examples/ManualSwapChainTest.cpp - dawn - Git at Google

 // Copyright 2020 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.

 // This is an example to manually test swapchain code. Controls are the following, scoped to the
 // currently focused window:
 //  - W: creates a new window.
 //  - L: Latches the current swapchain, to check what happens when the window changes but not the
 //    swapchain.
 //  - R: switches the rendering mode, between "The Red Triangle" and color-cycling clears that's
 //    (WARNING) likely seizure inducing.
 //  - D: cycles the divisor for the swapchain size.
 //  - P: switches present modes.
 //
 // Closing all the windows exits the example. ^C also works.
 //
 // Things to test manually:
 //
 //  - Basic tests (with the triangle render mode):
 //    - Check the triangle is red on a black background and with the pointy side up.
 //    - Cycle render modes a bunch and check that the triangle background is always solid black.
 //    - Check that rendering triangles to multiple windows works.
 //
 //  - Present mode single-window tests (with cycling color render mode):
 //    - Check that Fifo cycles at about 1 cycle per second and has no tearing.
 //    - Check that Mailbox cycles faster than Fifo and has no tearing.
 //    - Check that Immediate cycles faster than Fifo, it is allowed to have tearing. (dragging
 //      between two monitors can help see tearing)
 //
 //  - Present mode multi-window tests, it should have the same results as single-window tests when
 //    all windows are in the same present mode. In mixed present modes only Immediate windows are
 //    allowed to tear.
 //
 //  - Resizing tests (with the triangle render mode):
 //    - Check that cycling divisors on the triangle produces lower and lower resolution triangles.
 //    - Check latching the swapchain config and resizing the window a bunch (smaller, bigger, and
 //      diagonal aspect ratio).
 //
 //  - Config change tests:
 //    - Check that cycling between present modes works.
 //    - TODO can't be tested yet: check cycling the same window over multiple devices.
 //    - TODO can't be tested yet: check cycling the same window over multiple formats.

 #include "common/Assert.h"
 #include "common/Log.h"
 #include "utils/ComboRenderPipelineDescriptor.h"
 #include "utils/GLFWUtils.h"
 #include "utils/WGPUHelpers.h"

 #include <dawn/dawn_proc.h>
 #include <dawn/webgpu_cpp.h>
 #include <dawn_native/DawnNative.h>
 #include "GLFW/glfw3.h"

 #include <memory>
 #include <unordered_map>

 struct WindowData {
     GLFWwindow* window = nullptr;
     uint64_t serial = 0;

     float clearCycle = 1.0f;
     bool latched = false;
     bool renderTriangle = true;
     uint32_t divisor = 1;

     wgpu::Surface surface = nullptr;
     wgpu::SwapChain swapchain = nullptr;

     wgpu::SwapChainDescriptor currentDesc;
     wgpu::SwapChainDescriptor targetDesc;
 };

 static std::unordered_map<GLFWwindow*, std::unique_ptr<WindowData>> windows;
 static uint64_t windowSerial = 0;

 static std::unique_ptr<dawn_native::Instance> instance;
 static wgpu::Device device;
 static wgpu::Queue queue;
 static wgpu::RenderPipeline trianglePipeline;

 bool IsSameDescriptor(const wgpu::SwapChainDescriptor& a, const wgpu::SwapChainDescriptor& b) {
     return a.usage == b.usage && a.format == b.format && a.width == b.width &&
            a.height == b.height && a.presentMode == b.presentMode;
 }

 void OnKeyPress(GLFWwindow* window, int key, int, int action, int);

 void SyncFromWindow(WindowData* data) {
     int width;
     int height;
     glfwGetFramebufferSize(data->window, &width, &height);

     data->targetDesc.width = std::max(1u, width / data->divisor);
     data->targetDesc.height = std::max(1u, height / data->divisor);
 }

 void AddWindow() {
     glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
     GLFWwindow* window = glfwCreateWindow(400, 400, "", nullptr, nullptr);
     glfwSetKeyCallback(window, OnKeyPress);

