gl-surface-plot

Draws a surface plot

Example

var shell = require("gl-now")({ clearColor: [0,0,0,0] })
var camera = require("game-shell-orbit-camera")(shell)
var createSurfacePlot = require("gl-surface-plot")
var ndarray = require("ndarray")
var fill = require("ndarray-fill")
var diric = require("dirichlet")
var glm = require("gl-matrix")
var mat4 = glm.mat4

var surface

shell.on("gl-init", function() {
  var gl = shell.gl
  gl.enable(gl.DEPTH_TEST)

  //Set up camera
  camera.lookAt(
    [0, 0, 2],      //Eye position
    [256, 256, 64], //Eye target
    [0, 0, 1])      //Up direction

  //Create field
  var field = ndarray(new Float32Array(512*512), [512,512])
  fill(field, function(x,y) {
    return 128 * diric(10, 10.0*(x-256)/512) * diric(10, 10.0*(y-256)/512)
  })
  surface = createSurface(gl, field)
})

shell.on("gl-render", function() {
  surface.draw({
    view: camera.view(),
    projection:  mat4.perspective(new Array(16), Math.PI/4.0, shell.width/shell.height, 0.1, 10000.0)
  })
})

Here is what this should look like:

Test it in your browser (requires WebGL)

Install

npm install gl-surface-plot

API

var createSurfacePlot = require("gl-surface-plot")

var surface = createSurfacePlot(gl, field[, params])

Creates a surface plot object

• gl is a WebGL context
• field is a 2D ndarray

• params is an optional collection of arguments that contains any of the following:

  • colormap - the name of the color map to use for the surface (default "jet")
  • pickId is the picking id for the surface

Returns A surface object

surface.update(params)

Updates the surface. The parameter object may contain any of the following properties:

• field a new 2D field encoded as an ndarray
• colormap the name of the new color map for the surface
• pickId is the picking id for the surface
• ticks is a pair of arrays of ticks representing the spacing of the points for the axes of the surface
• showSurface if set, draw the surface
• showContour if set, draw contour lines
• contourWidth the width fo the contour lines
• contourTint the amount of tint of the contour lines
• contourColor the color of the contour line tint
• levels an array of arrays representing the level of the isolines.
• dynamicWidth the width of the dynamic isolines
• dynamicColors the color of the dynamic isolines
• dynamicTint the tint of the dynamic isolines

surface.draw([params])

Draws the surface. Accepts the following parameters

• model the 4x4 model matrix (in gl-matrix format)
• view the 4x4 view matrix
• projection the 4x4 projection matrix

surface.dispose()

Destroys the surface, releases all associated WebGL resources

surface.bounds

A pair of 3D arrays representing the lower/upper bounding box for the surface plot.

surface.clipBounds

A pair of arrays which bound the coordinates of the surface plot in 3D.

Interactivity/picking

surface.drawPick(camera)

Draws the surface for point picking mode

surface.pick(selection)

Test if the given selection is contained in the surface. If true, returns an object encoding the selected point.

Returns An object encoding the selected point on the surface with the following properties:

• position which is the position of the selected point on the surface
• index a vector encoding the [x,y] index of the closest data point
• uv the uv coordinate of the selection
• levels the closest levels to the selection

surface.dynamic(levels)

Toggles drawing level isolines and their projections.

• levels is an array of 3 arrays representing the x/y/z levels to draw

Lighting parameters

You can also tweak the lighting parameters for the surface using the following variables

surface.lightPosition

The position of the light source relative to the viewer in clip coordinates

surface.ambientLight

The fraction of light which is ambiently lit

surface.diffuseLight

The amount of diffuse light to apply to the surface

surface.specularLight

THe amount of speculare light to apply to the surface

surface.roughness

How rough the surface is (must be between 0 and 1)

surface.fresnel

The amount of rim lighting to apply. Higher values = more intense rim light.

License

MIT License.