Initial font work

apps/LoopThroughWithOpenGLCompositing/OpenGLComposite.cpp

@@ -47,7 +47,10 @@
 #include <cstdint>
 #include <cstring>
 #include <cctype>
+#include <gdiplus.h>
 #include <wincodec.h>
+#include <limits>
+#include <memory>
 #include <set>
 #include <sstream>
 #include <string>
@@ -64,6 +67,9 @@ constexpr GLuint kSourceHistoryTextureUnitBase = 2;
 constexpr GLuint kPackedVideoTextureUnit = 2;
 constexpr GLuint kGlobalParamsBindingPoint = 0;
 constexpr unsigned kPrerollFrameCount = 8;
+constexpr unsigned kTextTextureWidth = 1024;
+constexpr unsigned kTextTextureHeight = 128;
+constexpr int kTextSdfSpread = 10;
 const char* kVertexShaderSource =
 	"#version 430 core\n"
 	"out vec2 vTexCoord;\n"
@@ -108,6 +114,156 @@ void CopyErrorMessage(const std::string& message, int errorMessageSize, char* er
 	strncpy_s(errorMessage, errorMessageSize, message.c_str(), _TRUNCATE);
 }
 
+std::wstring Utf8ToWide(const std::string& text)
+{
+	if (text.empty())
+		return std::wstring();
+	const int required = MultiByteToWideChar(CP_UTF8, 0, text.c_str(), -1, NULL, 0);
+	if (required <= 1)
+		return std::wstring();
+	std::wstring wide(static_cast<std::size_t>(required - 1), L'\0');
+	MultiByteToWideChar(CP_UTF8, 0, text.c_str(), -1, wide.data(), required);
+	return wide;
+}
+
+std::string TextValueForBinding(const RuntimeRenderState& state, const std::string& parameterId)
+{
+	auto valueIt = state.parameterValues.find(parameterId);
+	return valueIt == state.parameterValues.end() ? std::string() : valueIt->second.textValue;
+}
+
+const ShaderFontAsset* FindFontAssetForParameter(const RuntimeRenderState& state, const ShaderParameterDefinition& definition)
+{
+	if (!definition.fontId.empty())
+	{
+		for (const ShaderFontAsset& fontAsset : state.fontAssets)
+		{
+			if (fontAsset.id == definition.fontId)
+				return &fontAsset;
+		}
+	}
+	return state.fontAssets.empty() ? nullptr : &state.fontAssets.front();
+}
+
+std::vector<unsigned char> BuildLocalSdf(const std::vector<unsigned char>& alpha, unsigned width, unsigned height)
+{
+	std::vector<unsigned char> sdf(static_cast<std::size_t>(width) * height * 4, 0);
+	for (unsigned y = 0; y < height; ++y)
+	{
+		for (unsigned x = 0; x < width; ++x)
+		{
+			const bool inside = alpha[static_cast<std::size_t>(y) * width + x] > 127;
+			int bestDistanceSq = kTextSdfSpread * kTextSdfSpread;
+			for (int oy = -kTextSdfSpread; oy <= kTextSdfSpread; ++oy)
+			{
+				const int sy = static_cast<int>(y) + oy;
+				if (sy < 0 || sy >= static_cast<int>(height))
+					continue;
+				for (int ox = -kTextSdfSpread; ox <= kTextSdfSpread; ++ox)
+				{
+					const int sx = static_cast<int>(x) + ox;
+					if (sx < 0 || sx >= static_cast<int>(width))
+						continue;
+					const bool sampleInside = alpha[static_cast<std::size_t>(sy) * width + sx] > 127;
+					if (sampleInside == inside)
+						continue;
+					const int distanceSq = ox * ox + oy * oy;
+					if (distanceSq < bestDistanceSq)
+						bestDistanceSq = distanceSq;
+				}
+			}
+
+			const float distance = std::sqrt(static_cast<float>(bestDistanceSq));
+			const float signedDistance = (inside ? 1.0f : -1.0f) * distance;
+			float normalized = 0.5f + signedDistance / static_cast<float>(kTextSdfSpread * 2);
+			if (normalized < 0.0f)
+				normalized = 0.0f;
+			if (normalized > 1.0f)
+				normalized = 1.0f;
+			const unsigned char value = static_cast<unsigned char>(normalized * 255.0f + 0.5f);
+			const std::size_t out = (static_cast<std::size_t>(y) * width + x) * 4;
+			sdf[out + 0] = value;
+			sdf[out + 1] = value;
+			sdf[out + 2] = value;
+			sdf[out + 3] = value;
+		}
+	}
+	return sdf;
+}
+
+bool RasterizeTextSdf(const std::string& text, const std::filesystem::path& fontPath, std::vector<unsigned char>& sdf, std::string& error)
+{
+	ULONG_PTR gdiplusToken = 0;
+	Gdiplus::GdiplusStartupInput startupInput;
+	if (Gdiplus::GdiplusStartup(&gdiplusToken, &startupInput, NULL) != Gdiplus::Ok)
+	{
+		error = "Could not start GDI+ for text rendering.";
+		return false;
+	}
+
+	Gdiplus::PrivateFontCollection fontCollection;
+	Gdiplus::FontFamily fallbackFamily(L"Arial");
+	Gdiplus::FontFamily* fontFamily = &fallbackFamily;
+	std::unique_ptr<Gdiplus::FontFamily[]> families;
+	const std::wstring wideFontPath = fontPath.empty() ? std::wstring() : fontPath.wstring();
+	if (!wideFontPath.empty())