     wgpu::SwapChainDescriptor descriptor;
     descriptor.usage = wgpu::TextureUsage::OutputAttachment;
     descriptor.format = wgpu::TextureFormat::BGRA8Unorm;
     descriptor.width = 0;
     descriptor.height = 0;
     descriptor.presentMode = wgpu::PresentMode::Fifo;

     std::unique_ptr<WindowData> data = std::make_unique<WindowData>();
     data->window = window;
     data->serial = windowSerial++;
     data->surface = utils::CreateSurfaceForWindow(instance->Get(), window);
     data->currentDesc = descriptor;
     data->targetDesc = descriptor;
     SyncFromWindow(data.get());

     windows[window] = std::move(data);
 }

 void DoRender(WindowData* data) {
     wgpu::TextureView view = data->swapchain.GetCurrentTextureView();
     wgpu::CommandEncoder encoder = device.CreateCommandEncoder();

     if (data->renderTriangle) {
         utils::ComboRenderPassDescriptor desc({view});
         // Use Load to check the swapchain is lazy cleared (we shouldn't see garbage from previous
         // frames).
         desc.cColorAttachments[0].loadOp = wgpu::LoadOp::Load;

         wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&desc);
         pass.SetPipeline(trianglePipeline);
         pass.Draw(3);
         pass.EndPass();
     } else {
         data->clearCycle -= 1.0 / 60.f;
         if (data->clearCycle < 0.0) {
             data->clearCycle = 1.0f;
         }

         utils::ComboRenderPassDescriptor desc({view});
         desc.cColorAttachments[0].loadOp = wgpu::LoadOp::Clear;
         desc.cColorAttachments[0].clearColor = {data->clearCycle, 1.0f - data->clearCycle, 0.0f, 1.0f};

         wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&desc);
         pass.EndPass();
     }

     wgpu::CommandBuffer commands = encoder.Finish();
     queue.Submit(1, &commands);

     data->swapchain.Present();
 }

 std::ostream& operator<<(std::ostream& o, const wgpu::SwapChainDescriptor& desc) {
     // For now only output attachment is possible.
     ASSERT(desc.usage == wgpu::TextureUsage::OutputAttachment);
     o << "OutputAttachment ";
     o << desc.width << "x" << desc.height << " ";

     // For now only BGRA is allowed
     ASSERT(desc.format == wgpu::TextureFormat::BGRA8Unorm);
     o << "BGRA8Unorm ";

     switch (desc.presentMode) {
         case wgpu::PresentMode::Immediate:
             o << "Immediate";
             break;
         case wgpu::PresentMode::Fifo:
             o << "Fifo";
             break;
         case wgpu::PresentMode::Mailbox:
             o << "Mailbox";
             break;
     }
     return o;
 }

 void UpdateTitle(WindowData* data) {
     std::ostringstream o;

     o << data->serial << " ";
     if (data->divisor != 1) {
         o << "Divisor:" << data->divisor << " ";
     }

     if (data->latched) {
         o << "Latched: (" << data->currentDesc << ") ";
         o << "Target: (" << data->targetDesc << ")";
     } else {
         o << "(" << data->currentDesc << ")";
     }

     glfwSetWindowTitle(data->window, o.str().c_str());
 }

 void OnKeyPress(GLFWwindow* window, int key, int, int action, int) {
     if (action != GLFW_PRESS) {
         return;
     }

     ASSERT(windows.count(window) == 1);

     WindowData* data = windows[window].get();
     switch (key) {
         case GLFW_KEY_W:
             AddWindow();
             break;

         case GLFW_KEY_L:
             data->latched = !data->latched;
             UpdateTitle(data);
             break;

         case GLFW_KEY_R:
             data->renderTriangle = !data->renderTriangle;
             UpdateTitle(data);
             break;

         case GLFW_KEY_D:
             data->divisor *= 2;
             if (data->divisor > 32) {
                 data->divisor = 1;
             }
             break;

         case GLFW_KEY_P:
             switch (data->targetDesc.presentMode) {
                 case wgpu::PresentMode::Immediate:
                     data->targetDesc.presentMode = wgpu::PresentMode::Fifo;
                     break;
                 case wgpu::PresentMode::Fifo:
                     data->targetDesc.presentMode = wgpu::PresentMode::Mailbox;
                     break;
                 case wgpu::PresentMode::Mailbox:
                     data->targetDesc.presentMode = wgpu::PresentMode::Immediate;
                     break;
             }
             break;

         default:
             break;
     }
 }

 int main(int argc, const char* argv[]) {
     // Setup GLFW
     glfwSetErrorCallback([](int code, const char* message) {
         dawn::ErrorLog() << "GLFW error " << code << " " << message;
     });
     if (!glfwInit()) {
         return 1;
     }

