58 lines
2.1 KiB
Common Lisp
58 lines
2.1 KiB
Common Lisp
;; Inset blend - fade a smaller frame into a larger background
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;; Uses distance-based alpha for smooth transition (no hard edges)
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(require-primitives "xector")
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(define-effect xector_inset_blend
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:params (
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(x :type int :default 0 :desc "X position of inset")
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(y :type int :default 0 :desc "Y position of inset")
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(fade-width :type int :default 50 :desc "Width of fade region in pixels")
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(overlay :type frame :default nil :desc "The smaller frame to inset")
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)
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(let* (
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;; Get dimensions
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(bg-h (first (list (nth (list (red frame)) 0)))) ;; TODO: need image:height
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(bg-w bg-h) ;; placeholder
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;; For now, create a simple centered circular blend
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;; Distance from center of overlay position
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(cx (+ x (/ (- bg-w (* 2 x)) 2)))
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(cy (+ y (/ (- bg-h (* 2 y)) 2)))
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;; Get coordinates as xectors
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(px (x-coords frame))
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(py (y-coords frame))
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;; Distance from center
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(dx (α- px cx))
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(dy (α- py cy))
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(dist (αsqrt (α+ (α* dx dx) (α* dy dy))))
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;; Inner radius (fully overlay) and outer radius (fully background)
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(inner-r (- (/ bg-w 2) x fade-width))
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(outer-r (- (/ bg-w 2) x))
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;; Blend factor: 1.0 inside inner-r, 0.0 outside outer-r, linear between
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(t (α/ (α- dist inner-r) fade-width))
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(blend (α- 1 (αclamp t 0 1)))
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;; Extract channels from both frames
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(bg-r (red frame))
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(bg-g (green frame))
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(bg-b (blue frame)))
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;; If overlay provided, blend it
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(if overlay
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(let* ((ov-r (red overlay))
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(ov-g (green overlay))
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(ov-b (blue overlay))
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;; Linear blend: result = bg * (1-blend) + overlay * blend
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(r-out (α+ (α* bg-r (α- 1 blend)) (α* ov-r blend)))
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(g-out (α+ (α* bg-g (α- 1 blend)) (α* ov-g blend)))
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(b-out (α+ (α* bg-b (α- 1 blend)) (α* ov-b blend))))
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(rgb r-out g-out b-out))
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;; No overlay - just show the blend mask for debugging
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(let ((mask-vis (α* blend 255)))
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(rgb mask-vis mask-vis mask-vis)))))
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