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fix(wall): Implement true double buffering to eliminate visual glitches

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- Created backBuffer canvas (same size as visible)
- All tile drawing now uses bbCtx (backBuffer context)
- Single ctx.drawImage(backBuffer) blit at frame end
- Eliminates tearing and square artifacts from partial renders
- BackBuffer resized in sync with visible canvas

Technical: Classic double buffering pattern - compose entire
frame offscreen, then atomic copy to display buffer.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
CyberMind-FR 2026-03-15 11:44:28 +01:00
parent 528e9e508c
commit abe3f0a944
1 changed files with 32 additions and 20 deletions
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52
config/samples/wall-magic-chess-360.html
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@ -865,6 +865,11 @@ const off=document.createElement('canvas');
const offCtx=off.getContext('2d');
const cv=document.getElementById('cv');
const ctx=cv.getContext('2d');
// ── TRUE DOUBLE BUFFERING ─────────────────────────────────
// BackBuffer: compose entire frame offscreen, then blit to visible
const backBuffer = document.createElement('canvas');
const bbCtx = backBuffer.getContext('2d');
let lastT=performance.now(),rafId=null;
// ── HELPERS ───────────────────────────────────────────────
@ -1353,8 +1358,9 @@ function rafLoop(now){
zF=Math.max(0.38,Math.min(2.6,zF));
// ── DRAW ──
ctx.imageSmoothingEnabled=false;
ctx.clearRect(0,0,W,H);
// ── DOUBLE BUFFER: Draw to backBuffer first ──
bbCtx.imageSmoothingEnabled=false;
bbCtx.clearRect(0,0,W,H);
const cx=W/2+panX+glitchX;
const cy=H/2+panY+glitchY;
@ -1367,10 +1373,10 @@ function rafLoop(now){
if(tileTTL>0 && tileScales.length>0){
// PER-TILE : zoom global + scale individuel par tuile
ctx.save();
ctx.translate(cx,cy);
ctx.scale(zF,zF);
ctx.translate(-cx,-cy);
bbCtx.save();
bbCtx.translate(cx,cy);
bbCtx.scale(zF,zF);
bbCtx.translate(-cx,-cy);
let ti=0;
for(let y=startY-margin;y<=H+margin*3;y+=motifPx){
@ -1378,31 +1384,34 @@ function rafLoop(now){
const ts=tileScales[ti%tileScales.length]??1;
ti++;
if(ts===1.0){
ctx.drawImage(off,x,y);
bbCtx.drawImage(off,x,y);
} else {
const tcx=x+motifPx/2, tcy=y+motifPx/2;
ctx.save();
ctx.translate(tcx,tcy);
ctx.scale(ts,ts);
ctx.translate(-tcx,-tcy);
ctx.drawImage(off,x,y);
ctx.restore();
bbCtx.save();
bbCtx.translate(tcx,tcy);
bbCtx.scale(ts,ts);
bbCtx.translate(-tcx,-tcy);
bbCtx.drawImage(off,x,y);
bbCtx.restore();
}
}
}
ctx.restore();
bbCtx.restore();
} else {
// ZOOM GLOBAL UNIFORME
ctx.save();
ctx.translate(cx,cy);
ctx.scale(zF,zF);
ctx.translate(-cx,-cy);
bbCtx.save();
bbCtx.translate(cx,cy);
bbCtx.scale(zF,zF);
bbCtx.translate(-cx,-cy);
for(let y=startY-margin;y<=H+margin*3;y+=motifPx)
for(let x=startX-margin;x<=W+margin*3;x+=motifPx)
ctx.drawImage(off,x,y);
ctx.restore();
bbCtx.drawImage(off,x,y);
bbCtx.restore();
}
// ── DOUBLE BUFFER: Single blit to visible canvas ──
ctx.drawImage(backBuffer, 0, 0);
document.getElementById('bZoom').textContent=
'Z'+zF.toFixed(2)
+' P'+panX.toFixed(0)+','+panY.toFixed(0)
@ -1493,6 +1502,9 @@ function resize(){
const scale = 2;
cv.width = Math.ceil(window.innerWidth * scale);
cv.height = Math.ceil(window.innerHeight * scale);
// Sync backBuffer size
backBuffer.width = cv.width;
backBuffer.height = cv.height;
// Center the oversized canvas in wrapper
cv.style.marginLeft = -cv.width/2 + 'px';
cv.style.marginTop = -cv.height/2 + 'px';