LibWeb/WebGL2: Implement bufferData with offset and length

Author: https://github.com/Lubrsi
Commit: 18ea91715b
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2943
Reviewed-by: https://github.com/kalenikaliaksandr

Libraries/LibWeb/WebGL/WebGL2RenderingContextOverloads.idl

@@ -10,7 +10,7 @@ interface mixin WebGL2RenderingContextOverloads {
     undefined bufferData(GLenum target, BufferSource? srcData, GLenum usage);
     undefined bufferSubData(GLenum target, GLintptr dstByteOffset, BufferSource srcData);
     // WebGL2:
-    [FIXME] undefined bufferData(GLenum target, [AllowShared] ArrayBufferView srcData, GLenum usage, unsigned long long srcOffset, optional GLuint length = 0);
+    undefined bufferData(GLenum target, [AllowShared] ArrayBufferView srcData, GLenum usage, unsigned long long srcOffset, optional GLuint length = 0);
     [FIXME] undefined bufferSubData(GLenum target, GLintptr dstByteOffset, [AllowShared] ArrayBufferView srcData, unsigned long long srcOffset, optional GLuint length = 0);
 
     // WebGL1 legacy entrypoints:

Libraries/LibWeb/WebIDL/Buffers.cpp

@@ -29,6 +29,21 @@ u32 BufferableObjectBase::byte_length() const
         [](GC::Ref<JS::ArrayBuffer> array_buffer) { return static_cast<u32>(array_buffer->byte_length()); });
 }
 
+u32 BufferableObjectBase::element_size() const
+{
+    return m_bufferable_object.visit(
+        [](GC::Ref<JS::TypedArrayBase> typed_array) -> u32 {
+            auto typed_array_record = JS::make_typed_array_with_buffer_witness_record(typed_array, JS::ArrayBuffer::Order::SeqCst);
+            return typed_array_record.object->element_size();
+        },
+        [](GC::Ref<JS::DataView>) -> u32 {
+            return 1;
+        },
+        [](GC::Ref<JS::ArrayBuffer>) -> u32 {
+            return 1;
+        });
+}
+
 GC::Ref<JS::Object> BufferableObjectBase::raw_object()
 {
     return m_bufferable_object.visit([](auto const& obj) -> GC::Ref<JS::Object> { return obj; });

Libraries/LibWeb/WebIDL/Buffers.h

@@ -27,6 +27,7 @@ public:
     virtual ~BufferableObjectBase() override = default;
 
     u32 byte_length() const;
+    u32 element_size() const;
 
     GC::Ref<JS::Object> raw_object();
     GC::Ref<JS::Object const> raw_object() const { return const_cast<BufferableObjectBase&>(*this).raw_object(); }

Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWebGLRenderingContext.cpp

@@ -802,6 +802,34 @@ public:
             continue;
         }
 
+        if (webgl_version == 2 && function.name == "bufferData"sv && function.overload_index == 2) {
+            function_impl_generator.append(R"~~~(
+    VERIFY(src_data);
+    auto const& viewed_array_buffer = src_data->viewed_array_buffer();
+    auto const& byte_buffer = viewed_array_buffer->buffer();
+    auto src_data_length = src_data->byte_length();
+    auto src_data_element_size = src_data->element_size();
+    u8 const* buffer_ptr = byte_buffer.data();
+
+    u64 copy_length = length == 0 ? src_data_length - src_offset : length;
+    copy_length *= src_data_element_size;
+
+    if (src_offset > src_data_length) {
+        set_error(GL_INVALID_VALUE);
+        return;
+    }
+
+    if (src_offset + copy_length > src_data_length) {
+        set_error(GL_INVALID_VALUE);
+        return;
+    }
+
+    buffer_ptr += src_offset * src_data_element_size;
+    glBufferData(target, copy_length, buffer_ptr, usage);
+)~~~");
+            continue;
+        }
+
         if (function.name == "readPixels"sv) {
             function_impl_generator.append(R"~~~(
     if (!pixels) {