blob Element Reference

Blobby shape comopsed of a set of metaobject elements. More...

Inheritance diagram for blob:

List of all members.

Attributes
real_t	threshold
	specifies the particular isocontour boundary which will define the surface of this blobby shape
vector3	resolution
	Grid resolution for marching cubes to generate a mesh from the metaobjects.
vector[metaobject]	metaObjects
	Array of metaobject elements comprising this blobby shape.

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Detailed Description

Blobby shape comopsed of a set of metaobject elements.

Note:

Blobby isosurface composed of a set of MetaObjects, all of which combine to form a scalar field whose contour at this blob's threshold value defines the surface. Upon initialization (Blob::init), the implicit surface is polygonized into triangles using a variant of the well-known Marching Cubes algorithm. A MetaObject exerts a positive or negative 'charge' in a scalar field, whose isocontours (level sets) define blobby surfaces with different threshold values corresponding to the contour level. MetaObjects positively or negatively affect their neighboring MetaObjects depending on their 'strength' and 'negative' attributes.

blob corresponds to the underlying Milton class 'Blob.'

Effect of varying the threshold parameter with 3 metaballs; also shown is an example octree spatial acceleration data structure being used for the resulting mesh. Thresholds of 0.1 (left), 0.18 (center), and 0.19999 (right) were used to create these blobs.

Example usage:

"blob" : {

// declare a blobby metaobject composed of three metaballs

"metaObjects" : [

{ "type" : "ball", "position" : [ .6, 0, 0 ], },

{ "type" : "ball", "position" : [ 0, .6, 0 ], },

{ "type" : "ball", "position" : [ 0, 0, .6 ], },

],

// optionally specify hints for resulting mesh's acceleration data structure

"spatialAccel" : "kdTree",

"kdMaxDepth" : 16,

// threshold may range from [0, 0.2)

"threshold" : .18,

},

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Attribute Documentation

real_t blob::threshold

specifies the particular isocontour boundary which will define the surface of this blobby shape

type	real scalar
optional	true
default	0.17
restrictions	valid within [0, 0.2)

vector3 blob::resolution

Grid resolution for marching cubes to generate a mesh from the metaobjects.

Note:

TODO: make this customizable; currently hard-coded

type	vector3
optional	true
default	[ 128, 128, 128 ]

vector [metaobject] blob::metaObjects

Array of metaobject elements comprising this blobby shape.

Note:

See also metaobject

type	vector[metaobject]
optional	false
restrictions	must be non-empty