PNG writer

CMakeLists.txt

@@ -67,6 +67,8 @@ set(APP_SOURCES
 	"${APP_DIR}/gl/OpenGLRenderer.h"
 	"${APP_DIR}/gl/OpenGLShaderPrograms.cpp"
 	"${APP_DIR}/gl/OpenGLShaderPrograms.h"
+	"${APP_DIR}/gl/PngScreenshotWriter.cpp"
+	"${APP_DIR}/gl/PngScreenshotWriter.h"
 	"${APP_DIR}/gl/ShaderProgramCompiler.cpp"
 	"${APP_DIR}/gl/ShaderProgramCompiler.h"
 	"${APP_DIR}/gl/ShaderBuildQueue.cpp"
@@ -123,6 +125,8 @@ target_link_libraries(LoopThroughWithOpenGLCompositing PRIVATE
 	Crypt32
 	Advapi32
 	Gdiplus
+	Ole32
+	Windowscodecs
 )
 
 target_compile_definitions(LoopThroughWithOpenGLCompositing PRIVATE

README.md

@@ -170,6 +170,12 @@ http://127.0.0.1:<serverPort>/docs
 
 Use those docs to inspect the `/api/state`, layer control, stack preset, and reload endpoints. Live state updates are also sent over the `/ws` WebSocket.
 
+The control UI also has a Screenshot button. It queues a capture of the final output render target and writes a PNG under:
+
+```text
+runtime/screenshots/
+```
+
 ## OSC Control
 
 The native host also listens for local OSC parameter control on the configured `oscPort`:

apps/LoopThroughWithOpenGLCompositing/LoopThroughWithOpenGLCompositing.vcxproj

@@ -99,7 +99,7 @@
       <LanguageStandard>stdcpp17</LanguageStandard>
     </ClCompile>
     <Link>
-      <AdditionalDependencies>opengl32.lib;Glu32.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>opengl32.lib;Glu32.lib;Windowscodecs.lib;Ole32.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <SubSystem>Windows</SubSystem>
       <TargetMachine>MachineX86</TargetMachine>
@@ -121,7 +121,7 @@
       <LanguageStandard>stdcpp17</LanguageStandard>
     </ClCompile>
     <Link>
-      <AdditionalDependencies>opengl32.lib;Glu32.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>opengl32.lib;Glu32.lib;Windowscodecs.lib;Ole32.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <SubSystem>Windows</SubSystem>
       <TargetMachine>MachineX64</TargetMachine>
@@ -141,7 +141,7 @@
       <LanguageStandard>stdcpp17</LanguageStandard>
     </ClCompile>
     <Link>
-      <AdditionalDependencies>opengl32.lib;Glu32.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>opengl32.lib;Glu32.lib;Windowscodecs.lib;Ole32.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <SubSystem>Windows</SubSystem>
       <OptimizeReferences>true</OptimizeReferences>
@@ -166,7 +166,7 @@
       <LanguageStandard>stdcpp17</LanguageStandard>
     </ClCompile>
     <Link>
-      <AdditionalDependencies>opengl32.lib;Glu32.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>opengl32.lib;Glu32.lib;Windowscodecs.lib;Ole32.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <SubSystem>Windows</SubSystem>
       <OptimizeReferences>true</OptimizeReferences>
@@ -181,6 +181,7 @@
     <ClCompile Include="gl\OpenGLRenderPass.cpp" />
     <ClCompile Include="gl\OpenGLRenderer.cpp" />
     <ClCompile Include="gl\OpenGLShaderPrograms.cpp" />
+    <ClCompile Include="gl\PngScreenshotWriter.cpp" />
     <ClCompile Include="gl\ShaderBuildQueue.cpp" />
     <ClCompile Include="gl\TemporalHistoryBuffers.cpp" />
     <ClCompile Include="stdafx.cpp">
@@ -202,6 +203,7 @@
     <ClInclude Include="gl\OpenGLRenderPass.h" />
     <ClInclude Include="gl\OpenGLRenderer.h" />
     <ClInclude Include="gl\OpenGLShaderPrograms.h" />
+    <ClInclude Include="gl\PngScreenshotWriter.h" />
     <ClInclude Include="gl\ShaderBuildQueue.h" />
     <ClInclude Include="gl\TemporalHistoryBuffers.h" />
     <ClInclude Include="resource.h" />

apps/LoopThroughWithOpenGLCompositing/LoopThroughWithOpenGLCompositing.vcxproj.filters

