnsHandle = true;
         }
     }

     TextureView::~TextureView() {
         if (mOwnsHandle) {
             ToBackend(GetDevice())->gl.DeleteTextures(1, &mHandle);
         }
     }

     GLuint TextureView::GetHandle() const {
         ASSERT(mHandle != 0);
         return mHandle;
     }

     GLenum TextureView::GetGLTarget() const {
         return mTarget;
     }

 }}  // namespace dawn_native::opengl
	// Copyright 2017 The Dawn Authors
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "dawn_native/opengl/TextureGL.h"

	#include "common/Assert.h"
	#include "common/Constants.h"
	#include "common/Math.h"
	#include "dawn_native/opengl/BufferGL.h"
	#include "dawn_native/opengl/DeviceGL.h"
	#include "dawn_native/opengl/UtilsGL.h"

	namespace dawn_native { namespace opengl {

	namespace {

	GLenum TargetForTexture(const TextureDescriptor* descriptor) {
	switch (descriptor->dimension) {
	case dawn::TextureDimension::e2D:
	if (descriptor->arrayLayerCount > 1) {
	ASSERT(descriptor->sampleCount == 1);
	return GL_TEXTURE_2D_ARRAY;
	} else {
	if (descriptor->sampleCount > 1) {
	return GL_TEXTURE_2D_MULTISAMPLE;
	} else {
	return GL_TEXTURE_2D;
	}
	}

	default:
	UNREACHABLE();
	return GL_TEXTURE_2D;
	}
	}

	GLenum TargetForTextureViewDimension(dawn::TextureViewDimension dimension,
	uint32_t sampleCount) {
	switch (dimension) {
	case dawn::TextureViewDimension::e2D:
	return (sampleCount > 1) ? GL_TEXTURE_2D_MULTISAMPLE : GL_TEXTURE_2D;
	case dawn::TextureViewDimension::e2DArray:
	ASSERT(sampleCount == 1);
	return GL_TEXTURE_2D_ARRAY;
	case dawn::TextureViewDimension::Cube:
	return GL_TEXTURE_CUBE_MAP;
	case dawn::TextureViewDimension::CubeArray:
	return GL_TEXTURE_CUBE_MAP_ARRAY;
	default:
	UNREACHABLE();
	return GL_TEXTURE_2D;
	}
	}

	GLuint GenTexture(const OpenGLFunctions& gl) {
	GLuint handle = 0;
	gl.GenTextures(1, &handle);
	return handle;
	}

	bool UsageNeedsTextureView(dawn::TextureUsage usage) {
	constexpr dawn::TextureUsage kUsageNeedingTextureView =
	dawn::TextureUsage::Storage \| dawn::TextureUsage::Sampled;
	return usage & kUsageNeedingTextureView;
	}

	bool RequiresCreatingNewTextureView(const TextureBase* texture,
	const TextureViewDescriptor* textureViewDescriptor) {
	if (texture->GetFormat().format != textureViewDescriptor->format) {
	return true;
	}

	if (texture->GetArrayLayers() != textureViewDescriptor->arrayLayerCount) {
	return true;
	}

	if (texture->GetNumMipLevels() != textureViewDescriptor->mipLevelCount) {
	return true;
	}

	switch (textureViewDescriptor->dimension) {
	case dawn::TextureViewDimension::Cube:
	case dawn::TextureViewDimension::CubeArray:
	return true;
	default:
	break;
	}

	return false;
	}

	} // namespace

	// Texture

	Texture::Texture(Device* device, const TextureDescriptor* descriptor)
	: Texture(device, descriptor, GenTexture(device->gl), TextureState::OwnedInternal) {
	const OpenGLFunctions& gl = ToBackend(GetDevice())->gl;

	uint32_t width = GetSize().width;
	uint32_t height = GetSize().height;
	uint32_t levels = GetNumMipLevels();
	uint32_t arrayLayers = GetArrayLayers();
	uint32_t sampleCount = GetSampleCount();

	const GLFormat& glFormat = GetGLFormat();

	gl.BindTexture(mTarget, mHandle);

	// glTextureView() requires the value of GL_TEXTURE_IMMUTABLE_FORMAT for origtexture to be
	// GL_TRUE, so the storage of the texture must be allocated with glTexStorage*D.
	// https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glTextureView.xhtml
	switch (GetDimension()) {
	case dawn::TextureDimension::e2D:
	if (arrayLayers > 1) {
	ASSERT(!IsMultisampledTexture());
	gl.TexStorage3D(mTarget, levels, glFormat.internalFormat, width, height,
	arrayLayers);
	} else {
	if (IsMultisampledTexture()) {
	gl.TexStorage2DMultisample(mTarget, sampleCount, glFormat.internalFormat,
	width, height, true);
	} else {
	gl.TexStorage2D(mTarget, levels, glFormat.internalFormat, width, height);
	}
	}
	break;
	default:
	UNREACHABLE();
	}