+	{
+		if (fontCollection.AddFontFile(wideFontPath.c_str()) != Gdiplus::Ok)
+		{
+			Gdiplus::GdiplusShutdown(gdiplusToken);
+			error = "Could not load packaged font file for text rendering: " + fontPath.string();
+			return false;
+		}
+
+		const INT familyCount = fontCollection.GetFamilyCount();
+		if (familyCount <= 0)
+		{
+			Gdiplus::GdiplusShutdown(gdiplusToken);
+			error = "Packaged font did not contain a usable font family: " + fontPath.string();
+			return false;
+		}
+
+		families.reset(new Gdiplus::FontFamily[familyCount]);
+		INT found = 0;
+		if (fontCollection.GetFamilies(familyCount, families.get(), &found) != Gdiplus::Ok || found <= 0)
+		{
+			Gdiplus::GdiplusShutdown(gdiplusToken);
+			error = "Could not read the packaged font family: " + fontPath.string();
+			return false;
+		}
+		fontFamily = &families[0];
+	}
+
+	Gdiplus::Bitmap bitmap(kTextTextureWidth, kTextTextureHeight, PixelFormat32bppARGB);
+	Gdiplus::Graphics graphics(&bitmap);
+	graphics.Clear(Gdiplus::Color(0, 0, 0, 0));
+	graphics.SetTextRenderingHint(Gdiplus::TextRenderingHintAntiAliasGridFit);
+	graphics.SetSmoothingMode(Gdiplus::SmoothingModeHighQuality);
+	Gdiplus::Font font(fontFamily, 72.0f, Gdiplus::FontStyleRegular, Gdiplus::UnitPixel);
+	Gdiplus::SolidBrush brush(Gdiplus::Color(255, 255, 255, 255));
+	Gdiplus::StringFormat format;
+	format.SetAlignment(Gdiplus::StringAlignmentNear);
+	format.SetLineAlignment(Gdiplus::StringAlignmentCenter);
+	format.SetFormatFlags(Gdiplus::StringFormatFlagsNoWrap | Gdiplus::StringFormatFlagsMeasureTrailingSpaces);
+	const Gdiplus::RectF layout(24.0f, 0.0f, static_cast<Gdiplus::REAL>(kTextTextureWidth - 48), static_cast<Gdiplus::REAL>(kTextTextureHeight));
+	const std::wstring wideText = Utf8ToWide(text);
+	graphics.DrawString(wideText.c_str(), -1, &font, layout, &format, &brush);
+
+	std::vector<unsigned char> alpha(static_cast<std::size_t>(kTextTextureWidth) * kTextTextureHeight, 0);
+	for (unsigned y = 0; y < kTextTextureHeight; ++y)
+	{
+		for (unsigned x = 0; x < kTextTextureWidth; ++x)
+		{
+			Gdiplus::Color pixel;
+			bitmap.GetPixel(x, y, &pixel);
+			alpha[static_cast<std::size_t>(y) * kTextTextureWidth + x] = pixel.GetAlpha();
+		}
+	}
+	sdf = BuildLocalSdf(alpha, kTextTextureWidth, kTextTextureHeight);
+	Gdiplus::GdiplusShutdown(gdiplusToken);
+	return true;
+}
+
 std::string NormalizeModeToken(const std::string& value)
 {
 	std::string normalized;
@@ -1488,6 +1644,26 @@ bool OpenGLComposite::compileSingleLayerProgram(const RuntimeRenderState& state,
 		}
 		textureBindings.push_back(textureBinding);
 	}
+	std::vector<LayerProgram::TextBinding> textBindings;
+	for (const ShaderParameterDefinition& definition : state.parameterDefinitions)
+	{
+		if (definition.type != ShaderParameterType::Text)
+			continue;
+		LayerProgram::TextBinding textBinding;
+		textBinding.parameterId = definition.id;
+		textBinding.samplerName = definition.id + "Texture";
+		textBinding.fontId = definition.fontId;
+		glGenTextures(1, &textBinding.texture);
+		glBindTexture(GL_TEXTURE_2D, textBinding.texture);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+		std::vector<unsigned char> empty(static_cast<std::size_t>(kTextTextureWidth) * kTextTextureHeight * 4, 0);
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, kTextTextureWidth, kTextTextureHeight, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, empty.data());
+		glBindTexture(GL_TEXTURE_2D, 0);
+		textBindings.push_back(textBinding);
+	}
 
 	const GLuint globalParamsIndex = glGetUniformBlockIndex(newProgram.get(), "GlobalParams");
 	if (globalParamsIndex != GL_INVALID_INDEX)
@@ -1517,6 +1693,13 @@ bool OpenGLComposite::compileSingleLayerProgram(const RuntimeRenderState& state,
 		if (textureSamplerLocation >= 0)
 			glUniform1i(textureSamplerLocation, static_cast<GLint>(shaderTextureBase + static_cast<GLuint>(index)));
 	}
+	const GLuint textTextureBase = shaderTextureBase + static_cast<GLuint>(textureBindings.size());
+	for (std::size_t index = 0; index < textBindings.size(); ++index)
+	{
+		const GLint textSamplerLocation = glGetUniformLocation(newProgram.get(), textBindings[index].samplerName.c_str());
+		if (textSamplerLocation >= 0)
+			glUniform1i(textSamplerLocation, static_cast<GLint>(textTextureBase + static_cast<GLuint>(index)));
+	}
 	glUseProgram(0);
 
