luma.gl/docs/api-reference/webgl/texture.md

Texture

A Texture is a WebGL object that contains one or more images that all have the same image format. Shaders can read from textures (through a sampler uniform) and they can be set up as render targets (by attaching them to a framebuffer).

Note: This section describes the Texture base class that implements functionality common to all four types of WebGL:

• Texture2D - Contains a "normal" image texture
• TextureCube - Holds 6 textures representing sides of a cube.
• Texture2DArray (WebGL2) - Holds an array of textures
• Texture3D (WebGL2) - Holds a "stack" of textures which enables 3D interpolation.

For more details see OpenGL Wiki.

Note that textures have a lot of optional capabilities made available by extensions, see the Limits section below.

Usage

• For additional usage examples, Texture inherits from Resource.

Configuring a Texture

const texture = new Texture2D(gl);
texture.setParameters({
  [GL.TEXTURE_WRAP_S]: GL.CLAMP
});

Using Textures

const texture = new Texture2D(gl, ...);

// For ease of use, the `Model` class can bind textures for a draw call
model.draw({
  uniforms({uMVMatrix: matrix, texture1: texture, texture2: texture})
});

// Alternatively, bind the textures using the `Texture` API directly
texture.bind(0);
texture.bind(1);
model.draw({
  uniforms({uMVMatrix: matrix})
});

Members

A number of read only accessors are available:

• width - width of one face of the cube map

• height - height of one face of the cube map

• format - internal format of the face textures

• border - Always 0.

• type - type used to create face textures

• dataFormat - data format used to create face textures.

• offset - offset used to create face textures. Always 0, unless specified using WebGL2 buffer constructor.

• handle - The underlying WebGL object.

• id - An identifying string that is intended to help debugging.

Sampler parameters can be accessed using Texture.getParameter, e.g:

texture.getParameter(GL.TEXTURE_MAG_FILTER);

Methods

constructor(gl : WebGLRenderingContext, props : Object)

The texture class cannot be constructed directly. It is a base class that provides common methods the the concrete texture classes.

• Texture2D,
• TextureCube,
• Texture2DArray and
• Texture3D.

The constructors for these classes should be used to create textures. They constructors all take common parameters, many of which are specified in this document.

• Sampling parameters are described in Sampler.
• Pixel store parameters are described in State Management.

generateMipmap() : Texture2D

Call to regenerate mipmaps after modifying texture(s)

WebGL References gl.generateMipmap

setImageData(options : Object) : Texture2D

Allocates storage and sets image data

  Texture.setImageData({
    target = this.target,
    pixels = null,
    data = null,
    width,
    height,
    level = 0,
    format = GL.RGBA,
    type,
    dataFormat,
    offset = 0,
    border = 0,
    compressed = false,
    parameters= {}
  });

• data (*) - Image data. Can be one of several data types see table below
• pixels (*) - alternative to data
• width (GLint) -
• height (GLint) -
• level (GLint) -
• format (GLenum) - format of image data.
• type (GLenum)

• format of array (autodetect from type) or
• (WEBGL2) format of buffer

• offset (Number) - (WEBGL2) offset from start of buffer
• border (GLint) - must be 0.
• compressed (Boolean) -
• parameters (Object) - GL parameters to be temporarily applied (most of the time, pixelStorage parameters) when updating the texture.

Valid image data types:

• null - create empty texture of specified format
• Typed array - initializes from image data in typed array according to format
• Buffer|WebGLBuffer - (WEBGL2) initialized from image data in WebGLBuffer accoeding to format.
• HTMLImageElement|Image - Initializes with content of image. Auto deduces texture width/height from image.
• HTMLCanvasElement - Inits with contents of canvas. Auto width/height.
• HTMLVideoElement - Creates video texture that continuously updates. Auto width/height.

setSubImageData(options : Object) : Texture2D

Redefines an area of an existing texture Note: does not allocate storage

  Texture.setSubImageData({
    target = this.target,
    pixels = null,
    data = null,
    x = 0,
    y = 0,
    width,
    height,
    level = 0,
    format = GL.RGBA,
    type,
    dataFormat,
    compressed = false,
    offset = 0,
    border = 0,
    parameters = {}
  });

