Port to run Craft in web browser using Emscripten

CMakeLists.txt

@@ -4,20 +4,42 @@ project(craft)
 
 FILE(GLOB SOURCE_FILES src/*.c)
 
-add_executable(
-    craft
-    ${SOURCE_FILES}
-    deps/glew/src/glew.c
-    deps/lodepng/lodepng.c
-    deps/noise/noise.c
-    deps/sqlite/sqlite3.c
-    deps/tinycthread/tinycthread.c)
+if (EMSCRIPTEN)
+    add_executable(
+        craft
+        ${SOURCE_FILES}
+        #deps/glew/src/glew.c
+        deps/lodepng/lodepng.c
+        deps/noise/noise.c
+        deps/sqlite/sqlite3.c
+        deps/tinycthread/tinycthread.c)
+    # Generate HTML file wrapper in addition to .js
+    set(CMAKE_EXECUTABLE_SUFFIX ".html")
+else ()
+    add_executable(
+        craft
+        ${SOURCE_FILES}
+        deps/glew/src/glew.c
+        deps/lodepng/lodepng.c
+        deps/noise/noise.c
+        deps/sqlite/sqlite3.c
+        deps/tinycthread/tinycthread.c)
+endif ()
 
 add_definitions(-std=c99 -O3)
 
-add_subdirectory(deps/glfw)
-include_directories(deps/glew/include)
-include_directories(deps/glfw/include)
+if (EMSCRIPTEN)
+    # Emscripten default is GLFW 2.x but we use GLFW 3.x, also include data files
+    set_target_properties(craft PROPERTIES LINK_FLAGS "-s USE_GLFW=3 --embed-file ../shaders/ -s TOTAL_MEMORY=33554432 --embed-file ../textures/")
+endif ()
+
+if (NOT EMSCRIPTEN)
+    # Emscripten includes its own GLFW and GLEW ports
+    add_subdirectory(deps/glfw)
+    include_directories(deps/glew/include)
+    include_directories(deps/glfw/include)
+endif ()
+
 include_directories(deps/lodepng)
 include_directories(deps/noise)
 include_directories(deps/sqlite)
@@ -30,8 +52,12 @@ if(MINGW)
         "C:/Program Files/CURL/include" "C:/Program Files (x86)/CURL/include")
 endif()
 
-find_package(CURL REQUIRED)
-include_directories(${CURL_INCLUDE_DIR})
+if (NOT EMSCRIPTEN)
+    find_package(CURL REQUIRED)
+    include_directories(${CURL_INCLUDE_DIR})
+else ()
+    set(CURL_LIBRARIES "")
+endif ()
 
 if(APPLE)
     target_link_libraries(craft glfw

README.md

@@ -59,9 +59,16 @@ terminal.
 
     git clone https://github.com/fogleman/Craft.git
     cd Craft
-    cmake .
+    mkdir build
+    pushd build
+    cmake ..
     make
-    ./craft
+    popd
+    ./build/craft
+
+To build for the web (experimental), install [Emscripten](http://emscripten.org) and instead run:
+
+    cmake -DCMAKE_TOOLCHAIN_FILE=$EMSCRIPTEN/cmake/Modules/Platform/Emscripten.cmake ..
 
 ### Multiplayer
 

shaders/block_fragment.glsl

@@ -1,4 +1,7 @@
-#version 120
+#ifdef GL_ES
+precision mediump float;
+precision mediump int;
+#endif
 
 uniform sampler2D sampler;
 uniform sampler2D sky_sampler;

shaders/block_vertex.glsl

@@ -1,4 +1,7 @@
-#version 120
+#ifdef GL_ES
+precision mediump float;
+precision mediump int;
+#endif
 
 uniform mat4 matrix;
 uniform vec3 camera;
@@ -17,7 +20,7 @@ varying float fog_height;
 varying float diffuse;
 