 	layerProgram.layerId = state.layerId;
@@ -1525,6 +1708,7 @@ bool OpenGLComposite::compileSingleLayerProgram(const RuntimeRenderState& state,
 	layerProgram.vertexShader = newVertexShader.release();
 	layerProgram.fragmentShader = newFragmentShader.release();
 	layerProgram.textureBindings.swap(textureBindings);
+	layerProgram.textBindings.swap(textBindings);
 	return true;
 }
 
@@ -1626,6 +1810,15 @@ void OpenGLComposite::destroySingleLayerProgram(LayerProgram& layerProgram)
 		}
 	}
 	layerProgram.textureBindings.clear();
+	for (LayerProgram::TextBinding& textBinding : layerProgram.textBindings)
+	{
+		if (textBinding.texture != 0)
+		{
+			glDeleteTextures(1, &textBinding.texture);
+			textBinding.texture = 0;
+		}
+	}
+	layerProgram.textBindings.clear();
 
 	if (layerProgram.program != 0)
 	{
@@ -1759,6 +1952,35 @@ bool OpenGLComposite::loadTextureAsset(const ShaderTextureAsset& textureAsset, G
 	return true;
 }
 
+bool OpenGLComposite::renderTextBindingTexture(const RuntimeRenderState& state, LayerProgram::TextBinding& textBinding, std::string& error)
+{
+	const std::string text = TextValueForBinding(state, textBinding.parameterId);
+	if (text == textBinding.renderedText && textBinding.renderedWidth == kTextTextureWidth && textBinding.renderedHeight == kTextTextureHeight)
+		return true;
+
+	auto definitionIt = std::find_if(state.parameterDefinitions.begin(), state.parameterDefinitions.end(),
+		[&textBinding](const ShaderParameterDefinition& definition) { return definition.id == textBinding.parameterId; });
+	if (definitionIt == state.parameterDefinitions.end())
+		return true;
+
+	const ShaderFontAsset* fontAsset = FindFontAssetForParameter(state, *definitionIt);
+	std::filesystem::path fontPath;
+	if (fontAsset)
+		fontPath = fontAsset->path;
+
+	std::vector<unsigned char> sdf;
+	if (!RasterizeTextSdf(text, fontPath, sdf, error))
+		return false;
+
+	glBindTexture(GL_TEXTURE_2D, textBinding.texture);
+	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, kTextTextureWidth, kTextTextureHeight, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, sdf.data());
+	glBindTexture(GL_TEXTURE_2D, 0);
+	textBinding.renderedText = text;
+	textBinding.renderedWidth = kTextTextureWidth;
+	textBinding.renderedHeight = kTextTextureHeight;
+	return true;
+}
+
 void OpenGLComposite::bindLayerTextureAssets(const LayerProgram& layerProgram)
 {
 	const unsigned historyCap = mRuntimeHost ? mRuntimeHost->GetMaxTemporalHistoryFrames() : 0;
@@ -1768,6 +1990,12 @@ void OpenGLComposite::bindLayerTextureAssets(const LayerProgram& layerProgram)
 		glActiveTexture(GL_TEXTURE0 + shaderTextureBase + static_cast<GLuint>(index));
 		glBindTexture(GL_TEXTURE_2D, layerProgram.textureBindings[index].texture);
 	}
+	const GLuint textTextureBase = shaderTextureBase + static_cast<GLuint>(layerProgram.textureBindings.size());
+	for (std::size_t index = 0; index < layerProgram.textBindings.size(); ++index)
+	{
+		glActiveTexture(GL_TEXTURE0 + textTextureBase + static_cast<GLuint>(index));
+		glBindTexture(GL_TEXTURE_2D, layerProgram.textBindings[index].texture);
+	}
 	glActiveTexture(GL_TEXTURE0);
 }
 
@@ -1798,8 +2026,15 @@ bool OpenGLComposite::validateTemporalTextureUnitBudget(const std::vector<Runtim
 	unsigned maxAssetTextures = 0;
 	for (const RuntimeRenderState& state : layerStates)
 	{
-		if (state.textureAssets.size() > maxAssetTextures)
-			maxAssetTextures = static_cast<unsigned>(state.textureAssets.size());
+		unsigned textTextureCount = 0;
+		for (const ShaderParameterDefinition& definition : state.parameterDefinitions)
+		{
+			if (definition.type == ShaderParameterType::Text)
+				++textTextureCount;
+		}
+		const unsigned totalShaderTextures = static_cast<unsigned>(state.textureAssets.size()) + textTextureCount;
+		if (totalShaderTextures > maxAssetTextures)
+			maxAssetTextures = totalShaderTextures;
 	}
 	GLint maxTextureUnits = 0;
 	glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, &maxTextureUnits);
@@ -2062,8 +2297,15 @@ void OpenGLComposite::renderEffect()
 		VideoFrameTransfer::endTextureInUse(VideoFrameTransfer::CPUtoGPU);
 }
 