• x (GLint) - xOffset from where texture to be updated
• y (GLint) - yOffset from where texture to be updated
• width (GLint) - width of the sub image to be updated
• height (GLint) - height of the sub image to be updated
• level (GLint) - mip level to be updated
• format (GLenum) - internal format of image data.
• typ (GLenum) - format of array (autodetect from type) or (WEBGL2) format of buffer or ArrayBufferView
• dataFormat (GLenum) - format of image data.
• offset (Number) - (WEBGL2) offset from start of buffer
• border (GLint) - must be 0.
• parameters - temporary settings to be applied, can be used to supply pixel store settings.

See also gl.compressedTexSubImage2D, gl.texSubImage2D, gl.bindTexture, gl.bindBuffer

getActiveUnit()

Returns number of active textures.

bind()

Binds itself to given textureUnit.

The following WebGL APIs are called in the function gl.activeTexture, gl.bindTexture

unbind()

The following WebGL APIs are called in the function gl.activeTexture, gl.bindTexture

Texture Image Data

WebGL allows textures to be created from a number of different data sources.

Type	Description
null	A texture will be created with the appropriate format, size and width. Bytes will be "uninitialized".
typed array	Bytes will be interpreted according to format/type parameters and pixel store parameters.
Buffer or WebGLBuffer (WebGL2)	Bytes will be interpreted according to format/type parameters and pixel store parameters.
Image (HTMLImageElement)	image will be used to fill the texture. width and height will be deduced.
Video (HTMLVideoElement)	video will be played, continously updating the texture. width and height will be deduced.
Canvas (HTMLCanvasElement)	canvas will be used to fill the texture. width and height will be deduced.
ImageData	canvas.getImageData() - Used to fill the texture. width and height will be deduced.

Texture Formats

Internal Format

If an application wants to store the texture at a certain resolution or in a certain format, it can request the resolution and format with internalFormat. WebGL will choose an internal representation with least the internal component sizes, and exactly the component types shown for that format, although it may not match exactly.

WebGL2 adds sized internal formats which enables the application to request specific components sizes and types (float and integer formats). While sized formats offer more control, unsized formats do give the GPU freedom to select the most performant internal representation.

Unsized Internal Format	Components	Description
GL.RGB	3	sampler reads the red, green and blue components, alpha is 1.0
GL.RGBA	4	Red, green, blue and alpha components are sampled from the color buffer.
GL.LUMINANCE	1	Each color contains a single luminance value. When sampled, rgb are all set to this luminance, alpha is 1.0.
GL.LUMINANCE_ALPHA	2	Each component is a luminance/alpha double. When sampled, rgb are all set to luminance, alpha from component.
GL.ALPHA	1	Discards the red, green and blue components and reads the alpha component.
GL.DEPTH_COMPONENT	1	WebGL2 or WEBGL_depth_texture
GL.DEPTH_STENCIL	2	WebGL2 or WEBGL_depth_texture