@@ -36,6 +36,9 @@
     <ClCompile Include="gl\OpenGLShaderPrograms.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="gl\PngScreenshotWriter.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="gl\ShaderBuildQueue.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -80,6 +83,9 @@
     <ClInclude Include="gl\OpenGLShaderPrograms.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="gl\PngScreenshotWriter.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="gl\ShaderBuildQueue.h">
       <Filter>Header Files</Filter>
     </ClInclude>

apps/LoopThroughWithOpenGLCompositing/control/ControlServer.cpp

@@ -433,6 +433,11 @@ bool ControlServer::InvokePostRoute(const std::string& path, const JsonValue& ro
 			{
 				return mCallbacks.reloadShader && mCallbacks.reloadShader(error);
 			}
+		},
+		{ "/api/screenshot", [this](const JsonValue&, std::string& error)
+			{
+				return mCallbacks.requestScreenshot && mCallbacks.requestScreenshot(error);
+			}
 		}
 	};
 

apps/LoopThroughWithOpenGLCompositing/control/ControlServer.h

@@ -32,6 +32,7 @@ public:
 		std::function<bool(const std::string&, std::string&)> saveStackPreset;
 		std::function<bool(const std::string&, std::string&)> loadStackPreset;
 		std::function<bool(std::string&)> reloadShader;
+		std::function<bool(std::string&)> requestScreenshot;
 	};
 
 	ControlServer();

apps/LoopThroughWithOpenGLCompositing/control/RuntimeControlBridge.cpp

@@ -26,6 +26,7 @@ bool StartRuntimeControlServices(
 	callbacks.resetLayerParameters = [&composite](const std::string& layerId, std::string& actionError) { return composite.ResetLayerParameters(layerId, actionError); };
 	callbacks.saveStackPreset = [&composite](const std::string& presetName, std::string& actionError) { return composite.SaveStackPreset(presetName, actionError); };
 	callbacks.loadStackPreset = [&composite](const std::string& presetName, std::string& actionError) { return composite.LoadStackPreset(presetName, actionError); };
+	callbacks.requestScreenshot = [&composite](std::string& actionError) { return composite.RequestScreenshot(actionError); };
 	callbacks.reloadShader = [&composite](std::string& actionError) {
 		if (!composite.ReloadShader())
 		{

apps/LoopThroughWithOpenGLCompositing/gl/OpenGLComposite.cpp

@@ -6,10 +6,17 @@
 #include "OpenGLDeckLinkBridge.h"
 #include "OpenGLRenderPass.h"
 #include "OpenGLShaderPrograms.h"
+#include "PngScreenshotWriter.h"
 #include "RuntimeServices.h"
 #include "ShaderBuildQueue.h"
 
+#include <algorithm>
+#include <chrono>
+#include <ctime>
+#include <filesystem>
+#include <iomanip>
 #include <memory>
+#include <sstream>
 #include <string>
 #include <vector>
 
