Class: Buffer

SQR.Buffer()

new Buffer()

A buffer represents a 2d or 3d geometry and an attribute buffer. A buffer is internally composed of a Float32Array array and a WebGL buffer object. Squareroot does rely on strides, so each geometry is only composed of one array/buffer. A stride is a portion of the array that holds data for all attributes in a specific order. For example if the geometry is composed of 3D vertices, normals and 2D UV coordinates, the stride look like this
vx, vy, vz, nx, ny, nz, u, v
The creation of strides in handled internally by the Buffer class.

More info on strides can be found in the specs.

Please read the basic-setup tutorial to see how to use a buffer
and the understanding-buffers tutorial for an in depth discussion on buffers.

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Methods

bind()

Binds the buffer in gl, which does the same thing as calling gl.bindBuffer directly.

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data()

Sets all the data for a given attribute.

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destroy()

Destroys the buffer and clears all data from the array.

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draw()

used by the {SQR.Renderer}, called when this geometry is drawn. Will call gl.drawArrays or gl.drawElements to draw the geometry using the current shader.

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getDataArray()

Returns the raw array data

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index(arrayopt)

Sets index data.

Parameters:
Name Type Attributes Description
array Array <optional>

either an array or argument list of all the indexes. Used when setting up meshes imported as OBJ or JSON object from Unity, Blender or similar.
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isIndexed()

returns true if buffer data is indexed and has an index array

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iterate(attributeopt, callback)

Iterates over each value for an attribute or over every stride. See example below to see how to move all the vertices by 4 on the y-axis.

Parameters:
Name Type Attributes Description
attribute string <optional>

the name of the attribute to interate over, if null, it will iterate over entire strides
callback SQR.Buffer~iterateCallback

the callback function processing the data.
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Example
b.iterate('aPosition', function(i, data, count)) {
	// i+0 = x, i+1 = y, i+2 = z
	// so, to increment the y value do:
	data[i+1] += 4;
});

layout(layout, size)

Sets the layout of the buffer. A layout describes all the attributes of the geometry and their respective sizes. SQR has a few global functions that ar shorthands for typical layouts, like ex. SQR.v2c3()

Parameters:
Name Type Description
layout object

the layout of the buffer (see desc above) and understanding-buffers
size Number

the size of the buffer i.e. how many vertices it has
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Example
var l = { aPosition: 3, aColor: 4, aUV: 2 };
// the `new` keyword is optional, all methods are chainable
var buffer = SQR.Buffer().layout(l, 100).update();

resize()

Resizes the data array and/or offsets all the data in the array.

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set(attribute, position, arrayopt)

Sets a value for an attribute at a defined position.

Parameters:
Name Type Attributes Description
attribute string

name of the attribute (ex. aPosition)
position Number

the index of this attrbute (related to the size of the buffer)
array Array <optional>

the data in form of an Array or as separate arguments or an object that has a toArray attribute (see example to see all the possible options)
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Example
b.set('aPosition', 1, 	[3, 5, 6]);
b.set('aPosition', 1, 	4, 8, 9);
b.set('aPosition', 1, 	new SQR.V3(3, 5, 6));

setMode()

set the drawing mode for this buffer. Can be any one of the supported webgl drawing modes such as gl.POINTS, gl.LINES or gl.TRIANGLES which is the default.

Reminder: all the gl constants are available through the `SQR.gl` property.
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setRawData()

sets the raw data into the array at offset

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update()

Updates the webgl buffer with the data from the internal array. When called for the first time it lazily creates the webgl buffer.

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Type Definitions

iterateCallback(i, data, count)

This callback for the iterate function allowing processing of the buffer data.

Parameters:
Name Type Description
i Number

the index of the first value for this attribute in the buffer

<p>Example: if a buffer has 2 attributes - aPosition (3d vector) and aUV (2d vector)
this means the stride size is 3 + 2 = 5. In this case i for the first position attribute is
0 and for the second one it is 6. This index points to the index of first component of the attribute
- in case of a position which is a 3d vector - it points to the x component. 
To access the next component - y - add 1 to i, so data[i+1] is the y component.</p>
data Float3dArray

the entire the buffer array. Use the i parameter to read/write data to this array.
count Number

the current index for the attribute - it is incremented by 1 at each iteration
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