	// The texture is not complete if it uses mipmapping and not all levels up to
	// MAX_LEVEL have been defined.
	gl.TexParameteri(mTarget, GL_TEXTURE_MAX_LEVEL, levels - 1);

	if (GetDevice()->IsToggleEnabled(Toggle::NonzeroClearResourcesOnCreationForTesting)) {
	GetDevice()->ConsumedError(ClearTexture(0, GetNumMipLevels(), 0, GetArrayLayers(),
	TextureBase::ClearValue::NonZero));
	}
	}

	Texture::Texture(Device* device,
	const TextureDescriptor* descriptor,
	GLuint handle,
	TextureState state)
	: TextureBase(device, descriptor, state), mHandle(handle) {
	mTarget = TargetForTexture(descriptor);
	}

	Texture::~Texture() {
	DestroyInternal();
	}

	void Texture::DestroyImpl() {
	ToBackend(GetDevice())->gl.DeleteTextures(1, &mHandle);
	mHandle = 0;
	}

	GLuint Texture::GetHandle() const {
	return mHandle;
	}

	GLenum Texture::GetGLTarget() const {
	return mTarget;
	}

	const GLFormat& Texture::GetGLFormat() const {
	return ToBackend(GetDevice())->GetGLFormat(GetFormat());
	}

	MaybeError Texture::ClearTexture(GLint baseMipLevel,
	GLint levelCount,
	GLint baseArrayLayer,
	uint32_t layerCount,
	TextureBase::ClearValue clearValue) {
	// TODO(jiawei.shao@intel.com): initialize the textures with compressed formats.
	if (GetFormat().isCompressed) {
	return {};
	}

	Device* device = ToBackend(GetDevice());
	const OpenGLFunctions& gl = device->gl;
	uint8_t clearColor = (clearValue == TextureBase::ClearValue::Zero) ? 0 : 1;
	if (GetFormat().isRenderable) {
	if (GetFormat().HasDepthOrStencil()) {
	bool doDepthClear = GetFormat().HasDepth();
	bool doStencilClear = GetFormat().HasStencil();
	GLfloat depth = clearColor;
	GLint stencil = clearColor;
	if (doDepthClear) {
	gl.DepthMask(GL_TRUE);
	}
	if (doStencilClear) {
	gl.StencilMask(GetStencilMaskFromStencilFormat(GetFormat().format));
	}

	GLuint framebuffer = 0;
	gl.GenFramebuffers(1, &framebuffer);
	gl.BindFramebuffer(GL_DRAW_FRAMEBUFFER, framebuffer);
	// TODO(natlee@microsoft.com): clear all mip levels and array layers.
	gl.FramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
	GetGLTarget(), GetHandle(), 0);
	if (doDepthClear && doStencilClear) {
	gl.ClearBufferfi(GL_DEPTH_STENCIL, 0, depth, stencil);
	} else if (doDepthClear) {
	gl.ClearBufferfv(GL_DEPTH, 0, &depth);
	} else if (doStencilClear) {
	gl.ClearBufferiv(GL_STENCIL, 0, &stencil);
	}
	gl.DeleteFramebuffers(1, &framebuffer);
	} else {
	static constexpr uint32_t MAX_TEXEL_SIZE = 16;
	ASSERT(GetFormat().blockByteSize <= MAX_TEXEL_SIZE);
	std::array<GLbyte, MAX_TEXEL_SIZE> clearColorData;
	clearColor = (clearValue == TextureBase::ClearValue::Zero) ? 0 : 255;
	clearColorData.fill(clearColor);

	const GLFormat& glFormat = GetGLFormat();
	for (GLint level = baseMipLevel; level < baseMipLevel + levelCount; ++level) {
	Extent3D mipSize = GetMipLevelPhysicalSize(level);
	gl.ClearTexSubImage(mHandle, level, 0, 0, baseArrayLayer, mipSize.width,
	mipSize.height, layerCount, glFormat.format, glFormat.type,
	clearColorData.data());
	}
	}
	} else {
	// TODO(natlee@microsoft.com): test compressed textures are cleared
	// create temp buffer with clear color to copy to the texture image
	ASSERT(kTextureRowPitchAlignment % GetFormat().blockByteSize == 0);
	uint32_t rowPitch =
	Align((GetSize().width / GetFormat().blockWidth) * GetFormat().blockByteSize,
	kTextureRowPitchAlignment);

