Merge pull request #1972 from juj/gl__opts

GL cleanup and optimizations.

2 files changed, 605 insertions, 588 deletions

diff --git a/src/library_browser.js b/src/library_browser.js
index e0f53052..d5e35339 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -319,7 +319,7 @@ mergeInto(LibraryManager.library, {
         }, false);
       }
       if (setInModule) {
-        Module.ctx = ctx;
+        GLctx = Module.ctx = ctx;
         Module.useWebGL = useWebGL;
         Browser.moduleContextCreatedCallbacks.forEach(function(callback) { callback() });
         Browser.init();
diff --git a/src/library_gl.js b/src/library_gl.js
index 19e64c32..0c601673 100644
--- a/src/library_gl.js
+++ b/src/library_gl.js
@@ -4,7 +4,7 @@
  */
 
 var LibraryGL = {
-  $GL__postset: 'GL.init()',
+  $GL__postset: 'var GLctx; GL.init()',
   $GL: {
 #if GL_DEBUG
     debug: true,
@@ -22,9 +22,13 @@ var LibraryGL = {
 
 #if FULL_ES2
     clientBuffers: [],
+    currArrayBuffer: 0,
+    currElementArrayBuffer: 0,
 #endif
+#if LEGACY_GL_EMULATION
     currArrayBuffer: 0,
     currElementArrayBuffer: 0,
+#endif
 
     byteSizeByTypeRoot: 0x1400, // GL_BYTE
     byteSizeByType: [
@@ -96,14 +100,14 @@ var LibraryGL = {
         }
         if (size != last) {
           curr++;
-          GL.tempVertexBuffers[curr] = Module.ctx.createBuffer();
-          Module.ctx.bindBuffer(Module.ctx.ARRAY_BUFFER, GL.tempVertexBuffers[curr]);
-          Module.ctx.bufferData(Module.ctx.ARRAY_BUFFER, size, Module.ctx.DYNAMIC_DRAW);
-          Module.ctx.bindBuffer(Module.ctx.ARRAY_BUFFER, null);
-          GL.tempIndexBuffers[curr] = Module.ctx.createBuffer();
-          Module.ctx.bindBuffer(Module.ctx.ELEMENT_ARRAY_BUFFER, GL.tempIndexBuffers[curr]);
-          Module.ctx.bufferData(Module.ctx.ELEMENT_ARRAY_BUFFER, size, Module.ctx.DYNAMIC_DRAW);
-          Module.ctx.bindBuffer(Module.ctx.ELEMENT_ARRAY_BUFFER, null);
+          GL.tempVertexBuffers[curr] = GLctx.createBuffer();
+          GLctx.bindBuffer(GLctx.ARRAY_BUFFER, GL.tempVertexBuffers[curr]);
+          GLctx.bufferData(GLctx.ARRAY_BUFFER, size, GLctx.DYNAMIC_DRAW);
+          GLctx.bindBuffer(GLctx.ARRAY_BUFFER, null);
+          GL.tempIndexBuffers[curr] = GLctx.createBuffer();
+          GLctx.bindBuffer(GLctx.ELEMENT_ARRAY_BUFFER, GL.tempIndexBuffers[curr]);
+          GLctx.bufferData(GLctx.ELEMENT_ARRAY_BUFFER, size, GLctx.DYNAMIC_DRAW);
+          GLctx.bindBuffer(GLctx.ELEMENT_ARRAY_BUFFER, null);
           last = size;
         }
         GL.tempBufferIndexLookup[i] = curr;
@@ -111,8 +115,8 @@ var LibraryGL = {
 
       if (quads) {
         // GL_QUAD indexes can be precalculated
-        GL.tempQuadIndexBuffer = Module.ctx.createBuffer();
-        Module.ctx.bindBuffer(Module.ctx.ELEMENT_ARRAY_BUFFER, GL.tempQuadIndexBuffer);
+        GL.tempQuadIndexBuffer = GLctx.createBuffer();
+        GLctx.bindBuffer(GLctx.ELEMENT_ARRAY_BUFFER, GL.tempQuadIndexBuffer);
         var numIndexes = GL.MAX_TEMP_BUFFER_SIZE >> 1;
         var quadIndexes = new Uint16Array(numIndexes);
         var i = 0, v = 0;
@@ -131,8 +135,8 @@ var LibraryGL = {
           if (i >= numIndexes) break;
           v += 4;
         }
-        Module.ctx.bufferData(Module.ctx.ELEMENT_ARRAY_BUFFER, quadIndexes, Module.ctx.STATIC_DRAW);
-        Module.ctx.bindBuffer(Module.ctx.ELEMENT_ARRAY_BUFFER, null);
+        GLctx.bufferData(GLctx.ELEMENT_ARRAY_BUFFER, quadIndexes, GLctx.STATIC_DRAW);
+        GLctx.bindBuffer(GLctx.ELEMENT_ARRAY_BUFFER, null);
       }
     },
 
