Clever Geek Handbook

Is there life without WebGL 2.0?

WebGL 2.0 came out back in 2017, brought the OpenGL ES 3.0graphics stack(2012), and it would seem that all modern browsers should have supported it for a long time. However, there are laggards among the leaders, and Safari users are still (early 2021) forced to limit themselves to the capabilities of WebGL 1.0, published in 2011 based on OpenGL ES 2.0.





Developers who have come across OpenGL ES 2.0 know firsthand how limited this graphics stack is. The limitations of the software interface largely reflected the weakness of mobile graphics cards of that time, so the massive transition of Android devices to OpenGL ES 3.0 a few years ago turned out to be very useful, although it began with a serious delay from desktop video cards.





Browser technologies turned out to be even more inert - while Android devices have long supported OpenGL ES 3.2 with computational shaders, implement support for Vulkan, and web standards developers are preparing WebGPU, an ordinary developer still has access to the outdated WebGL 2.0 at the time of publication, and even Stone Age WebGL 1.0 ...





Recently, the Open CASCADE Technology (OCCT) C ++ graphics engine added PBR (physics-based lighting) support for the metal-roughness material model. The advancement of glTF 2.0 , known as “JPEG for 3D”, has led to the emergence of this material model as an interchange standard between graphics engines.





PBR   / OpenGL 1.1. , PBR “” OpenGL 3.0 ( 2008 !) OpenGL ES 3.0.





( WebAssembly) - WebKit Safari WebGL 2.0! Safari macOS , iOS Apple. AppStore , WebKit, , Safari - AppStore .





, WebGL 1.0 , Apple , OpenGL ES 3.0 iOS .





, Safari , WebGL 2.0. , , - WebGL 2.0 iOS 14. , Emscripten, WebGL 2.0, OCCT PBR :





 function _glUniform4fv(location, count, value) {
   GL.validateGLObjectID(GL.uniforms, location, 'glUniform4fv', 'location');
   if (GL.currentContext.version >= 2) {
      // WebGL 2 provides new garbage-free entry points to call to WebGL.
      // Use those always when possible.
-     GLctx.uniform4fv(GL.uniforms[location], HEAPF32, value>>2, count*4);
-     return;
+     //GLctx.uniform4fv(GL.uniforms[location], HEAPF32, value>>2, count*4);
+     //return;
   }
...

-: OCCT PBR WebGL 1.0

, Safari - WebGL 2.0, - ( ). , PBR WebGL 2.0, , PBR WebGL 1.0 .





, , “” WebGL 1.0, PBR iPad WebGL. iPad ‘2020 (Apple A12 Bionic) iOS 14.4 / Safari:





EGLVersion: 1.4 Emscripten EGL
EGLVendor: Emscripten
EGLClientAPIs: OpenGL_ES
GLvendor: WebKit
GLdevice: WebKit WebGL
GLunmaskedVendor: Apple Inc.
GLunmaskedDevice: Apple GPU
GLversion: OpenGL ES 2.0 (WebGL 1.0)
GLSL: OpenGL ES GLSL ES 1.00 (WebGL GLSL ES 1.0 (1.0))
Max texture size: 16384
Max FBO dump size: 16384x16384
Max combined texture units: 32
Viewport: 1560x1080
GLextensions: GL_EXT_blend_minmax GL_EXT_sRGB GL_OES_texture_float
GL_OES_texture_half_float GL_OES_texture_half_float_linear
GL_OES_standard_derivatives GL_EXT_shader_texture_lod
GL_EXT_texture_filter_anisotropic GL_OES_vertex_array_object
GL_OES_element_index_uint GL_WEBGL_lose_context GL_WEBGL_compressed_texture_astc
GL_WEBGL_compressed_texture_etc GL_WEBGL_compressed_texture_etc1
GL_WEBKIT_WEBGL_compressed_texture_pvrtc GL_WEBGL_depth_texture
GL_ANGLE_instanced_arrays GL_WEBGL_debug_shaders GL_WEBGL_debug_renderer_info
GL_EXT_color_buffer_half_float

- , WebGL 1.0:





  • WebGL 2.0 Firefox.





    • “webgl.enable-webgl2=false



      ” “about:config



      ”.





    • - WebGL 1.0, WebGL 1.0 WebGL 2.0.





    • JavaScript .





  • WebGL 2.0 Emscripten.





    • “MAX_WEBGL_VERSION=1



      ”.





    • - WebGL 1.0.





    • JavaScript ( ).





  • Chromium “MAX_WEBGL_VERSION=1



    ”.





    • WebGL 1.0, - .





    • JavaScript ( ).





  • Draw Harness OpenGL ES, ANGLE.





    • OpenGL ES, .





    • “vcaps -maxversion 2 0



      ” OpenGL ES 2.0 ( OpenGL ES 3.0).





    • , - WebGL .





  • Safari macOS.





    • - WebGL 1.0.





    • Apple M1 (ARM64) iPad, !





    • JavaScript .





  • Safari iOS.





    • - WebGL 1.0.





    • JavaScript .





- , , … . WebGL - OpenGL OpenGL ES , - , WebGL GLSL.





