impeller/renderer/render_target.cc - mirrors/engine - Git at Google

 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "impeller/renderer/render_target.h"

 #include <sstream>

 #include "impeller/base/strings.h"
 #include "impeller/base/validation.h"
 #include "impeller/core/allocator.h"
 #include "impeller/core/texture.h"
 #include "impeller/renderer/context.h"

 namespace impeller {

 RenderTargetAllocator::RenderTargetAllocator(
     std::shared_ptr<Allocator> allocator)
     : allocator_(std::move(allocator)) {}

 void RenderTargetAllocator::Start() {}

 void RenderTargetAllocator::End() {}

 std::shared_ptr<Texture> RenderTargetAllocator::CreateTexture(
     const TextureDescriptor& desc) {
   return allocator_->CreateTexture(desc);
 }

 RenderTarget::RenderTarget() = default;

 RenderTarget::~RenderTarget() = default;

 bool RenderTarget::IsValid() const {
   // Validate that there is a color attachment at zero index.
   if (!HasColorAttachment(0u)) {
     VALIDATION_LOG
         << "Render target does not have color attachment at index 0.";
     return false;
   }

   // Validate that all attachments are of the same size.
   {
     std::optional<ISize> size;
     bool sizes_are_same = true;
     auto iterator = [&](const Attachment& attachment) -> bool {
       if (!size.has_value()) {
         size = attachment.texture->GetSize();
       }
       if (size != attachment.texture->GetSize()) {
         sizes_are_same = false;
         return false;
       }
       return true;
     };
     IterateAllAttachments(iterator);
     if (!sizes_are_same) {
       VALIDATION_LOG
           << "Sizes of all render target attachments are not the same.";
       return false;
     }
   }

   // Validate that all attachments are of the same type and sample counts.
   {
     std::optional<TextureType> texture_type;
     std::optional<SampleCount> sample_count;
     bool passes_type_validation = true;
     auto iterator = [&](const Attachment& attachment) -> bool {
       if (!texture_type.has_value() || !sample_count.has_value()) {
         texture_type = attachment.texture->GetTextureDescriptor().type;
         sample_count = attachment.texture->GetTextureDescriptor().sample_count;
       }

       if (texture_type != attachment.texture->GetTextureDescriptor().type) {
         passes_type_validation = false;
         VALIDATION_LOG << "Render target has incompatible texture types: "
                        << TextureTypeToString(texture_type.value()) << " != "
                        << TextureTypeToString(
                               attachment.texture->GetTextureDescriptor().type)
                        << " on target " << ToString();
         return false;
       }

       if (sample_count !=
           attachment.texture->GetTextureDescriptor().sample_count) {
         passes_type_validation = false;
         VALIDATION_LOG << "Render target (" << ToString()
                        << ") has incompatible sample counts.";

         return false;
       }

       return true;
     };
     IterateAllAttachments(iterator);
     if (!passes_type_validation) {
       return false;
     }
   }

   return true;
 }

 void RenderTarget::IterateAllAttachments(
     const std::function<bool(const Attachment& attachment)>& iterator) const {
   for (const auto& color : colors_) {
     if (!iterator(color.second)) {
       return;
     }
   }

   if (depth_.has_value()) {
     if (!iterator(depth_.value())) {
       return;
     }
   }

   if (stencil_.has_value()) {
     if (!iterator(stencil_.value())) {
       return;
     }
   }
 }

 SampleCount RenderTarget::GetSampleCount() const {
   if (auto found = colors_.find(0u); found != colors_.end()) {
     return found->second.texture->GetTextureDescriptor().sample_count;
   }
   return SampleCount::kCount1;
 }

 bool RenderTarget::HasColorAttachment(size_t index) const {
   if (auto found = colors_.find(index); found != colors_.end()) {
     return true;
   }
   return false;
 }

 std::optional<ISize> RenderTarget::GetColorAttachmentSize(size_t index) const {
   auto found = colors_.find(index);

   if (found == colors_.end()) {
     return std::nullopt;
   }

   return found->second.texture->GetSize();
 }

 ISize RenderTarget::GetRenderTargetSize() const {
   auto size = GetColorAttachmentSize(0u);
   return size.has_value() ? size.value() : ISize{};
 }

 std::shared_ptr<Texture> RenderTarget::GetRenderTargetTexture() const {
   auto found = colors_.find(0u);
   if (found == colors_.end()) {
     return nullptr;
   }
   return found->second.resolve_texture ? found->second.resolve_texture
                                        : found->second.texture;
 }

