1 files changed, 58 insertions, 0 deletions
diff --git a/picom/gradient-border.glsl b/picom/gradient-border.glsl
new file mode 100644
index 0000000..0c2c25c
--- /dev/null
+++ b/picom/gradient-border.glsl
@@ -0,0 +1,58 @@
+#version 330
+
+// ── Gradient border shader for picom ─────────────────────────────────────────
+// Blends a diagonal gradient (top-left → bottom-right) over the window border.
+//
+// COLOR_A : top-left colour  — #7B2FBE (purple)
+// COLOR_B : bottom-right     — #2FB8BE (teal)
+//
+// To change colours: convert hex → float by dividing each channel by 255.
+
+// ── Tuneable constants ────────────────────────────────────────────────────────
+
+const float BORDER_WIDTH   = 4.0;   // Border band thickness in pixels
+const float BORDER_OPACITY = 0.95;  // How strongly the gradient is applied
+
+// COLOR_A: #7B2FBE  (vibrant purple)
+const vec3 COLOR_A = vec3(0.106,  0.992,  0.612);
+
+// COLOR_B: #2FB8BE  (cyan-teal)
+const vec3 COLOR_B = vec3(0.651,  1.0,  0.788);
+
+// ── Picom-provided ────────────────────────────────────────────────────────────
+
+in vec2 texcoord;           // Fragment texture coordinate (in pixels)
+uniform sampler2D tex;      // Window texture
+
+// Picom's built-in post-processing (opacity, rounded corners, etc.)
+vec4 default_post_processing(vec4 c);
+
+// ── Entry point ───────────────────────────────────────────────────────────────
+
+vec4 window_shader() {
+    // Sample the original window pixel
+    vec4 c = texelFetch(tex, ivec2(texcoord), 0);
+
+    // Derive texture size from the sampler
+    vec2 size = vec2(textureSize(tex, 0));
+
+    // Normalised UV (0,0) top-left → (1,1) bottom-right
+    vec2 uv = texcoord / size;
+
+    // Diagonal gradient factor
+    float t = (uv.x + uv.y) * 0.5;
+    vec3 gradient = mix(COLOR_A, COLOR_B, t);
+
+    // Border mask: 1.0 on the edge band, 0.0 in the interior
+    float left   = smoothstep(0.0, BORDER_WIDTH, texcoord.x);
+    float right  = smoothstep(0.0, BORDER_WIDTH, size.x - texcoord.x);
+    float top    = smoothstep(0.0, BORDER_WIDTH, texcoord.y);
+    float bottom = smoothstep(0.0, BORDER_WIDTH, size.y - texcoord.y);
+    float mask   = 1.0 - (left * right * top * bottom);
+
+    // Blend gradient onto border region only
+    c.rgb = mix(c.rgb, gradient, mask * BORDER_OPACITY);
+
+    // Let picom handle opacity, rounded corners, etc.
+    return default_post_processing(c);
+}