@@ -182,13 +186,13 @@ var LibraryGL = {
         source += frag;
       }
       // Let's see if we need to enable the standard derivatives extension
-      type = Module.ctx.getShaderParameter(GL.shaders[shader], 0x8B4F /* GL_SHADER_TYPE */);
+      type = GLctx.getShaderParameter(GL.shaders[shader], 0x8B4F /* GL_SHADER_TYPE */);
       if (type == 0x8B30 /* GL_FRAGMENT_SHADER */) {
         if (GL.findToken(source, "dFdx") ||
             GL.findToken(source, "dFdy") ||
             GL.findToken(source, "fwidth")) {
           source = "#extension GL_OES_standard_derivatives : enable\n" + source;
-          var extension = Module.ctx.getExtension("OES_standard_derivatives");
+          var extension = GLctx.getExtension("OES_standard_derivatives");
 #if GL_DEBUG
           if (!extension) {
             Module.printErr("Shader attempts to use the standard derivatives extension which is not available.");
@@ -240,7 +244,7 @@ var LibraryGL = {
         case 0x86A2: // GL_NUM_COMPRESSED_TEXTURE_FORMATS
           // WebGL doesn't have GL_NUM_COMPRESSED_TEXTURE_FORMATS (it's obsolete since GL_COMPRESSED_TEXTURE_FORMATS returns a JS array that can be queried for length),
           // so implement it ourselves to allow C++ GLES2 code get the length.
-          var formats = Module.ctx.getParameter(0x86A3 /*GL_COMPRESSED_TEXTURE_FORMATS*/);
+          var formats = GLctx.getParameter(0x86A3 /*GL_COMPRESSED_TEXTURE_FORMATS*/);
           ret = formats.length;
           break;
         case 0x8B9A: // GL_IMPLEMENTATION_COLOR_READ_TYPE
@@ -252,7 +256,7 @@ var LibraryGL = {
       }
 
       if (ret === undefined) {
-        var result = Module.ctx.getParameter(name_);
+        var result = GLctx.getParameter(name_);
         switch (typeof(result)) {
           case "number":
             ret = result;
@@ -391,7 +395,7 @@ var LibraryGL = {
             default:
               throw 'Invalid format (' + format + ')';
           }
-          internalFormat = Module.ctx.RGBA;
+          internalFormat = GLctx.RGBA;
           break;
         default:
           throw 'Invalid type (' + type + ')';
@@ -417,13 +421,13 @@ var LibraryGL = {
     enableVertexAttribArray: function enableVertexAttribArray(index) {
       if (!GL.enabledClientAttribIndices[index]) {
         GL.enabledClientAttribIndices[index] = true;
-        Module.ctx.enableVertexAttribArray(index);
+        GLctx.enableVertexAttribArray(index);
       }
     },
     disableVertexAttribArray: function disableVertexAttribArray(index) {
       if (GL.enabledClientAttribIndices[index]) {
         GL.enabledClientAttribIndices[index] = false;
-        Module.ctx.disableVertexAttribArray(index);
+        GLctx.disableVertexAttribArray(index);
       }
     },
 #endif
@@ -462,20 +466,20 @@ var LibraryGL = {
           buf = GL.tempVertexBuffers[index++];
         } while (used.indexOf(buf) >= 0);
         used.push(buf);
-        Module.ctx.bindBuffer(Module.ctx.ARRAY_BUFFER, buf);
-        Module.ctx.bufferSubData(Module.ctx.ARRAY_BUFFER,
+        GLctx.bindBuffer(GLctx.ARRAY_BUFFER, buf);
+        GLctx.bufferSubData(GLctx.ARRAY_BUFFER,
                                  0,
                                  HEAPU8.subarray(cb.ptr, cb.ptr + size));
 #if GL_ASSERTIONS
         GL.validateVertexAttribPointer(cb.size, cb.type, cb.stride, 0);
 #endif
-        Module.ctx.vertexAttribPointer(i, cb.size, cb.type, cb.normalized, cb.stride, 0);
+        GLctx.vertexAttribPointer(i, cb.size, cb.type, cb.normalized, cb.stride, 0);
       }
     },
 
     postDrawHandleClientVertexAttribBindings: function postDrawHandleClientVertexAttribBindings() {
       if (GL.resetBufferBinding) {
-        Module.ctx.bindBuffer(Module.ctx.ARRAY_BUFFER, GL.buffers[GL.currArrayBuffer]);
+        GLctx.bindBuffer(GLctx.ARRAY_BUFFER, GL.buffers[GL.currArrayBuffer]);
       }
     },
 #endif
@@ -544,7 +548,7 @@ var LibraryGL = {
         GL.miniTempBufferViews[i] = GL.miniTempBuffer.subarray(0, i+1);
       }
 
-      GL.maxVertexAttribs = Module.ctx.getParameter(Module.ctx.MAX_VERTEX_ATTRIBS);
+      GL.maxVertexAttribs = GLctx.getParameter(GLctx.MAX_VERTEX_ATTRIBS);
 #if FULL_ES2
       for (var i = 0; i < GL.maxVertexAttribs; i++) {
         GL.clientBuffers[i] = { enabled: false, clientside: false, size: 0, type: 0, normalized: 0, stride: 0, ptr: 0 };
@@ -554,18 +558,18 @@ var LibraryGL = {
 #endif
 
       // Detect the presence of a few extensions manually, this GL interop layer itself will need to know if they exist. 
-      GL.compressionExt = Module.ctx.getExtension('WEBGL_compressed_texture_s3tc') ||
-                          Module.ctx.getExtension('MOZ_WEBGL_compressed_texture_s3tc') ||
-                          Module.ctx.getExtension('WEBKIT_WEBGL_compressed_texture_s3tc');
+      GL.compressionExt = GLctx.getExtension('WEBGL_compressed_texture_s3tc') ||
+                          GLctx.getExtension('MOZ_WEBGL_compressed_texture_s3tc') ||
+                          GLctx.getExtension('WEBKIT_WEBGL_compressed_texture_s3tc');
 
-      GL.anisotropicExt = Module.ctx.getExtension('EXT_texture_filter_anisotropic') ||
-                          Module.ctx.getExtension('MOZ_EXT_texture_filter_anisotropic') ||
-                          Module.ctx.getExtension('WEBKIT_EXT_texture_filter_anisotropic');
+      GL.anisotropicExt = GLctx.getExtension('EXT_texture_filter_anisotropic') ||
+                          GLctx.getExtension('MOZ_EXT_texture_filter_anisotropic') ||
+                          GLctx.getExtension('WEBKIT_EXT_texture_filter_anisotropic');
 
