gl-triangle-strip-indexer

Creates typed arrays capable of being passed to WebGL element arrays for triangle strip meshes.

var createIndices = require('gl-triangle-strip-indexer')
var createBuffer = require('gl-buffer')
var createVAO = require('gl-vao')

var indexData = createIndices(256, 256)
var vertexData = createSomeContiguousSurface(256, 256)

// to use element indexes >= 65535, use "OES_element_index_uint."
gl.getExtension('OES_element_index_uint')

var indexBuffer = createBuffer(gl, ndarray(indexData), gl.ELEMENT_ARRAY_BUFFER);
var vao = createVAO(gl, [{
  buffer: createBuffer(gl, vertexData, gl.ARRAY_BUFFER, gl.STATIC_DRAW),
  type: gl.FLOAT,
  size: 3
}], indexBuffer, gl.UNSIGNED_INT)

vao.bind()
vao.draw(gl.TRIANGLE_STRIP, indexBuffer.length)

API

createIndices(width, height[, out]) -> out

Returns a typed array containing indexes representing a triangle strip. Each alternating column will introduce one degenerate triangle, and produces the following pattern:

  *--*--*
  | /|\ |
  |/ | \|
  *--*--*
  | /|\ |
  |/ | \|
  *--*--*

The size of the returned array will be height + (height - 1) * (2 * (width - 1)). The array can be passed in as the optional out parameter, in which case a subarray will be returned. If out is not provided, createIndices will instantiate one of the correct datatype and size.

License

MIT