CanvasKit: Switch to WebGL 2.0

CQ_INCLUDE_TRYBOTS=skia.primary:Test-Debian9-EMCC-GCE-GPU-AVX2-wasm-Release-All-CanvasKit,Test-Debian9-EMCC-GCE-CPU-AVX2-wasm-Release-All-CanvasKit

Bug: skia:9052
Change-Id: I444031276aea90d82f289b16ba6cd36de5192abd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/248927
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>

modules/canvaskit/CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  - and `no_embedded_font` option now allows creating a `SkFontMgr.FromData` instead of
    always having an empty one.
  - Updated to emscripten 1.38.47
+ - Switch to WebGL 2.0, but fall back to 1.0 when unavailable - bug.skia.org/9052
 
 ### Fixed
  - Null terminator bug in draw text - skbug.com/9314

modules/canvaskit/compile.sh

@@ -48,12 +48,13 @@ mkdir -p $BUILD_DIR
 GN_GPU="skia_enable_gpu=true skia_gl_standard = \"webgl\""
 GN_GPU_FLAGS="\"-DSK_DISABLE_LEGACY_SHADERCONTEXT\","
 WASM_GPU="-lEGL -lGLESv2 -DSK_SUPPORT_GPU=1 \
-          -DSK_DISABLE_LEGACY_SHADERCONTEXT --pre-js $BASE_DIR/cpu.js --pre-js $BASE_DIR/gpu.js"
+          -DSK_DISABLE_LEGACY_SHADERCONTEXT --pre-js $BASE_DIR/cpu.js --pre-js $BASE_DIR/gpu.js\
+          -s USE_WEBGL2=1"
 if [[ $@ == *cpu* ]]; then
   echo "Using the CPU backend instead of the GPU backend"
   GN_GPU="skia_enable_gpu=false"
   GN_GPU_FLAGS=""
-  WASM_GPU="-DSK_SUPPORT_GPU=0 --pre-js $BASE_DIR/cpu.js"
+  WASM_GPU="-DSK_SUPPORT_GPU=0 --pre-js $BASE_DIR/cpu.js -s USE_WEBGL2=0"
 fi
 
 SKOTTIE_JS="--pre-js $BASE_DIR/skottie.js"
@@ -258,6 +259,5 @@ ${EMCXX} \
     -s USE_FREETYPE=1 \
     -s USE_LIBPNG=1 \
     -s WARN_UNALIGNED=1 \
-    -s USE_WEBGL2=0 \
     -s WASM=1 \
     -o $BUILD_DIR/canvaskit.js

modules/canvaskit/gpu.js

@@ -21,7 +21,7 @@
           preserveDrawingBuffer: get(attrs, 'preserveDrawingBuffer', 0),
           preferLowPowerToHighPerformance: get(attrs, 'preferLowPowerToHighPerformance', 0),
           failIfMajorPerformanceCaveat: get(attrs, 'failIfMajorPerformanceCaveat', 0),
-          majorVersion: get(attrs, 'majorVersion', 1),
+          majorVersion: get(attrs, 'majorVersion', 2),
           minorVersion: get(attrs, 'minorVersion', 0),
           enableExtensionsByDefault: get(attrs, 'enableExtensionsByDefault', 1),
           explicitSwapControl: get(attrs, 'explicitSwapControl', 0),
@@ -38,7 +38,14 @@
         }
         // GL is an enscripten provided helper
         // See https://github.com/emscripten-core/emscripten/blob/incoming/src/library_webgl.js
-        return GL.createContext(canvas, contextAttributes);
+        var ctx = GL.createContext(canvas, contextAttributes);
+
+        if (!ctx && contextAttributes.majorVersion > 1) {
+          contextAttributes.majorVersion = 1;  // fall back to WebGL 1.0
+          contextAttributes.minorVersion = 0;
+          ctx = GL.createContext(canvas, contextAttributes);
+        }
+        return ctx;
       }
 