-      GL.floatExt = Module.ctx.getExtension('OES_texture_float');
+      GL.floatExt = GLctx.getExtension('OES_texture_float');
       
       // Extension available from Firefox 26 and Google Chrome 30
-      GL.instancedArraysExt = Module.ctx.getExtension('ANGLE_instanced_arrays');
+      GL.instancedArraysExt = GLctx.getExtension('ANGLE_instanced_arrays');
 
       // These are the 'safe' feature-enabling extensions that don't add any performance impact related to e.g. debugging, and
       // should be enabled by default so that client GLES2/GL code will not need to go through extra hoops to get its stuff working.
@@ -589,11 +593,11 @@ var LibraryGL = {
         return false;
       }
 
-      var extensions = Module.ctx.getSupportedExtensions();
+      var extensions = GLctx.getSupportedExtensions();
       for(var e in extensions) {
         var ext = extensions[e].replace('MOZ_', '').replace('WEBKIT_', '');
         if (automaticallyEnabledExtensions.indexOf(ext) != -1) {
-          Module.ctx.getExtension(ext); // Calling .getExtension enables that extension permanently, no need to store the return value to be enabled.
+          GLctx.getExtension(ext); // Calling .getExtension enables that extension permanently, no need to store the return value to be enabled.
         }
       }
     },
@@ -620,9 +624,9 @@ var LibraryGL = {
       var utable = ptable.uniforms;
       // A program's uniform table maps the string name of an uniform to an integer location of that uniform.
       // The global GL.uniforms map maps integer locations to WebGLUniformLocations.
-      var numUniforms = Module.ctx.getProgramParameter(p, Module.ctx.ACTIVE_UNIFORMS);
+      var numUniforms = GLctx.getProgramParameter(p, GLctx.ACTIVE_UNIFORMS);
       for (var i = 0; i < numUniforms; ++i) {
-        var u = Module.ctx.getActiveUniform(p, i);
+        var u = GLctx.getActiveUniform(p, i);
 
         var name = u.name;
         ptable.maxUniformLength = Math.max(ptable.maxUniformLength, name.length+1);
@@ -636,14 +640,14 @@ var LibraryGL = {
         // Optimize memory usage slightly: If we have an array of uniforms, e.g. 'vec3 colors[3];', then 
         // only store the string 'colors' in utable, and 'colors[0]', 'colors[1]' and 'colors[2]' will be parsed as 'colors'+i.
         // Note that for the GL.uniforms table, we still need to fetch the all WebGLUniformLocations for all the indices.
-        var loc = Module.ctx.getUniformLocation(p, name);
+        var loc = GLctx.getUniformLocation(p, name);
         var id = GL.getNewId(GL.uniforms);
         utable[name] = [u.size, id];
         GL.uniforms[id] = loc;
 
         for (var j = 1; j < u.size; ++j) {
           var n = name + '['+j+']';
-          loc = Module.ctx.getUniformLocation(p, n);
+          loc = GLctx.getUniformLocation(p, n);
           id = GL.getNewId(GL.uniforms);
 
           GL.uniforms[id] = loc;
@@ -659,7 +663,7 @@ var LibraryGL = {
     } else if (pname == 0x0cf5 /* GL_UNPACK_ALIGNMENT */) {
       GL.unpackAlignment = param;
     }
-    Module.ctx.pixelStorei(pname, param);
+    GLctx.pixelStorei(pname, param);
   },
 
   glGetString__sig: 'ii',
@@ -670,10 +674,10 @@ var LibraryGL = {
       case 0x1F00 /* GL_VENDOR */:
       case 0x1F01 /* GL_RENDERER */:
       case 0x1F02 /* GL_VERSION */:
-        ret = allocate(intArrayFromString(Module.ctx.getParameter(name_)), 'i8', ALLOC_NORMAL);
+        ret = allocate(intArrayFromString(GLctx.getParameter(name_)), 'i8', ALLOC_NORMAL);
         break;
       case 0x1F03 /* GL_EXTENSIONS */:
-        var exts = Module.ctx.getSupportedExtensions();
+        var exts = GLctx.getSupportedExtensions();
         var gl_exts = [];
         for (i in exts) {
           gl_exts.push(exts[i]);
@@ -714,7 +718,7 @@ var LibraryGL = {
   glGenTextures: function(n, textures) {
     for (var i = 0; i < n; i++) {
       var id = GL.getNewId(GL.textures);
-      var texture = Module.ctx.createTexture();
+      var texture = GLctx.createTexture();
       texture.name = id;
       GL.textures[id] = texture;
       {{{ makeSetValue('textures', 'i*4', 'id', 'i32') }}};
@@ -726,7 +730,7 @@ var LibraryGL = {
     for (var i = 0; i < n; i++) {
       var id = {{{ makeGetValue('textures', 'i*4', 'i32') }}};
       var texture = GL.textures[id];
-      Module.ctx.deleteTexture(texture);
+      GLctx.deleteTexture(texture);
       texture.name = 0;
       GL.textures[id] = null;
     }
@@ -742,7 +746,8 @@ var LibraryGL = {
     } else {
       data = null;
     }
-    Module.ctx['compressedTexImage2D'](target, level, internalFormat, width, height, border, data);
+    // N.b. using array notation explicitly to not confuse Closure minification.
+    GLctx['compressedTexImage2D'](target, level, internalFormat, width, height, border, data);
   },
 