-void OpenGLComposite::renderShaderProgram(GLuint sourceTexture, GLuint destinationFrameBuffer, const LayerProgram& layerProgram, const RuntimeRenderState& state)
+void OpenGLComposite::renderShaderProgram(GLuint sourceTexture, GLuint destinationFrameBuffer, LayerProgram& layerProgram, const RuntimeRenderState& state)
 {
+	for (LayerProgram::TextBinding& textBinding : layerProgram.textBindings)
+	{
+		std::string textError;
+		if (!renderTextBindingTexture(state, textBinding, textError))
+			OutputDebugStringA((textError + "\n").c_str());
+	}
+
 	glBindFramebuffer(GL_FRAMEBUFFER, destinationFrameBuffer);
 	glViewport(0, 0, mInputFrameWidth, mInputFrameHeight);
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
@@ -2086,7 +2328,7 @@ void OpenGLComposite::renderShaderProgram(GLuint sourceTexture, GLuint destinati
 		glBindTexture(GL_TEXTURE_2D, 0);
 	}
 	const GLuint shaderTextureBase = kSourceHistoryTextureUnitBase + historyCap + historyCap;
-	for (std::size_t index = 0; index < layerProgram.textureBindings.size(); ++index)
+	for (std::size_t index = 0; index < layerProgram.textureBindings.size() + layerProgram.textBindings.size(); ++index)
 	{
 		glActiveTexture(GL_TEXTURE0 + shaderTextureBase + static_cast<GLuint>(index));
 		glBindTexture(GL_TEXTURE_2D, 0);
@@ -2223,6 +2465,8 @@ bool OpenGLComposite::updateGlobalParamsBuffer(const RuntimeRenderState& state,
 			AppendStd140Int(buffer, selectedIndex);
 			break;
 		}
+		case ShaderParameterType::Text:
+			break;
 		}
 	}
 

apps/LoopThroughWithOpenGLCompositing/OpenGLComposite.h

@@ -167,12 +167,24 @@ private:
 			GLuint texture = 0;
 		};
 
+		struct TextBinding
+		{
+			std::string parameterId;
+			std::string samplerName;
+			std::string fontId;
+			GLuint texture = 0;
+			std::string renderedText;
+			unsigned renderedWidth = 0;
+			unsigned renderedHeight = 0;
+		};
+
 		std::string layerId;
 		std::string shaderId;
 		GLuint program = 0;
 		GLuint vertexShader = 0;
 		GLuint fragmentShader = 0;
 		std::vector<TextureBinding> textureBindings;
+		std::vector<TextBinding> textBindings;
 	};
 	std::vector<LayerProgram>				mLayerPrograms;
 
@@ -203,8 +215,9 @@ private:
 	void destroySingleLayerProgram(LayerProgram& layerProgram);
 	void destroyDecodeShaderProgram();
 	void renderDecodePass();
-	void renderShaderProgram(GLuint sourceTexture, GLuint destinationFrameBuffer, const LayerProgram& layerProgram, const RuntimeRenderState& state);
+	void renderShaderProgram(GLuint sourceTexture, GLuint destinationFrameBuffer, LayerProgram& layerProgram, const RuntimeRenderState& state);
 	bool loadTextureAsset(const ShaderTextureAsset& textureAsset, GLuint& textureId, std::string& error);
+	bool renderTextBindingTexture(const RuntimeRenderState& state, LayerProgram::TextBinding& textBinding, std::string& error);
 	void bindLayerTextureAssets(const LayerProgram& layerProgram);
 	void renderEffect();
 	bool PollRuntimeChanges();

apps/LoopThroughWithOpenGLCompositing/RuntimeHost.cpp

@@ -133,6 +133,7 @@ std::string ShaderParameterTypeToString(ShaderParameterType type)
 	case ShaderParameterType::Color: return "color";
 	case ShaderParameterType::Boolean: return "bool";
 	case ShaderParameterType::Enum: return "enum";
+	case ShaderParameterType::Text: return "text";
 	}
 	return "unknown";
 }
@@ -179,6 +180,11 @@ bool ParseShaderParameterType(const std::string& typeName, ShaderParameterType&
 		type = ShaderParameterType::Enum;
 		return true;
 	}
+	if (typeName == "text")
+	{
+		type = ShaderParameterType::Text;
+		return true;
+	}
 	return false;
 }
 
@@ -200,6 +206,24 @@ bool TextureAssetsEqual(const std::vector<ShaderTextureAsset>& left, const std::
 	return true;
 }
 
+bool FontAssetsEqual(const std::vector<ShaderFontAsset>& left, const std::vector<ShaderFontAsset>& right)
+{
+	if (left.size() != right.size())
+		return false;
+
+	for (std::size_t index = 0; index < left.size(); ++index)
+	{
+		if (left[index].id != right[index].id ||
+			left[index].path != right[index].path ||
+			left[index].writeTime != right[index].writeTime)
+		{
+			return false;
+		}
+	}
+
+	return true;
+}
+
 std::string ManifestPathMessage(const std::filesystem::path& manifestPath)
 {
 	return manifestPath.string();
@@ -379,6 +403,49 @@ bool ParseTextureAssets(const JsonValue& manifestJson, ShaderPackage& shaderPack
 	return true;
 }
 