 PixelFormat RenderTarget::GetRenderTargetPixelFormat() const {
   if (auto texture = GetRenderTargetTexture(); texture != nullptr) {
     return texture->GetTextureDescriptor().format;
   }

   return PixelFormat::kUnknown;
 }

 size_t RenderTarget::GetMaxColorAttacmentBindIndex() const {
   size_t max = 0;
   for (const auto& color : colors_) {
     max = std::max(color.first, max);
   }
   return max;
 }

 RenderTarget& RenderTarget::SetColorAttachment(
     const ColorAttachment& attachment,
     size_t index) {
   if (attachment.IsValid()) {
     colors_[index] = attachment;
   }
   return *this;
 }

 RenderTarget& RenderTarget::SetDepthAttachment(
     std::optional<DepthAttachment> attachment) {
   if (!attachment.has_value()) {
     depth_ = std::nullopt;
   } else if (attachment->IsValid()) {
     depth_ = std::move(attachment);
   }
   return *this;
 }

 RenderTarget& RenderTarget::SetStencilAttachment(
     std::optional<StencilAttachment> attachment) {
   if (!attachment.has_value()) {
     stencil_ = std::nullopt;
   } else if (attachment->IsValid()) {
     stencil_ = std::move(attachment);
   }
   return *this;
 }

 const std::map<size_t, ColorAttachment>& RenderTarget::GetColorAttachments()
     const {
   return colors_;
 }

 const std::optional<DepthAttachment>& RenderTarget::GetDepthAttachment() const {
   return depth_;
 }

 const std::optional<StencilAttachment>& RenderTarget::GetStencilAttachment()
     const {
   return stencil_;
 }

 RenderTarget RenderTarget::CreateOffscreen(
     const Context& context,
     RenderTargetAllocator& allocator,
     ISize size,
     const std::string& label,
     AttachmentConfig color_attachment_config,
     std::optional<AttachmentConfig> stencil_attachment_config) {
   if (size.IsEmpty()) {
     return {};
   }

   RenderTarget target;
   PixelFormat pixel_format = context.GetCapabilities()->GetDefaultColorFormat();
   TextureDescriptor color_tex0;
   color_tex0.storage_mode = color_attachment_config.storage_mode;
   color_tex0.format = pixel_format;
   color_tex0.size = size;
   color_tex0.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget) |
                      static_cast<uint64_t>(TextureUsage::kShaderRead);

   ColorAttachment color0;
   color0.clear_color = color_attachment_config.clear_color;
   color0.load_action = color_attachment_config.load_action;
   color0.store_action = color_attachment_config.store_action;
   color0.texture = allocator.CreateTexture(color_tex0);

   if (!color0.texture) {
     return {};
   }
   color0.texture->SetLabel(SPrintF("%s Color Texture", label.c_str()));
   target.SetColorAttachment(color0, 0u);

   if (stencil_attachment_config.has_value()) {
     target.SetupStencilAttachment(context, allocator, size, false, label,
                                   stencil_attachment_config.value());
   } else {
     target.SetStencilAttachment(std::nullopt);
   }

   return target;
 }

 RenderTarget RenderTarget::CreateOffscreenMSAA(
     const Context& context,
     RenderTargetAllocator& allocator,
     ISize size,
     const std::string& label,
     AttachmentConfigMSAA color_attachment_config,
     std::optional<AttachmentConfig> stencil_attachment_config) {
   if (size.IsEmpty()) {
     return {};
   }

   RenderTarget target;
   PixelFormat pixel_format = context.GetCapabilities()->GetDefaultColorFormat();

   // Create MSAA color texture.

   TextureDescriptor color0_tex_desc;
   color0_tex_desc.storage_mode = color_attachment_config.storage_mode;
   color0_tex_desc.type = TextureType::kTexture2DMultisample;
   color0_tex_desc.sample_count = SampleCount::kCount4;
   color0_tex_desc.format = pixel_format;
   color0_tex_desc.size = size;
   color0_tex_desc.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget);

   if (context.GetCapabilities()->SupportsImplicitResolvingMSAA()) {
     // See below ("SupportsImplicitResolvingMSAA") for more details.
     color0_tex_desc.storage_mode = StorageMode::kDevicePrivate;
   }

   auto color0_msaa_tex = allocator.CreateTexture(color0_tex_desc);
   if (!color0_msaa_tex) {
     VALIDATION_LOG << "Could not create multisample color texture.";
     return {};
   }
   color0_msaa_tex->SetLabel(
       SPrintF("%s Color Texture (Multisample)", label.c_str()));

   // Create color resolve texture.

