net: implement async HTTP requests for the emscripten backend.

Does not work very well because of CORS restrictions in browsers.

.gitignore

@@ -66,6 +66,7 @@ build/visualstudio/ipch
 build/visualstudio/*.log
 build/visualstudio/*.XGD
 # Emscripten cruft
+a.out*
 doc/samples/*.html
 doc/samples/*.wasm
 doc/samples/*.wasm.*

doc/tutorial/17_net.cpp

@@ -0,0 +1,55 @@
+//
+//  Lol Engine — HTTP client sample
+//
+//  Copyright © 2016—2020 Sam Hocevar <sam@hocevar.net>
+//
+//  Lol Engine is free software. It comes without any warranty, to
+//  the extent permitted by applicable law. You can redistribute it
+//  and/or modify it under the terms of the Do What the Fuck You Want
+//  to Public License, Version 2, as published by the WTFPL Task Force.
+//  See http://www.wtfpl.net/ for more details.
+//
+
+#if HAVE_CONFIG_H
+#   include "config.h"
+#endif
+
+#include <lol/engine.h>
+
+class demo : public lol::entity
+{
+public:
+    virtual bool init_game() override
+    {
+        // Choose URL that works with CORS (cross-origin resource sharing)
+        client.get("https://api.github.com/");
+        return true;
+    }
+
+    virtual void tick_game(float seconds) override
+    {
+        entity::tick_game(seconds);
+
+        if (client.get_status() == lol::net::http::status::success)
+        {
+            lol::msg::info("Downloaded %d bytes: %s\n",
+                           (int)client.get_result().size(),
+                           client.get_result().c_str());
+            client.reset();
+        }
+    }
+
+    lol::net::http::client client;
+};
+
+int main(int argc, char **argv)
+{
+    lol::sys::init(argc, argv);
+
+    lol::Application app("Tutorial 17: HTTP", lol::ivec2(800, 600), 60.0f);
+    auto p = new demo();
+    app.Run();
+
+    return 0;
+}
+

doc/tutorial/17_net.vcxproj

@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup Label="LolMacros">
+    <LolDir Condition="Exists('$(SolutionDir)\lol')">$(SolutionDir)\lol</LolDir>
+    <LolDir Condition="!Exists('$(SolutionDir)\lol')">$(SolutionDir)</LolDir>
+  </PropertyGroup>
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|NX64">
+      <Configuration>Debug</Configuration>
+      <Platform>NX64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|ORBIS">
+      <Configuration>Debug</Configuration>
+      <Platform>ORBIS</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|NX64">
+      <Configuration>Release</Configuration>
+      <Platform>NX64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|ORBIS">
+      <Configuration>Release</Configuration>
+      <Platform>ORBIS</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <ItemGroup>
+    <ClCompile Include="17_net.cpp" />
+  </ItemGroup>
+  <Import Project="$(LolDir)\build\msbuild\lol-core.props" />
+  <Import Project="$(LolDir)\build\msbuild\lol-bullet.props" />
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{46910277-18E3-4151-9AD9-DC5B551772A9}</ProjectGuid>
+    <ConfigurationType>Application</ConfigurationType>
+    <Keyword>Win32Proj</Keyword>
+  </PropertyGroup>
+  <Import Project="$(LolDir)\build\msbuild\lol.config.props" />
+  <ImportGroup Label="ExtensionSettings">
+    <Import Project="$(LolDir)\build\msbuild\lolfx.props" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="$(LolDir)\build\msbuild\lol.vars.props" />
+  </ImportGroup>
+  <PropertyGroup Label="UserMacros" />
+  <Import Project="$(LolDir)\build\msbuild\lol.rules.props" />
+  <ItemDefinitionGroup />
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+    <Import Project="$(LolDir)\build\msbuild\lolfx.targets" />
+  </ImportGroup>
+</Project>

doc/tutorial/Makefile.am

@@ -11,7 +11,7 @@ tutorials += 01_triangle 02_cube 03_noise 04_texture 05_easymesh \
              06_sprite 07_input 08_fbo 09_sound 11_fractal \
              12_voronoi 13_shader_builder 14_lua 15_gui
 endif
-tutorials += 16_movie
+tutorials += 16_movie 17_net
 
 01_triangle_SOURCES = 01_triangle.cpp 01_triangle.lolfx
 01_triangle_CPPFLAGS = $(AM_CPPFLAGS)
@@ -81,3 +81,7 @@ endif
 16_movie_CPPFLAGS = $(AM_CPPFLAGS)
 16_movie_DEPENDENCIES = @LOL_DEPS@
 
+17_net_SOURCES = 17_net.cpp
+17_net_CPPFLAGS = $(AM_CPPFLAGS)
+17_net_DEPENDENCIES = @LOL_DEPS@
+

