gl-vis / snap-points-2d

Hierarchically snap round a set of 2d points for optimizing level of detail rendering in WebGL

snap-points-2d

Runs iterative snap rounding on a set of 2D coordinates to produce a hierarchical level of detail for optimizing online rendering of huge 2D plots.

Install

npm i snap-points-2d

API

{levels, ids, weights, points} = require('snap-points-2d')(points, bounds?)

Reorders the points hierarchically such that those which are drawn at the same pixel coordinate are grouped together.

Inputs

• points is an input array of 2*n coordinate values. It is kept untouched.
• bounds is an optional array of 4 bounding box values of the points.

Outputs

• points is an output float64 array with reordered an normalized to bounds point values.
• ids is an output uint32 array which gets the reordered index of the points.
• weights is an output uint32 array of point weights (number of points at the same pixel), which can be used for transparent rendering.
• levels is an array of LOD scales. Each record is an object with the following properties:
  • pixelSize the pixel size of this level of detail in data units
  • offset the offset of this lod within the output array
  • count the number of items in the lod

License

(c) 2015 Mikola Lysenko. MIT License

snap-points-2d's Issues

Artifacts

We can spot it easily for simple gaussian distribution gl-vis/gl-scatter2d#8.

If we fix it by removing https://github.com/gl-vis/snap-points-2d/blob/master/snap.js#L104-L108, as in optimize-2 branch, sometimes (very rarely) we get other mysterious artifact: