Interface DeckGlBinaryDataExperimental

deck.gl binary accessor names, for example getPosition and getFillColor.

For scatterplot: the feature/row count. For feature-path and feature-polygon: the total addressed vertex count across every path or ring, matching the deck.gl binary geometry contract (path/polygon feature count is startIndices.length - 1).

Required for feature-path (getPath) and feature-polygon (getPolygon); forbidden otherwise. One vertex-index boundary per feature plus a trailing boundary, i.e. length featureCount + 1, startIndices[0] === 0, non-decreasing, and startIndices[featureCount] === length.