gl-texture2d

WebGL texture wrapper

npm install gl-texture2d
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gl-texture2d

ndarray compatible wrapper for WebGLTexture objects

Example

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var shell = require("gl-now")()
var createShader = require("gl-shader")
var createTexture = require("gl-texture2d")

var lena = require("lena")

shell.on("gl-init", function() {
  var gl = shell.gl

  var texture = createTexture(gl, lena)

  var shader = createShader(gl, "\
    attribute vec2 position;\
    varying vec2 texCoord;\
    void main() {\
      gl_Position = vec4(position, 0, 1);\
      texCoord = vec2(0.5,-0.5) * (position + 1.0);\
    }", "\
    precision highp float;\
    uniform sampler2D texture;\
    varying vec2 texCoord;\
    void main() {\
      gl_FragColor = texture2D(texture, texCoord);\
    }")

  gl.bindBuffer(gl.ARRAY_BUFFER, gl.createBuffer())
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
    -1, -1,
     4, -1,
    -1,  4
  ]), gl.STATIC_DRAW)

  texture.bind(0)
  shader.bind()
  shader.uniforms.texture = 0
  shader.attributes.position.pointer()
  shader.attributes.position.enable()
})

shell.on("gl-render", function() {
  var gl = shell.gl
  gl.drawArrays(gl.TRIANGLES, 0, 3)
})

Here is what it should look like:

Install

npm install gl-texture2d

API

var createTexture = require("gl-texture2d")

Constructor

There are three basic usage patterns for createTexture:

var tex = createTexture(gl, width, height[, format, type])

Creates an unitialized texture with the given dimensions and format

  • width is the width of texture
  • height is the height of the texture
  • format (optional) is the format of the texture (default gl.RGBA)
  • type is the type of texture (default gl.UNSIGNED_BYTE)

var tex = createTexture(gl, dom_element[, format, type])

Creates a texture from the given data source. Where dom_element is one of the following items:

  • An ImageData object
  • An HTMLCanvas object
  • An HTMLImage object
  • An HTMLVideo object

And format is an OpenGL data format or defaults to gl.RGBA and type is the storage type which defaults to gl.UNSIGNED_BYTE

var tex = createTexture(gl, array)

Creates a texture from an ndarray. The rules for selecting the format and type depend on the shape of the ndarray. The type of the texture is inferred according to the following rules. Let:

  • dtype = ndarray.dtype(array)
  • shape = array.shape

Then the rules for type and format are defined according to the following table:

dtype shape format type
float* [m,n] LUMINANCE FLOAT
float* [m,n,1] ALPHA FLOAT
float* [m,n,2] LUMINANCE_ALPHA FLOAT
float* [m,n,3] RGB FLOAT
float* [m,n,4] RGBA FLOAT
(u)int* [m,n] LUMINANCE UNSIGNED_BYTE
(u)int* [m,n,1] ALPHA UNSIGNED_BYTE
(u)int* [m,n,2] LUMINANCE_ALPHA UNSIGNED_BYTE
(u)int* [m,n,3] RGB UNSIGNED_BYTE
(u)int* [m,n,4] RGBA UNSIGNED_BYTE

Other combinations of shape and dtype are invalid and throw an error.

Texture Methods

tex.bind([tex_unit])

Binds the texture for use. Basically a short cut for:

gl.activeTexture(gl.TEXTURE0 + tex_unit)
gl.bindTexture(gl.TEXTURE_2D, this.handle)

If tex_unit is not specified then the active texture is not changed.

Returns The texture unit the texture is bound to.

`tex.dispose()``

Destroys the texture object and releases all of its resources. Under the hood this is equivalent to:

gl.deleteTexture(this.handle)

tex.setPixels(data[, x_off, y_off, mip_level])

Unpacks data into a subregion of the texture. As before in the constructor data can be either an ndarray, HTMLCanvas, HTMLImage or HTMLVideo object. If data is an ndarray it must have a compatible format with the initial array layout.

  • x_off is the x offset to write from. (default 0)
  • y_off is the y offset to write from. (default 0)
  • mip_level is the mip level to write to. (default 0)

If data is an ndarray the same rules as in the constructor are followed for converting the type of the buffer.

tex.generateMipmap()

Generates mipmaps for the texture. This will fail if the texture dimensions are not a power of two.

Texture Properties

tex.shape

An array representing the [height, width] of the texture

tex.wrapS

S wrap around behavior. Used to set/get gl.TEXTURE_WRAP_S. Defaults to gl.CLAMP_TO_EDGE

tex.wrapT

T wrap around behavior. Used to set/get gl.TEXTURE_WRAP_T. Defaults to gl.CLAMP_TO_EDGE

tex.magFilter

Magnification filter. Used to set/get gl.TEXTURE_MAG_FILTER. Defaults to gl.NEAREST

tex.minFilter

Minification filter. Used to set/get gl.TEXTURE_MIN_FILTER. Defaults to gl.NEAREST

tex.mipSamples

The number of anisotropic filtering samples to use. This requires EXT_texture_filter_anisotropic to have any effect. High values will improve mipmap quality, but decrease performance.

Internals

tex.gl

A reference to the WebGL context of the texture.

tex.handle

A handle to the underlying texture object.

tex.format

The internal format of the texture.

tex.type

The internal data type of the texture.

Credits

(c) 2013 Mikola Lysenko. MIT License

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