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Merges full history from art-dag/mono.git into the monorepo under the artdag/ directory. Contains: core (DAG engine), l1 (Celery rendering server), l2 (ActivityPub registry), common (shared templates/middleware), client (CLI), test (e2e). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> git-subtree-dir: artdag git-subtree-mainline:1a179de547git-subtree-split:4c2e716558
59 lines
2.8 KiB
Common Lisp
59 lines
2.8 KiB
Common Lisp
;; N-way weighted blend effect
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;; Streaming-compatible: pass inputs as a list of frames
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;; Usage: (blend_multi :inputs [(read a) (read b) (read c)] :weights [0.3 0.4 0.3])
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;;
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;; Parameters:
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;; inputs - list of N frames to blend
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;; weights - list of N floats, one per input (resolved per-frame)
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;; mode - blend mode applied when folding each frame in:
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;; "alpha" — pure weighted average (default)
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;; "multiply" — darken by multiplication
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;; "screen" — lighten (inverse multiply)
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;; "overlay" — contrast-boosting midtone blend
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;; "soft-light" — gentle dodge/burn
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;; "hard-light" — strong dodge/burn
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;; "color-dodge" — brightens towards white
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;; "color-burn" — darkens towards black
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;; "difference" — absolute pixel difference
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;; "exclusion" — softer difference
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;; "add" — additive (clamped)
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;; "subtract" — subtractive (clamped)
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;; "darken" — per-pixel minimum
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;; "lighten" — per-pixel maximum
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;; resize_mode - how to match frame dimensions (fit, crop, stretch)
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;;
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;; Uses a left-fold over inputs[1..N-1]. At each step the running
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;; opacity is: w[i] / (w[0] + w[1] + ... + w[i])
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;; which produces the correct normalised weighted result.
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(require-primitives "image" "blending")
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(define-effect blend_multi
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:params (
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(inputs :type list :default [])
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(weights :type list :default [])
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(mode :type string :default "alpha")
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(resize_mode :type string :default "fit")
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)
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(let [n (len inputs)
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;; Target dimensions from first frame
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target-w (image:width (nth inputs 0))
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target-h (image:height (nth inputs 0))
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;; Fold over indices 1..n-1
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;; Accumulator is (list blended-frame running-weight-sum)
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seed (list (nth inputs 0) (nth weights 0))
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result (reduce (range 1 n) seed
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(lambda (pair i)
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(let [acc (nth pair 0)
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running (nth pair 1)
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w (nth weights i)
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new-running (+ running w)
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opacity (/ w (max new-running 0.001))
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f (image:resize (nth inputs i) target-w target-h "linear")
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;; Apply blend mode then mix with opacity
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blended (if (= mode "alpha")
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(blending:blend-images acc f opacity)
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(blending:blend-images acc (blending:blend-mode acc f mode) opacity))]
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(list blended new-running))))]
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(nth result 0)))
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