@@ -17,7 +24,8 @@ OpenGLComposite::OpenGLComposite(HWND hWnd, HDC hDC, HGLRC hRC) :
 	hGLWnd(hWnd), hGLDC(hDC), hGLRC(hRC),
 	mDeckLink(std::make_unique<DeckLinkSession>()),
 	mRenderer(std::make_unique<OpenGLRenderer>()),
-	mUseCommittedLayerStates(false)
+	mUseCommittedLayerStates(false),
+	mScreenshotRequested(false)
 {
 	InitializeCriticalSection(&pMutex);
 	mRuntimeHost = std::make_unique<RuntimeHost>();
@@ -29,6 +37,7 @@ OpenGLComposite::OpenGLComposite(HWND hWnd, HDC hDC, HGLRC hRC) :
 		hGLDC,
 		hGLRC,
 		[this]() { renderEffect(); },
+		[this]() { ProcessScreenshotRequest(); },
 		[this]() { paintGL(); });
 	mRenderPass = std::make_unique<OpenGLRenderPass>(*mRenderer);
 	mShaderPrograms = std::make_unique<OpenGLShaderPrograms>(*mRenderer, *mRuntimeHost);
@@ -283,6 +292,13 @@ bool OpenGLComposite::ReloadShader()
 	return true;
 }
 
+bool OpenGLComposite::RequestScreenshot(std::string& error)
+{
+	(void)error;
+	mScreenshotRequested.store(true);
+	return true;
+}
+
 void OpenGLComposite::renderEffect()
 {
 	ProcessRuntimePollResults();
@@ -324,6 +340,69 @@ void OpenGLComposite::renderEffect()
 		});
 }
 
+void OpenGLComposite::ProcessScreenshotRequest()
+{
+	if (!mScreenshotRequested.exchange(false))
+		return;
+
+	const unsigned width = mDeckLink ? mDeckLink->OutputFrameWidth() : 0;
+	const unsigned height = mDeckLink ? mDeckLink->OutputFrameHeight() : 0;
+	if (width == 0 || height == 0)
+		return;
+
+	std::vector<unsigned char> bottomUpPixels(static_cast<std::size_t>(width) * height * 4);
+	std::vector<unsigned char> topDownPixels(bottomUpPixels.size());
+
+	glBindFramebuffer(GL_READ_FRAMEBUFFER, mRenderer->OutputFramebuffer());
+	glReadBuffer(GL_COLOR_ATTACHMENT0);
+	glPixelStorei(GL_PACK_ALIGNMENT, 1);
+	glPixelStorei(GL_PACK_ROW_LENGTH, 0);
+	glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, bottomUpPixels.data());
+	glPixelStorei(GL_PACK_ALIGNMENT, 4);
+
+	const std::size_t rowBytes = static_cast<std::size_t>(width) * 4;
+	for (unsigned y = 0; y < height; ++y)
+	{
+		const unsigned sourceY = height - 1 - y;
+		std::copy(
+			bottomUpPixels.begin() + static_cast<std::ptrdiff_t>(sourceY * rowBytes),
+			bottomUpPixels.begin() + static_cast<std::ptrdiff_t>((sourceY + 1) * rowBytes),
+			topDownPixels.begin() + static_cast<std::ptrdiff_t>(y * rowBytes));
+	}
+
+	try
+	{
+		const std::filesystem::path outputPath = BuildScreenshotPath();
+		std::filesystem::create_directories(outputPath.parent_path());
+		WritePngFileAsync(outputPath, width, height, std::move(topDownPixels));
+	}
+	catch (const std::exception& exception)
+	{
+		OutputDebugStringA((std::string("Screenshot request failed: ") + exception.what() + "\n").c_str());
+	}
+}
+
+std::filesystem::path OpenGLComposite::BuildScreenshotPath() const
+{
+	const std::filesystem::path root = mRuntimeHost && !mRuntimeHost->GetRuntimeRoot().empty()
+		? mRuntimeHost->GetRuntimeRoot()
+		: std::filesystem::current_path();
+
+	const auto now = std::chrono::system_clock::now();
+	const auto milliseconds = std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch()) % 1000;
+	const std::time_t nowTime = std::chrono::system_clock::to_time_t(now);
+	std::tm localTime = {};
+	localtime_s(&localTime, &nowTime);
+
+	std::ostringstream filename;
+	filename << "video-shader-toys-"
+		<< std::put_time(&localTime, "%Y%m%d-%H%M%S")
+		<< "-" << std::setw(3) << std::setfill('0') << milliseconds.count()
+		<< ".png";
+
+	return root / "screenshots" / filename.str();
+}
+
 bool OpenGLComposite::ProcessRuntimePollResults()
 {
 	if (!mRuntimeHost || !mRuntimeServices)

