Import L1 (celery) as l1/

l1/sexp_effects/effects/cell_pattern.sexp

@@ -0,0 +1,65 @@
+;; Cell Pattern effect - custom patterns within cells
+;;
+;; Demonstrates building arbitrary per-cell visuals from primitives.
+;; Uses local coordinates within cells to draw patterns scaled by luminance.
+
+(require-primitives "xector")
+
+(define-effect cell_pattern
+  :params (
+    (cell-size :type int :default 16 :range [8 48] :desc "Cell size")
+    (pattern :type string :default "diagonal" :desc "Pattern: diagonal, cross, ring")
+  )
+  (let* (
+         ;; Pool to get cell colors
+         (pooled (pool-frame frame cell-size))
+         (cell-r (nth pooled 0))
+         (cell-g (nth pooled 1))
+         (cell-b (nth pooled 2))
+         (cell-lum (α/ (nth pooled 3) 255))
+
+         ;; Cell indices for each pixel
+         (cell-idx (cell-indices frame cell-size))
+
+         ;; Look up cell values for each pixel
+         (pix-r (gather cell-r cell-idx))
+         (pix-g (gather cell-g cell-idx))
+         (pix-b (gather cell-b cell-idx))
+         (pix-lum (gather cell-lum cell-idx))
+
+         ;; Local position within cell [0, 1]
+         (lx (local-x-norm frame cell-size))
+         (ly (local-y-norm frame cell-size))
+
+         ;; Pattern mask based on pattern type
+         (mask
+           (cond
+             ;; Diagonal lines - thickness based on luminance
+             ((= pattern "diagonal")
+              (let* ((diag (αmod (α+ lx ly) 0.25))
+                     (thickness (α* pix-lum 0.125)))
+                (α< diag thickness)))
+
+             ;; Cross pattern
+             ((= pattern "cross")
+              (let* ((cx (αabs (α- lx 0.5)))
+                     (cy (αabs (α- ly 0.5)))
+                     (thickness (α* pix-lum 0.25)))
+                (αor (α< cx thickness) (α< cy thickness))))
+
+             ;; Ring pattern
+             ((= pattern "ring")
+              (let* ((dx (α- lx 0.5))
+                     (dy (α- ly 0.5))
+                     (dist (αsqrt (α+ (α² dx) (α² dy))))
+                     (target (α* pix-lum 0.4))
+                     (thickness 0.05))
+                (α< (αabs (α- dist target)) thickness)))
+
+             ;; Default: solid
+             (else (α> pix-lum 0)))))
+
+    ;; Apply mask: show cell color where mask is true, black elsewhere
+    (rgb (where mask pix-r 0)
+         (where mask pix-g 0)
+         (where mask pix-b 0))))