diff --git a/crt/crt-geom.slang b/crt/crt-geom.slang
index 884ff0a..b29c798 100644
--- a/crt/crt-geom.slang
+++ b/crt/crt-geom.slang
@@ -170,7 +170,7 @@ vec4 scanlineWeights(float distance, vec4 color)
 void main()
 {
     gl_Position = global.MVP * Position;
-    vTexCoord = TexCoord;
+    vTexCoord = TexCoord * vec2(1.00001);
 
     // Precalculate a bunch of useful values we'll need in the fragment
     // shader.
@@ -178,13 +178,13 @@ void main()
     cosangle = cos(angle);
     stretch  = maxscale();
 
-    ilfac = vec2(1.0,(global.SourceSize.y/200.0));
+    ilfac = vec2(1.0, 1.0000001);//vec2(1.0,(global.SourceSize.y/200.0));
 
     // The size of one texel, in texture-coordinates.
     one = ilfac / global.SourceSize.xy;
 
     // Resulting X pixel-coordinate of the pixel we're drawing.
-    mod_factor = TexCoord.x * global.SourceSize.x * global.OutputSize.x / global.SourceSize.x;
+    mod_factor = vTexCoord.x * global.SourceSize.x * global.OutputSize.x / global.SourceSize.x;
 }
 
 #pragma stage fragment
@@ -408,7 +408,7 @@ void main()
     vec3 dotMaskWeights = mix(
         vec3(1.0, 1.0 - DOTMASK, 1.0),
         vec3(1.0 - DOTMASK, 1.0, 1.0 - DOTMASK),
-        floor(mod(mod_factor, 2.01))
+        floor(mod(mod_factor, 2.0))
     );
       
     mul_res *= dotMaskWeights;
diff --git a/crt/shaders/dotmask.slang b/crt/shaders/dotmask.slang
new file mode 100644
index 0000000..48cbd7b
--- /dev/null
+++ b/crt/shaders/dotmask.slang
@@ -0,0 +1,102 @@
+#version 450
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+   mat4 MVP;
+   vec4 OutputSize;
+   vec4 OriginalSize;
+   vec4 SourceSize;
+} global;
+
+#define DOTMASK_STRENGTH 0.3
+#define maskDark 0.5
+#define maskLight 1.5
+#define shadowMask 0.0
+
+#define mod_factor vTexCoord.x * global.SourceSize.x * global.OutputSize.x / global.SourceSize.x
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 2) uniform sampler2D Source;
+
+// Shadow mask.
+vec3 Mask(vec2 pos){
+  vec3 mask=vec3(maskDark,maskDark,maskDark);
+  
+// Very compressed TV style shadow mask.
+  if (shadowMask == 1.0) {
+    float line=maskLight;
+    float odd=0.0;
+    if(fract(pos.x/6.0)<0.5)odd=1.0;
+    if(fract((pos.y+odd)/2.0)<0.5)line=maskDark;  
+    pos.x=fract(pos.x/3.0);
+   
+    if(pos.x<0.333)mask.r=maskLight;
+    else if(pos.x<0.666)mask.g=maskLight;
+    else mask.b=maskLight;
+    mask*=line;  
+  } 
+
+// Aperture-grille.
+  else if (shadowMask == 2.0) {
+    pos.x=fract(pos.x/3.0);
+
+    if(pos.x<0.333)mask.r=maskLight;
+    else if(pos.x<0.666)mask.g=maskLight;
+    else mask.b=maskLight;
+  } 
+
+// Stretched VGA style shadow mask (same as prior shaders).
+  else if (shadowMask == 3.0) {
+    pos.x+=pos.y*3.0;
+    pos.x=fract(pos.x/6.0);
+
+    if(pos.x<0.333)mask.r=maskLight;
+    else if(pos.x<0.666)mask.g=maskLight;
+    else mask.b=maskLight;
+  }
+
+// VGA style shadow mask.
+  else if (shadowMask == 4.0) {
+    pos.xy=floor(pos.xy*vec2(1.0,0.5));
+    pos.x+=pos.y*3.0;
+    pos.x=fract(pos.x/6.0);
+
+    if(pos.x<0.333)mask.r=maskLight;
+    else if(pos.x<0.666)mask.g=maskLight;
+    else mask.b=maskLight;
+  }
+
+  return mask;}
+
+void main()
+{
+vec3 res = texture(Source, vTexCoord).rgb;
+
+float mask = 1.0 - DOTMASK_STRENGTH;
+
+//cgwg's dotmask emulation:
+//Output pixels are alternately tinted green and magenta
+vec3 dotMaskWeights = mix(vec3(1.0, mask, 1.0),
+						  vec3(mask, 1.0, mask),
+						  floor(mod(mod_factor, 2.0)));
+if (shadowMask == 0) {
+	res *= dotMaskWeights;
+	}
+else {
+	res *= Mask(floor(1.000001 * vTexCoord.xy * global.OutputSize.xy + vec2(0.5)));
+	}
+   FragColor = vec4(res, 1.0);
+}
\ No newline at end of file