WebGLBackend

A renderer for a Scene, implemented per target (WebGL / Canvas / SVG).

Implements

Backend

Properties

stylesNeedDrawables

readonly stylesNeedDrawables: false = false

WebGL renders from the GPU flag/color textures, not the vector view — the drawables arg to updateLayerStyles is only stashed for toSVG export. So the engine may omit it on hot paths (per-frame declutter) to skip an O(n) rebuild.

Implementation of

Backend.stylesNeedDrawables

supportsPassThrough

readonly supportsPassThrough: true = true

Defined in: webgl/webgl-backend.ts:20

True if this backend supports pass-through (canvas/webgl yes, svg no).

Implementation of

Backend.supportsPassThrough

Methods

appendToLayer()

appendToLayer(delta): void

Defined in: webgl/webgl-backend.ts:132

O(new) incremental append: grow the existing GroupRenderer’s geometry buffers (capacity-doubling) and color/flag textures with only the appended tail, instead of rebuilding from full buffers. The engine calls this (not updateLayer) for appends.

The layer is always registered (via setLayers) before any append, so the renderer exists; if it somehow doesn’t, we no-op (nothing to grow from a delta alone). If a new geometry-type pass appears that can’t be grown incrementally (renderer.append returns false), fall back to a full rebuild via updateLayer so the result stays correct.

Parameters

delta

RenderDelta

Returns

void

Implementation of

Backend.appendToLayer

destroy()

destroy(): void

Defined in: webgl/webgl-backend.ts:386

Returns

void

Implementation of

Backend.destroy

drawPassThrough()

drawPassThrough(name, batch, mode): void

Defined in: webgl/webgl-backend.ts:173

Draw a batch into the layer’s accumulation buffer. mode: "replace-first" clears the layer’s buffer first (start of a full repaint), "replace-rest" continues a chunked full repaint without clearing, "append" draws on top (incremental).

Parameters

name

string

batch

DrawBatch

mode

"replace-first" | "replace-rest" | "append"

Returns

void

Implementation of

Backend.drawPassThrough

readPixel()

readPixel(x, y): number[]

Defined in: webgl/webgl-backend.ts:375

Read a pixel from the offscreen framebuffer (renders first). Flips y for WebGL origin.

Parameters

x

number

y

number

Returns

number[]

readScreenPixel()

readScreenPixel(x, y): number[]

Defined in: webgl/webgl-backend.ts:364

Read a pixel from the ONSCREEN canvas default framebuffer after render(). Test aid. Coords are in CSS px; the onscreen buffer is device px, so scale by the buffer ratio.

Parameters

x

number

y

number

Returns

number[]

removeInstancedLayer()

removeInstancedLayer(name): void

Defined in: webgl/webgl-backend.ts:208

Remove an instanced primitive layer by name.

Parameters

name

string

Returns

void

Implementation of

Backend.removeInstancedLayer

removePassThroughLayer()

removePassThroughLayer(name): void

Defined in: webgl/webgl-backend.ts:165

Remove a pass-through layer.

Parameters

name

string

Returns

void

Implementation of

Backend.removePassThroughLayer

render()

render(): void

Defined in: webgl/webgl-backend.ts:273

Returns

void

Implementation of

Backend.render

resize()

resize(width, height): void

Defined in: webgl/webgl-backend.ts:224

Resize the onscreen canvas drawing buffer (luma owns it via useDevicePixels), recompute the clip matrix at the new size, push the new viewport to every renderer (screen-mode point sizing) and recreate the offscreen export framebuffer. The engine re-pushes layers + renders after. Globe mode reads this.width/height per draw, so it follows automatically.

Parameters

width

number

height

number

Returns

void

Implementation of

Backend.resize

setGlobeMode()

setGlobeMode(on, texW?, texH?): void

Defined in: webgl/webgl-backend.ts:257

Enter/leave globe mode. texW/texH = equirect bake size. Idempotent re-entry resizes.

Parameters

on

boolean

texW?

number = 2048

texH?

number = 1024

Returns

void

setGlobeRotation()

setGlobeRotation(m): void

Defined in: webgl/webgl-backend.ts:271

Update the globe rotation (mat3, column-major) and repaint. No re-bake.

Parameters

m

Float32Array

Returns

void

setInstancedLayer()

setInstancedLayer(layer): void

Defined in: webgl/webgl-backend.ts:192

Register/replace a GPU-instanced primitive layer (the network rendering lane). Optional — only the WebGL backend implements it; other backends omit it, so network instanced rendering is WebGL-only (small-N / export go through the PathContext emitter).

Parameters

layer

InstancedLayer

Returns

void

Implementation of

Backend.setInstancedLayer

setLayers()

setLayers(newLayers): void

Defined in: webgl/webgl-backend.ts:70

Parameters

newLayers

RenderLayer[]

Returns

void

Implementation of

Backend.setLayers

setPassThroughLayer()

setPassThroughLayer(layer): void

Defined in: webgl/webgl-backend.ts:159

Parameters

layer

PassThroughLayer

Returns

void

Implementation of

Backend.setPassThroughLayer

setTransform()

setTransform(t): void

Defined in: webgl/webgl-backend.ts:213

Parameters

t

ViewTransform

Returns

void

Implementation of

Backend.setTransform

snapshotPassThrough()

snapshotPassThrough(): void

Defined in: webgl/webgl-backend.ts:190

No-op for WebGL: the accumulation FBO persists across gestures and PassThroughGL.fboTransform already records the reference transform (set on the last clear), so the composite blit can offset it during a pan with no extra snapshot. (The canvas backend, by contrast, must copy the canvas here because it has no retained FBO.)

Returns

void

Implementation of

Backend.snapshotPassThrough

toPNG()

toPNG(): string

Defined in: webgl/webgl-backend.ts:351

Returns

string

Implementation of

Backend.toPNG

toSVG()

toSVG(): string

Defined in: webgl/webgl-backend.ts:357

Returns

string

Implementation of

Backend.toSVG

updateLayer()

updateLayer(name, layer): void

Defined in: webgl/webgl-backend.ts:93

Replace a layer’s geometry + tables: destroy the old renderer and rebuild from the full buffers. updateLayer deliberately has NO same-count recolor shortcut: equal drawable counts do NOT imply unchanged geometry (the hover overlay re-targets a different drawable at the same count every pointer move). Styles-only changes go through updateLayerStyles; appends through appendToLayer (O(new)).

Parameters

name

string

layer

RenderLayer

Returns

void

Implementation of

Backend.updateLayer

updateLayerStyles()

updateLayerStyles(name, tables, drawables?): void

Defined in: webgl/webgl-backend.ts:111

Styles-only update: rewrite the palette/flags textures, refresh the stored vector view (toSVG reads it), leave geometry buffers untouched. drawables omitted ⇒ keep the previously-stored vector view (export may lag the textures until the next update with it).