   glCompressedTexSubImage2D__sig: 'viiiiiiiii',
@@ -755,7 +760,7 @@ var LibraryGL = {
     } else {
       data = null;
     }
-    Module.ctx['compressedTexSubImage2D'](target, level, xoffset, yoffset, width, height, data);
+    CLctx['compressedTexSubImage2D'](target, level, xoffset, yoffset, width, height, data);
   },
 
   glTexImage2D__sig: 'viiiiiiiii',
@@ -767,7 +772,7 @@ var LibraryGL = {
     } else {
       pixels = null;
     }
-    Module.ctx.texImage2D(target, level, internalFormat, width, height, border, format, type, pixels);
+    GLctx.texImage2D(target, level, internalFormat, width, height, border, format, type, pixels);
   },
 
   glTexSubImage2D__sig: 'viiiiiiiii',
@@ -778,7 +783,7 @@ var LibraryGL = {
     } else {
       pixels = null;
     }
-    Module.ctx.texSubImage2D(target, level, xoffset, yoffset, width, height, format, type, pixels);
+    GLctx.texSubImage2D(target, level, xoffset, yoffset, width, height, format, type, pixels);
   },
 
   glReadPixels__sig: 'viiiiiii',
@@ -802,7 +807,7 @@ var LibraryGL = {
         return;
     }
     var totalSize = width*height*sizePerPixel;
-    Module.ctx.readPixels(x, y, width, height, format, type, HEAPU8.subarray(pixels, pixels + totalSize));
+    GLctx.readPixels(x, y, width, height, format, type, HEAPU8.subarray(pixels, pixels + totalSize));
   },
 
   glBindTexture__sig: 'vii',
@@ -810,7 +815,7 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.textures, texture, 'glBindTexture', 'texture');
 #endif
-    Module.ctx.bindTexture(target, texture ? GL.textures[texture] : null);
+    GLctx.bindTexture(target, texture ? GL.textures[texture] : null);
   },
 
   glGetTexParameterfv__sig: 'viii',
@@ -826,27 +831,27 @@ var LibraryGL = {
   glTexParameterfv__sig: 'viii',
   glTexParameterfv: function(target, pname, params) {
     var param = {{{ makeGetValue('params', '0', 'float') }}};
-    Module.ctx.texParameterf(target, pname, param);
+    GLctx.texParameterf(target, pname, param);
   },
 
   glTexParameteriv__sig: 'viii',
   glTexParameteriv: function(target, pname, params) {
     var param = {{{ makeGetValue('params', '0', 'i32') }}};
-    Module.ctx.texParameteri(target, pname, param);
+    GLctx.texParameteri(target, pname, param);
   },
 
   glIsTexture__sig: 'ii',
   glIsTexture: function(texture) {
     var texture = GL.textures[texture];
     if (!texture) return 0;
-    return Module.ctx.isTexture(texture);
+    return GLctx.isTexture(texture);
   },
 
   glGenBuffers__sig: 'vii',
   glGenBuffers: function(n, buffers) {
     for (var i = 0; i < n; i++) {
       var id = GL.getNewId(GL.buffers);
-      var buffer = Module.ctx.createBuffer();
+      var buffer = GLctx.createBuffer();
       buffer.name = id;
       GL.buffers[id] = buffer;
       {{{ makeSetValue('buffers', 'i*4', 'id', 'i32') }}};
@@ -863,7 +868,7 @@ var LibraryGL = {
       // correspond to existing buffer objects."
       if (!buffer) continue;
 
-      Module.ctx.deleteBuffer(buffer);
+      GLctx.deleteBuffer(buffer);
       buffer.name = 0;
       GL.buffers[id] = null;
 
@@ -874,7 +879,7 @@ var LibraryGL = {
 
   glGetBufferParameteriv__sig: 'viii',
   glGetBufferParameteriv: function(target, value, data) {
-    {{{ makeSetValue('data', '0', 'Module.ctx.getBufferParameter(target, value)', 'i32') }}};
+    {{{ makeSetValue('data', '0', 'GLctx.getBufferParameter(target, value)', 'i32') }}};
   },
 
   glBufferData__sig: 'viiii',
@@ -893,26 +898,26 @@ var LibraryGL = {
         usage = 0x88E8; // GL_DYNAMIC_DRAW
         break;
     }
-    Module.ctx.bufferData(target, HEAPU8.subarray(data, data+size), usage);
+    GLctx.bufferData(target, HEAPU8.subarray(data, data+size), usage);
   },
 
   glBufferSubData__sig: 'viiii',
   glBufferSubData: function(target, offset, size, data) {
-    Module.ctx.bufferSubData(target, offset, HEAPU8.subarray(data, data+size));
+    GLctx.bufferSubData(target, offset, HEAPU8.subarray(data, data+size));
   },
 
   glIsBuffer__sig: 'ii',
   glIsBuffer: function(buffer) {
     var b = GL.buffers[buffer];
     if (!b) return 0;
-    return Module.ctx.isBuffer(b);
+    return GLctx.isBuffer(b);
   },
 
