[WebGL] Emulate glMapBuffer API in WebGL backend.

- glMapBufferRange is supported in GLES 3 but not in WebGL 2,
  so we emulate it by manually mapping the GL buffer data to CPU memory space.
- Use <webgl/webgl2.h> header instead of <GLES/gl32.h>, since WebGL 2.0 is based on GLES 3.0;
  This also enables glGetBufferSubData(), which is supported in WebGL 2 but not in GLES 3.
- Added more assertions of unimplemented functions in GLProfile namespace for WebGL and GLES backends.

sources/Renderer/OpenGL/GLESProfile/GLESProfile.cpp

@@ -7,6 +7,7 @@
 
 #include "../GLProfile.h"
 #include "../Ext/GLExtensions.h"
+#include "../../../Core/Assertion.h"
 #include <LLGL/RenderSystemFlags.h>
 #include <cstring>
 
@@ -53,13 +54,13 @@ void GetTexParameterInternalFormat(GLenum target, GLint* params)
     #ifdef GL_ES_VERSION_3_1
     glGetTexLevelParameteriv(target, 0, GL_TEXTURE_INTERNAL_FORMAT, params);
     #else
-    //TODO...
+    LLGL_TRAP_NOT_IMPLEMENTED(); //TODO
     #endif
 }
 
 void GetInternalformativ(GLenum target, GLenum internalformat, GLenum pname, GLsizei bufsize, GLint* params)
 {
-    //TODO
+    LLGL_TRAP_NOT_IMPLEMENTED(); //TODO
 }
 
 void DepthRange(GLclamp_t nearVal, GLclamp_t farVal)
@@ -74,6 +75,7 @@ void ClearDepth(GLclamp_t depth)
 
 void GetBufferSubData(GLenum target, GLintptr offset, GLsizeiptr size, void* data)
 {
+    LLGL_ASSERT_PTR(data);
     if (void* srcData = glMapBufferRange(target, offset, size, GL_MAP_READ_BIT))
     {
         ::memcpy(data, srcData, static_cast<std::size_t>(size));

sources/Renderer/OpenGL/GLTypes.cpp

@@ -6,6 +6,7 @@
  */
 
 #include "GLTypes.h"
+#include "GLProfile.h"
 #include "../../Core/Exception.h"
 
 
@@ -1192,6 +1193,40 @@ bool IsDepthStencilFormat(GLenum internalFormat)
     }
 }
 
+GLenum BufferTargetToBindingPname(GLenum target)
+{
+    switch (target)
+    {
+        case GL_ARRAY_BUFFER:               return GL_ARRAY_BUFFER_BINDING;
+        case GL_COPY_READ_BUFFER:           return GL_COPY_READ_BUFFER_BINDING;
+        case GL_COPY_WRITE_BUFFER:          return GL_COPY_WRITE_BUFFER_BINDING;
+        case GL_ELEMENT_ARRAY_BUFFER:       return GL_ELEMENT_ARRAY_BUFFER_BINDING;
+        case GL_PIXEL_PACK_BUFFER:          return GL_PIXEL_PACK_BUFFER_BINDING;
+        case GL_PIXEL_UNPACK_BUFFER:        return GL_PIXEL_UNPACK_BUFFER_BINDING;
+        case GL_TRANSFORM_FEEDBACK_BUFFER:  return GL_TRANSFORM_FEEDBACK_BUFFER_BINDING;
+        case GL_UNIFORM_BUFFER:             return GL_UNIFORM_BUFFER_BINDING;
+
+        #if GL_VERSION_4_0 || GL_ES_VERSION_3_1
+        case GL_DRAW_INDIRECT_BUFFER:       return GL_DRAW_INDIRECT_BUFFER_BINDING;
+        #endif
+
+        #if GL_VERSION_4_2 || GL_ES_VERSION_3_1
+        case GL_ATOMIC_COUNTER_BUFFER:      return GL_ATOMIC_COUNTER_BUFFER_BINDING;
+        #endif
+
+        #if GL_VERSION_4_3 || GL_ES_VERSION_3_1
+        case GL_DISPATCH_INDIRECT_BUFFER:   return GL_DISPATCH_INDIRECT_BUFFER_BINDING;
+        case GL_SHADER_STORAGE_BUFFER:      return GL_SHADER_STORAGE_BUFFER_BINDING;
+        #endif
+
+        #if GL_VERSION_4_4 || GL_ES_VERSION_3_2
+        case GL_TEXTURE_BUFFER:             return GL_TEXTURE_BUFFER_BINDING;
+        #endif
+
+        default:                            return 0;
+    }
+}
+
 
 } // /namespace GLTypes
 

sources/Renderer/OpenGL/GLTypes.h

@@ -83,6 +83,10 @@ bool IsDepthFormat(GLenum internalFormat);
 // Returns true if the specified GL internal format is a depth-and-stencil format.
 bool IsDepthStencilFormat(GLenum internalFormat);
 
+// Returns the binding parameter name for the specified buffer target,
+// e.g. GL_UNIFOMR_BUFFER to GL_UNIFORM_BUFFER_BINDING, used for glGetIntegerv().
+GLenum BufferTargetToBindingPname(GLenum target);
+
 
