devilreef/blockyserver
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

feat: add median-cut quantization for custom GIF palette

Browse source 
Generate optimal 256-color palette from rendered frames when
dithering disabled, replacing generic Plan9 palette for better
color accuracy without dithering artifacts.
This commit is contained in:
devilreef 2026-01-23 00:54:53 +06:00
parent fb3c4a0107
commit 6345eb9821
2 changed files with 179 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

35
internal/render/gif.go
View file

@ -4,6 +4,7 @@ import (
"bytes"
"fmt"
"image"
"image/color"
"image/color/palette"
"image/draw"
"image/gif"
@ -32,6 +33,27 @@ func RenderGIF(glbBytes []byte, atlas *texture.Atlas, background string, frames,
// Calculate rotation per frame
rotationPerFrame := 360.0 / float64(frames)
// Render all frames first (in parallel)
renderedFrames := make([]image.Image, frames)
var wg sync.WaitGroup
for i := 0; i < frames; i++ {
wg.Add(1)
go func(frameIdx int) {
defer wg.Done()
rotation := float64(frameIdx) * rotationPerFrame
renderedFrames[frameIdx] = RenderScene(mesh, atlasImage, rotation, width, height, bgColor)
}(i)
}
wg.Wait()
// Determine palette
var pal color.Palette
if dithering {
pal = palette.Plan9
} else {
pal = MedianCutQuantize(renderedFrames, 256)
}
// Create GIF structure
g := &gif.GIF{
Image: make([]*image.Paletted, frames),
@ -39,25 +61,18 @@ func RenderGIF(glbBytes []byte, atlas *texture.Atlas, background string, frames,
LoopCount: 0, // 0 = infinite loop
}
// Render frames in parallel
var wg sync.WaitGroup
// Quantize frames to palette (in parallel)
for i := 0; i < frames; i++ {
wg.Add(1)
go func(frameIdx int) {
defer wg.Done()
rotation := float64(frameIdx) * rotationPerFrame
// Render frame
img := RenderScene(mesh, atlasImage, rotation, width, height, bgColor)
// Quantize to palette
paletted := image.NewPaletted(img.Bounds(), palette.Plan9)
img := renderedFrames[frameIdx]
paletted := image.NewPaletted(img.Bounds(), pal)
if dithering {
draw.FloydSteinberg.Draw(paletted, img.Bounds(), img, image.Point{})
} else {
draw.Draw(paletted, img.Bounds(), img, image.Point{}, draw.Src)
}
g.Image[frameIdx] = paletted
g.Delay[frameIdx] = delay
}(i)