   glGenRenderbuffers__sig: 'vii',
   glGenRenderbuffers: function(n, renderbuffers) {
     for (var i = 0; i < n; i++) {
       var id = GL.getNewId(GL.renderbuffers);
-      var renderbuffer = Module.ctx.createRenderbuffer();
+      var renderbuffer = GLctx.createRenderbuffer();
       renderbuffer.name = id;
       GL.renderbuffers[id] = renderbuffer;
       {{{ makeSetValue('renderbuffers', 'i*4', 'id', 'i32') }}};
@@ -924,7 +929,7 @@ var LibraryGL = {
     for (var i = 0; i < n; i++) {
       var id = {{{ makeGetValue('renderbuffers', 'i*4', 'i32') }}};
       var renderbuffer = GL.renderbuffers[id];
-      Module.ctx.deleteRenderbuffer(renderbuffer);
+      GLctx.deleteRenderbuffer(renderbuffer);
       renderbuffer.name = 0;
       GL.renderbuffers[id] = null;
     }
@@ -935,19 +940,19 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.renderbuffers, renderbuffer, 'glBindRenderbuffer', 'renderbuffer');
 #endif
-    Module.ctx.bindRenderbuffer(target, renderbuffer ? GL.renderbuffers[renderbuffer] : null);
+    GLctx.bindRenderbuffer(target, renderbuffer ? GL.renderbuffers[renderbuffer] : null);
   },
 
   glGetRenderbufferParameteriv__sig: 'viii',
   glGetRenderbufferParameteriv: function(target, pname, params) {
-    {{{ makeSetValue('params', '0', 'Module.ctx.getRenderbufferParameter(target, pname)', 'i32') }}};
+    {{{ makeSetValue('params', '0', 'GLctx.getRenderbufferParameter(target, pname)', 'i32') }}};
   },
 
   glIsRenderbuffer__sig: 'ii',
   glIsRenderbuffer: function(renderbuffer) {
     var rb = GL.renderbuffers[renderbuffer];
     if (!rb) return 0;
-    return Module.ctx.isRenderbuffer(rb);
+    return GLctx.isRenderbuffer(rb);
   },
 
   glGetUniformfv__sig: 'viii',
@@ -956,7 +961,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.programs, program, 'glGetUniformfv', 'program');
     GL.validateGLObjectID(GL.uniforms, location, 'glGetUniformfv', 'location');
 #endif
-    var data = Module.ctx.getUniform(GL.programs[program], GL.uniforms[location]);
+    var data = GLctx.getUniform(GL.programs[program], GL.uniforms[location]);
     if (typeof data == 'number') {
       {{{ makeSetValue('params', '0', 'data', 'float') }}};
     } else {
@@ -972,7 +977,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.programs, program, 'glGetUniformiv', 'program');
     GL.validateGLObjectID(GL.uniforms, location, 'glGetUniformiv', 'location');
 #endif
-    var data = Module.ctx.getUniform(GL.programs[program], GL.uniforms[location]);
+    var data = GLctx.getUniform(GL.programs[program], GL.uniforms[location]);
     if (typeof data == 'number' || typeof data == 'boolean') {
       {{{ makeSetValue('params', '0', 'data', 'i32') }}};
     } else {
@@ -1023,7 +1028,7 @@ var LibraryGL = {
       Module.printErr("glGetVertexAttribfv on client-side array: not supported, bad data returned");
     }
 #endif
-    var data = Module.ctx.getVertexAttrib(index, pname);
+    var data = GLctx.getVertexAttrib(index, pname);
     if (typeof data == 'number') {
       {{{ makeSetValue('params', '0', 'data', 'float') }}};
     } else {
@@ -1040,7 +1045,7 @@ var LibraryGL = {
       Module.printErr("glGetVertexAttribiv on client-side array: not supported, bad data returned");
     }
 #endif
-    var data = Module.ctx.getVertexAttrib(index, pname);
+    var data = GLctx.getVertexAttrib(index, pname);
     if (typeof data == 'number' || typeof data == 'boolean') {
       {{{ makeSetValue('params', '0', 'data', 'i32') }}};
     } else {
@@ -1057,7 +1062,7 @@ var LibraryGL = {
       Module.printErr("glGetVertexAttribPointer on client-side array: not supported, bad data returned");
     }
 #endif
-    {{{ makeSetValue('pointer', '0', 'Module.ctx.getVertexAttribOffset(index, pname)', 'i32') }}};
+    {{{ makeSetValue('pointer', '0', 'GLctx.getVertexAttribOffset(index, pname)', 'i32') }}};
   },
 
   glGetActiveUniform__sig: 'viiiiiii',
@@ -1066,7 +1071,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.programs, program, 'glGetActiveUniform', 'program');
 #endif
     program = GL.programs[program];
-    var info = Module.ctx.getActiveUniform(program, index);
+    var info = GLctx.getActiveUniform(program, index);
 
     var infoname = info.name.slice(0, Math.max(0, bufSize - 1));
     writeStringToMemory(infoname, name);
@@ -1088,7 +1093,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.uniforms, location, 'glUniform1f', 'location');
 #endif
     location = GL.uniforms[location];
-    Module.ctx.uniform1f(location, v0);
+    GLctx.uniform1f(location, v0);
   },
 
   glUniform2f__sig: 'viff',
@@ -1097,7 +1102,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.uniforms, location, 'glUniform2f', 'location');
 #endif
     location = GL.uniforms[location];
-    Module.ctx.uniform2f(location, v0, v1);
+    GLctx.uniform2f(location, v0, v1);
   },
 
   glUniform3f__sig: 'vifff',
@@ -1106,7 +1111,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.uniforms, location, 'glUniform3f', 'location');
 #endif
     location = GL.uniforms[location];
-    Module.ctx.uniform3f(location, v0, v1, v2);
+    GLctx.uniform3f(location, v0, v1, v2);
   },
 
   glUniform4f__sig: 'viffff',
@@ -1115,7 +1120,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.uniforms, location, 'glUniform4f', 'location');
 #endif
     location = GL.uniforms[location];
-    Module.ctx.uniform4f(location, v0, v1, v2, v3);
+    GLctx.uniform4f(location, v0, v1, v2, v3);
   },
 