     // Choose an adapter we like.
     // TODO: allow switching the window between devices.
     DawnProcTable procs = dawn_native::GetProcs();
     dawnProcSetProcs(&procs);

     instance = std::make_unique<dawn_native::Instance>();
     instance->DiscoverDefaultAdapters();

     std::vector<dawn_native::Adapter> adapters = instance->GetAdapters();
     dawn_native::Adapter chosenAdapter;
     for (dawn_native::Adapter& adapter : adapters) {
         wgpu::AdapterProperties properties;
         adapter.GetProperties(&properties);
         if (properties.backendType != wgpu::BackendType::Null) {
             chosenAdapter = adapter;
             break;
         }
     }
     ASSERT(chosenAdapter);

     // Setup the device on that adapter.
     device = wgpu::Device::Acquire(chosenAdapter.CreateDevice());
     device.SetUncapturedErrorCallback(
         [](WGPUErrorType errorType, const char* message, void*) {
             const char* errorTypeName = "";
             switch (errorType) {
                 case WGPUErrorType_Validation:
                     errorTypeName = "Validation";
                     break;
                 case WGPUErrorType_OutOfMemory:
                     errorTypeName = "Out of memory";
                     break;
                 case WGPUErrorType_Unknown:
                     errorTypeName = "Unknown";
                     break;
                 case WGPUErrorType_DeviceLost:
                     errorTypeName = "Device lost";
                     break;
                 default:
                     UNREACHABLE();
                     return;
             }
             dawn::ErrorLog() << errorTypeName << " error: " << message;
         },
         nullptr);
     queue = device.GetDefaultQueue();

     // The hacky pipeline to render a triangle.
     utils::ComboRenderPipelineDescriptor pipelineDesc(device);
     pipelineDesc.vertexStage.module =
         utils::CreateShaderModule(device, utils::SingleShaderStage::Vertex, R"(
         #version 450
         const vec2 pos[3] = vec2[3](vec2(0.0f, 0.5f), vec2(-0.5f, -0.5f), vec2(0.5f, -0.5f));
         void main() {
            gl_Position = vec4(pos[gl_VertexIndex], 0.0, 1.0);
         })");
     pipelineDesc.cFragmentStage.module =
         utils::CreateShaderModule(device, utils::SingleShaderStage::Fragment, R"(
         #version 450
         layout(location = 0) out vec4 fragColor;
         void main() {
            fragColor = vec4(1.0, 0.0, 0.0, 1.0);
         })");
     pipelineDesc.colorStateCount = 1;
     // BGRA shouldn't be hardcoded. Consider having a map[format -> pipeline].
     pipelineDesc.cColorStates[0].format = wgpu::TextureFormat::BGRA8Unorm;
     trianglePipeline = device.CreateRenderPipeline(&pipelineDesc);

     // Craete the first window, since the example exits when there are no windows.
     AddWindow();

     while (windows.size() != 0) {
         glfwPollEvents();

         for (auto it = windows.begin(); it != windows.end();) {
             GLFWwindow* window = it->first;

             if (glfwWindowShouldClose(window)) {
                 glfwDestroyWindow(window);
                 it = windows.erase(it);
             } else {
                 it++;
             }
         }

         for (auto& it : windows) {
             WindowData* data = it.second.get();

             SyncFromWindow(data);
             if (!IsSameDescriptor(data->currentDesc, data->targetDesc) && !data->latched) {
                 data->swapchain = device.CreateSwapChain(data->surface, &data->targetDesc);
                 data->currentDesc = data->targetDesc;
             }
             UpdateTitle(data);
             DoRender(data);
         }
     }
 }
	// Copyright 2020 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.

