Add selectable GPU backend to wasm debugger
Bug: skia:
Change-Id: If34e08cb320a141cb838caafeffa4f1f69c5234f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/201404
Commit-Queue: Nathaniel Nifong <nifong@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
diff --git a/experimental/wasm-skp-debugger/gpu.js b/experimental/wasm-skp-debugger/gpu.js
new file mode 100644
index 0000000..61b8787
--- /dev/null
+++ b/experimental/wasm-skp-debugger/gpu.js
@@ -0,0 +1,92 @@
+// Adds compile-time JS functions to augment the DebuggerView interface.
+// Specifically, anything that should only be on the GPU version of DebuggerView.
+(function(DebuggerView){
+ function makeWebGLContext(canvas, attrs) {
+ // These defaults come from the emscripten _emscripten_webgl_create_context
+ // TODO(nifong): All these settings appear to be ignored. investigate.
+ var contextAttributes = {
+ alpha: 1,
+ depth: 1,
+ stencil: 0,
+ antialias: 1,
+ premultipliedAlpha: 1,
+ preserveDrawingBuffer: 0,
+ preferLowPowerToHighPerformance: 0,
+ failIfMajorPerformanceCaveat: 0,
+ majorVersion: 1,
+ minorVersion: 0,
+ enableExtensionsByDefault: 1,
+ explicitSwapControl: 0,
+ renderViaOffscreenBackBuffer: 0,
+ };
+ if (!canvas) {
+ console.log('null canvas passed into makeWebGLContext');
+ return 0;
+ }
+ // This check is from the emscripten version
+ if (contextAttributes['explicitSwapControl']) {
+ console.log('explicitSwapControl is not supported');
+ return 0;
+ }
+ // GL is an enscripten provided helper
+ // See https://github.com/emscripten-core/emscripten/blob/incoming/src/library_webgl.js
+ let context = GL.createContext(canvas, contextAttributes);
+ if (!context) {
+ console.log('Could not get a WebGL context from the canvas element.');
+ }
+ console.log('Made Web Gl Canvas Surface');
+ return context
+ }
+
+ DebuggerView.GetWebGLContext = function(canvas, attrs) {
+ return makeWebGLContext(canvas, attrs);
+ };
+
+ // arg can be of types:
+ // - String - in which case it is interpreted as an id of a
+ // canvas element.
+ // - HTMLCanvasElement - in which the provided canvas element will
+ // be used directly.
+ // Width and height can be provided to override those on the canvas
+ // element, or specify a height for when a context is provided.
+ DebuggerView.MakeWebGLCanvasSurface = function(arg, width, height) {
+ var canvas = arg;
+ if (canvas.tagName !== 'CANVAS') {
+ canvas = document.getElementById(arg);
+ if (!canvas) {
+ throw 'Canvas with id ' + arg + ' was not found';
+ }
+ }
+ // we are ok with all the defaults
+ var ctx = DebuggerView.GetWebGLContext(canvas);
+
+ if (!ctx || ctx < 0) {
+ throw 'failed to create webgl context: err ' + ctx;
+ }
+
+ if (!canvas && (!width || !height)) {
+ throw 'height and width must be provided with context';
+ }
+
+ var grcontext = this.MakeGrContext(ctx);
+ if (!grcontext) {
+ throw (
+ 'failed to create grcontext. Open GL driver may not support all needed functions: err '
+ + grcontext);
+ }
+
+ // Maybe better to use clientWidth/height. See:
+ // https://webglfundamentals.org/webgl/lessons/webgl-anti-patterns.html
+ var surface = this.MakeOnScreenGLSurface(grcontext,
+ width || canvas.width,
+ height || canvas.height);
+ if (!surface) {
+ // Don't fall back silently in the debugger, the user explicitly controls which backend he
+ // wants via the UI. Calling function may catch this and show the user an error.
+ throw ('Failed to create OpenGL surface. GPU Backend unavailable.');
+ }
+ return surface;
+ };
+ // Default to trying WebGL first.
+ DebuggerView.MakeCanvasSurface = DebuggerView.MakeWebGLCanvasSurface;
+}(Module)); // When this file is loaded in, the high level object is "Module";