 const float pi = 3.14159265;
-const vec3 light_direction = normalize(vec3(-1.0, 1.0, -1.0));
+vec3 light_direction = normalize(vec3(-1.0, 1.0, -1.0));
 
 void main() {
     gl_Position = matrix * position;
@@ -34,6 +37,6 @@ void main() {
         fog_factor = pow(clamp(camera_distance / fog_distance, 0.0, 1.0), 4.0);
         float dy = position.y - camera.y;
         float dx = distance(position.xz, camera.xz);
-        fog_height = (atan(dy, dx) + pi / 2) / pi;
+        fog_height = (atan(dy, dx) + pi / 2.0) / pi;
     }
 }

shaders/line_fragment.glsl

@@ -1,4 +1,6 @@
-#version 120
+#ifdef GL_ES
+precision mediump float;
+#endif
 
 void main() {
     gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);

shaders/line_vertex.glsl

@@ -1,4 +1,6 @@
-#version 120
+#ifdef GL_ES
+precision mediump float;
+#endif
 
 uniform mat4 matrix;
 

shaders/sky_fragment.glsl

@@ -1,4 +1,6 @@
-#version 120
+#ifdef GL_ES
+precision mediump float;
+#endif
 
 uniform sampler2D sampler;
 uniform float timer;

shaders/sky_vertex.glsl

@@ -1,4 +1,6 @@
-#version 120
+#ifdef GL_ES
+precision mediump float;
+#endif
 
 uniform mat4 matrix;
 

shaders/text_fragment.glsl

@@ -1,4 +1,6 @@
-#version 120
+#ifdef GL_ES
+precision mediump float;
+#endif
 
 uniform sampler2D sampler;
 uniform bool is_sign;

shaders/text_vertex.glsl

@@ -1,4 +1,6 @@
-#version 120
+#ifdef GL_ES
+precision mediump float;
+#endif
 
 uniform mat4 matrix;
 

src/auth.c

@@ -1,4 +1,6 @@
+#ifndef __EMSCRIPTEN__
 #include <curl/curl.h>
+#endif
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -21,6 +23,9 @@ size_t write_function(char *data, size_t size, size_t count, void *arg) {
 int get_access_token(
     char *result, int length, char *username, char *identity_token)
 {
+#ifdef __EMSCRIPTEN__
+    return 0;
+#else
     static char url[] = "https://craft.michaelfogleman.com/api/1/identity";
     strncpy(result, "", length);
     CURL *curl = curl_easy_init();
@@ -46,4 +51,5 @@ int get_access_token(
         }
     }
     return 0;
+#endif
 }

src/main.c

@@ -1,6 +1,11 @@
 #include <GL/glew.h>
 #include <GLFW/glfw3.h>
+#ifndef __EMSCRIPTEN__
 #include <curl/curl.h>
+#endif
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#endif
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -2583,9 +2588,26 @@ void reset_model() {
     g->time_changed = 1;
 }
 
+void one_iter();
+static FPS fps = {0, 0, 0};
+static double last_commit;
+static double last_update;
+static double previous;
+static State *s;
+static Player *me;
+static Attrib block_attrib = {0};
+static Attrib line_attrib = {0};
+static Attrib text_attrib = {0};
+static Attrib sky_attrib = {0};
+static GLuint sky_buffer;
+static int g_running;
+static int g_inner_break;
+
 int main(int argc, char **argv) {
     // INITIALIZATION //
+#ifndef __EMSCRIPTEN__
     curl_global_init(CURL_GLOBAL_DEFAULT);
+#endif
     srand(time(NULL));
     rand();
 