 } // /namespace GLTypes
 

sources/Renderer/OpenGL/WebGLProfile/WebGL.h

@@ -14,8 +14,7 @@
 #if defined(LLGL_OS_WASM)
 #   define GL_GLEXT_PROTOTYPES 1
 #   define EGL_EGLEXT_PROTOTYPES 1
-#   include <GLES3/gl3.h>
-#   include <GLES3/gl32.h>
+#   include <webgl/webgl2.h>
 #else
 #   error Unsupported platform for WebGL
 #endif

sources/Renderer/OpenGL/WebGLProfile/WebGLProfile.cpp

@@ -6,8 +6,11 @@
  */
 
 #include "../GLProfile.h"
+#include "../GLTypes.h"
 #include "../Ext/GLExtensions.h"
+#include "../../../Core/Assertion.h"
 #include <LLGL/RenderSystemFlags.h>
+#include <LLGL/Container/DynamicArray.h>
 #include <cstring>
 
 
@@ -50,12 +53,12 @@ GLint GetMaxViewports()
 
 void GetTexParameterInternalFormat(GLenum target, GLint* params)
 {
-    //TODO...
+    LLGL_TRAP_NOT_IMPLEMENTED(); //TODO
 }
 
 void GetInternalformativ(GLenum target, GLenum internalformat, GLenum pname, GLsizei bufsize, GLint* params)
 {
-    //TODO
+    LLGL_TRAP_NOT_IMPLEMENTED(); //TODO
 }
 
 void DepthRange(GLclamp_t nearVal, GLclamp_t farVal)
@@ -70,22 +73,76 @@ void ClearDepth(GLclamp_t depth)
 
 void GetBufferSubData(GLenum target, GLintptr offset, GLsizeiptr size, void* data)
 {
-    // dummy
+    LLGL_ASSERT_PTR(data);
+    glGetBufferSubData(target, offset, size, data); // supported in WebGL 2 but not in GLES 3
+}
+
+static GLbitfield ToGLESMapBufferRangeAccess(GLenum access)
+{
+    switch (access)
+    {
+        case GL_READ_ONLY:  return GL_MAP_READ_BIT;
+        case GL_WRITE_ONLY: return GL_MAP_WRITE_BIT;
+        case GL_READ_WRITE: return GL_MAP_READ_BIT | GL_MAP_WRITE_BIT;
+        default:            return 0;
+    }
 }
 
+// This emulates the glMapBuffer API from GLES3 for WebGL
+static struct MapBufferContext
+{
+    GLuint              buffer  = 0;
+    GLintptr            offset  = 0;
+    GLsizeiptr          size    = 0;
+    GLbitfield          access  = 0;
+    DynamicByteArray    data;
+}
+g_mapBufferContext;
+
 void* MapBuffer(GLenum target, GLenum access)
 {
-    return nullptr; //TODO: allocate intermdiate CPU buffer
+    /* Translate GL access type to GLES bitfield, determine buffer length, and map entire buffer range */
+    GLbitfield flags = ToGLESMapBufferRangeAccess(access);
+    GLint length = 0;
+    glGetBufferParameteriv(target, GL_BUFFER_SIZE, &length);
+    return MapBufferRange(target, 0, length, flags);
 }
 
 void* MapBufferRange(GLenum target, GLintptr offset, GLsizeiptr length, GLbitfield access)
 {
-    return nullptr; //TODO: allocate intermdiate CPU buffer
+    LLGL_ASSERT(g_mapBufferContext.access == 0, "cannot map multiple GL buffers interleaved in WebGL backend");
+
+    if (access == 0 || !(length > 0))
+        return nullptr;
+
+    /* Get currently bound buffer at the specified target */
+    GLint bufferBinding = GLTypes::BufferTargetToBindingPname(target);
+    GLint buffer = 0;
+    glGetIntegerv(bufferBinding, &buffer);
+
+    /* Allocate intermdiate buffer and store in global context */
+    g_mapBufferContext.buffer   = static_cast<GLuint>(buffer);
+    g_mapBufferContext.offset   = offset;
+    g_mapBufferContext.size     = length;
+    g_mapBufferContext.access   = access;
+    g_mapBufferContext.data.resize(static_cast<std::size_t>(length), UninitializeTag{});
+
+    /* Manually map GL buffer into CPU memory space to emulate glMapBuffer API for WebGL */
+    if ((access & GL_MAP_READ_BIT) != 0)
+        glGetBufferSubData(target, offset, length, g_mapBufferContext.data.get()); // supported in WebGL 2 but not in GLES 3
+
+    return g_mapBufferContext.data.get();
 }
 
 void UnmapBuffer(GLenum target)
 {
-    //TODO: release intermediate CPU buffer
+    if (g_mapBufferContext.access != 0)
+    {
+        /* Write data back to buffer */
+        if ((g_mapBufferContext.access & GL_MAP_WRITE_BIT) != 0)
+            glBufferSubData(target, g_mapBufferContext.offset, g_mapBufferContext.size, g_mapBufferContext.data.get());
+        g_mapBufferContext.access = 0;
+    }
 }
 
 void DrawBuffer(GLenum buf)