Sized Internal Format	Comp.	Size	Description
GL.R8 (WebGL2)	1	8 bits	red component
GL.R16F (WebGL2)	1	16 bits	half float red component
GL.R32F (WebGL2)	1	32 bits	float red component
GL.R8UI (WebGL2)	1	8 bits	unsigned int red component, usampler, no filtering
GL.RG8 (WebGL2)	1	16 bits	red and green components
GL.RG16F (WebGL2)	2	32 bits	red and green components, half float
GL.RG32F (WebGL2)	2	64 bits	red and green components, float
GL.RGUI (WebGL2)	2	16 bits	red and green components, usampler, no filtering
GL.RGB8 (WebGL2)	3	24 bits	red, green and blue components
GL.SRGB8 (WebGL2, EXT_sRGB)	3	24 bits	Color values are encoded to/decoded from sRGB before being written to/read from framebuffer
GL.RGB565 (WebGL2)	3	16 bits	5 bit red, 6 bit green, 5 bit blue
GL.R11F_G11F_B10F (WebGL2)	3	32 bits	11 and 10 bit floating point colors
GL.RGB9_E5 (WebGL2)	3	32 bits	14 bit floating point RGB, shared exponent
GL.RGB16F (WebGL2)	3	48 bits	half float RGB
GL.RGB32F (WebGL2)	3	96 bits	float RBG
GL.RGB8UI (WebGL2)	3	24 bits	unsigned integer 8 bit RGB: use usampler, no filtering
GL.RGBA8 (WebGL2)	4	32 bits	8 bit RGBA, typically what GL.RGBA "resolves" to
GL.SRGB_APLHA8 (WebGL2, EXT_sRGB)	4	32 bits	Color values are encoded to/decoded from sRGB before being written to/read from framebuffer
GL.RGB5_A1 (WebGL2)	4	16 bits	5 bit RGB, 1 bit alpha
GL.RGBA4444 (WebGL2)	4	16 bits	4 bit RGBA
GL.RGBA16F (WebGL2)	4	64 bits	half float RGBA
GL.RGBA32F (WebGL2)	4	128 bits	float RGA
GL.RGBA8UI (WebGL2)	4	32 bits	unsigned integer 8 bit RGBA, usampler, no filtering

Texture Component Type

Describes the layout of each color component in memory.

Value	WebGL2	WebGL1	Description
GL.UNSIGNED_BYTE	Yes	Yes	GLbyte 8 bits per channel for GL.RGBA
GL.UNSIGNED_SHORT_5_6_5	Yes	Yes	5 red bits, 6 green bits, 5 blue bits
GL.UNSIGNED_SHORT_4_4_4_4	Yes	Yes	4 red bits, 4 green bits, 4 blue bits, 4 alpha bits
GL.UNSIGNED_SHORT_5_5_5_1	Yes	Yes	5 red bits, 5 green bits, 5 blue bits, 1 alpha bit
GL.BYTE	Yes	No
GL.UNSIGNED_SHORT	Yes	WEBGL_depth_texture
GL.SHORT	Yes	No
GL.UNSIGNED_INT	Yes	WEBGL_depth_texture
GL.INT	Yes	No
GL.HALF_FLOAT	Yes	OES_texture_half_float
GL.FLOAT	Yes	OES_texture_float
GL.UNSIGNED_INT_2_10_10_10_REV	Yes	No
GL.UNSIGNED_INT_10F_11F_11F_REV	Yes	No
GL.UNSIGNED_INT_5_9_9_9_REV	Yes	No
GL.UNSIGNED_INT_24_8	Yes	WEBGL_depth_texture
GL.FLOAT_32_UNSIGNED_INT_24_8_REV	Yes	No	(pixels must be null)

Texture Format Combinations

This a simplified table illustrating what combinations of internal formats work with what formats and types. Note that luma.gl deduces format and type from internalFormat by taking the first value from the format and type entries in this table.

For more details, see tables in:

