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Increase WebGL buffer cap from 4096 to 7232 for sharper text #48

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Merged
mcollina merged 1 commit into from
Dec 24, 2025
Merged

Increase WebGL buffer cap from 4096 to 7232 for sharper text #48

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16 changes: 13 additions & 3 deletions src/renderer/WebGLManager.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -168,9 +168,19 @@ export class WebGLManager {
let bufferWidth = Math.round(width * dpr)
let bufferHeight = Math.round(height * dpr)

// Cap buffer size to avoid GPU/driver issues with very large framebuffers
// Some systems have rendering issues when buffer dimensions exceed 4096px
const MAX_BUFFER_DIM = 4096
// Cap buffer size to avoid GPU/driver issues with very large framebuffers.
// On some systems (observed on macOS with Apple Silicon), content rendered at Y=0
// becomes invisible when the WebGL buffer exceeds a certain size.
//
// This limit (7232px) was found through binary search testing:
// - 7232: works
// - 7234: fails (content at Y=0 disappears)
//
// The value doesn't align with typical GPU limits (4096, 8192, 16384) or memory
// boundaries, suggesting a driver-specific bug rather than a documented limit.
// At DPR 2, this allows ~3616px CSS width before scaling kicks in.
// When this cap is triggered, the canvas is CSS-upscaled with minimal quality loss.
const MAX_BUFFER_DIM = 7232
const maxDim = Math.max(bufferWidth, bufferHeight)
if (maxDim > MAX_BUFFER_DIM) {
const scale = MAX_BUFFER_DIM / maxDim
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