+bool ParseFontAssets(const JsonValue& manifestJson, ShaderPackage& shaderPackage, const std::filesystem::path& manifestPath, std::string& error)
+{
+	const JsonValue* fontsValue = nullptr;
+	if (!OptionalArrayField(manifestJson, "fonts", fontsValue, manifestPath, error))
+		return false;
+	if (!fontsValue)
+		return true;
+
+	for (const JsonValue& fontJson : fontsValue->asArray())
+	{
+		if (!fontJson.isObject())
+		{
+			error = "Shader font entry must be an object in: " + ManifestPathMessage(manifestPath);
+			return false;
+		}
+
+		std::string fontId;
+		std::string fontPath;
+		if (!RequireNonEmptyStringField(fontJson, "id", fontId, manifestPath, error) ||
+			!RequireNonEmptyStringField(fontJson, "path", fontPath, manifestPath, error))
+		{
+			error = "Shader font is missing required 'id' or 'path' in: " + ManifestPathMessage(manifestPath);
+			return false;
+		}
+		if (!ValidateShaderIdentifier(fontId, "fonts[].id", manifestPath, error))
+			return false;
+
+		ShaderFontAsset fontAsset;
+		fontAsset.id = fontId;
+		fontAsset.path = shaderPackage.directoryPath / fontPath;
+		if (!std::filesystem::exists(fontAsset.path))
+		{
+			error = "Shader font asset not found for package " + shaderPackage.id + ": " + fontAsset.path.string();
+			return false;
+		}
+
+		fontAsset.writeTime = std::filesystem::last_write_time(fontAsset.path);
+		shaderPackage.fontAssets.push_back(fontAsset);
+	}
+
+	return true;
+}
+
 bool ParseTemporalSettings(const JsonValue& manifestJson, ShaderPackage& shaderPackage, unsigned maxTemporalHistoryFrames, const std::filesystem::path& manifestPath, std::string& error)
 {
 	const JsonValue* temporalValue = nullptr;
@@ -461,6 +528,17 @@ bool ParseParameterDefault(const JsonValue& parameterJson, ShaderParameterDefini
 		return true;
 	}
 
+	if (definition.type == ShaderParameterType::Text)
+	{
+		if (!defaultValue->isString())
+		{
+			error = "Text parameter default must be a string for: " + definition.id;
+			return false;
+		}
+		definition.defaultTextValue = defaultValue->asString();
+		return true;
+	}
+
 	return NumberListFromJsonValue(*defaultValue, definition.defaultNumbers, "default", manifestPath, error);
 }
 
@@ -543,6 +621,30 @@ bool ParseParameterDefinition(const JsonValue& parameterJson, ShaderParameterDef
 		return false;
 	}
 
+	if (definition.type == ShaderParameterType::Text)
+	{
+		if (const JsonValue* fontValue = parameterJson.find("font"))
+		{
+			if (!fontValue->isString())
+			{
+				error = "Text parameter 'font' must be a string for: " + definition.id;
+				return false;
+			}
+			definition.fontId = fontValue->asString();
+			if (!definition.fontId.empty() && !ValidateShaderIdentifier(definition.fontId, "parameters[].font", manifestPath, error))
+				return false;
+		}
+		if (const JsonValue* maxLengthValue = parameterJson.find("maxLength"))
+		{
+			if (!maxLengthValue->isNumber() || maxLengthValue->asNumber() < 1.0 || maxLengthValue->asNumber() > 256.0)
+			{
+				error = "Text parameter 'maxLength' must be a number from 1 to 256 for: " + definition.id;
+				return false;
+			}
+			definition.maxLength = static_cast<unsigned>(maxLengthValue->asNumber());
+		}
+	}
+
 	if (definition.type == ShaderParameterType::Enum)
 		return ParseParameterOptions(parameterJson, definition, manifestPath, error);
 
@@ -693,7 +795,8 @@ bool RuntimeHost::PollFileChanges(bool& registryChanged, bool& reloadRequested,
 				}
 				if (previous->second.shaderWriteTime != item.second.shaderWriteTime ||
 					previous->second.manifestWriteTime != item.second.manifestWriteTime ||
-					!TextureAssetsEqual(previous->second.textureAssets, item.second.textureAssets))
+					!TextureAssetsEqual(previous->second.textureAssets, item.second.textureAssets) ||
+					!FontAssetsEqual(previous->second.fontAssets, item.second.fontAssets))
 				{
 					registryChanged = true;
 					break;
@@ -714,7 +817,8 @@ bool RuntimeHost::PollFileChanges(bool& registryChanged, bool& reloadRequested,
 				if (previous->second.first != active->second.shaderWriteTime ||
 					previous->second.second != active->second.manifestWriteTime ||
 					(previousPackage != previousPackages.end() &&
-						!TextureAssetsEqual(previousPackage->second.textureAssets, active->second.textureAssets)))
+						(!TextureAssetsEqual(previousPackage->second.textureAssets, active->second.textureAssets) ||
+							!FontAssetsEqual(previousPackage->second.fontAssets, active->second.fontAssets))))
 				{
 					mReloadRequested = true;
 				}
@@ -1143,6 +1247,7 @@ std::vector<RuntimeRenderState> RuntimeHost::GetLayerRenderStates(unsigned outpu
 		state.outputHeight = outputHeight;
 		state.parameterDefinitions = shaderIt->second.parameters;
 		state.textureAssets = shaderIt->second.textureAssets;
+		state.fontAssets = shaderIt->second.fontAssets;
 		state.isTemporal = shaderIt->second.temporal.enabled;
 		state.temporalHistorySource = shaderIt->second.temporal.historySource;
 		state.requestedTemporalHistoryLength = shaderIt->second.temporal.requestedHistoryLength;
@@ -1447,6 +1552,7 @@ bool RuntimeHost::ParseShaderManifest(const std::filesystem::path& manifestPath,
 	shaderPackage.manifestWriteTime = std::filesystem::last_write_time(shaderPackage.manifestPath);
 