       CanvasKit.GetWebGLContext = function(canvas, attrs) {

src/gpu/gl/GrGLAssembleWebGLInterfaceAutogen.cpp

@@ -180,6 +180,10 @@ sk_sp<const GrGLInterface> GrGLMakeAssembledWebGLInterface(void *ctx, GrGLGetPro
         GET_PROC(TexStorage2D);
     }
 
+    if (glVer >= GR_GL_VER(2,0)) {
+        GET_PROC(VertexAttribDivisor);
+    }
+
     if (glVer >= GR_GL_VER(2,0)) {
         GET_PROC(VertexAttribIPointer);
     }

src/gpu/gl/GrGLCaps.cpp

@@ -986,8 +986,12 @@ void GrGLCaps::initFSAASupport(const GrContextOptions& contextOptions, const GrG
             fMSFBOType = kES_Apple_MSFBOType;
         }
     } else if (GR_IS_GR_WEBGL(ctxInfo.standard())) {
-        // No support in WebGL
-        fMSFBOType = kNone_MSFBOType;
+        // No support in WebGL 1, but there is for 2.0
+        if (ctxInfo.version() >= GR_GL_VER(2,0)) {
+            fMSFBOType = kStandard_MSFBOType;
+        } else {
+            fMSFBOType = kNone_MSFBOType;
+        }
     }
 
     // We disable MSAA for all Intel GPUs. Before Gen9, performance was very bad. Even with Gen9,

src/gpu/gl/GrGLGLSL.cpp

@@ -46,7 +46,7 @@ bool GrGLGetGLSLGeneration(const GrGLInterface* gl, GrGLSLGeneration* generation
             *generation = k110_GrGLSLGeneration;
         }
         return true;
-    } else if (GR_IS_GR_GL_ES(gl->fStandard) || GR_IS_GR_WEBGL(gl->fStandard)) {
+    } else if (GR_IS_GR_GL_ES(gl->fStandard)) {
         SkASSERT(ver >= GR_GL_VER(1,00));
         if (ver >= GR_GLSL_VER(3,20)) {
             *generation = k320es_GrGLSLGeneration;
@@ -58,6 +58,14 @@ bool GrGLGetGLSLGeneration(const GrGLInterface* gl, GrGLSLGeneration* generation
             *generation = k110_GrGLSLGeneration;
         }
         return true;
+    } else if (GR_IS_GR_WEBGL(gl->fStandard)) {
+        SkASSERT(ver >= GR_GL_VER(1,0));
+        if (ver >= GR_GLSL_VER(2,0)) {
+            *generation = k330_GrGLSLGeneration;  // ES 3.0
+        } else {
+            *generation = k110_GrGLSLGeneration;
+        }
+        return true;
     }
     SK_ABORT("Unknown GL Standard");
 }

src/gpu/gl/GrGLInterfaceAutogen.cpp

@@ -346,7 +346,9 @@ bool GrGLInterface::validate() const {
           fExtensions.has("GL_ARB_instanced_arrays"))) ||
        (GR_IS_GR_GL_ES(fStandard) && (
           (glVer >= GR_GL_VER(3,0)) ||
-          fExtensions.has("GL_EXT_instanced_arrays")))) {
+          fExtensions.has("GL_EXT_instanced_arrays"))) ||
+       (GR_IS_GR_WEBGL(fStandard) && (
+          (glVer >= GR_GL_VER(2,0))))) {
         if (!fFunctions.fVertexAttribDivisor) {
             RETURN_FALSE_INTERFACE;
         }

tools/gpu/gl/interface/interface.json5

@@ -279,7 +279,7 @@
               {/*    else if      */  "ext": "GL_ARB_instanced_arrays"}],
     "GLES":  [{"min_version": [3, 0], "ext": "<core>"},
               {/*    else if      */  "ext": "GL_EXT_instanced_arrays"}],
-    "WebGL": null,
+    "WebGL": [{"min_version": [2, 0], "ext": "<core>"}],
 
     "functions": [
       "VertexAttribDivisor",