apps/LoopThroughWithOpenGLCompositing/gl/OpenGLComposite.h

@@ -18,6 +18,7 @@
 
 #include <functional>
 #include <atomic>
+#include <filesystem>
 #include <map>
 #include <memory>
 #include <string>
@@ -54,6 +55,7 @@ public:
 	bool ResetLayerParameters(const std::string& layerId, std::string& error);
 	bool SaveStackPreset(const std::string& presetName, std::string& error);
 	bool LoadStackPreset(const std::string& presetName, std::string& error);
+	bool RequestScreenshot(std::string& error);
 	unsigned short GetControlServerPort() const;
 	unsigned short GetOscPort() const;
 	std::string GetControlUrl() const;
@@ -87,11 +89,14 @@ private:
 	std::unique_ptr<RuntimeServices>		mRuntimeServices;
 	std::vector<RuntimeRenderState>			mCachedLayerRenderStates;
 	std::atomic<bool>						mUseCommittedLayerStates;
+	std::atomic<bool>						mScreenshotRequested;
 
 	bool InitOpenGLState();
 	void renderEffect();
 	bool ProcessRuntimePollResults();
 	void RequestShaderBuild();
+	void ProcessScreenshotRequest();
+	std::filesystem::path BuildScreenshotPath() const;
 	void broadcastRuntimeState();
 	void resetTemporalHistoryState();
 };

apps/LoopThroughWithOpenGLCompositing/gl/OpenGLDeckLinkBridge.cpp

@@ -15,6 +15,7 @@ OpenGLDeckLinkBridge::OpenGLDeckLinkBridge(
 	HDC hdc,
 	HGLRC hglrc,
 	RenderEffectCallback renderEffect,
+	OutputReadyCallback outputReady,
 	PaintCallback paint) :
 	mDeckLink(deckLink),
 	mRenderer(renderer),
@@ -23,6 +24,7 @@ OpenGLDeckLinkBridge::OpenGLDeckLinkBridge(
 	mHdc(hdc),
 	mHglrc(hglrc),
 	mRenderEffect(renderEffect),
+	mOutputReady(outputReady),
 	mPaint(paint)
 {
 }
@@ -129,6 +131,8 @@ void OpenGLDeckLinkBridge::PlayoutFrameCompleted(IDeckLinkVideoFrame* completedF
 	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, mRenderer.OutputFramebuffer());
 	glBlitFramebuffer(0, 0, mDeckLink.InputFrameWidth(), mDeckLink.InputFrameHeight(), 0, 0, mDeckLink.OutputFrameWidth(), mDeckLink.OutputFrameHeight(), GL_COLOR_BUFFER_BIT, GL_LINEAR);
 	glBindFramebuffer(GL_FRAMEBUFFER, mRenderer.OutputFramebuffer());
+	if (mOutputReady)
+		mOutputReady();
 	if (mDeckLink.OutputIsTenBit())
 	{
 		glBindFramebuffer(GL_FRAMEBUFFER, mRenderer.OutputPackFramebuffer());

apps/LoopThroughWithOpenGLCompositing/gl/OpenGLDeckLinkBridge.h

@@ -16,6 +16,7 @@ class OpenGLDeckLinkBridge
 {
 public:
 	using RenderEffectCallback = std::function<void()>;
+	using OutputReadyCallback = std::function<void()>;
 	using PaintCallback = std::function<void()>;
 