WebGL, ANGLE, OpenGL Metal Apple. CG NVIDIA , AMD , OpenGL Apple , GLSL 110 GLSL 120!





PBR WebGL 1.0 :





  • PBR - 128x128



    GL_RG32F



    GL_RG16F



    .





    • #1: GL_RG32F



      /GL_RG16F



      iPad + WebGL 1.0 ( GL_EXT_texture_rg ).





    • #2: GL_RGBA32F



      iPad + WebGL 1.0. iPad GL_OES_texture_float_linear, GL_OES_texture_float. , iPad GL_OES_texture_half_float_linear, .





    • #3: GL_RGBA16F



      OpenGL ES 3.0 / WebGL 2.0, WebGL 1.0 + GL_OES_texture_half_float .





  • PBR 9x1 GL_RGBA32F



    .





    • : GL_RGBA32F



      FBO iPad + WebGL 1.0. iPad WEBGL_color_buffer_float.





  • - PBR 512x512x6



    GL_RGBA8



    .





    • : iPad + WebGL 1.0 -, ( GL_OES_fbo_render_mipmap ).





  • PBR GLSL - , .





    • : textureCubeLod()



      GLSL 100 es



      , GL_EXT_shader_texture_lod iPad + WebGL 1.0.





  • PBR GLSL , %



    .





    • #1: %



      GLSL 100 es



      , mod()



      .





    • #2: GLSL 100 es



      .





    • #3: GLSL 100 es



      (non-constant index expressions).





  • sRGB .





    • #1: GL_EXT_sRGB iPad + WenGL 1.0, , - glGenerateMipmap()



      .





    • #2: - sRGB WebGL 2.0 (5 !).





- OpenGL. - glGetError()



, WebGL , . , GLSL , , .





GL_RGBA16F



WebGL 1.0 + GL_OES_texture_half_float  32 16 - C/C++ . OpenGL 3.0 OpenGL ES 3.0 , WebGL 1.0 . GL_RGBA32F



GL_RGBA16F



:





GL_RGBA32F



PBR, . , PBR 9x1 - OpenGL, … , : 9x3 GL_RGBA8



  ( RGB ), glReadPixels()



, GL_RGBA32F



.





- PBR , - - glCopyTexImage2D()



. , - , , .





textureCubeLod()



PBR , , WebGL 1.0 GL_EXT_shader_texture_lod, GLSL :





+#extension GL_EXT_shader_texture_lod : enable
+#define textureCubeLod textureCubeLodEXT

PBR , textureCubeLod()



textureCube()



, .. - :





GLSL 100 es



. %



mod()



, :





  • GLSL :

    > const float aSHBasisFuncCoeffs[9] = float[9] { 0.0, 1.0, 2.0, … };







    • uniform , C/C++ - , -, , , .





  • for(;;)



    . PBR , ():

    > uniform int uSamplesNum;

    > for (int aSampleIter = 0; aSampleIter < uSamplesNum; ++aSampleIter) {}







    • , , , , - . GLSL 100 es



      - uniform



      . :

      > uniform int uSamplesNum;

      > int TheMaxSamples = 1024;

      > for (int aSampleIter = 0; aSampleIter < TheMaxSamples; ++aSampleIter) {

      >   if (aSampleIter >= uSamplesNum) { break; }

      > }







  • “Non-constant index expressions are disallowed”. PBR :

    > int anIndex = int(gl_FragCoord.x);

    > float aCoef = aSHCosCoeffs[anId] * aSHBasisFuncCoeffs[anId];







    • GLSL 100 es



      if/else.

      >  if  (anId == 0) { aCoef = aSHCosCoeffs[0] * aSHBasisFuncCoeffs[0]; }

      >  else if (anId == 1) { aCoef = aSHCosCoeffs[1] * aSHBasisFuncCoeffs[1]; }

      >  else if (anId == 2) { aCoef = aSHCosCoeffs[2] * aSHBasisFuncCoeffs[2]; }







GLSL 100 es



, . GLSL , , (trivially unrolled) , .. .





sRGB

sRGB . , WebGL 1.0 + GL_EXT_sRGB - -. sRGB , -. - ( ), PBR - .





WebGL 2.0, - sRGB , . - 2048x2048x6 5 ! OpenGL / OpenGL ES .





, WebGL - - WebGL sRGB, , - . , WebGL sRGB ( ), - , mip-map .





- PBR OCCT Safari iPad c WebGL 1.0. , (iPad ‘2020, Apple A12 SoC 2018 ), , Apple .





, WebGL 2.0 - - .





, Microsoft Internet Explorer Microsoft Edge Legacy ( -Chromium ) -, . - (Mozilla Firefox, Chromium, Safari/WebKit)  - , .





Apple's strategy of keeping the iOS ecosystem under the hood and keeping out competitors' solutions deprives users of the system of their own choice. Numerous rumors indicate that WebKit's jaded experimental support for WebGL 2.0 is about to end its experimental support (thanks in part to the switch to OpenGL ES implementation by the ANGLE library, which has been used by other browsers for a long time), although the timeline, as usual, remains unknown.





The original publication in English can be found here .







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