	// Make sure that we are not rounding
	ASSERT(rowPitch % GetFormat().blockByteSize == 0);
	ASSERT(GetSize().height % GetFormat().blockHeight == 0);

	dawn_native::BufferDescriptor descriptor;
	descriptor.size = rowPitch * (GetSize().height / GetFormat().blockHeight);
	if (descriptor.size > std::numeric_limits<uint32_t>::max()) {
	return DAWN_OUT_OF_MEMORY_ERROR("Unable to allocate buffer.");
	}
	descriptor.nextInChain = nullptr;
	descriptor.usage = dawn::BufferUsage::CopySrc \| dawn::BufferUsage::MapWrite;
	// TODO(natlee@microsoft.com): use Dynamic Uplaoder here for temp buffer
	Ref<Buffer> srcBuffer = ToBackend(device->CreateBuffer(&descriptor));
	// Call release here to prevent memory leak since CreateBuffer will up the ref count to
	// 1, then assigning to Ref<Buffer> ups the ref count to 2. Release will reduce the ref
	// count and ensure it to reach 0 when out of use.
	srcBuffer->Release();

	// Fill the buffer with clear color
	uint8_t* clearBuffer = nullptr;
	DAWN_TRY(srcBuffer->MapAtCreation(&clearBuffer));
	std::fill(reinterpret_cast<uint32_t*>(clearBuffer),
	reinterpret_cast<uint32_t*>(clearBuffer + descriptor.size), clearColor);
	srcBuffer->Unmap();

	// Bind buffer and texture, and make the buffer to texture copy
	gl.PixelStorei(GL_UNPACK_ROW_LENGTH,
	(rowPitch / GetFormat().blockByteSize) * GetFormat().blockWidth);
	gl.PixelStorei(GL_UNPACK_IMAGE_HEIGHT, 0);
	for (GLint level = baseMipLevel; level < baseMipLevel + levelCount; ++level) {
	gl.BindBuffer(GL_PIXEL_UNPACK_BUFFER, srcBuffer->GetHandle());
	gl.ActiveTexture(GL_TEXTURE0);
	gl.BindTexture(GetGLTarget(), GetHandle());

	Extent3D size = GetMipLevelPhysicalSize(level);
	switch (GetDimension()) {
	case dawn::TextureDimension::e2D:
	// TODO(natlee@microsoft.com): This will break when layerCount is greater
	// than 1, because the buffer is only sized for one layer.
	ASSERT(layerCount == 1);
	gl.TexSubImage2D(GetGLTarget(), level, 0, 0, size.width, size.height,
	GetGLFormat().format, GetGLFormat().type, 0);
	break;

	default:
	UNREACHABLE();
	}
	gl.PixelStorei(GL_UNPACK_ROW_LENGTH, 0);
	gl.PixelStorei(GL_UNPACK_IMAGE_HEIGHT, 0);

	gl.BindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
	}
	}
	return {};
	}

	void Texture::EnsureSubresourceContentInitialized(uint32_t baseMipLevel,
	uint32_t levelCount,
	uint32_t baseArrayLayer,
	uint32_t layerCount,
	bool isLazyClear) {
	if (!GetDevice()->IsToggleEnabled(Toggle::LazyClearResourceOnFirstUse)) {
	return;
	}
	if (!IsSubresourceContentInitialized(baseMipLevel, levelCount, baseArrayLayer,
	layerCount)) {
	GetDevice()->ConsumedError(ClearTexture(baseMipLevel, levelCount, baseArrayLayer,
	layerCount, TextureBase::ClearValue::Zero));
	if (isLazyClear) {
	GetDevice()->IncrementLazyClearCountForTesting();
	}
	SetIsSubresourceContentInitialized(baseMipLevel, levelCount, baseArrayLayer,
	layerCount);
	}
	}

	// TextureView

	TextureView::TextureView(TextureBase* texture, const TextureViewDescriptor* descriptor)
	: TextureViewBase(texture, descriptor), mOwnsHandle(false) {
	mTarget = TargetForTextureViewDimension(descriptor->dimension, texture->GetSampleCount());

	if (!UsageNeedsTextureView(texture->GetUsage())) {
	mHandle = 0;
	} else if (!RequiresCreatingNewTextureView(texture, descriptor)) {
	mHandle = ToBackend(texture)->GetHandle();
	} else {
	// glTextureView() is supported on OpenGL version >= 4.3
	// TODO(jiawei.shao@intel.com): support texture view on OpenGL version <= 4.2
	const OpenGLFunctions& gl = ToBackend(GetDevice())->gl;
	mHandle = GenTexture(gl);
	const Texture* textureGL = ToBackend(texture);
	const GLFormat& glFormat = ToBackend(GetDevice())->GetGLFormat(GetFormat());
	gl.TextureView(mHandle, mTarget, textureGL->GetHandle(), glFormat.internalFormat,
	descriptor->baseMipLevel, descriptor->mipLevelCount,
	descriptor->baseArrayLayer, descriptor->arrayLayerCount);
	mOwnsHandle = true;
	}
	}

	TextureView::~TextureView() {
	if (mOwnsHandle) {
	ToBackend(GetDevice())->gl.DeleteTextures(1, &mHandle);
	}
	}

	GLuint TextureView::GetHandle() const {
	ASSERT(mHandle != 0);
	return mHandle;
	}

	GLenum TextureView::GetGLTarget() const {
	return mTarget;
	}

	}} // namespace dawn_native::opengl