 	OpenGLDeckLinkBridge(
@@ -26,6 +27,7 @@ public:
 		HDC hdc,
 		HGLRC hglrc,
 		RenderEffectCallback renderEffect,
+		OutputReadyCallback outputReady,
 		PaintCallback paint);
 
 	void VideoFrameArrived(IDeckLinkVideoInputFrame* inputFrame, bool hasNoInputSource);
@@ -41,6 +43,7 @@ private:
 	HDC mHdc;
 	HGLRC mHglrc;
 	RenderEffectCallback mRenderEffect;
+	OutputReadyCallback mOutputReady;
 	PaintCallback mPaint;
 	std::chrono::steady_clock::time_point mLastPlayoutCompletionTime;
 	double mCompletionIntervalMilliseconds = 0.0;

apps/LoopThroughWithOpenGLCompositing/gl/PngScreenshotWriter.cpp

@@ -0,0 +1,133 @@
+#include "PngScreenshotWriter.h"
+
+#include <windows.h>
+#include <wincodec.h>
+#include <atlbase.h>
+
+#include <sstream>
+#include <thread>
+
+namespace
+{
+std::string HResultToString(HRESULT hr)
+{
+	std::ostringstream stream;
+	stream << "HRESULT 0x" << std::hex << static_cast<unsigned long>(hr);
+	return stream.str();
+}
+
+bool WritePngFile(
+	const std::filesystem::path& outputPath,
+	unsigned width,
+	unsigned height,
+	const std::vector<unsigned char>& rgbaPixels,
+	std::string& error)
+{
+	if (width == 0 || height == 0 || rgbaPixels.size() < static_cast<std::size_t>(width) * height * 4)
+	{
+		error = "Invalid screenshot dimensions or pixel buffer.";
+		return false;
+	}
+
+	HRESULT initializeResult = CoInitializeEx(nullptr, COINIT_MULTITHREADED);
+	const bool shouldUninitialize = SUCCEEDED(initializeResult);
+	if (FAILED(initializeResult) && initializeResult != RPC_E_CHANGED_MODE)
+	{
+		error = "CoInitializeEx failed: " + HResultToString(initializeResult);
+		return false;
+	}
+
+	CComPtr<IWICImagingFactory> factory;
+	HRESULT result = CoCreateInstance(
+		CLSID_WICImagingFactory,
+		nullptr,
+		CLSCTX_INPROC_SERVER,
+		IID_PPV_ARGS(&factory));
+	if (FAILED(result))
+	{
+		error = "Could not create WIC imaging factory: " + HResultToString(result);
+		if (shouldUninitialize)
+			CoUninitialize();
+		return false;
+	}
+
+	CComPtr<IWICStream> stream;
+	result = factory->CreateStream(&stream);
+	if (SUCCEEDED(result))
+		result = stream->InitializeFromFilename(outputPath.wstring().c_str(), GENERIC_WRITE);
+	if (FAILED(result))
+	{
+		error = "Could not open screenshot output file: " + HResultToString(result);
+		if (shouldUninitialize)
+			CoUninitialize();
+		return false;
+	}
+
+	CComPtr<IWICBitmapEncoder> encoder;
+	result = factory->CreateEncoder(GUID_ContainerFormatPng, nullptr, &encoder);
+	if (SUCCEEDED(result))
+		result = encoder->Initialize(stream, WICBitmapEncoderNoCache);
+	if (FAILED(result))
+	{
+		error = "Could not initialize PNG encoder: " + HResultToString(result);
+		if (shouldUninitialize)
+			CoUninitialize();
+		return false;
+	}
+
+	CComPtr<IWICBitmapFrameEncode> frame;
+	CComPtr<IPropertyBag2> propertyBag;
+	result = encoder->CreateNewFrame(&frame, &propertyBag);
+	if (SUCCEEDED(result))
+		result = frame->Initialize(propertyBag);
+	if (SUCCEEDED(result))
+		result = frame->SetSize(width, height);
+
+	WICPixelFormatGUID pixelFormat = GUID_WICPixelFormat32bppRGBA;
+	if (SUCCEEDED(result))
+		result = frame->SetPixelFormat(&pixelFormat);
+	if (SUCCEEDED(result) && pixelFormat != GUID_WICPixelFormat32bppRGBA)
+	{
+		error = "PNG encoder did not accept RGBA pixel format.";
+		result = E_FAIL;
+	}
+
+	const UINT stride = width * 4;
+	const UINT imageSize = stride * height;
+	if (SUCCEEDED(result))
+		result = frame->WritePixels(height, stride, imageSize, const_cast<BYTE*>(rgbaPixels.data()));
+	if (SUCCEEDED(result))
+		result = frame->Commit();
+	if (SUCCEEDED(result))
+		result = encoder->Commit();
+
+	if (shouldUninitialize)
+		CoUninitialize();
+
+	if (FAILED(result))
+	{
+		error = "Could not write screenshot PNG: " + HResultToString(result);
+		return false;
+	}
+
+	return true;
+}
+}
+
+void WritePngFileAsync(
+	const std::filesystem::path& outputPath,
+	unsigned width,
+	unsigned height,
+	std::vector<unsigned char> rgbaPixels)
+{
+	std::thread(
+		[outputPath, width, height, pixels = std::move(rgbaPixels)]() mutable
+		{
+			std::string error;
+			if (!WritePngFile(outputPath, width, height, pixels, error))
+				OutputDebugStringA(("Screenshot write failed: " + error + "\n").c_str());
+			else
+				OutputDebugStringA(("Screenshot written: " + outputPath.string() + "\n").c_str());
+		}).detach();
+}
+