 	return ParseTextureAssets(manifestJson, shaderPackage, manifestPath, error) &&
+		ParseFontAssets(manifestJson, shaderPackage, manifestPath, error) &&
 		ParseTemporalSettings(manifestJson, shaderPackage, mConfig.maxTemporalHistoryFrames, manifestPath, error) &&
 		ParseParameterDefinitions(manifestJson, shaderPackage, manifestPath, error);
 }
@@ -1692,6 +1798,12 @@ JsonValue RuntimeHost::SerializeLayerStackLocked() const
 				}
 				parameter.set("options", options);
 			}
+			if (definition.type == ShaderParameterType::Text)
+			{
+				parameter.set("maxLength", JsonValue(static_cast<double>(definition.maxLength)));
+				if (!definition.fontId.empty())
+					parameter.set("font", JsonValue(definition.fontId));
+			}
 
 			ShaderParameterValue value = DefaultValueForDefinition(definition);
 			auto valueIt = layer.parameterValues.find(definition.id);
@@ -1830,6 +1942,8 @@ JsonValue RuntimeHost::SerializeParameterValue(const ShaderParameterDefinition&
 		return JsonValue(value.booleanValue);
 	case ShaderParameterType::Enum:
 		return JsonValue(value.enumValue);
+	case ShaderParameterType::Text:
+		return JsonValue(value.textValue);
 	case ShaderParameterType::Float:
 		return JsonValue(value.numberValues.empty() ? 0.0 : value.numberValues.front());
 	case ShaderParameterType::Vec2:

apps/LoopThroughWithOpenGLCompositing/RuntimeParameterUtils.cpp

@@ -36,6 +36,21 @@ std::vector<double> JsonArrayToNumbers(const JsonValue& value)
 	}
 	return numbers;
 }
+
+std::string NormalizeTextValue(const std::string& text, unsigned maxLength)
+{
+	std::string normalized;
+	normalized.reserve(std::min<std::size_t>(text.size(), maxLength));
+	for (unsigned char ch : text)
+	{
+		if (ch < 32 || ch > 126)
+			continue;
+		if (normalized.size() >= maxLength)
+			break;
+		normalized.push_back(static_cast<char>(ch));
+	}
+	return normalized;
+}
 }
 
 std::string MakeSafePresetFileStem(const std::string& presetName)
@@ -82,6 +97,9 @@ ShaderParameterValue DefaultValueForDefinition(const ShaderParameterDefinition&
 	case ShaderParameterType::Enum:
 		value.enumValue = definition.defaultEnumValue;
 		break;
+	case ShaderParameterType::Text:
+		value.textValue = NormalizeTextValue(definition.defaultTextValue, definition.maxLength);
+		break;
 	}
 	return value;
 }
@@ -164,6 +182,14 @@ bool NormalizeAndValidateParameterValue(const ShaderParameterDefinition& definit
 		error = "Enum parameter '" + definition.id + "' received unsupported option '" + selectedValue + "'.";
 		return false;
 	}
+	case ShaderParameterType::Text:
+		if (!value.isString())
+		{
+			error = "Expected string value for text parameter '" + definition.id + "'.";
+			return false;
+		}
+		normalizedValue.textValue = NormalizeTextValue(value.asString(), definition.maxLength);
+		return true;
 	}
 
 	return false;

apps/LoopThroughWithOpenGLCompositing/ShaderCompiler.cpp

@@ -4,6 +4,7 @@
 #include "NativeHandles.h"
 
 #include <fstream>
+#include <cctype>
 #include <regex>
 #include <sstream>
 #include <vector>
@@ -30,15 +31,29 @@ std::string SlangCBufferTypeForParameter(ShaderParameterType type)
 	case ShaderParameterType::Color: return "float4";
 	case ShaderParameterType::Boolean: return "bool";
 	case ShaderParameterType::Enum: return "int";
+	case ShaderParameterType::Text: return "";
 	}
 	return "float";
 }
 
+std::string CapitalizeIdentifier(const std::string& identifier)
+{
+	if (identifier.empty())
+		return identifier;
+	std::string text = identifier;
+	text[0] = static_cast<char>(std::toupper(static_cast<unsigned char>(text[0])));
+	return text;
+}
+
 std::string BuildParameterUniforms(const std::vector<ShaderParameterDefinition>& parameters)
 {
 	std::ostringstream source;
 	for (const ShaderParameterDefinition& definition : parameters)
+	{
+		if (definition.type == ShaderParameterType::Text)
+			continue;
 		source << "\t" << SlangCBufferTypeForParameter(definition.type) << " " << definition.id << ";\n";
+	}
 	return source.str();
 }
 
