making text pretty

apps/LoopThroughWithOpenGLCompositing/OpenGLComposite.cpp

@@ -68,9 +68,12 @@ 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;
+constexpr unsigned kTextTextureWidth = 2048;
+constexpr unsigned kTextTextureHeight = 256;
+constexpr int kTextSdfSpread = 20;
+constexpr unsigned kTextSdfBlurPasses = 1;
+constexpr float kTextFontPixelSize = 144.0f;
+constexpr float kTextLayoutPadding = 48.0f;
 const char* kVertexShaderSource =
 	"#version 430 core\n"
 	"out vec2 vTexCoord;\n"
@@ -230,6 +233,48 @@ std::vector<unsigned char> FlipTextTextureForShaderUv(const std::vector<unsigned
 	return flipped;
 }
 
+std::vector<unsigned char> BlurTextSdf(const std::vector<unsigned char>& pixels, unsigned width, unsigned height, unsigned passes)
+{
+	std::vector<unsigned char> current = pixels;
+	std::vector<unsigned char> next(pixels.size(), 0);
+	for (unsigned pass = 0; pass < passes; ++pass)
+	{
+		for (unsigned y = 0; y < height; ++y)
+		{
+			for (unsigned x = 0; x < width; ++x)
+			{
+				unsigned weightedTotal = 0;
+				unsigned weightSum = 0;
+				for (int oy = -1; oy <= 1; ++oy)
+				{
+					const int sy = static_cast<int>(y) + oy;
+					if (sy < 0 || sy >= static_cast<int>(height))
+						continue;
+					for (int ox = -1; ox <= 1; ++ox)
+					{
+						const int sx = static_cast<int>(x) + ox;
+						if (sx < 0 || sx >= static_cast<int>(width))
+							continue;
+						const unsigned weight = (ox == 0 && oy == 0) ? 4u : ((ox == 0 || oy == 0) ? 2u : 1u);
+						const std::size_t sample = (static_cast<std::size_t>(sy) * width + sx) * 4;
+						weightedTotal += static_cast<unsigned>(current[sample]) * weight;
+						weightSum += weight;
+					}
+				}
+
+				const unsigned char value = static_cast<unsigned char>((weightedTotal + weightSum / 2) / weightSum);
+				const std::size_t out = (static_cast<std::size_t>(y) * width + x) * 4;
+				next[out + 0] = value;
+				next[out + 1] = value;
+				next[out + 2] = value;
+				next[out + 3] = value;
+			}
+		}
+		current.swap(next);
+	}
+	return current;
+}
+
 void WriteTextMaskDebugDump(const std::string& text, const std::vector<unsigned char>& alpha, const std::vector<unsigned char>& sdf, unsigned width, unsigned height)
 {
 	try
@@ -338,15 +383,19 @@ bool RasterizeTextSdf(const std::string& text, const std::filesystem::path& font
 	graphics.SetCompositingMode(Gdiplus::CompositingModeSourceCopy);
 	graphics.Clear(Gdiplus::Color(255, 0, 0, 0));
 	graphics.SetCompositingMode(Gdiplus::CompositingModeSourceOver);
-	graphics.SetTextRenderingHint(Gdiplus::TextRenderingHintAntiAliasGridFit);
+	graphics.SetTextRenderingHint(Gdiplus::TextRenderingHintAntiAlias);
 	graphics.SetSmoothingMode(Gdiplus::SmoothingModeHighQuality);
-	Gdiplus::Font font(fontFamily, 72.0f, Gdiplus::FontStyleRegular, Gdiplus::UnitPixel);
+	Gdiplus::Font font(fontFamily, kTextFontPixelSize, 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 Gdiplus::RectF layout(
+		kTextLayoutPadding,
+		0.0f,
+		static_cast<Gdiplus::REAL>(kTextTextureWidth) - (kTextLayoutPadding * 2.0f),
+		static_cast<Gdiplus::REAL>(kTextTextureHeight));
 	const std::wstring wideText = Utf8ToWide(text);
 	graphics.DrawString(wideText.c_str(), -1, &font, layout, &format, &brush);
 
@@ -366,6 +415,7 @@ bool RasterizeTextSdf(const std::string& text, const std::filesystem::path& font
 		}
 	}
 	sdf = BuildLocalSdf(alpha, kTextTextureWidth, kTextTextureHeight);
+	sdf = BlurTextSdf(sdf, kTextTextureWidth, kTextTextureHeight, kTextSdfBlurPasses);
 	sdf = FlipTextTextureForShaderUv(sdf, kTextTextureWidth, kTextTextureHeight);
 	WriteTextMaskDebugDump(text, alpha, sdf, kTextTextureWidth, kTextTextureHeight);
 	return true;

shaders/text-overlay/shader.slang

@@ -20,8 +20,12 @@ float4 shadeVideo(ShaderContext context)
 	bool insideTextRect = textUv.x >= 0.0 && textUv.x <= 1.0 && textUv.y >= 0.0 && textUv.y <= 1.0;
 
 	float mask = insideTextRect ? sampleTitleText(textUv) : 0.0;
-	float fill = smoothstep(0.48, 0.54, mask);
-	float outline = smoothstep(0.48 - outlineWidth, 0.54 - outlineWidth, mask);
+	float edge = 0.5;
+	float aa = max(fwidth(mask) * 1.5, 0.006);
+	float outlineAmount = min(outlineWidth * 0.25, 0.24);
+	float fill = smoothstep(edge - aa, edge + aa, mask);
+	float outlineField = smoothstep(edge - outlineAmount - aa, edge - outlineAmount + aa, mask);
+	float outline = saturate(outlineField - fill);
 	float textAlpha = max(fill * fillColor.a, outline * outlineColor.a);
 	if (textAlpha <= 0.0001)
 		return context.sourceColor;