geom-builder
Simplicial-complex-like geometry builder backed by typed arrays.
Installation
npm install geom-builder
Usage
import createGeomBuilder from "geom-builder";
const builder = createGeomBuilder({ colors: 4, cells: 3 });
builder.addPosition([0, 0, 0]);
builder.addPosition([1, 0, 0]);
builder.addPosition([1, 1, 0]);
builder.addColor([1, 0, 0, 1]);
builder.addColor([0, 1, 0, 1]);
builder.addColor([0, 0, 1, 1]);
builder.addCell([0, 1, 0]);
// or builder.addCell(0, 1, 0)
//builder.count = 3 //vertex count
//builder.indexCount = 3 //indices count
//builder.positions = Float32Array(0, 0, 0, 1, 0, 0, 1, 1, 0, ..,)
//builder.colors = Float32Array(1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, ...)
//builder.cells = Uint16Array(0, 1, 2, ...)
API
GeomBuilder
var createGeomBuilder = require("geom-builder");
builder = createGeomBuilder(opts)
Create new geometry builder. Each attribute can be enabledby passing an integer number e.g.: createGeomBuilder({ positions: 3, colors: 4, cells: 2 })
for colored lines.
-
opts
-
size
: Int - preallocated vertex buffer size,32
-
positions
: Int - enable positions attribute,3
-
colors
: Int - enable colors attribute -
normals
: Int - enable normals attribute -
uvs
: Int - enable uvs attribute -
cells
: Int - enable cells (indices)
-
Note: positions
attribute is always enabled and defaults to size 3
Adding vertex and index data
Every time we add vertex position, color etc internal buffer size is checked and expanded by doubling its capacity as necessary. Therefore builder.count
should be used to determine how many vertices to draw instead of builder.positions.length
as not all allocated vertex has to be used. Similarly for meshes with cells builder.indexCount
should be used instead of builder.cells.length
.
All enabled attributes can be accessed by builder.attribName
e.g.: builder.colors
.
All data methods accept structs or individual components. E.g. builder.addPosition(v)
and builder.addPosition(v[0], v[1], v[2])
.
builder.reset()
Reset all the counters to prepare arrays for reuse. Nothing is deallocated.
builder.addPosition(pos)
-
pos
: vec3 - position to add
Note: adding a vertex position will increment builder.count
counter indicanting number of vertices added so far
builder.addColor(color)
-
color
: vec4 - color to add
Note: you need to enable colors in constructor
builder.addNormal(normal)
-
normal
: vec3 - normal to add
Note: you need to enable normals in constructor
builder.addUV(uv)
-
uv
: vec2 - uv texture coord to add
Note: you need to enable uvs in constructor
builder.addCell(cell)
-
cell
: number, vec2, vec3 - cell (face) with vertex indices to add
Note: you need to enable cells in constructor
License
MIT, see LICENSE.md for details.