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// Copyright 2017 The Emscripten Authors. All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License. Both these licenses can be
// found in the LICENSE file.
#include <GLES3/gl3.h>
#include <GLES2/gl2ext.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <emscripten.h>
#include <emscripten/html5.h>
EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context;
int main()
{
// Hack context creation to fail for WebGL2 at runtime.
EM_ASM({
var original = Module.canvas.getContext;
Module.canvas.getContext = function(name, attrs) {
out('ask', name, attrs);
if (name === "webgl2") return null;
out('provide!');
return original.call(Module.canvas, name, attrs);
};
});
EmscriptenWebGLContextAttributes attrs;
emscripten_webgl_init_context_attributes(&attrs);
EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context;
// Request WebGL2 in a build compiled to allow 1 or 2. This should fail
// because we forced it to in that EM_ASM.
attrs.majorVersion = 2;
attrs.minorVersion = 0;
context = emscripten_webgl_create_context("#canvas", &attrs);
assert(!context);
// Request WebGL1, which succeeds.
attrs.majorVersion = 1;
context = emscripten_webgl_create_context("#canvas", &attrs);
assert(context);
// Verify it is indeed WebGL1.
EmscriptenWebGLContextAttributes outAttrs;
EMSCRIPTEN_RESULT res = emscripten_webgl_get_context_attributes(context, &outAttrs);
assert(res == EMSCRIPTEN_RESULT_SUCCESS);
printf("requested: %d actual: %d\n", attrs.majorVersion, outAttrs.majorVersion);
assert(outAttrs.majorVersion == 1);
return 0;
}
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