apps/LoopThroughWithOpenGLCompositing/gl/PngScreenshotWriter.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include <filesystem>
+#include <string>
+#include <vector>
+
+void WritePngFileAsync(
+	const std::filesystem::path& outputPath,
+	unsigned width,
+	unsigned height,
+	std::vector<unsigned char> rgbaPixels);
+

docs/openapi.yaml

@@ -214,6 +214,24 @@ paths:
           $ref: "#/components/responses/ActionOk"
         "400":
           $ref: "#/components/responses/ActionError"
+  /api/screenshot:
+    post:
+      tags: [Runtime]
+      summary: Queue a PNG screenshot of the final output render target
+      description: Captures the next completed output render target and writes it under `runtime/screenshots/`.
+      operationId: queueScreenshot
+      requestBody:
+        required: false
+        content:
+          application/json:
+            schema:
+              type: object
+              additionalProperties: false
+      responses:
+        "200":
+          $ref: "#/components/responses/ActionOk"
+        "400":
+          $ref: "#/components/responses/ActionError"
 components:
   responses:
     ActionOk:

shaders/fisheye-equirectangular-mirror/shader.json

@@ -0,0 +1,90 @@
+{
+  "id": "fisheye-equirectangular-mirror",
+  "name": "Fisheye Equirectangular Mirror",
+  "description": "Unwraps a single fisheye lens into a 360x180 equirectangular map by mirroring the rear hemisphere into the same fisheye source.",
+  "category": "Projection",
+  "entryPoint": "shadeVideo",
+  "parameters": [
+    {
+      "id": "lensFovDegrees",
+      "label": "Lens FOV",
+      "type": "float",
+      "default": 180.0,
+      "min": 1.0,
+      "max": 220.0,
+      "step": 0.1
+    },
+    {
+      "id": "center",
+      "label": "Optical Center",
+      "type": "vec2",
+      "default": [0.5, 0.5],
+      "min": [0.0, 0.0],
+      "max": [1.0, 1.0],
+      "step": [0.001, 0.001]
+    },
+    {
+      "id": "radius",
+      "label": "Fisheye Radius",
+      "type": "vec2",
+      "default": [0.5, 0.5],
+      "min": [0.001, 0.001],
+      "max": [2.0, 2.0],
+      "step": [0.001, 0.001]
+    },
+    {
+      "id": "yawDegrees",
+      "label": "Yaw",
+      "type": "float",
+      "default": 0.0,
+      "min": -180.0,
+      "max": 180.0,
+      "step": 0.1
+    },
+    {
+      "id": "pitchDegrees",
+      "label": "Pitch",
+      "type": "float",
+      "default": 0.0,
+      "min": -120.0,
+      "max": 120.0,
+      "step": 0.1
+    },
+    {
+      "id": "rollDegrees",
+      "label": "Roll",
+      "type": "float",
+      "default": 0.0,
+      "min": -180.0,
+      "max": 180.0,
+      "step": 0.1
+    },
+    {
+      "id": "seamAngleDegrees",
+      "label": "Seam Angle",
+      "type": "float",
+      "default": 0.0,
+      "min": -180.0,
+      "max": 180.0,
+      "step": 0.1
+    },
+    {
+      "id": "fisheyeModel",
+      "label": "Fisheye Model",
+      "type": "enum",
+      "default": "equidistant",
