ag-gl-vao
v1.3.1
Published
Vertex array object wrapper/shim for WebGL
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gl-vao
WebGL vertex array object wrapper/polyfill
Example
Try out the demo in your browser
var shell = require("gl-now")()
var createBuffer = require("gl-buffer")
var createVAO = require("gl-vao")
var glslify = require("glslify")
var createShader = require("gl-shader")
var vao, shader
shell.on("gl-init", function() {
var gl = shell.gl
//Create shader object
shader = createShader(gl,
glslify("\
attribute vec2 position;\
attribute vec3 color;\
varying vec3 fragColor;\
void main() {\
gl_Position = vec4(position, 0, 1.0);\
fragColor = color;\
}"
, {inline: true}
),
glslify("\
precision highp float;\
varying vec3 fragColor;\
void main() {\
gl_FragColor = vec4(fragColor, 1.0);\
}"
, {inline: true}
)
);
shader.attributes.position.location = 0
shader.attributes.color.location = 1
//Create vertex array object
vao = createVAO(gl, [
{ "buffer": createBuffer(gl, [-1, 0, 0, -1, 1, 1]),
"type": gl.FLOAT,
"size": 2
},
[0.8, 1, 0.5]
])
})
shell.on("gl-render", function(t) {
var gl = shell.gl
//Bind the shader
shader.bind()
//Bind vertex array object and draw it
vao.bind()
vao.draw(gl.TRIANGLES, 3)
//Unbind vertex array when fini
vao.unbind()
})
Assuming everything worked, here is what it should look like:
Install
Use npm:
npm install gl-vao
To compile demos in for your browser try browserify or beefy.
API
var createVAO = require("gl-vao")
var vao = createVAO(gl, attributes[, elements][, elementsType])
Creates a vertex array object
gl
is the gl context in which the vertex array object is createdattributes
is an array of objects that give the attributes bound to particular locations starting at 0. Each of these attributes is either an array-like object of length 4 or less representing a constant attribute value, or else it is an object with the following properties that correspond to the parameters passed togl.vertexAttribPointer
buffer
agl-buffer
object encoding a webgl buffersize
the size of the attribute (default 4)type
the type of the attribute (defaultgl.FLOAT
)normalized
a flag that checks whether the attribute should be normalized or notstride
the stride of the attribute in bytes (default 0)offset
offset to the start of the attribute in the buffer in bytes (default 0)
elements
is a buffer created usinggl-buffer
encoding the state of the vertex elementselementsType
the type of data contained within the element buffer, if given. Defaults togl.UNSIGNED_SHORT
. Acceptable values aregl.UNSIGNED_BYTE
,gl.UNSIGNED_SHORT
. If theOES_element_index_uint
extension is available and active,gl.UNSIGNED_INT
may also be used.
vao.bind()
Binds the vertex array object to the active vertex state.
vao.unbind()
Unbinds the vertex array object.
Note You should call this method before switching back to using vertex arrays and buffers as usual. Failing to do so can cause the state of the vertex array object to become corrupted. However, it is acceptable to skip the unbind step if another vertex array object is immediately bound.
vao.draw(mode, count[, offset])
Draws the vertex array object.
mode
is the mode to use when drawing the buffer, for examplegl.TRIANGLES
,gl.LINES
, etc.count
is the number of vertices to draw.offset
is the offset to start drawing from. Default0
vao.update(attributes[, elements][, elementsType])
Updates the contents of the vertex array object using the same syntax and conventions as the constructor.
vao.dispose()
Destroys the vertex array object and releases all of its resources.
Credits
(c) 2013 Mikola Lysenko. MIT License