@@ -60,6 +75,42 @@ std::string BuildTextureSamplerDeclarations(const std::vector<ShaderTextureAsset
 	return source.str();
 }
 
+std::string BuildTextSamplerDeclarations(const std::vector<ShaderParameterDefinition>& parameters)
+{
+	std::ostringstream source;
+	for (const ShaderParameterDefinition& definition : parameters)
+	{
+		if (definition.type != ShaderParameterType::Text)
+			continue;
+		source << "Sampler2D<float4> " << definition.id << "Texture;\n";
+	}
+	if (source.tellp() > 0)
+		source << "\n";
+	return source.str();
+}
+
+std::string BuildTextHelpers(const std::vector<ShaderParameterDefinition>& parameters)
+{
+	std::ostringstream source;
+	for (const ShaderParameterDefinition& definition : parameters)
+	{
+		if (definition.type != ShaderParameterType::Text)
+			continue;
+		const std::string suffix = CapitalizeIdentifier(definition.id);
+		source
+			<< "float sample" << suffix << "(float2 uv)\n"
+			<< "{\n"
+			<< "\treturn " << definition.id << "Texture.Sample(uv).r;\n"
+			<< "}\n\n"
+			<< "float4 draw" << suffix << "(float2 uv, float4 fillColor)\n"
+			<< "{\n"
+			<< "\tfloat alpha = sample" << suffix << "(uv) * fillColor.a;\n"
+			<< "\treturn float4(fillColor.rgb * alpha, alpha);\n"
+			<< "}\n\n";
+	}
+	return source.str();
+}
+
 std::string BuildHistorySwitchCases(const std::string& samplerPrefix, unsigned historyLength)
 {
 	std::ostringstream source;
@@ -118,6 +169,8 @@ bool ShaderCompiler::BuildWrapperSlangSource(const ShaderPackage& shaderPackage,
 	wrapperSource = ReplaceAll(wrapperSource, "{{SOURCE_HISTORY_SAMPLERS}}", BuildHistorySamplerDeclarations("gSourceHistory", mMaxTemporalHistoryFrames));
 	wrapperSource = ReplaceAll(wrapperSource, "{{TEMPORAL_HISTORY_SAMPLERS}}", BuildHistorySamplerDeclarations("gTemporalHistory", mMaxTemporalHistoryFrames));
 	wrapperSource = ReplaceAll(wrapperSource, "{{TEXTURE_SAMPLERS}}", BuildTextureSamplerDeclarations(shaderPackage.textureAssets));
+	wrapperSource = ReplaceAll(wrapperSource, "{{TEXT_SAMPLERS}}", BuildTextSamplerDeclarations(shaderPackage.parameters));
+	wrapperSource = ReplaceAll(wrapperSource, "{{TEXT_HELPERS}}", BuildTextHelpers(shaderPackage.parameters));
 	wrapperSource = ReplaceAll(wrapperSource, "{{SOURCE_HISTORY_SWITCH_CASES}}", BuildHistorySwitchCases("gSourceHistory", mMaxTemporalHistoryFrames));
 	wrapperSource = ReplaceAll(wrapperSource, "{{TEMPORAL_HISTORY_SWITCH_CASES}}", BuildHistorySwitchCases("gTemporalHistory", mMaxTemporalHistoryFrames));
 	wrapperSource = ReplaceAll(wrapperSource, "{{USER_SHADER_INCLUDE}}", shaderPackage.shaderPath.generic_string());

apps/LoopThroughWithOpenGLCompositing/ShaderPackageRegistry.cpp

@@ -67,6 +67,11 @@ bool ParseShaderParameterType(const std::string& typeName, ShaderParameterType&
 		type = ShaderParameterType::Enum;
 		return true;
 	}
+	if (typeName == "text")
+	{
+		type = ShaderParameterType::Text;
+		return true;
+	}
 	return false;
 }
 
@@ -283,6 +288,49 @@ bool ParseTextureAssets(const JsonValue& manifestJson, ShaderPackage& shaderPack
 	return true;
 }
 
+bool ParseFontAssets(const JsonValue& manifestJson, ShaderPackage& shaderPackage, const std::filesystem::path& manifestPath, std::string& error)
+{
+	const JsonValue* fontsValue = nullptr;
+	if (!OptionalArrayField(manifestJson, "fonts", fontsValue, manifestPath, error))
+		return false;
+	if (!fontsValue)
+		return true;
+
+	for (const JsonValue& fontJson : fontsValue->asArray())
+	{
+		if (!fontJson.isObject())
+		{
+			error = "Shader font entry must be an object in: " + ManifestPathMessage(manifestPath);
+			return false;
+		}
+
+		std::string fontId;
+		std::string fontPath;
+		if (!RequireNonEmptyStringField(fontJson, "id", fontId, manifestPath, error) ||
+			!RequireNonEmptyStringField(fontJson, "path", fontPath, manifestPath, error))
+		{
+			error = "Shader font is missing required 'id' or 'path' in: " + ManifestPathMessage(manifestPath);
+			return false;
+		}
+		if (!ValidateShaderIdentifier(fontId, "fonts[].id", manifestPath, error))
+			return false;
+
+		ShaderFontAsset fontAsset;
+		fontAsset.id = fontId;
+		fontAsset.path = shaderPackage.directoryPath / fontPath;
+		if (!std::filesystem::exists(fontAsset.path))
+		{
+			error = "Shader font asset not found for package " + shaderPackage.id + ": " + fontAsset.path.string();
+			return false;
+		}
+
+		fontAsset.writeTime = std::filesystem::last_write_time(fontAsset.path);
+		shaderPackage.fontAssets.push_back(fontAsset);
+	}
+
+	return true;
+}
+
 bool ParseTemporalSettings(const JsonValue& manifestJson, ShaderPackage& shaderPackage, unsigned maxTemporalHistoryFrames, const std::filesystem::path& manifestPath, std::string& error)
 {
 	const JsonValue* temporalValue = nullptr;
@@ -365,6 +413,17 @@ bool ParseParameterDefault(const JsonValue& parameterJson, ShaderParameterDefini
 		return true;
 	}
 