lol.sln

@@ -62,6 +62,8 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "14_lua", "doc\tutorial\14_l
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "16_movie", "doc\tutorial\16_movie.vcxproj", "{5F5714D0-1C3D-4522-A409-214C5A2951AA}"
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "17_net", "doc\tutorial\17_net.vcxproj", "{46910277-18E3-4151-9AD9-DC5B551772A9}"
+EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "09_sound", "doc\tutorial\09_sound.vcxproj", "{51626A22-DD68-4450-9696-13B03BF7A2C5}"
 EndProject
 Global
@@ -418,6 +420,22 @@ Global
 		{5F5714D0-1C3D-4522-A409-214C5A2951AA}.Release|Win32.Build.0 = Release|Win32
 		{5F5714D0-1C3D-4522-A409-214C5A2951AA}.Release|Win64.ActiveCfg = Release|x64
 		{5F5714D0-1C3D-4522-A409-214C5A2951AA}.Release|Win64.Build.0 = Release|x64
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Debug|NX64.ActiveCfg = Debug|NX64
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Debug|NX64.Build.0 = Debug|NX64
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Debug|ORBIS.ActiveCfg = Debug|ORBIS
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Debug|ORBIS.Build.0 = Debug|ORBIS
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Debug|Win32.ActiveCfg = Debug|Win32
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Debug|Win32.Build.0 = Debug|Win32
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Debug|Win64.ActiveCfg = Debug|x64
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Debug|Win64.Build.0 = Debug|x64
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Release|NX64.ActiveCfg = Release|NX64
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Release|NX64.Build.0 = Release|NX64
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Release|ORBIS.ActiveCfg = Release|ORBIS
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Release|ORBIS.Build.0 = Release|ORBIS
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Release|Win32.ActiveCfg = Release|Win32
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Release|Win32.Build.0 = Release|Win32
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Release|Win64.ActiveCfg = Release|x64
+		{46910277-18E3-4151-9AD9-DC5B551772A9}.Release|Win64.Build.0 = Release|x64
 		{51626A22-DD68-4450-9696-13B03BF7A2C5}.Debug|NX64.ActiveCfg = Debug|NX64
 		{51626A22-DD68-4450-9696-13B03BF7A2C5}.Debug|NX64.Build.0 = Debug|NX64
 		{51626A22-DD68-4450-9696-13B03BF7A2C5}.Debug|ORBIS.ActiveCfg = Debug|ORBIS
@@ -463,6 +481,7 @@ Global
 		{81C83B42-D00A-4FA3-9A3D-80F9D46524BF} = {E74CF679-CA2A-47E9-B1F4-3779D6AC6B04}
 		{31B96262-1C41-43B9-BA38-27AA385B05DB} = {E74CF679-CA2A-47E9-B1F4-3779D6AC6B04}
 		{5F5714D0-1C3D-4522-A409-214C5A2951AA} = {E74CF679-CA2A-47E9-B1F4-3779D6AC6B04}
+		{46910277-18E3-4151-9AD9-DC5B551772A9} = {E74CF679-CA2A-47E9-B1F4-3779D6AC6B04}
 		{51626A22-DD68-4450-9696-13B03BF7A2C5} = {E74CF679-CA2A-47E9-B1F4-3779D6AC6B04}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution

src/lol/net/http.h

@@ -25,15 +25,29 @@ namespace http
 
 class client_impl;
 
+enum class status : uint8_t
+{
+    ready   = 0,
+    pending = 1,
+    success = 2,
+    error   = 3,
+};
+
 class client
 {
 public:
     client();
     ~client();
 
+    // Enqueue a query
     void get(std::string const &url);
-    bool is_ready() const;
-    std::tuple<int, std::string> result();
+
+    // Reset state
+    void reset();
+
+    // Get status (may be pending) and result
+    status get_status() const;
+    std::string const & get_result() const;
 
 private:
     std::unique_ptr<client_impl> impl;

src/net/http.cpp

@@ -10,10 +10,14 @@
 //  See http://www.wtfpl.net/ for more details.
 //
 
-#pragma once
-
 #include <lol/engine-internal.h>
 
+#if __EMSCRIPTEN__
+#   include <emscripten/fetch.h>
+#else
+#   include <httplib.h>
+#endif
+
 namespace lol
 {
 
@@ -23,22 +27,41 @@ namespace net
 namespace http
 {
 
-#if __EMSCRIPTEN__
-class client_impl
-{
-    // FIXME
-};
-#else
 class client_impl
 {
 public:
+#if __EMSCRIPTEN__
+    static void on_success(emscripten_fetch_t *fetch)
+    {
+        auto *that = (client_impl *)fetch->userData;
+        msg::info("finished downloading %llu bytes from URL %s.\n",
+                  fetch->numBytes, fetch->url);
+        that->m_result.assign(fetch->data, fetch->numBytes);
+        that->m_status = status::success;
+    }
+
+    static void on_failure(emscripten_fetch_t *fetch)
+    {
+        auto *that = (client_impl *)fetch->userData;
+        msg::error("downloading %s failed, HTTP failure status code: %d.\n",
+                   fetch->url, fetch->status);
+        that->m_status = status::error;
+    }
+
+    emscripten_fetch_t *m_fetch = nullptr;
+#else
     void get(std::string const& url)
     {
 
     }
-};
+
+    //httplib::Client &client;
 #endif
 
+    status m_status;
+    std::string m_result;
+};
+
 client::client()
   : impl(std::make_unique<client_impl>())
 {
@@ -46,20 +69,41 @@ client::client()
 
 client::~client()
 {
+#if __EMSCRIPTEN__
+    emscripten_fetch_close(impl->m_fetch);
+#endif
 }
 
 void client::get(std::string const &url)
 {
+    impl->m_status = status::pending;
+#if __EMSCRIPTEN__
+    emscripten_fetch_attr_t attr;
+    emscripten_fetch_attr_init(&attr);
+    strcpy(attr.requestMethod, "GET");
+    attr.userData = impl.get();
+    attr.attributes = EMSCRIPTEN_FETCH_LOAD_TO_MEMORY;
+    attr.onsuccess = client_impl::on_success;
+    attr.onerror = client_impl::on_failure;
+    impl->m_fetch = emscripten_fetch(&attr, url.c_str());
+#else
+#endif
+}
+
+void client::reset()
+{
+    impl->m_status = status::ready;
+    impl->m_result.assign("");
 }
 
-bool client::is_ready() const
+status client::get_status() const
 {
-    return false;
+    return impl->m_status;
 }
 
-std::tuple<int, std::string> client::result()
+std::string const & client::get_result() const
 {
-    return std::make_tuple(404, std::string());
+    return impl->m_result;
 }
 
 } // namespace http