@@ -2600,7 +2622,6 @@ int main(int argc, char **argv) {
     }
 
     glfwMakeContextCurrent(g->window);
-    glfwSwapInterval(VSYNC);
     glfwSetInputMode(g->window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
     glfwSetKeyCallback(g->window, on_key);
     glfwSetCharCallback(g->window, on_char);
@@ -2613,7 +2634,9 @@ int main(int argc, char **argv) {
 
     glEnable(GL_CULL_FACE);
     glEnable(GL_DEPTH_TEST);
+#ifndef __EMSCRIPTEN__ // TODO: remove, what is replacement? glLogicOp not in >=GLES2: https://github.com/kripken/emscripten/issues/1416
     glLogicOp(GL_INVERT);
+#endif
     glClearColor(0, 0, 0, 1);
 
     // LOAD TEXTURES //
@@ -2652,10 +2675,6 @@ int main(int argc, char **argv) {
     load_png_texture("textures/sign.png");
 
     // LOAD SHADERS //
-    Attrib block_attrib = {0};
-    Attrib line_attrib = {0};
-    Attrib text_attrib = {0};
-    Attrib sky_attrib = {0};
     GLuint program;
 
     program = load_program(
@@ -2727,8 +2746,8 @@ int main(int argc, char **argv) {
     }
 
     // OUTER LOOP //
-    int running = 1;
-    while (running) {
+    g_running = 1;
+    while (g_running) {
         // DATABASE INITIALIZATION //
         if (g->mode == MODE_OFFLINE || USE_CACHE) {
             db_enable();
@@ -2752,13 +2771,13 @@ int main(int argc, char **argv) {
 
         // LOCAL VARIABLES //
         reset_model();
-        FPS fps = {0, 0, 0};
-        double last_commit = glfwGetTime();
-        double last_update = glfwGetTime();
-        GLuint sky_buffer = gen_sky_buffer();
+        //FPS fps = {0, 0, 0};
+        last_commit = glfwGetTime();
+        last_update = glfwGetTime();
+        sky_buffer = gen_sky_buffer();
 
-        Player *me = g->players;
-        State *s = &g->players->state;
+        me = g->players;
+        s = &g->players->state;
         me->id = 0;
         me->name[0] = '\0';
         me->buffer = 0;
@@ -2772,8 +2791,37 @@ int main(int argc, char **argv) {
         }
 
         // BEGIN MAIN LOOP //
-        double previous = glfwGetTime();
+        previous = glfwGetTime();
+#ifdef __EMSCRIPTEN__
+        emscripten_set_main_loop(one_iter, 60, 1);
+#else
+        glfwSwapInterval(VSYNC);
+        g_inner_break = 0;
         while (1) {
+            one_iter();
+            if (g_inner_break) break;
+        }
+#endif
+
+        // SHUTDOWN //
+        db_save_state(s->x, s->y, s->z, s->rx, s->ry);
+        db_close();
+        db_disable();
+        client_stop();
+        client_disable();
+        del_buffer(sky_buffer);
+        delete_all_chunks();
+        delete_all_players();
+    }
+
+    glfwTerminate();
+#ifndef __EMSCRIPTEN__
+    curl_global_cleanup();
+#endif
+    return 0;
+}
+
+void one_iter() {
             // WINDOW SIZE AND SCALE //
             g->scale = get_scale_factor();
             glfwGetFramebufferSize(g->window, &g->width, &g->height);
@@ -2937,27 +2985,12 @@ int main(int argc, char **argv) {
             glfwSwapBuffers(g->window);
             glfwPollEvents();
             if (glfwWindowShouldClose(g->window)) {
-                running = 0;
-                break;
+                g_running = 0;
+                g_inner_break = 1;
             }
             if (g->mode_changed) {
                 g->mode_changed = 0;
-                break;
+                g_inner_break = 1;
             }
-        }
-
-        // SHUTDOWN //
-        db_save_state(s->x, s->y, s->z, s->rx, s->ry);
-        db_close();
-        db_disable();
-        client_stop();
-        client_disable();
-        del_buffer(sky_buffer);
-        delete_all_chunks();
-        delete_all_players();
-    }
-
-    glfwTerminate();
-    curl_global_cleanup();
-    return 0;
 }
+