+      "options": [
+        { "value": "equidistant", "label": "Equidistant" },
+        { "value": "equisolid", "label": "Equisolid" },
+        { "value": "stereographic", "label": "Stereographic" },
+        { "value": "orthographic", "label": "Orthographic" }
+      ]
+    },
+    {
+      "id": "outsideColor",
+      "label": "Outside Color",
+      "type": "color",
+      "default": [0.0, 0.0, 0.0, 1.0]
+    }
+  ]
+}

shaders/fisheye-equirectangular-mirror/shader.slang

@@ -0,0 +1,93 @@
+static const float PI = 3.14159265358979323846;
+static const float TWO_PI = 6.28318530717958647692;
+
+float radiansFromDegrees(float degrees)
+{
+	return degrees * (PI / 180.0);
+}
+
+float3 rotateX(float3 ray, float angle)
+{
+	float s = sin(angle);
+	float c = cos(angle);
+	return float3(ray.x, c * ray.y - s * ray.z, s * ray.y + c * ray.z);
+}
+
+float3 rotateY(float3 ray, float angle)
+{
+	float s = sin(angle);
+	float c = cos(angle);
+	return float3(c * ray.x + s * ray.z, ray.y, -s * ray.x + c * ray.z);
+}
+
+float3 rotateZ(float3 ray, float angle)
+{
+	float s = sin(angle);
+	float c = cos(angle);
+	return float3(c * ray.x - s * ray.y, s * ray.x + c * ray.y, ray.z);
+}
+
+float normalizedFisheyeRadius(float theta, float halfFov)
+{
+	float safeHalfFov = max(halfFov, 0.0001);
+
+	if (fisheyeModel == 1)
+	{
+		return sin(theta * 0.5) / max(sin(safeHalfFov * 0.5), 0.0001);
+	}
+	else if (fisheyeModel == 2)
+	{
+		return tan(theta * 0.5) / max(tan(safeHalfFov * 0.5), 0.0001);
+	}
+	else if (fisheyeModel == 3)
+	{
+		return sin(theta) / max(sin(safeHalfFov), 0.0001);
+	}
+
+	return theta / safeHalfFov;
+}
+
+float3 equirectangularRay(float2 uv)
+{
+	float longitude = (uv.x - 0.5) * TWO_PI + radiansFromDegrees(seamAngleDegrees);
+	float latitude = (0.5 - uv.y) * PI;
+	float latitudeCos = cos(latitude);
+
+	return normalize(float3(
+		sin(longitude) * latitudeCos,
+		sin(latitude),
+		cos(longitude) * latitudeCos
+	));
+}
+
+float4 shadeVideo(ShaderContext context)
+{
+	float3 ray = equirectangularRay(context.uv);
+
+	ray = rotateZ(ray, radiansFromDegrees(rollDegrees));
+	ray = rotateX(ray, radiansFromDegrees(-pitchDegrees));
+	ray = rotateY(ray, radiansFromDegrees(yawDegrees));
+
+	// Mirror the rear hemisphere into the front-facing fisheye image so one
+	// circular lens source fills both halves of the equirectangular output.
+	ray.z = abs(ray.z);
+	ray = normalize(ray);
+
+	float halfFov = radiansFromDegrees(clamp(lensFovDegrees, 1.0, 220.0) * 0.5);
+	float theta = acos(clamp(ray.z, -1.0, 1.0));
+	if (theta > halfFov)
+		return outsideColor;
+
+	float phi = atan2(ray.y, ray.x);
+	float fisheyeRadius = normalizedFisheyeRadius(theta, halfFov);
+
+	float2 sourceUv = float2(
+		center.x + cos(phi) * fisheyeRadius * radius.x,
+		center.y - sin(phi) * fisheyeRadius * radius.y
+	);
+
+	if (sourceUv.x < 0.0 || sourceUv.x > 1.0 || sourceUv.y < 0.0 || sourceUv.y > 1.0)
+		return outsideColor;
+
+	return sampleVideo(sourceUv);
+}