+	if (definition.type == ShaderParameterType::Text)
+	{
+		if (!defaultValue->isString())
+		{
+			error = "Text parameter default must be a string for: " + definition.id;
+			return false;
+		}
+		definition.defaultTextValue = defaultValue->asString();
+		return true;
+	}
+
 	return NumberListFromJsonValue(*defaultValue, definition.defaultNumbers, "default", manifestPath, error);
 }
 
@@ -447,6 +506,30 @@ bool ParseParameterDefinition(const JsonValue& parameterJson, ShaderParameterDef
 		return false;
 	}
 
+	if (definition.type == ShaderParameterType::Text)
+	{
+		if (const JsonValue* fontValue = parameterJson.find("font"))
+		{
+			if (!fontValue->isString())
+			{
+				error = "Text parameter 'font' must be a string for: " + definition.id;
+				return false;
+			}
+			definition.fontId = fontValue->asString();
+			if (!definition.fontId.empty() && !ValidateShaderIdentifier(definition.fontId, "parameters[].font", manifestPath, error))
+				return false;
+		}
+		if (const JsonValue* maxLengthValue = parameterJson.find("maxLength"))
+		{
+			if (!maxLengthValue->isNumber() || maxLengthValue->asNumber() < 1.0 || maxLengthValue->asNumber() > 256.0)
+			{
+				error = "Text parameter 'maxLength' must be a number from 1 to 256 for: " + definition.id;
+				return false;
+			}
+			definition.maxLength = static_cast<unsigned>(maxLengthValue->asNumber());
+		}
+	}
+
 	if (definition.type == ShaderParameterType::Enum)
 		return ParseParameterOptions(parameterJson, definition, manifestPath, error);
 
@@ -544,6 +627,7 @@ bool ShaderPackageRegistry::ParseManifest(const std::filesystem::path& manifestP
 	shaderPackage.manifestWriteTime = std::filesystem::last_write_time(shaderPackage.manifestPath);
 
 	return ParseTextureAssets(manifestJson, shaderPackage, manifestPath, error) &&
+		ParseFontAssets(manifestJson, shaderPackage, manifestPath, error) &&
 		ParseTemporalSettings(manifestJson, shaderPackage, mMaxTemporalHistoryFrames, manifestPath, error) &&
 		ParseParameterDefinitions(manifestJson, shaderPackage, manifestPath, error);
 }

apps/LoopThroughWithOpenGLCompositing/ShaderTypes.h

@@ -11,7 +11,8 @@ enum class ShaderParameterType
 	Vec2,
 	Color,
 	Boolean,
-	Enum
+	Enum,
+	Text
 };
 
 struct ShaderParameterOption
@@ -31,6 +32,9 @@ struct ShaderParameterDefinition
 	std::vector<double> stepNumbers;
 	bool defaultBoolean = false;
 	std::string defaultEnumValue;
+	std::string defaultTextValue;
+	std::string fontId;
+	unsigned maxLength = 64;
 	std::vector<ShaderParameterOption> enumOptions;
 };
 
@@ -39,6 +43,7 @@ struct ShaderParameterValue
 	std::vector<double> numberValues;
 	bool booleanValue = false;
 	std::string enumValue;
+	std::string textValue;
 };
 
 enum class TemporalHistorySource
@@ -63,6 +68,13 @@ struct ShaderTextureAsset
 	std::filesystem::file_time_type writeTime;
 };
 
+struct ShaderFontAsset
+{
+	std::string id;
+	std::filesystem::path path;
+	std::filesystem::file_time_type writeTime;
+};
+
 struct ShaderPackage
 {
 	std::string id;
@@ -75,6 +87,7 @@ struct ShaderPackage
 	std::filesystem::path manifestPath;
 	std::vector<ShaderParameterDefinition> parameters;
 	std::vector<ShaderTextureAsset> textureAssets;
+	std::vector<ShaderFontAsset> fontAssets;
 	TemporalSettings temporal;
 	std::filesystem::file_time_type shaderWriteTime;
 	std::filesystem::file_time_type manifestWriteTime;
@@ -87,6 +100,7 @@ struct RuntimeRenderState
 	std::vector<ShaderParameterDefinition> parameterDefinitions;
 	std::map<std::string, ShaderParameterValue> parameterValues;
 	std::vector<ShaderTextureAsset> textureAssets;
+	std::vector<ShaderFontAsset> fontAssets;
 	double timeSeconds = 0.0;
 	double frameCount = 0.0;
 	double mixAmount = 1.0;