Annotations

shaders/waveform-overlay/shader.slang

@@ -18,6 +18,8 @@ float4 shadeVideo(ShaderContext context)
 	float resolutionAspect = max(context.outputResolution.x, 1.0) / max(context.outputResolution.y, 1.0);
 	float width = saturate(overlayScale);
 	float height = width * resolutionAspect / targetAspect;
+	// Keep the scope in a 16:9 frame, then shrink it if the requested scale
+	// would push the overlay beyond the screen bounds.
 	float fitScale = min(1.0 / max(width, 0.001), 1.0 / max(height, 0.001));
 	width *= min(fitScale, 1.0);
 	height *= min(fitScale, 1.0);
@@ -36,6 +38,8 @@ float4 shadeVideo(ShaderContext context)
 
 	float3 bg = lerp(color.rgb, float3(0.0, 0.0, 0.0), saturate(backgroundOpacity));
 	float labelHeight = min(max(pad.x * 0.95, 0.048), 0.12);
+	// Label textures are authored in UV space, so compensate for the overlay
+	// and output aspect ratios to keep the glyphs from stretching.
 	float labelWidth = labelHeight * height * max(context.outputResolution.y, 1.0) / max(width * max(context.outputResolution.x, 1.0), 0.001);
 	float labelX = max(pad.x * 0.5, labelWidth * 0.55);
 	float y0 = pad.y;
@@ -63,6 +67,8 @@ float4 shadeVideo(ShaderContext context)
 	float requestedSamples = clamp(waveformSamples, 1.0, 96.0);
 	float density = 0.0;
 
+	// For each output pixel, march through source rows at the same X coordinate
+	// and accumulate hits where sampled luma lands near this pixel's Y level.
 	for (int sampleIndex = 0; sampleIndex < 96; sampleIndex++)
 	{
 		float samplePosition = float(sampleIndex);