	// This is an example to manually test swapchain code. Controls are the following, scoped to the
	// currently focused window:
	// - W: creates a new window.
	// - L: Latches the current swapchain, to check what happens when the window changes but not the
	// swapchain.
	// - R: switches the rendering mode, between "The Red Triangle" and color-cycling clears that's
	// (WARNING) likely seizure inducing.
	// - D: cycles the divisor for the swapchain size.
	// - P: switches present modes.
	//
	// Closing all the windows exits the example. ^C also works.
	//
	// Things to test manually:
	//
	// - Basic tests (with the triangle render mode):
	// - Check the triangle is red on a black background and with the pointy side up.
	// - Cycle render modes a bunch and check that the triangle background is always solid black.
	// - Check that rendering triangles to multiple windows works.
	//
	// - Present mode single-window tests (with cycling color render mode):
	// - Check that Fifo cycles at about 1 cycle per second and has no tearing.
	// - Check that Mailbox cycles faster than Fifo and has no tearing.
	// - Check that Immediate cycles faster than Fifo, it is allowed to have tearing. (dragging
	// between two monitors can help see tearing)
	//
	// - Present mode multi-window tests, it should have the same results as single-window tests when
	// all windows are in the same present mode. In mixed present modes only Immediate windows are
	// allowed to tear.
	//
	// - Resizing tests (with the triangle render mode):
	// - Check that cycling divisors on the triangle produces lower and lower resolution triangles.
	// - Check latching the swapchain config and resizing the window a bunch (smaller, bigger, and
	// diagonal aspect ratio).
	//
	// - Config change tests:
	// - Check that cycling between present modes works.
	// - TODO can't be tested yet: check cycling the same window over multiple devices.
	// - TODO can't be tested yet: check cycling the same window over multiple formats.

	#include "common/Assert.h"
	#include "common/Log.h"
	#include "utils/ComboRenderPipelineDescriptor.h"
	#include "utils/GLFWUtils.h"
	#include "utils/WGPUHelpers.h"

	#include <dawn/dawn_proc.h>
	#include <dawn/webgpu_cpp.h>
	#include <dawn_native/DawnNative.h>
	#include "GLFW/glfw3.h"

	#include <memory>
	#include <unordered_map>

	struct WindowData {
	GLFWwindow* window = nullptr;
	uint64_t serial = 0;

	float clearCycle = 1.0f;
	bool latched = false;
	bool renderTriangle = true;
	uint32_t divisor = 1;

	wgpu::Surface surface = nullptr;
	wgpu::SwapChain swapchain = nullptr;

	wgpu::SwapChainDescriptor currentDesc;
	wgpu::SwapChainDescriptor targetDesc;
	};

	static std::unordered_map<GLFWwindow*, std::unique_ptr<WindowData>> windows;
	static uint64_t windowSerial = 0;

	static std::unique_ptr<dawn_native::Instance> instance;
	static wgpu::Device device;
	static wgpu::Queue queue;
	static wgpu::RenderPipeline trianglePipeline;

	bool IsSameDescriptor(const wgpu::SwapChainDescriptor& a, const wgpu::SwapChainDescriptor& b) {
	return a.usage == b.usage && a.format == b.format && a.width == b.width &&
	a.height == b.height && a.presentMode == b.presentMode;
	}

	void OnKeyPress(GLFWwindow* window, int key, int, int action, int);

	void SyncFromWindow(WindowData* data) {
	int width;
	int height;
	glfwGetFramebufferSize(data->window, &width, &height);

	data->targetDesc.width = std::max(1u, width / data->divisor);
	data->targetDesc.height = std::max(1u, height / data->divisor);
	}

	void AddWindow() {
	glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
	GLFWwindow* window = glfwCreateWindow(400, 400, "", nullptr, nullptr);
	glfwSetKeyCallback(window, OnKeyPress);