   glUniform1i__sig: 'vii',
@@ -1124,7 +1129,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.uniforms, location, 'glUniform1i', 'location');
 #endif
     location = GL.uniforms[location];
-    Module.ctx.uniform1i(location, v0);
+    GLctx.uniform1i(location, v0);
   },
 
   glUniform2i__sig: 'viii',
@@ -1133,7 +1138,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.uniforms, location, 'glUniform2i', 'location');
 #endif
     location = GL.uniforms[location];
-    Module.ctx.uniform2i(location, v0, v1);
+    GLctx.uniform2i(location, v0, v1);
   },
 
   glUniform3i__sig: 'viiii',
@@ -1142,7 +1147,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.uniforms, location, 'glUniform3i', 'location');
 #endif
     location = GL.uniforms[location];
-    Module.ctx.uniform3i(location, v0, v1, v2);
+    GLctx.uniform3i(location, v0, v1, v2);
   },
 
   glUniform4i__sig: 'viiiii',
@@ -1151,7 +1156,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.uniforms, location, 'glUniform4i', 'location');
 #endif
     location = GL.uniforms[location];
-    Module.ctx.uniform4i(location, v0, v1, v2, v3);
+    GLctx.uniform4i(location, v0, v1, v2, v3);
   },
 
   glUniform1iv__sig: 'viii',
@@ -1161,7 +1166,7 @@ var LibraryGL = {
 #endif
     location = GL.uniforms[location];
     value = {{{ makeHEAPView('32', 'value', 'value+count*4') }}};
-    Module.ctx.uniform1iv(location, value);
+    GLctx.uniform1iv(location, value);
   },
 
   glUniform2iv__sig: 'viii',
@@ -1172,7 +1177,7 @@ var LibraryGL = {
     location = GL.uniforms[location];
     count *= 2;
     value = {{{ makeHEAPView('32', 'value', 'value+count*4') }}};
-    Module.ctx.uniform2iv(location, value);
+    GLctx.uniform2iv(location, value);
   },
 
   glUniform3iv__sig: 'viii',
@@ -1183,7 +1188,7 @@ var LibraryGL = {
     location = GL.uniforms[location];
     count *= 3;
     value = {{{ makeHEAPView('32', 'value', 'value+count*4') }}};
-    Module.ctx.uniform3iv(location, value);
+    GLctx.uniform3iv(location, value);
   },
 
   glUniform4iv__sig: 'viii',
@@ -1194,7 +1199,7 @@ var LibraryGL = {
     location = GL.uniforms[location];
     count *= 4;
     value = {{{ makeHEAPView('32', 'value', 'value+count*4') }}};
-    Module.ctx.uniform4iv(location, value);
+    GLctx.uniform4iv(location, value);
   },
 
   glUniform1fv__sig: 'viii',
@@ -1211,7 +1216,7 @@ var LibraryGL = {
     } else {
       view = {{{ makeHEAPView('F32', 'value', 'value+count*4') }}};
     }
-    Module.ctx.uniform1fv(location, view);
+    GLctx.uniform1fv(location, view);
   },
 
   glUniform2fv__sig: 'viii',
@@ -1229,7 +1234,7 @@ var LibraryGL = {
     } else {
       view = {{{ makeHEAPView('F32', 'value', 'value+count*8') }}};
     }
-    Module.ctx.uniform2fv(location, view);
+    GLctx.uniform2fv(location, view);
   },
 
   glUniform3fv__sig: 'viii',
@@ -1248,7 +1253,7 @@ var LibraryGL = {
     } else {
       view = {{{ makeHEAPView('F32', 'value', 'value+count*12') }}};
     }
-    Module.ctx.uniform3fv(location, view);
+    GLctx.uniform3fv(location, view);
   },
 
   glUniform4fv__sig: 'viii',
@@ -1268,7 +1273,7 @@ var LibraryGL = {
     } else {
       view = {{{ makeHEAPView('F32', 'value', 'value+count*16') }}};
     }
-    Module.ctx.uniform4fv(location, view);
+    GLctx.uniform4fv(location, view);
   },
 
   glUniformMatrix2fv__sig: 'viiii',
@@ -1287,7 +1292,7 @@ var LibraryGL = {
     } else {
       view = {{{ makeHEAPView('F32', 'value', 'value+count*16') }}};
     }
-    Module.ctx.uniformMatrix2fv(location, transpose, view);
+    GLctx.uniformMatrix2fv(location, transpose, view);
   },
 
   glUniformMatrix3fv__sig: 'viiii',
@@ -1306,7 +1311,7 @@ var LibraryGL = {
     } else {
       view = {{{ makeHEAPView('F32', 'value', 'value+count*36') }}};
     }
-    Module.ctx.uniformMatrix3fv(location, transpose, view);
+    GLctx.uniformMatrix3fv(location, transpose, view);
   },
 
   glUniformMatrix4fv__sig: 'viiii',
@@ -1325,7 +1330,7 @@ var LibraryGL = {
     } else {
       view = {{{ makeHEAPView('F32', 'value', 'value+count*64') }}};
     }
-    Module.ctx.uniformMatrix4fv(location, transpose, view);
+    GLctx.uniformMatrix4fv(location, transpose, view);
   },
 
   glBindBuffer__sig: 'vii',
@@ -1335,44 +1340,53 @@ var LibraryGL = {
 #endif
     var bufferObj = buffer ? GL.buffers[buffer] : null;
 
