diff --git a/Assets/test/QRCode.mat b/Assets/test/QRCode.mat
index 68b50ec..c9b6cac 100644
--- a/Assets/test/QRCode.mat
+++ b/Assets/test/QRCode.mat
@@ -77,7 +77,9 @@ Material:
     - _SmoothnessTextureChannel: 0
     - _SpecularHighlights: 1
     - _SrcBlend: 1
+    - _TimeSlider: 0
     - _UVSec: 0
+    - _Version: 1
     - _ZWrite: 1
     m_Colors:
     - _Color: {r: 1, g: 1, b: 1, a: 1}
diff --git a/Assets/test/QRCode.shader b/Assets/test/QRCode.shader
index f6e0b77..3645021 100644
--- a/Assets/test/QRCode.shader
+++ b/Assets/test/QRCode.shader
@@ -3,6 +3,7 @@ Properties {
 	[HideInInspector]
 	_("",2D)=""{}
 	_Version("Version", Range(1, 40)) = 1
+	_TimeSlider("Time", Range(0, 250)) = 0
 }
 SubShader {
 Tags { "RenderType"="Opaque" }
@@ -11,6 +12,7 @@ CGPROGRAM
 	#pragma surface s Standard
 	struct Input{float2 uv_;};
 	uint _Version;
+	float _TimeSlider;
 
 	#define VERSION _Version
 	#define WIDTH (17 + VERSION * 4)
@@ -20,6 +22,9 @@ CGPROGRAM
 	#define ALIGNER_SPACING_IDEAL ((WIDTH - 13) / (ALIGNERS-1))
 	#define ALIGNER_SPACING (ALIGNER_SPACING_IDEAL + ALIGNER_SPACING_IDEAL % 2)
 	#define MISALIGNMENT ((WIDTH - 13) - ALIGNER_SPACING * ALIGNERS)
+	#define BIT_COUNT (WIDTH * WIDTH - 225 - (WIDTH - 17)*2)
+	#define TIME (_Time.y*24)
+	// #define TIME (uint)(_TimeSlider)
 
 	#define EC_LEVEL_L 1
 	#define EC_LEVEL_M 0
@@ -44,6 +49,7 @@ CGPROGRAM
 	#define BLACK 0
 	#define PINK float3(1, .3, .5)
 	#define BLUE float3(0, .4, .7)
+	#define CYAN float3(0,1,1)
 
 	float3 finder_pattern(uint x, uint y) {
 		if (x < 6 && x > 0 && y < 6 && y > 0) return !(x < 5 && x > 1 && y < 5 && y > 1);
@@ -101,8 +107,34 @@ CGPROGRAM
 		// bottom
 		if (px == 8 && py > WIDTH - 8) return (FORMAT_BITS & (1 << py + 15 - WIDTH)) == 0;
 
-		uint column = (WIDTH - px - (px > 6))/2;
-		uint direction_up = column & 1;
+		// data bit layout
+		uint column = (WIDTH - px - (px < 6)-1)/2;
+		uint direction_up = column % 2 == 0;
+		uint full_columns = column > 4 ? column - 4 : 0;
+		full_columns = min(full_columns, VERSION*2);
+		// the 4 columns under the right finder
+		uint short_columns = min(column, 4);
+		// between the left two finder patterns
+		uint tiny_columns = column > (VERSION*2 + 4) ? column - (VERSION*2 + 4) : 0;
+		uint bit_index = full_columns * (WIDTH - 1) * 2;
+		bit_index += short_columns * (WIDTH - 9) * 2;
+		bit_index += tiny_columns * (WIDTH - 17) * 2;
+		bit_index += (px + (px < 6)) % 2;
+
+		if (direction_up) {
+			bit_index += (WIDTH - py - 1 - (py < 7)) * 2;
+		} else {// direction down
+			const uint diff = (full_columns == 0) ? 9 : (py > 6);
+			bit_index += (py - diff)*2;
+		}
+		if (px < 9)	bit_index -= 16; // rightmost tiny column
+
+		// debugging worm
+		uint worm = abs(TIME % BIT_COUNT - bit_index);
+		const uint length = 4;
+		if (worm < length) return CYAN * (worm/(float)length);
+		return (float)(bit_index%BIT_COUNT)/(float)BIT_COUNT;
+
 		// return lerp(BLUE, PINK, column / (WIDTH/2.));
 		return lerp(BLUE, PINK, (px+py)&1);
 		// return float3((px%5)/5., (px/10+py/10)&1, (py%5)/5.);
diff --git a/Assets/test/TestProps.unity b/Assets/test/TestProps.unity
index 982416b..e6c90d1 100644
--- a/Assets/test/TestProps.unity
+++ b/Assets/test/TestProps.unity
@@ -1360,7 +1360,7 @@ Transform:
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 1500710831}
   m_LocalRotation: {x: 0, y: 1, z: 0, w: 0}
-  m_LocalPosition: {x: 0, y: 0.45, z: 1}
+  m_LocalPosition: {x: 0, y: 1, z: 1}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_ConstrainProportionsScale: 0
   m_Children: []