ui/src/components/StackPresetToolbar.jsx

@@ -1,4 +1,5 @@
-import { FolderOpen, RefreshCw, Save } from "lucide-react";
+import { Camera, FolderOpen, RefreshCw, Save } from "lucide-react";
+import { useState } from "react";
 
 import { postJson } from "../api/controlApi";
 
@@ -9,6 +10,17 @@ export function StackPresetToolbar({
   onPresetNameChange,
   onSelectedPresetNameChange,
 }) {
+  const [screenshotQueued, setScreenshotQueued] = useState(false);
+
+  async function requestScreenshot() {
+    setScreenshotQueued(true);
+    try {
+      await postJson("/api/screenshot", {});
+    } finally {
+      window.setTimeout(() => setScreenshotQueued(false), 1200);
+    }
+  }
+
   return (
     <div className="panel stack-panel">
       <div className="panel__header stack-panel__header">
@@ -16,14 +28,24 @@ export function StackPresetToolbar({
           <h3>Stack presets</h3>
           <p className="muted">Save or recall the current layer chain.</p>
         </div>
-        <button
+        <div className="stack-panel__actions">
-          type="button"
+          <button
-          className="button-with-icon stack-panel__reload"
+            type="button"
-          onClick={() => postJson("/api/reload", {})}
+            className="button-with-icon stack-panel__screenshot"
-        >
+            onClick={requestScreenshot}
-          <RefreshCw size={16} strokeWidth={1.9} aria-hidden="true" />
+          >
-          <span>Reload shader</span>
+            <Camera size={16} strokeWidth={1.9} aria-hidden="true" />
-        </button>
+            <span>{screenshotQueued ? "Queued" : "Screenshot"}</span>
+          </button>
+          <button
+            type="button"
+            className="button-with-icon stack-panel__reload"
+            onClick={() => postJson("/api/reload", {})}
+          >
+            <RefreshCw size={16} strokeWidth={1.9} aria-hidden="true" />
+            <span>Reload shader</span>
+          </button>
+        </div>
       </div>
 
       <div className="stack-panel__grid">

ui/src/styles.css

@@ -498,10 +498,21 @@ pre {
   align-content: start;
 }
 
+.stack-panel__actions {
+  display: flex;
+  flex-wrap: wrap;
+  justify-content: flex-end;
+  gap: 0.5rem;
+}
+
 .stack-panel__reload {
   min-width: 8.75rem;
 }
 
+.stack-panel__screenshot {
+  min-width: 8.75rem;
+}
+
 .toolbar__group {
   display: grid;
   gap: 0.5rem;