V1 text, needs improvements

README.md

@@ -232,7 +232,7 @@ If your Windows runner stores the Blackmagic SDK outside the repo, configure `GP
 
 ## Still todo
 Audio
-Fonts
+improve text rendering
 genlock
 Logs
 anamorphic desqueeze
@@ -240,6 +240,6 @@ solid color layer
 refactor, cleanup of source files
 display URL (Maybe clicakable) for control in the windows app (Not on the output)
 Sound shader as seperate .slang in shader package?
-runtime date time
+runtime date time UTC and offset from PCs internal clock
 Add a value control to the color wheels
 ![alt text](image.png)

apps/LoopThroughWithOpenGLCompositing/OpenGLComposite.cpp

@@ -205,6 +205,9 @@ std::vector<unsigned char> BuildLocalSdf(const std::vector<unsigned char>& alpha
 			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);
+			const unsigned char sourceAlpha = alpha[static_cast<std::size_t>(y) * width + x];
+			if (sourceAlpha > 0 && sourceAlpha < 255)
+				normalized = static_cast<float>(sourceAlpha) / 255.0f;
 			if (normalized < 0.0f)
 				normalized = 0.0f;
 			if (normalized > 1.0f)
@@ -220,6 +223,24 @@ std::vector<unsigned char> BuildLocalSdf(const std::vector<unsigned char>& alpha
 	return sdf;
 }
 
+std::vector<unsigned char> BuildTextCoverageTexture(const std::vector<unsigned char>& alpha, unsigned width, unsigned height)
+{
+	std::vector<unsigned char> coverage(static_cast<std::size_t>(width) * height * 4, 0);
+	for (unsigned y = 0; y < height; ++y)
+	{
+		for (unsigned x = 0; x < width; ++x)
+		{
+			const unsigned char value = alpha[static_cast<std::size_t>(y) * width + x];
+			const std::size_t out = (static_cast<std::size_t>(y) * width + x) * 4;
+			coverage[out + 0] = value;
+			coverage[out + 1] = value;
+			coverage[out + 2] = value;
+			coverage[out + 3] = value;
+		}
+	}
+	return coverage;
+}
+
 std::vector<unsigned char> FlipTextTextureForShaderUv(const std::vector<unsigned char>& pixels, unsigned width, unsigned height)
 {
 	std::vector<unsigned char> flipped(pixels.size(), 0);
@@ -414,7 +435,7 @@ bool RasterizeTextSdf(const std::string& text, const std::filesystem::path& font
 			alpha[static_cast<std::size_t>(y) * kTextTextureWidth + x] = static_cast<unsigned char>(luminance);
 		}
 	}
-	sdf = BuildLocalSdf(alpha, kTextTextureWidth, kTextTextureHeight);
+	sdf = BuildTextCoverageTexture(alpha, kTextTextureWidth, kTextTextureHeight);
 	sdf = BlurTextSdf(sdf, kTextTextureWidth, kTextTextureHeight, kTextSdfBlurPasses);
 	sdf = FlipTextTextureForShaderUv(sdf, kTextTextureWidth, kTextTextureHeight);
 	WriteTextMaskDebugDump(text, alpha, sdf, kTextTextureWidth, kTextTextureHeight);

shaders/text-overlay/shader.json

@@ -57,6 +57,15 @@
       "min": 0.0,
       "max": 0.5,
       "step": 0.01
+    },
+    {
+      "id": "softness",
+      "label": "Softness",
+      "type": "float",
+      "default": 0.04,
+      "min": 0.0,
+      "max": 0.3,
+      "step": 0.01
     }
   ]
 }

shaders/text-overlay/shader.slang

@@ -20,18 +20,27 @@ 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 edge = 0.5;
-	float aa = max(fwidth(mask) * 1.5, 0.006);
-	float outlineAmount = min(outlineWidth * 0.25, 0.24);
+	float edge = 0.02;
+	float aa = max(fwidth(mask) * 1.5, 0.002);
 	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);
+	float shadowRadius = min((outlineWidth + softness) * 0.025, 0.018);
+	float shadow = 0.0;
+	if (shadowRadius > 0.0001)
+	{
+		shadow = max(shadow, sampleTitleText(textUv + float2(shadowRadius, shadowRadius)));
+		shadow = max(shadow, sampleTitleText(textUv + float2(-shadowRadius, shadowRadius)));
+		shadow = max(shadow, sampleTitleText(textUv + float2(shadowRadius, -shadowRadius)));
+		shadow = max(shadow, sampleTitleText(textUv + float2(-shadowRadius, -shadowRadius)));
+	}
+	shadow = smoothstep(edge - aa, edge + aa, shadow) * (0.35 + softness);
+	float outlineAlpha = saturate(shadow * (1.0 - fill)) * outlineColor.a;
+	float fillAlpha = fill * fillColor.a;
+	float textAlpha = max(fillAlpha, outlineAlpha);
 	if (textAlpha <= 0.0001)
 		return context.sourceColor;
 
 	float4 base = context.sourceColor;
-	float4 outlineLayer = float4(outlineColor.rgb * outlineColor.a, outline * outlineColor.a);
-	float4 fillLayer = float4(fillColor.rgb * fillColor.a, fill * fillColor.a);
+	float4 outlineLayer = float4(outlineColor.rgb * outlineAlpha, outlineAlpha);
+	float4 fillLayer = float4(fillColor.rgb * fillAlpha, fillAlpha);
 	return saturate(compositeOver(compositeOver(base, outlineLayer), fillLayer));
 }