seanwcom · December 28, 2024 05:33 · Dec 28, 2024
diff --git a/amber_crt.glsl b/amber_crt.glsl
@@ -0,0 +1,73 @@
+// NOTE:
+// This is neat, but I don't find it usable day to day - but it takes me back to good memories 
+// from many years ago when I was playing Flight Sim on my grandfather's amber CRT.  :)
+//
+// I know ZERO glsl shader coding, the code below is courtesy of the work that @m-ahdal has done
+//   (https://github.com/m-ahdal/ghostty-shadershttps://github.com/m-ahdal/ghostty-shaders)
+// and asking Claude 3.5 Sonnet for assistance. I would love to see someone improve this and make 
+// it usable. :)
+//
+// OH! And it looks way better if you also apply the bloom filter from the github link mentioned.
+// 
+// Example ~/.config/ghostty/config:
+//   custom-shader = "/Users/foo/.config/ghostty/shaders/amber_crt.glsl"
+//   custom-shader = "/Users/foo/.config/ghostty/shaders/bloom.glsl"
+
+float warp = 0.25; // simulate curvature of CRT monitor
+float scan = 0.50; // simulate darkness between scanlines
+
+void mainImage(out vec4 fragColor, in vec2 fragCoord)
+{
+    // // Normalized pixel coordinates (from 0 to 1)
+    // vec2 uv = fragCoord/iResolution.xy;
+
+    // squared distance from center
+    vec2 uv = fragCoord / iResolution.xy;
+    vec2 dc = abs(0.5 - uv);
+    dc *= dc;
+
+    // warp the fragment coordinates
+    uv.x -= 0.5; uv.x *= 1.0 + (dc.y * (0.3 * warp)); uv.x += 0.5;
+    uv.y -= 0.5; uv.y *= 1.0 + (dc.x * (0.4 * warp)); uv.y += 0.5;
+
+    // Soft radial gradient
+    float gradient = length(uv - 0.5) * 2.0;
+    gradient = 1.0 - smoothstep(0.0, 1.0, gradient);
+
+    // Base color from terminal text
+    vec3 terminalText = texture(iChannel0, uv).rgb;
+
+    // Base color gradient with subtle variation
+    vec3 color = mix(
+        vec3(0.2), // Lighter center (increased from 0.1)
+        vec3(0.4), // Lighter edges (increased from 0.3)
+        gradient
+    );
+
+    // Vignette effect
+    float vignette = 1.0 - dot(uv - 0.5, uv - 0.5);
+    vignette = smoothstep(0.0, 0.7, vignette); // Reduced darkness at edges
+
+    // Scanline effect - barely visible
+    float scanline = sin(uv.y * iResolution.y * 0.7 + iTime * 5.0) * 0.025 + 0.975; // Extremely subtle contrast
+    scanline = pow(scanline, 1.02); // Very minimal falloff
+
+    // Subtle noise overlay
+    float noise = fract(sin(dot(uv + iTime * 0.01, vec2(12.9898, 78.233))) * 43758.5453);
+    noise = smoothstep(0.4, 0.6, noise) * 0.03; // Reduced noise
+
+    // Amber color transformation
+    vec3 amberColor = vec3(1.0, 0.7, 0.2);  // Brighter, more saturated amber
+    vec3 finalColor = mix(color, terminalText, 0.9) * amberColor * 1.2; // Increased text visibility and overall brightness
+
+    // Combine effects
+    finalColor *= vignette;
+    finalColor *= scanline;
+    finalColor += noise;
+
+    // Slight color softening
+    finalColor = mix(finalColor, finalColor * 1.1, 0.1);
+
+    // Output to screen
+    fragColor = vec4(finalColor, 1.0);
+}