aesthetic.computer / core
Monorepo for Aesthetic.Computer aesthetic.computer
fork atom
core / INVERT-IMPLEMENTATION.md
at main 2.4 kB view raw view code
Jeffrey Alan Scudder restore 4270 files deleted by papers oven auto-build (aaa62f4a1)
ea1fd8af

Invert Function Implementation#

This document describes the implementation of the invert function for KidLisp.

Summary#

Added the missing invert function to the graphics system, with both CPU and GPU implementations. The function inverts RGB color values (255 - value) while preserving the alpha channel, following the same pattern as other image effects like contrast and brightness.

Implementation Details#

CPU Implementation (graph.mjs)#

  • Added invert() function that processes pixel buffer
  • Performs RGB inversion: RGB' = 255 - RGB
  • Preserves alpha channel unchanged
  • Supports masking for partial screen effects
  • Skips fully transparent pixels (optimization)
  • Uses performance tracking for monitoring

GPU Implementation (gpu-effects.mjs)#

  • Added INVERT_FRAGMENT_SHADER with simple inversion logic
  • Created gpuInvert() function with same signature as other GPU effects
  • Compiled and cached shader program and uniform locations
  • Follows GPU-first, CPU-fallback pattern used by other effects
  • Properly handles cleanup in cleanupGpuEffects()

Integration#

  • Exported invert from graph.mjs
  • Added to disk.mjs API (already present, was just calling non-existent function)
  • KidLisp can now call (invert) in code
  • Works with embedded layers and baking system (uses existing post-composite infrastructure)

Usage Examples#

KidLisp Code#

; Simple invert
(wipe "red")
(invert)
; Screen is now cyan

; Partial invert with masking
(wipe "white")
(ink "blue")
(box 50 50 100 100)
(mask 60 60 80 80)
(invert)
(unmask)
; Only the masked region is inverted

; Animation with invert
(wipe "black")
(ink "yellow")
(circle width/2 height/2 50)
(if (even frame) (invert))
; Flashing circle effect

Testing#

  • Created tests/invert.test.mjs with comprehensive logic tests
  • Verified RGB inversion formula for various colors
  • Tested alpha channel preservation
  • Confirmed double invert restores original values
  • Validated boundary cases

Performance#

  • GPU implementation provides hardware acceleration when available
  • CPU fallback ensures compatibility on all platforms
  • Transparent pixel skipping reduces unnecessary computation
  • Performance tracking integrated for monitoring

This implementation enables KidLisp codes like $beli (similar to $4bb but with invert) to work correctly.