• WebGL2 spec
• OpenGL ES spec

Internal Format	Data Format	Data Type
GL.RGB	GL.RGB	GL.UNSIGNED_BYTE GL.UNSIGNED_SHORT_5_6_5
GL.RGBA	GL.RGBA	GL.UNSIGNED_BYTE GL.UNSIGNED_SHORT_4_4_4_4 GL.UNSIGNED_SHORT_5_5_5_1
GL.LUMINANCE_ALPHA	GL.LUMINANCE_ALPHA	GL.UNSIGNED_BYTE
GL.LUMINANCE	GL.LUMINANCE	GL.UNSIGNED_BYTE
GL.ALPHA	GL.ALPHA	GL.UNSIGNED_BYTE
GL.R8	GL.RED	GL.UNSIGNED_BYTE
GL.R16F	GL.RED	GL.HALF_FLOAT GL.FLOAT
GL.R32F	GL.RED	GL.FLOAT
GL.R8UI	GL.RED_INTEGER	GL.UNSIGNED_BYTE
GL.RG8	GL.RG	GL.UNSIGNED_BYTE
GL.RG16F	GL.RG	GL.HALF_FLOAT GL.FLOAT
GL.RG32F	GL.RG	GL.FLOAT
GL.RG8UI	GL.RG_INTEGER	GL.UNSIGNED_BYTE
GL.RGB8	GL.RGB	GL.UNSIGNED_BYTE
GL.SRGB8	GL.RGB	GL.UNSIGNED_BYTE
GL.RGB565	GL.RGB	GL.UNSIGNED_BYTE GL.UNSIGNED_SHORT_5_6_5
GL.R11F_G11F_B10F	GL.RGB	GL.UNSIGNED_INT_10F_11F_11F_REV GL.HALF_FLOAT GL.FLOAT
GL.RGB9_E5	GL.RGB	GL.HALF_FLOAT GL.FLOAT
GL.RGB16FG	GL.RGB	GL.HALF_FLOAT GL.FLOAT
GL.RGB32F	GL.RGB	GL.FLOAT
GL.RGB8UI	GL.RGB_INTEGER	GL.UNSIGNED_BYTE
GL.RGBA8	GL.RGBA	GL.UNSIGNED_BYTE
GL.SRGB8_ALPHA8	GL.RGBA	GL.UNSIGNED_BYTE
GL.RGB5_A1	GL.RGBA	GL.UNSIGNED_BYTE GL.UNSIGNED_SHORT_5_5_5_1
GL.RGBA4	GL.RGBA	GL.UNSIGNED_BYTE GL.UNSIGNED_SHORT_4_4_4_4
GL.RGBA16F	GL.RGBA	GL.HALF_FLOAT GL.FLOAT
GL.RGBA32F	GL.RGBA	GL.FLOAT
GL.RGBA8UI	GL.RGBA_INTEGER	GL.UNSIGNED_BYTE

Limits and Capabilities

Optional capabilities	controlled by extensions
Create floating point textures (GL.NEAREST sampling only)	TEXTURE_FLOAT
Create half-floating point textures (GL.NEAREST sampling)	TEXTURE_HALF_FLOAT
Floating point textures are color-renderable and readable	COLOR_BUFFER_FLOAT
Half float textures are color-renderable and readable	COLOR_BUFFER_HALF_FLOAT
sRGB format support	SRGB
depth texture support	DEPTH_TEXTURE
anisotropic filtering	TEXTURE_FILTER_ANISOTROPIC
GL.LINEAR_* sampling of floating point textures	TEXTURE_FILTER_LINEAR_FLOAT
GL.LINEAR_* sampling of half-floating point textures	TEXTURE_FILTER_LINEAR_HALF_FLOAT

NPOT Textures (WebGL1)

• Any texture with a non power of two dimension (width or height) is referred as NPOT texture, under WebGL1 NPOT textures have following limitations.

State	Limitation
Mipmapping	Should be disabled
GL.TEXTURE_MIN_FILTER	Must be either GL.LINEAR or GL.NEAREST
GL.TEXTURE_WRAP_S	Must be GL.CLAMP_TO_EDGE
GL.TEXTURE_WRAP_T	Must be GL.CLAMP_TO_EDGE

• 'Texture' class will perform above settings when NPOT texture resource is created. When un-supported filtering is set using Texture.setParameters, those will be overwritten with above supported values (GL.TEXTURE_MIN_FILTER will be set to GL.LINEAR). This only happens for NPOT textures when using WebGL1, and a warning log will be printed every time a setting is overwritten.

Remarks

• Textures can be supplied as uniforms to shaders that can sample them using texture coordinates and color pixels accordingly.
• Parameters that affect texture sampling can be set on textures or sampler objects.
• Textures can be created from a number of different sources, including typed arrays, HTML Images, HTML Canvases, HTML Videos and WebGLBuffers (WebGL2).
• The WebGL Context has global "pixel store" parameters that control how pixel data is laid out, including Y direction, color space etc.
• Textures are read from supplied data and written to the specified format/type parameters and pixel store parameters.