   TextureDescriptor color0_resolve_tex_desc;
   color0_resolve_tex_desc.storage_mode =
       color_attachment_config.resolve_storage_mode;
   color0_resolve_tex_desc.format = pixel_format;
   color0_resolve_tex_desc.size = size;
   color0_resolve_tex_desc.compression_type = CompressionType::kLossy;
   color0_resolve_tex_desc.usage =
       static_cast<uint64_t>(TextureUsage::kRenderTarget) |
       static_cast<uint64_t>(TextureUsage::kShaderRead);

   auto color0_resolve_tex = allocator.CreateTexture(color0_resolve_tex_desc);
   if (!color0_resolve_tex) {
     VALIDATION_LOG << "Could not create color texture.";
     return {};
   }
   color0_resolve_tex->SetLabel(SPrintF("%s Color Texture", label.c_str()));

   // Color attachment.

   ColorAttachment color0;
   color0.clear_color = color_attachment_config.clear_color;
   color0.load_action = color_attachment_config.load_action;
   color0.store_action = color_attachment_config.store_action;
   color0.texture = color0_msaa_tex;
   color0.resolve_texture = color0_resolve_tex;

   if (context.GetCapabilities()->SupportsImplicitResolvingMSAA()) {
     // If implicit MSAA is supported, then the resolve texture is not needed
     // because the multisample texture is automatically resolved. We instead
     // provide a view of the multisample texture as the resolve texture (because
     // the HAL does expect a resolve texture).
     //
     // In practice, this is used for GLES 2.0 EXT_multisampled_render_to_texture
     // https://registry.khronos.org/OpenGL/extensions/EXT/EXT_multisampled_render_to_texture.txt
     color0.resolve_texture = color0_msaa_tex;
   }

   target.SetColorAttachment(color0, 0u);

   // Create MSAA stencil texture.

   if (stencil_attachment_config.has_value()) {
     target.SetupStencilAttachment(context, allocator, size, true, label,
                                   stencil_attachment_config.value());
   } else {
     target.SetStencilAttachment(std::nullopt);
   }

   return target;
 }

 void RenderTarget::SetupStencilAttachment(
     const Context& context,
     RenderTargetAllocator& allocator,
     ISize size,
     bool msaa,
     const std::string& label,
     AttachmentConfig stencil_attachment_config) {
   TextureDescriptor stencil_tex0;
   stencil_tex0.storage_mode = stencil_attachment_config.storage_mode;
   if (msaa) {
     stencil_tex0.type = TextureType::kTexture2DMultisample;
     stencil_tex0.sample_count = SampleCount::kCount4;
   }
   stencil_tex0.format = context.GetCapabilities()->GetDefaultStencilFormat();
   stencil_tex0.size = size;
   stencil_tex0.usage =
       static_cast<TextureUsageMask>(TextureUsage::kRenderTarget);

   StencilAttachment stencil0;
   stencil0.load_action = stencil_attachment_config.load_action;
   stencil0.store_action = stencil_attachment_config.store_action;
   stencil0.clear_stencil = 0u;
   stencil0.texture = allocator.CreateTexture(stencil_tex0);

   if (!stencil0.texture) {
     return;  // Error messages are handled by `Allocator::CreateTexture`.
   }
   stencil0.texture->SetLabel(SPrintF("%s Stencil Texture", label.c_str()));
   SetStencilAttachment(std::move(stencil0));
 }

 size_t RenderTarget::GetTotalAttachmentCount() const {
   size_t count = 0u;
   for (const auto& [_, color] : colors_) {
     if (color.texture) {
       count++;
     }
     if (color.resolve_texture) {
       count++;
     }
   }
   if (depth_.has_value()) {
     count++;
   }
   if (stencil_.has_value()) {
     count++;
   }
   return count;
 }

 std::string RenderTarget::ToString() const {
   std::stringstream stream;

   for (const auto& [index, color] : colors_) {
     stream << SPrintF("Color[%zu]=(%s)", index,
                       ColorAttachmentToString(color).c_str());
   }
   if (depth_) {
     stream << ",";
     stream << SPrintF("Depth=(%s)",
                       DepthAttachmentToString(depth_.value()).c_str());
   }
   if (stencil_) {
     stream << ",";
     stream << SPrintF("Stencil=(%s)",
                       StencilAttachmentToString(stencil_.value()).c_str());
   }
   return stream.str();
 }

