[HTML5] Use compatibility function for glGetBufferSubData.

The "webgl/webgl2.h" include provides that function, but it's not
available in emscripten versions < 2.0.17 .

Since we need to support emscripten 1.39.9 (mono builds), this commit
adds a JS function in library_godot_display.js as a compatibility layer
for it, and implement glGetBufferSubData by funneling the call to that
function (so we don't have name collisions JS-side with recent emcc).

All those hacks are now moved to the platform directory instead of being
ifdefs inside the drivers implementations.

drivers/gles3/rasterizer_storage_gles3.h

@@ -45,11 +45,6 @@
 #include "shaders/cubemap_filter.glsl.gen.h"
 #include "shaders/particles.glsl.gen.h"
 
-// WebGL 2.0 has no MapBufferRange/UnmapBuffer, but offers a non-ES style BufferSubData API via glGetBufferSubData instead.
-#ifdef __EMSCRIPTEN__
-#include <webgl/webgl2.h>
-#endif
-
 template <class K>
 class ThreadedCallableQueue;
 class RasterizerCanvasGLES3;

platform/javascript/SCsub

@@ -4,6 +4,7 @@ Import("env")
 
 javascript_files = [
     "audio_driver_javascript.cpp",
+    "godot_webgl2.cpp",
     "http_client_javascript.cpp",
     "javascript_singleton.cpp",
     "javascript_main.cpp",

platform/javascript/godot_webgl2.cpp

@@ -0,0 +1,39 @@
+/*************************************************************************/
+/*  godot_webgl2.cpp                                                     */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "godot_webgl2.h"
+
+extern "C" {
+extern void godot_js_display_glGetBufferSubData(GLenum target, GLintptr offset, GLsizeiptr size, GLvoid *data);
+}
+
+void glGetBufferSubData(GLenum target, GLintptr offset, GLsizeiptr size, GLvoid *data) {
+	godot_js_display_glGetBufferSubData(target, offset, size, data);
+}

platform/javascript/godot_webgl2.h

@@ -0,0 +1,37 @@
+/*************************************************************************/
+/*  godot_webgl2.h                                                       */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef GODOT_WEBGL2_H
+#include "GLES3/gl3.h"
+
+// We could include "webgl/webgl2.h", but old (< 2.0.17) emscripten versions do not have it, so use our own wrapper instead.
+void glGetBufferSubData(GLenum target, GLintptr offset, GLsizeiptr size, GLvoid *data);
+
+#endif

platform/javascript/js/libs/library_godot_display.js

@@ -320,6 +320,18 @@ const GodotDisplay = {
 		},
 	},
 
+	// This is implemented as "glGetBufferSubData" in new emscripten versions.
+	// Since we have to support older (pre 2.0.17) emscripten versions, we add this wrapper function instead.
+	godot_js_display_glGetBufferSubData__sig: 'viiii',
+	godot_js_display_glGetBufferSubData__deps: ['$GL', 'emscripten_webgl_get_current_context'],
+	godot_js_display_glGetBufferSubData: function (target, offset, size, data) {
+		const gl_context_handle = _emscripten_webgl_get_current_context(); // eslint-disable-line no-undef
+		const gl = GL.getContext(gl_context_handle);
+		if (gl) {
+			gl.GLctx['getBufferSubData'](target, offset, HEAPU8, data, size);
+		}
+	},
+
 	godot_js_display_is_swap_ok_cancel__sig: 'i',
 	godot_js_display_is_swap_ok_cancel: function () {
 		const win = (['Windows', 'Win64', 'Win32', 'WinCE']);

platform/javascript/platform_config.h

@@ -29,3 +29,5 @@
 /*************************************************************************/
 
 #include <alloca.h>
+
+#define GLES3_INCLUDE_H "platform/javascript/godot_webgl2.h"