luma.gl/docs/api-reference/advanced/extensions.md

WebGL Extensions

This section provides an overview of WebGL extensions and describes luma's builtin support for them.

While the Khronos group's official list of WebGL Extensions is intimidatingly long, the extensions can be categorized into a few basic categories

Note that because luma.gl gives the application direct access to the WebGL context, the application can always work directly with any extensions it needs.

General Extensions

These extensions expose optional general capability that was not included in the initial standard perhaps due to performance or security concerns.

Extension	Enables	luma.gl support
WEBGL_shared_resources	Share resource between WebGL contexts	N/A
WEBGL_security_sensitive_resources	Cross-origin resource loading	N/A

Debug Extensions

These extensions expose additional information and capabilities that help debug and profile a WebGL program. luma.gl carefully uses these extensions under the hood to provide a better debug experience.

Extension	Enables	luma.gl support
WEBGL_lose_context	Simulate context loss	N/A
WEBGL_debug_renderer_info	Returns strings identifying GPU	glGetDebugInfo, logged to console on startup
WEBGL_debug_shaders	Gives access to translated shader source	Shader class method
EXT_disjoint_timer_query	Enables async queries of GPU timings	Used to implement Query under WebGL1
EXT_disjoint_timer_query_webgl2	Enables async queries of GPU timings	Built into WebGL2 Query object

WebGL1 Extensions

These extensions expose various OpenGL ES 3.0 features that are often available on the target devices that run the OpenGL ES 2.0 based WebGL1 standard today.

Note that many of these extensions are no longer available in WebGL2 as the functionality they enable is provided by default in WebGL2 (which requires an OpenGL ES 3.0 compliant device).

Extension	Enables	luma.gl support
OES_vertex_array_object	WebGL2 VertexArrayObjects	VertexArrayObject uses this extension under WebGL1
ANGLE_instanced_arrays	Offers WebGL2 instanced draw functions and instance divisor	luma's draw function automatically uses this extension when required
OES_texture_float	Enables Float32Array textures
OES_texture_half_float	Enables Uint16Array / HALF_FLOAT_OES textures
OES_standard_derivatives	Enables derivative functions in GLSL
WEBGL_depth_texture	Enables storing depth buffers in textures
OES_element_index_uint	Querying enables Uint32Array ELEMENTS	luma queries on startup to enable, app needs to query again it wants to test platform
EXT_frag_depth	Enables fragment shader to control depth value
WEBGL_draw_buffers	Enables fragment shaders to draw to multiple framebuffers
OES_texture_half_float_linear	Enables linear filter for half float textures
EXT_blend_minmax	Extends blending function
EXT_shader_texture_lod	enables shader control of LOD
EXT_texture_filter_anisotropic	Enables anisotropic filtering
OES_texture_float_linear	Enables linear filter for float textures
OES_fbo_render_mipmap	Render to specific texture mipmap level
EXT_sRGB	sRGB encoded rendering
EXT_color_buffer_half_float	framebuffer render to half float color buffer

WebGL2 Extensions

These extensions expose various OpenGL ES 3.1 and 3.2 features that are often available on target devices that run the OpenGL ES 3.0 based WebGL2 standard today. These extensions can bring OpenGL ES 3.1 or 3.2 capabilities to WebGL2 contexts, if the device supports them.

Extension	Enables	luma.gl support
EXT_color_buffer_float	framebuffer render to float color buffer
WEBGL_color_buffer_float	frame buffer render of various floating point format

Proposed Extensions

Khronos lists a couple of proposed extensions. They will be considered by luma.gl as they become available in browsers.

Extension	Enables	luma.gl support
EXT_clip_cull_distance (WebGL2)	hardware clip/cull planes (ES3.2)	N/A
EXT_float_blend	32 bit color blending	N/A
EXT_texture_storage	texture storage effiency	N/A
WEBGL_debug	Debug events	N/A
WEBGL_dynamic_texture	frequently changin textures	N/A
WEBGL_subarray_uploads	Efficient buffer update	N/A

Compressed Texture Format Extensions

Used to query if the GPU supports specific proprietary compressed texture formats.

These enable various proprietary (patent-encumbered) compressed texture formats.

The primary advantage of compressed texture formats is that in contrast to JPGs or PNGs, they do not have to be decompressed to be used by the GPU. As a non-scientific guideline, compressed texture formats might achieve about 4x compression, compared to say 16x compression for JPEG. So while they are usually slower to load, but they could allow 4x more textures to be stored in the same amount of GPU memory.

Because of patent issues, to use these formats an application would typically:

1. generate these in external commercial applications (which have already licensed any supported formats).
2. load them in binary form without touching the content
3. Pass them directly to a texture, so that they are processed inside the GPU driver (which also has licensed the formats).

Also note that due to the patent issues, finding a compressed texture format which is supported across a range of target devices can be challenging.

For these reasons, luma.gl leaves the handling of these formats (and extensions) to the application.

Extension	Enables	luma.gl support
WEBGL_compressed_texture_s3tc	Certain S3TC compressed texture formats	N/A
WEBGL_compressed_texture_atc	Certain AMD compressed texture formats	N/A
WEBGL_compressed_texture_pvrtc	Certain IMG compressed texture formats	N/A
WEBGL_compressed_texture_etc1	Certain compressed texture formats	N/A
WEBGL_compressed_texture_etc	Certaincompressed texture formats	N/A
WEBGL_compressed_texture_astc	Certain compressed texture formats	N/A
WEBGL_compressed_texture_s3tc_srgb	Certain compressed texture formats	N/A