 }  // namespace impeller
	// Copyright 2013 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "impeller/renderer/render_target.h"

	#include <sstream>

	#include "impeller/base/strings.h"
	#include "impeller/base/validation.h"
	#include "impeller/core/allocator.h"
	#include "impeller/core/texture.h"
	#include "impeller/renderer/context.h"

	namespace impeller {

	RenderTargetAllocator::RenderTargetAllocator(
	std::shared_ptr<Allocator> allocator)
	: allocator_(std::move(allocator)) {}

	void RenderTargetAllocator::Start() {}

	void RenderTargetAllocator::End() {}

	std::shared_ptr<Texture> RenderTargetAllocator::CreateTexture(
	const TextureDescriptor& desc) {
	return allocator_->CreateTexture(desc);
	}

	RenderTarget::RenderTarget() = default;

	RenderTarget::~RenderTarget() = default;

	bool RenderTarget::IsValid() const {
	// Validate that there is a color attachment at zero index.
	if (!HasColorAttachment(0u)) {
	VALIDATION_LOG
	<< "Render target does not have color attachment at index 0.";
	return false;
	}

	// Validate that all attachments are of the same size.
	{
	std::optional<ISize> size;
	bool sizes_are_same = true;
	auto iterator = [&](const Attachment& attachment) -> bool {
	if (!size.has_value()) {
	size = attachment.texture->GetSize();
	}
	if (size != attachment.texture->GetSize()) {
	sizes_are_same = false;
	return false;
	}
	return true;
	};
	IterateAllAttachments(iterator);
	if (!sizes_are_same) {
	VALIDATION_LOG
	<< "Sizes of all render target attachments are not the same.";
	return false;
	}
	}

	// Validate that all attachments are of the same type and sample counts.
	{
	std::optional<TextureType> texture_type;
	std::optional<SampleCount> sample_count;
	bool passes_type_validation = true;
	auto iterator = [&](const Attachment& attachment) -> bool {
	if (!texture_type.has_value() \|\| !sample_count.has_value()) {
	texture_type = attachment.texture->GetTextureDescriptor().type;
	sample_count = attachment.texture->GetTextureDescriptor().sample_count;
	}

	if (texture_type != attachment.texture->GetTextureDescriptor().type) {
	passes_type_validation = false;
	VALIDATION_LOG << "Render target has incompatible texture types: "
	<< TextureTypeToString(texture_type.value()) << " != "
	<< TextureTypeToString(
	attachment.texture->GetTextureDescriptor().type)
	<< " on target " << ToString();
	return false;
	}

	if (sample_count !=
	attachment.texture->GetTextureDescriptor().sample_count) {
	passes_type_validation = false;
	VALIDATION_LOG << "Render target (" << ToString()
	<< ") has incompatible sample counts.";

	return false;
	}

	return true;
	};
	IterateAllAttachments(iterator);
	if (!passes_type_validation) {
	return false;
	}
	}

	return true;
	}

	void RenderTarget::IterateAllAttachments(
	const std::function<bool(const Attachment& attachment)>& iterator) const {
	for (const auto& color : colors_) {
	if (!iterator(color.second)) {
	return;
	}
	}

	if (depth_.has_value()) {
	if (!iterator(depth_.value())) {
	return;
	}
	}

	if (stencil_.has_value()) {
	if (!iterator(stencil_.value())) {
	return;
	}
	}
	}

	SampleCount RenderTarget::GetSampleCount() const {
	if (auto found = colors_.find(0u); found != colors_.end()) {
	return found->second.texture->GetTextureDescriptor().sample_count;
	}
	return SampleCount::kCount1;
	}

	bool RenderTarget::HasColorAttachment(size_t index) const {
	if (auto found = colors_.find(index); found != colors_.end()) {
	return true;
	}
	return false;
	}

	std::optional<ISize> RenderTarget::GetColorAttachmentSize(size_t index) const {
	auto found = colors_.find(index);

	if (found == colors_.end()) {
	return std::nullopt;
	}

	return found->second.texture->GetSize();
	}

	ISize RenderTarget::GetRenderTargetSize() const {
	auto size = GetColorAttachmentSize(0u);
	return size.has_value() ? size.value() : ISize{};
	}

	std::shared_ptr<Texture> RenderTarget::GetRenderTargetTexture() const {
	auto found = colors_.find(0u);
	if (found == colors_.end()) {
	return nullptr;
	}
	return found->second.resolve_texture ? found->second.resolve_texture
	: found->second.texture;
	}