	wgpu::SwapChainDescriptor descriptor;
	descriptor.usage = wgpu::TextureUsage::OutputAttachment;
	descriptor.format = wgpu::TextureFormat::BGRA8Unorm;
	descriptor.width = 0;
	descriptor.height = 0;
	descriptor.presentMode = wgpu::PresentMode::Fifo;

	std::unique_ptr<WindowData> data = std::make_unique<WindowData>();
	data->window = window;
	data->serial = windowSerial++;
	data->surface = utils::CreateSurfaceForWindow(instance->Get(), window);
	data->currentDesc = descriptor;
	data->targetDesc = descriptor;
	SyncFromWindow(data.get());

	windows[window] = std::move(data);
	}

	void DoRender(WindowData* data) {
	wgpu::TextureView view = data->swapchain.GetCurrentTextureView();
	wgpu::CommandEncoder encoder = device.CreateCommandEncoder();

	if (data->renderTriangle) {
	utils::ComboRenderPassDescriptor desc({view});
	// Use Load to check the swapchain is lazy cleared (we shouldn't see garbage from previous
	// frames).
	desc.cColorAttachments[0].loadOp = wgpu::LoadOp::Load;

	wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&desc);
	pass.SetPipeline(trianglePipeline);
	pass.Draw(3);
	pass.EndPass();
	} else {
	data->clearCycle -= 1.0 / 60.f;
	if (data->clearCycle < 0.0) {
	data->clearCycle = 1.0f;
	}

	utils::ComboRenderPassDescriptor desc({view});
	desc.cColorAttachments[0].loadOp = wgpu::LoadOp::Clear;
	desc.cColorAttachments[0].clearColor = {data->clearCycle, 1.0f - data->clearCycle, 0.0f, 1.0f};

	wgpu::RenderPassEncoder pass = encoder.BeginRenderPass(&desc);
	pass.EndPass();
	}

	wgpu::CommandBuffer commands = encoder.Finish();
	queue.Submit(1, &commands);

	data->swapchain.Present();
	}

	std::ostream& operator<<(std::ostream& o, const wgpu::SwapChainDescriptor& desc) {
	// For now only output attachment is possible.
	ASSERT(desc.usage == wgpu::TextureUsage::OutputAttachment);
	o << "OutputAttachment ";
	o << desc.width << "x" << desc.height << " ";

	// For now only BGRA is allowed
	ASSERT(desc.format == wgpu::TextureFormat::BGRA8Unorm);
	o << "BGRA8Unorm ";

	switch (desc.presentMode) {
	case wgpu::PresentMode::Immediate:
	o << "Immediate";
	break;
	case wgpu::PresentMode::Fifo:
	o << "Fifo";
	break;
	case wgpu::PresentMode::Mailbox:
	o << "Mailbox";
	break;
	}
	return o;
	}

	void UpdateTitle(WindowData* data) {
	std::ostringstream o;

	o << data->serial << " ";
	if (data->divisor != 1) {
	o << "Divisor:" << data->divisor << " ";
	}

	if (data->latched) {
	o << "Latched: (" << data->currentDesc << ") ";
	o << "Target: (" << data->targetDesc << ")";
	} else {
	o << "(" << data->currentDesc << ")";
	}

	glfwSetWindowTitle(data->window, o.str().c_str());
	}

	void OnKeyPress(GLFWwindow* window, int key, int, int action, int) {
	if (action != GLFW_PRESS) {
	return;
	}

	ASSERT(windows.count(window) == 1);

	WindowData* data = windows[window].get();
	switch (key) {
	case GLFW_KEY_W:
	AddWindow();
	break;

	case GLFW_KEY_L:
	data->latched = !data->latched;
	UpdateTitle(data);
	break;

	case GLFW_KEY_R:
	data->renderTriangle = !data->renderTriangle;
	UpdateTitle(data);
	break;

	case GLFW_KEY_D:
	data->divisor *= 2;
	if (data->divisor > 32) {
	data->divisor = 1;
	}
	break;

	case GLFW_KEY_P:
	switch (data->targetDesc.presentMode) {
	case wgpu::PresentMode::Immediate:
	data->targetDesc.presentMode = wgpu::PresentMode::Fifo;
	break;
	case wgpu::PresentMode::Fifo:
	data->targetDesc.presentMode = wgpu::PresentMode::Mailbox;
	break;
	case wgpu::PresentMode::Mailbox:
	data->targetDesc.presentMode = wgpu::PresentMode::Immediate;
	break;
	}
	break;

	default:
	break;
	}
	}

	int main(int argc, const char* argv[]) {
	// Setup GLFW
	glfwSetErrorCallback([](int code, const char* message) {
	dawn::ErrorLog() << "GLFW error " << code << " " << message;
	});
	if (!glfwInit()) {
	return 1;
	}

