ColumnData Unification Plan

============================

GOAL

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Replace the current zoo of data representations (Float32Array, regl texture,

_packed textures, { texture, _isLive: true } live refs, ad-hoc duck-typed

objects) with a single ColumnData class hierarchy. Every column resolves to:

col.resolve(path, regl) -> { glslExpr: string, textures: { name: () => texture } }

col.toTexture(regl) -> regl texture (R channel, 1 value/texel, 2D layout)

col.refresh(plot) -> boolean (true if texture was updated)

col.length / .domain / .quantityKind

Three concrete subtypes:

ArrayColumn(array, meta) - Float32Array, lazy-uploads to texture on demand

TextureColumn(ref, meta) - { texture } mutable ref, axis-dependent refreshFn

GlslColumn(inputs, glslFn) - expression tree node; collects inputs' textures,

composes GLSL expression inline

KEY DESIGN DECISIONS

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1. No roundtrip via CPU: data stays on GPU once uploaded.

2. All column data stored as textures (R channel, 1 value per texel, 2D).

One GLSL helper: sampleColumn(sampler2D, float idx) using texelFetch+textureSize.

3. Float32Array in layer attributes still means fixed geometry (corners, indices).

4. GlslColumn inputs are listed explicitly; resolve() recurses and merges textures.

5. TextureComputation.compute() still returns raw regl texture (impls unchanged).

createColumn() wraps it in TextureColumn with refreshFn for axis tracking.

6. GlslComputation.createColumn(inputs) returns GlslColumn.

7. All textures are effectively "live" (dynamic uniforms) - no static vs live split.

8. textureSize() in GLSL eliminates separate width/height uniforms entirely.

9. refresh() returns boolean; chain: GlslColumn propagates to inputs, consumer

TextureComputations recompute if inputs refreshed OR own axes changed.

PIPELINE

--------

Data (ArrayColumn via Data.getData)

-> ComputedData (top-level transform, produces TextureColumns in ComputedDataNode)

-> TextureComputation / GlslComputation expressions in layer params

GlslComputation can be input to TextureComputation:

TextureComputation.compute() calls inputs.someCol.toTexture(regl), which for

GlslColumn runs a GPU point-render pass to materialize the expression.

TEXTURE FORMAT

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All column textures: RGBA float, values in R channel, 1 value per texel.

w = min(n, maxTextureSize), h = ceil(n/w), tex._dataLength = n

sampleColumn GLSL: texelFetch(tex, ivec2(i%sz.x, i/sz.x), 0).r

Intermediate compute textures (FFT=complex RG, filter=R) stay in their own

formats since they are not directly consumed via sampleColumn.

FFT/conv require ArrayColumn inputs (CPU data) - GPU readback not supported.

REMOVED

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- resolveToGlslExpr / resolveToRawValue

- TextureComputation.resolveDataParam

- ComputedData.resolveDataParam

- isTexture(), dataShape()

- _isLive: true flag

- context.axisUpdaters / layer._axisUpdaters -> layer._dataColumns

- Packed texture format (_packed, _samplePacked_* GLSL)

- Scalar uniforms for texture width/height

LINES LAYER EXCEPTION

---------------------

LinesLayer uses subarray() to slice adjacent point pairs. It requires

ArrayColumn inputs (calls .array). Does not support computed columns.

FILES CHANGED

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src/compute/ComputationRegistry.js - major rewrite: add ColumnData classes,

resolveExprToColumn, resolveParams, update

base classes, simplify resolveAttributeExpr

src/core/Data.js - getData returns ArrayColumn/TextureColumn

src/core/LayerType.js - createDrawCommand uses textures map,

injects SAMPLE_COLUMN_GLSL, sets _dataColumns

src/core/Plot.js - render()/pick() refresh _dataColumns

src/compute/hist.js - update to new API

src/compute/elementwise.js - simplify: col.toTexture() replaces evalExpr

src/compute/axisFilter.js - update to new API

src/compute/kde.js - update to new API

src/compute/filter.js - update texture format (R channel), update API

src/compute/fft.js - update API (ArrayColumn inputs only)

src/compute/conv.js - update API (ArrayColumn inputs only)

src/layers/BarsLayer.js - use col.length, col.domain

src/layers/ScatterShared.js - update _resolveColorData to use .array

src/layers/PointsLayer.js - use col.length for vertexCount

src/layers/LinesLayer.js - explicit .array calls for subarray()