-    if (target == Module.ctx.ARRAY_BUFFER) {
+#if FULL_ES2
+    if (target == GLctx.ARRAY_BUFFER) {
       GL.currArrayBuffer = buffer;
-    } else if (target == Module.ctx.ELEMENT_ARRAY_BUFFER) {
+    } else if (target == GLctx.ELEMENT_ARRAY_BUFFER) {
+      GL.currElementArrayBuffer = buffer;
+    }
+#endif
+#if LEGACY_GL_EMULATION
+    if (target == GLctx.ARRAY_BUFFER) {
+      GLImmediate.lastArrayBuffer = GL.currArrayBuffer = buffer;
+    } else if (target == GLctx.ELEMENT_ARRAY_BUFFER) {
       GL.currElementArrayBuffer = buffer;
     }
+#endif
 
-    Module.ctx.bindBuffer(target, bufferObj);
+    GLctx.bindBuffer(target, bufferObj);
   },
 
   glVertexAttrib1fv__sig: 'vii',
   glVertexAttrib1fv: function(index, v) {
     v = {{{ makeHEAPView('F32', 'v', 'v+' + (1*4)) }}};
-    Module.ctx.vertexAttrib1fv(index, v);
+    GLctx.vertexAttrib1fv(index, v);
   },
 
   glVertexAttrib2fv__sig: 'vii',
   glVertexAttrib2fv: function(index, v) {
     v = {{{ makeHEAPView('F32', 'v', 'v+' + (2*4)) }}};
-    Module.ctx.vertexAttrib2fv(index, v);
+    GLctx.vertexAttrib2fv(index, v);
   },
 
   glVertexAttrib3fv__sig: 'vii',
   glVertexAttrib3fv: function(index, v) {
     v = {{{ makeHEAPView('F32', 'v', 'v+' + (3*4)) }}};
-    Module.ctx.vertexAttrib3fv(index, v);
+    GLctx.vertexAttrib3fv(index, v);
   },
 
   glVertexAttrib4fv__sig: 'vii',
   glVertexAttrib4fv: function(index, v) {
     v = {{{ makeHEAPView('F32', 'v', 'v+' + (4*4)) }}};
-    Module.ctx.vertexAttrib4fv(index, v);
+    GLctx.vertexAttrib4fv(index, v);
   },
 
   glGetAttribLocation__sig: 'vii',
   glGetAttribLocation: function(program, name) {
     program = GL.programs[program];
     name = Pointer_stringify(name);
-    return Module.ctx.getAttribLocation(program, name);
+    return GLctx.getAttribLocation(program, name);
   },
 
   glGetActiveAttrib__sig: 'viiiiiii',
@@ -1381,7 +1395,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.programs, program, 'glGetActiveAttrib', 'program');
 #endif
     program = GL.programs[program];
-    var info = Module.ctx.getActiveAttrib(program, index);
+    var info = GLctx.getActiveAttrib(program, index);
 
     var infoname = info.name.slice(0, Math.max(0, bufSize - 1));
     writeStringToMemory(infoname, name);
@@ -1400,13 +1414,13 @@ var LibraryGL = {
   glCreateShader__sig: 'ii',
   glCreateShader: function(shaderType) {
     var id = GL.getNewId(GL.shaders);
-    GL.shaders[id] = Module.ctx.createShader(shaderType);
+    GL.shaders[id] = GLctx.createShader(shaderType);
     return id;
   },
 
   glDeleteShader__sig: 'vi',
   glDeleteShader: function(shader) {
-    Module.ctx.deleteShader(GL.shaders[shader]);
+    GLctx.deleteShader(GL.shaders[shader]);
     GL.shaders[shader] = null;
   },
 
@@ -1415,7 +1429,7 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.programs, program, 'glGetAttachedShaders', 'program');
 #endif
-    var result = Module.ctx.getAttachedShaders(GL.programs[program]);
+    var result = GLctx.getAttachedShaders(GL.programs[program]);
     var len = result.length;
     if (len > maxCount) {
       len = maxCount;
@@ -1436,7 +1450,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.shaders, shader, 'glShaderSource', 'shader');
 #endif
     var source = GL.getSource(shader, count, string, length);
-    Module.ctx.shaderSource(GL.shaders[shader], source);
+    GLctx.shaderSource(GL.shaders[shader], source);
   },
 
   glGetShaderSource__sig: 'viiii',
@@ -1444,7 +1458,7 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.shaders, shader, 'glGetShaderSource', 'shader');
 #endif
-    var result = Module.ctx.getShaderSource(GL.shaders[shader]);
+    var result = GLctx.getShaderSource(GL.shaders[shader]);
     result = result.slice(0, Math.max(0, bufSize - 1));
     writeStringToMemory(result, source);
     if (length) {
@@ -1457,7 +1471,7 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.shaders, shader, 'glCompileShader', 'shader');
 #endif
-    Module.ctx.compileShader(GL.shaders[shader]);
+    GLctx.compileShader(GL.shaders[shader]);
   },
 
   glGetShaderInfoLog__sig: 'viiii',
@@ -1465,7 +1479,7 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.shaders, shader, 'glGetShaderInfoLog', 'shader');
 #endif
-    var log = Module.ctx.getShaderInfoLog(GL.shaders[shader]);
+    var log = GLctx.getShaderInfoLog(GL.shaders[shader]);
     // Work around a bug in Chromium which causes getShaderInfoLog to return null
     if (!log) {
       log = "";
@@ -1483,9 +1497,9 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.shaders, shader, 'glGetShaderiv', 'shader');
 #endif
     if (pname == 0x8B84) { // GL_INFO_LOG_LENGTH
-      {{{ makeSetValue('p', '0', 'Module.ctx.getShaderInfoLog(GL.shaders[shader]).length + 1', 'i32') }}};
+      {{{ makeSetValue('p', '0', 'GLctx.getShaderInfoLog(GL.shaders[shader]).length + 1', 'i32') }}};
     } else {
-      {{{ makeSetValue('p', '0', 'Module.ctx.getShaderParameter(GL.shaders[shader], pname)', 'i32') }}};
+      {{{ makeSetValue('p', '0', 'GLctx.getShaderParameter(GL.shaders[shader], pname)', 'i32') }}};
     }
   },
 