	// Choose an adapter we like.
	// TODO: allow switching the window between devices.
	DawnProcTable procs = dawn_native::GetProcs();
	dawnProcSetProcs(&procs);

	instance = std::make_unique<dawn_native::Instance>();
	instance->DiscoverDefaultAdapters();

	std::vector<dawn_native::Adapter> adapters = instance->GetAdapters();
	dawn_native::Adapter chosenAdapter;
	for (dawn_native::Adapter& adapter : adapters) {
	wgpu::AdapterProperties properties;
	adapter.GetProperties(&properties);
	if (properties.backendType != wgpu::BackendType::Null) {
	chosenAdapter = adapter;
	break;
	}
	}
	ASSERT(chosenAdapter);

	// Setup the device on that adapter.
	device = wgpu::Device::Acquire(chosenAdapter.CreateDevice());
	device.SetUncapturedErrorCallback(
	[](WGPUErrorType errorType, const char* message, void*) {
	const char* errorTypeName = "";
	switch (errorType) {
	case WGPUErrorType_Validation:
	errorTypeName = "Validation";
	break;
	case WGPUErrorType_OutOfMemory:
	errorTypeName = "Out of memory";
	break;
	case WGPUErrorType_Unknown:
	errorTypeName = "Unknown";
	break;
	case WGPUErrorType_DeviceLost:
	errorTypeName = "Device lost";
	break;
	default:
	UNREACHABLE();
	return;
	}
	dawn::ErrorLog() << errorTypeName << " error: " << message;
	},
	nullptr);
	queue = device.GetDefaultQueue();

	// The hacky pipeline to render a triangle.
	utils::ComboRenderPipelineDescriptor pipelineDesc(device);
	pipelineDesc.vertexStage.module =
	utils::CreateShaderModule(device, utils::SingleShaderStage::Vertex, R"(
	#version 450
	const vec2 pos[3] = vec2[3](vec2(0.0f, 0.5f), vec2(-0.5f, -0.5f), vec2(0.5f, -0.5f));
	void main() {
	gl_Position = vec4(pos[gl_VertexIndex], 0.0, 1.0);
	})");
	pipelineDesc.cFragmentStage.module =
	utils::CreateShaderModule(device, utils::SingleShaderStage::Fragment, R"(
	#version 450
	layout(location = 0) out vec4 fragColor;
	void main() {
	fragColor = vec4(1.0, 0.0, 0.0, 1.0);
	})");
	pipelineDesc.colorStateCount = 1;
	// BGRA shouldn't be hardcoded. Consider having a map[format -> pipeline].
	pipelineDesc.cColorStates[0].format = wgpu::TextureFormat::BGRA8Unorm;
	trianglePipeline = device.CreateRenderPipeline(&pipelineDesc);

	// Craete the first window, since the example exits when there are no windows.
	AddWindow();

	while (windows.size() != 0) {
	glfwPollEvents();

	for (auto it = windows.begin(); it != windows.end();) {
	GLFWwindow* window = it->first;

	if (glfwWindowShouldClose(window)) {
	glfwDestroyWindow(window);
	it = windows.erase(it);
	} else {
	it++;
	}
	}

	for (auto& it : windows) {
	WindowData* data = it.second.get();

	SyncFromWindow(data);
	if (!IsSameDescriptor(data->currentDesc, data->targetDesc) && !data->latched) {
	data->swapchain = device.CreateSwapChain(data->surface, &data->targetDesc);
	data->currentDesc = data->targetDesc;
	}
	UpdateTitle(data);
	DoRender(data);
	}
	}
	}