	PixelFormat RenderTarget::GetRenderTargetPixelFormat() const {
	if (auto texture = GetRenderTargetTexture(); texture != nullptr) {
	return texture->GetTextureDescriptor().format;
	}

	return PixelFormat::kUnknown;
	}

	size_t RenderTarget::GetMaxColorAttacmentBindIndex() const {
	size_t max = 0;
	for (const auto& color : colors_) {
	max = std::max(color.first, max);
	}
	return max;
	}

	RenderTarget& RenderTarget::SetColorAttachment(
	const ColorAttachment& attachment,
	size_t index) {
	if (attachment.IsValid()) {
	colors_[index] = attachment;
	}
	return *this;
	}

	RenderTarget& RenderTarget::SetDepthAttachment(
	std::optional<DepthAttachment> attachment) {
	if (!attachment.has_value()) {
	depth_ = std::nullopt;
	} else if (attachment->IsValid()) {
	depth_ = std::move(attachment);
	}
	return *this;
	}

	RenderTarget& RenderTarget::SetStencilAttachment(
	std::optional<StencilAttachment> attachment) {
	if (!attachment.has_value()) {
	stencil_ = std::nullopt;
	} else if (attachment->IsValid()) {
	stencil_ = std::move(attachment);
	}
	return *this;
	}

	const std::map<size_t, ColorAttachment>& RenderTarget::GetColorAttachments()
	const {
	return colors_;
	}

	const std::optional<DepthAttachment>& RenderTarget::GetDepthAttachment() const {
	return depth_;
	}

	const std::optional<StencilAttachment>& RenderTarget::GetStencilAttachment()
	const {
	return stencil_;
	}

	RenderTarget RenderTarget::CreateOffscreen(
	const Context& context,
	RenderTargetAllocator& allocator,
	ISize size,
	const std::string& label,
	AttachmentConfig color_attachment_config,
	std::optional<AttachmentConfig> stencil_attachment_config) {
	if (size.IsEmpty()) {
	return {};
	}

	RenderTarget target;
	PixelFormat pixel_format = context.GetCapabilities()->GetDefaultColorFormat();
	TextureDescriptor color_tex0;
	color_tex0.storage_mode = color_attachment_config.storage_mode;
	color_tex0.format = pixel_format;
	color_tex0.size = size;
	color_tex0.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget) \|
	static_cast<uint64_t>(TextureUsage::kShaderRead);

	ColorAttachment color0;
	color0.clear_color = color_attachment_config.clear_color;
	color0.load_action = color_attachment_config.load_action;
	color0.store_action = color_attachment_config.store_action;
	color0.texture = allocator.CreateTexture(color_tex0);

	if (!color0.texture) {
	return {};
	}
	color0.texture->SetLabel(SPrintF("%s Color Texture", label.c_str()));
	target.SetColorAttachment(color0, 0u);

	if (stencil_attachment_config.has_value()) {
	target.SetupStencilAttachment(context, allocator, size, false, label,
	stencil_attachment_config.value());
	} else {
	target.SetStencilAttachment(std::nullopt);
	}

	return target;
	}

	RenderTarget RenderTarget::CreateOffscreenMSAA(
	const Context& context,
	RenderTargetAllocator& allocator,
	ISize size,
	const std::string& label,
	AttachmentConfigMSAA color_attachment_config,
	std::optional<AttachmentConfig> stencil_attachment_config) {
	if (size.IsEmpty()) {
	return {};
	}

	RenderTarget target;
	PixelFormat pixel_format = context.GetCapabilities()->GetDefaultColorFormat();

	// Create MSAA color texture.

	TextureDescriptor color0_tex_desc;
	color0_tex_desc.storage_mode = color_attachment_config.storage_mode;
	color0_tex_desc.type = TextureType::kTexture2DMultisample;
	color0_tex_desc.sample_count = SampleCount::kCount4;
	color0_tex_desc.format = pixel_format;
	color0_tex_desc.size = size;
	color0_tex_desc.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget);

	if (context.GetCapabilities()->SupportsImplicitResolvingMSAA()) {
	// See below ("SupportsImplicitResolvingMSAA") for more details.
	color0_tex_desc.storage_mode = StorageMode::kDevicePrivate;
	}

	auto color0_msaa_tex = allocator.CreateTexture(color0_tex_desc);
	if (!color0_msaa_tex) {
	VALIDATION_LOG << "Could not create multisample color texture.";
	return {};
	}
	color0_msaa_tex->SetLabel(
	SPrintF("%s Color Texture (Multisample)", label.c_str()));

	// Create color resolve texture.