@@ -1495,7 +1509,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.programs, program, 'glGetProgramiv', 'program');
 #endif
     if (pname == 0x8B84) { // GL_INFO_LOG_LENGTH
-      {{{ makeSetValue('p', '0', 'Module.ctx.getProgramInfoLog(GL.programs[program]).length + 1', 'i32') }}};
+      {{{ makeSetValue('p', '0', 'GLctx.getProgramInfoLog(GL.programs[program]).length + 1', 'i32') }}};
     } else if (pname == 0x8B87 /* GL_ACTIVE_UNIFORM_MAX_LENGTH */) {
       var ptable = GL.programInfos[program];
       if (ptable) {
@@ -1517,10 +1531,10 @@ var LibraryGL = {
       if (ptable) {
         if (ptable.maxAttributeLength == -1) {
           var program = GL.programs[program];
-          var numAttribs = Module.ctx.getProgramParameter(program, Module.ctx.ACTIVE_ATTRIBUTES);
+          var numAttribs = GLctx.getProgramParameter(program, GLctx.ACTIVE_ATTRIBUTES);
           ptable.maxAttributeLength = 0; // Spec says if there are no active attribs, 0 must be returned.
           for(var i = 0; i < numAttribs; ++i) {
-            var activeAttrib = Module.ctx.getActiveAttrib(program, i);
+            var activeAttrib = GLctx.getActiveAttrib(program, i);
             ptable.maxAttributeLength = Math.max(ptable.maxAttributeLength, activeAttrib.name.length+1);
           }
         }
@@ -1538,7 +1552,7 @@ var LibraryGL = {
         GL.recordError(0x0501 /* GL_INVALID_VALUE */);
       }
     } else {
-      {{{ makeSetValue('p', '0', 'Module.ctx.getProgramParameter(GL.programs[program], pname)', 'i32') }}};
+      {{{ makeSetValue('p', '0', 'GLctx.getProgramParameter(GL.programs[program], pname)', 'i32') }}};
     }
   },
 
@@ -1546,13 +1560,13 @@ var LibraryGL = {
   glIsShader: function(shader) {
     var s = GL.shaders[shader];
     if (!s) return 0;
-    return Module.ctx.isShader(s);
+    return GLctx.isShader(s);
   },
 
   glCreateProgram__sig: 'i',
   glCreateProgram: function() {
     var id = GL.getNewId(GL.programs);
-    var program = Module.ctx.createProgram();
+    var program = GLctx.createProgram();
     program.name = id;
     GL.programs[id] = program;
     return id;
@@ -1561,7 +1575,7 @@ var LibraryGL = {
   glDeleteProgram__sig: 'vi',
   glDeleteProgram: function(program) {
     var program = GL.programs[program];
-    Module.ctx.deleteProgram(program);
+    GLctx.deleteProgram(program);
     program.name = 0;
     GL.programs[program] = null;
     GL.programInfos[program] = null;
@@ -1573,7 +1587,7 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.programs, program, 'glAttachShader', 'program');
     GL.validateGLObjectID(GL.shaders, shader, 'glAttachShader', 'shader');
 #endif
-    Module.ctx.attachShader(GL.programs[program],
+    GLctx.attachShader(GL.programs[program],
                             GL.shaders[shader]);
   },
 
@@ -1583,12 +1597,12 @@ var LibraryGL = {
     GL.validateGLObjectID(GL.programs, program, 'glDetachShader', 'program');
     GL.validateGLObjectID(GL.shaders, shader, 'glDetachShader', 'shader');
 #endif
-    Module.ctx.detachShader(GL.programs[program],
+    GLctx.detachShader(GL.programs[program],
                             GL.shaders[shader]);
   },
 
   glGetShaderPrecisionFormat: function(shaderType, precisionType, range, precision) {
-    var result = Module.ctx.getShaderPrecisionFormat(shaderType, precisionType);
+    var result = GLctx.getShaderPrecisionFormat(shaderType, precisionType);
     {{{ makeSetValue('range', '0', 'result.rangeMin', 'i32') }}};
     {{{ makeSetValue('range', '4', 'result.rangeMax', 'i32') }}};
     {{{ makeSetValue('precision', '0', 'result.precision', 'i32') }}};
@@ -1599,7 +1613,7 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.programs, program, 'glLinkProgram', 'program');
 #endif
-    Module.ctx.linkProgram(GL.programs[program]);
+    GLctx.linkProgram(GL.programs[program]);
     GL.programInfos[program] = null; // uniforms no longer keep the same names after linking
     GL.populateUniformTable(program);
   },
@@ -1609,7 +1623,7 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.programs, program, 'glGetProgramInfoLog', 'program');
 #endif
-    var log = Module.ctx.getProgramInfoLog(GL.programs[program]);
+    var log = GLctx.getProgramInfoLog(GL.programs[program]);
     // Work around a bug in Chromium which causes getProgramInfoLog to return null
     if (!log) {
       log = "";
@@ -1626,7 +1640,7 @@ var LibraryGL = {
 #if GL_ASSERTIONS
     GL.validateGLObjectID(GL.programs, program, 'glUseProgram', 'program');
 #endif
-    Module.ctx.useProgram(program ? GL.programs[program] : null);
+    GLctx.useProgram(program ? GL.programs[program] : null);
   },
 
   glValidateProgram__sig: 'vi',
@@ -1634,14 +1648,14 @@ var LibraryGL = {
 #