NodeDataTexture

Defined in: packages/sigma/src/rendering/node-data-texture.ts:35

Manages a GPU texture storing node data, two RGBA32F texels per node.

Texel 0 - geometry, read by every node-data consumer:

• R: x position (graph coordinates)
• G: y position (graph coordinates)
• B: size
• A: shapeId (integer ID for shape registry lookup)

Texel 1 - rotation flags (0 = viewport/screen-upright, 1 = graph) and color:

• R: nodeRotation (shape orientation follows the camera)
• G: labelRotation (label orbits/turns with the camera)
• B: color RGB packed as r65536 + g256 + b (< 2^24, exact in float32)
• A: color alpha in [0, 1]

Node index N maps to a base texel N * 2; consumers fetch texel 0 there and texel 1 at N * 2 + 1 (see GLSL_READ_NODE_DATA / GLSL_READ_NODE_FLAGS / GLSL_READ_NODE_COLOR).

Extends

• DataTexture

Constructors

Constructor

new NodeDataTexture(gl, initialCapacity?): NodeDataTexture

Defined in: packages/sigma/src/rendering/node-data-texture.ts:36

Parameters

gl

WebGL2RenderingContext

initialCapacity?

number

Returns

NodeDataTexture

Overrides

DataTexture.constructor

Methods

allocate()

allocate(key): number

Defined in: packages/sigma/src/rendering/data-texture.ts:152

Allocates a texture index for an item. Returns existing index if item already allocated.

Parameters

key

string | number

Returns

number

Inherited from

DataTexture.allocate

---

bind()

bind(textureUnit): void

Defined in: packages/sigma/src/rendering/data-texture.ts:271

Binds the texture to a texture unit.

Parameters

textureUnit

number

Returns

void

Inherited from

DataTexture.bind

---

clear()

clear(): void

Defined in: packages/sigma/src/rendering/data-texture.ts:339

Clears all item allocations (but keeps the texture).

Returns

void

Inherited from

DataTexture.clear

---

free()

free(key): void

Defined in: packages/sigma/src/rendering/data-texture.ts:179

Frees an item’s texture index for reuse.

Parameters

key

string | number

Returns

void

Inherited from

DataTexture.free

---

getCapacity()

getCapacity(): number

Defined in: packages/sigma/src/rendering/data-texture.ts:287

Gets the current capacity (max items).

Returns

number

Inherited from

DataTexture.getCapacity

---

getCount()

getCount(): number

Defined in: packages/sigma/src/rendering/data-texture.ts:316

Gets the number of allocated items.

Returns

number

Inherited from

DataTexture.getCount

---

getHighWaterMark()

getHighWaterMark(): number

Defined in: packages/sigma/src/rendering/data-texture.ts:325

Highest index ever allocated + 1. Unlike getCount, this spans freed holes, so it bounds every live item’s row (what a per-row gl_VertexID pass must cover).

Returns

number

Inherited from

DataTexture.getHighWaterMark

---

getIndex()

getIndex(key): number

Defined in: packages/sigma/src/rendering/data-texture.ts:199

Gets the texture index for an item. Returns -1 if item not found.

Parameters

key

string | number

Returns

number

Inherited from

DataTexture.getIndex

---

getTexelsPerItem()

getTexelsPerItem(): number

Defined in: packages/sigma/src/rendering/data-texture.ts:309

Gets the number of texels per item.

Returns

number

Inherited from

DataTexture.getTexelsPerItem

---

getTexture()

getTexture(): WebGLTexture | null

Defined in: packages/sigma/src/rendering/data-texture.ts:280

Gets the WebGL texture object.

Returns

WebGLTexture | null

Inherited from

DataTexture.getTexture

---

getTextureHeight()

getTextureHeight(): number

Defined in: packages/sigma/src/rendering/data-texture.ts:302

Gets the texture height (needed to cover the full texture when rendering into it).

Returns

number

Inherited from

DataTexture.getTextureHeight

---

getTextureWidth()

getTextureWidth(): number

Defined in: packages/sigma/src/rendering/data-texture.ts:294

Gets the texture width (needed for 2D coordinate calculation in shaders).

Returns

number

Inherited from

DataTexture.getTextureWidth

---

has()

has(key): boolean

Defined in: packages/sigma/src/rendering/data-texture.ts:206

Checks if an item has been allocated.

Parameters

key

string | number

Returns

boolean

Inherited from

DataTexture.has

---

isDirty()

isDirty(): boolean

Defined in: packages/sigma/src/rendering/data-texture.ts:332

Checks if there are pending changes to upload.

Returns

boolean

Inherited from

DataTexture.isDirty

---

kill()

kill(): void

Defined in: packages/sigma/src/rendering/data-texture.ts:360

Destroys the texture and clears all data.

Returns

void

Inherited from

DataTexture.kill

---

restore()

restore(): void

Defined in: packages/sigma/src/rendering/data-texture.ts:350

Recreates the GPU texture after a context loss, re-uploading the CPU-side data.

Returns

void

Inherited from

DataTexture.restore

---

updateNode()

updateNode(nodeKey, x, y, size, shapeId, nodeRotation, labelRotation, color): void

Defined in: packages/sigma/src/rendering/node-data-texture.ts:44

Updates all data for a node. nodeRotation and labelRotation are the per-node rotation-alignment flags (0 = viewport, 1 = graph).

Parameters

nodeKey

string

x

number

y

number

size

number

shapeId

number

nodeRotation

number

labelRotation

number

color

string

Returns

void

---

upload()

upload(): void

Defined in: packages/sigma/src/rendering/data-texture.ts:223

Uploads dirty data to the GPU texture. With 2D layout and multiple texels per item, uploads affected rows.

Returns

void

Inherited from

DataTexture.upload