	TextureDescriptor color0_resolve_tex_desc;
	color0_resolve_tex_desc.storage_mode =
	color_attachment_config.resolve_storage_mode;
	color0_resolve_tex_desc.format = pixel_format;
	color0_resolve_tex_desc.size = size;
	color0_resolve_tex_desc.compression_type = CompressionType::kLossy;
	color0_resolve_tex_desc.usage =
	static_cast<uint64_t>(TextureUsage::kRenderTarget) \|
	static_cast<uint64_t>(TextureUsage::kShaderRead);

	auto color0_resolve_tex = allocator.CreateTexture(color0_resolve_tex_desc);
	if (!color0_resolve_tex) {
	VALIDATION_LOG << "Could not create color texture.";
	return {};
	}
	color0_resolve_tex->SetLabel(SPrintF("%s Color Texture", label.c_str()));

	// Color attachment.

	ColorAttachment color0;
	color0.clear_color = color_attachment_config.clear_color;
	color0.load_action = color_attachment_config.load_action;
	color0.store_action = color_attachment_config.store_action;
	color0.texture = color0_msaa_tex;
	color0.resolve_texture = color0_resolve_tex;

	if (context.GetCapabilities()->SupportsImplicitResolvingMSAA()) {
	// If implicit MSAA is supported, then the resolve texture is not needed
	// because the multisample texture is automatically resolved. We instead
	// provide a view of the multisample texture as the resolve texture (because
	// the HAL does expect a resolve texture).
	//
	// In practice, this is used for GLES 2.0 EXT_multisampled_render_to_texture
	// https://registry.khronos.org/OpenGL/extensions/EXT/EXT_multisampled_render_to_texture.txt
	color0.resolve_texture = color0_msaa_tex;
	}

	target.SetColorAttachment(color0, 0u);

	// Create MSAA stencil texture.

	if (stencil_attachment_config.has_value()) {
	target.SetupStencilAttachment(context, allocator, size, true, label,
	stencil_attachment_config.value());
	} else {
	target.SetStencilAttachment(std::nullopt);
	}

	return target;
	}

	void RenderTarget::SetupStencilAttachment(
	const Context& context,
	RenderTargetAllocator& allocator,
	ISize size,
	bool msaa,
	const std::string& label,
	AttachmentConfig stencil_attachment_config) {
	TextureDescriptor stencil_tex0;
	stencil_tex0.storage_mode = stencil_attachment_config.storage_mode;
	if (msaa) {
	stencil_tex0.type = TextureType::kTexture2DMultisample;
	stencil_tex0.sample_count = SampleCount::kCount4;
	}
	stencil_tex0.format = context.GetCapabilities()->GetDefaultStencilFormat();
	stencil_tex0.size = size;
	stencil_tex0.usage =
	static_cast<TextureUsageMask>(TextureUsage::kRenderTarget);

	StencilAttachment stencil0;
	stencil0.load_action = stencil_attachment_config.load_action;
	stencil0.store_action = stencil_attachment_config.store_action;
	stencil0.clear_stencil = 0u;
	stencil0.texture = allocator.CreateTexture(stencil_tex0);

	if (!stencil0.texture) {
	return; // Error messages are handled by `Allocator::CreateTexture`.
	}
	stencil0.texture->SetLabel(SPrintF("%s Stencil Texture", label.c_str()));
	SetStencilAttachment(std::move(stencil0));
	}

	size_t RenderTarget::GetTotalAttachmentCount() const {
	size_t count = 0u;
	for (const auto& [_, color] : colors_) {
	if (color.texture) {
	count++;
	}
	if (color.resolve_texture) {
	count++;
	}
	}
	if (depth_.has_value()) {
	count++;
	}
	if (stencil_.has_value()) {
	count++;
	}
	return count;
	}

	std::string RenderTarget::ToString() const {
	std::stringstream stream;

	for (const auto& [index, color] : colors_) {
	stream << SPrintF("Color[%zu]=(%s)", index,
	ColorAttachmentToString(color).c_str());
	}
	if (depth_) {
	stream << ",";
	stream << SPrintF("Depth=(%s)",
	DepthAttachmentToString(depth_.value()).c_str());
	}
	if (stencil_) {
	stream << ",";
	stream << SPrintF("Stencil=(%s)",
	StencilAttachmentToString(stencil_.value()).c_str());
	}
	return stream.str();
	}

	} // namespace impeller