Init commit template for emscripten Rust

.gitignore

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+/dist/

Makefile

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+ifdef RELEASE
+	RUST_BUILD_TYPE := release
+	RUST_EXTRA_FLAGS := --release
+	C_OTHER_FLAGS := -DNDEBUG -O2
+else
+	RUST_BUILD_TYPE := debug
+	RUST_EXTRA_FLAGS :=
+	C_OTHER_FLAGS := -Og
+endif
+
+CC := source ${HOME}/git/emsdk/emsdk_env.sh && emcc
+CFLAGS := \
+		-Irust_src/include \
+		-sEXPORTED_FUNCTIONS=_main \
+		-sSTACK_SIZE=2097152 \
+		${C_OTHER_FLAGS}
+# Check https://emscripten.org/docs/tools_reference/emcc.html for more compiler
+# flags to pass to emcc.
+
+HEADERS := \
+		rust_src/include/rust_src.h
+
+all: dist
+
+rust_src/target/wasm32-unknown-emscripten/${RUST_BUILD_TYPE}/libems_rust_template.a:
+	cd rust_src && cargo build --target=wasm32-unknown-emscripten ${RUST_EXTRA_FLAGS}
+
+dist: rust_src/target/wasm32-unknown-emscripten/${RUST_BUILD_TYPE}/libems_rust_template.a src/main.c.o
+	@mkdir dist
+	${CC} -o dist/game.html ${CFLAGS} $^
+	ln -s game.html dist/index.html
+
+.PHONY: clean
+
+clean:
+	cd rust_src && cargo clean
+	rm -f src/*.c.o
+	rm -rf dist
+
+%.c.o: %.c ${HEADERS}
+	${CC} -o $@ -c ${CFLAGS} $<

rust_src/.gitignore

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+/target
+
+
+# Added by cargo
+#
+# already existing elements were commented out
+
+#/target

rust_src/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "ems_rust_template"
+version = "0.1.0"

rust_src/Cargo.toml

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+[package]
+name = "ems_rust_template"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["staticlib"]
+
+[profile.release]
+panic = "abort"
+
+[profile.dev]
+panic = "abort"
+
+[dependencies]

rust_src/include/rust_src.h

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+#ifndef EMSCRIPTEN_RUST_TEMPLATE_RUST_SRC_H_
+#define EMSCRIPTEN_RUST_TEMPLATE_RUST_SRC_H_
+
+extern void *get_main_ctx(void);
+extern void ctx_update(void *ctx);
+extern void ctx_draw(void *ctx);
+extern void ctx_resize_event_callback(void *ctx, int width, int height);
+
+#endif

rust_src/src/lib.rs

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+use std::ffi;
+
+#[no_mangle]
+pub extern "C" fn get_main_ctx() -> *mut ffi::c_void {
+    Context::ems_new()
+}
+
+#[no_mangle]
+pub extern "C" fn ctx_update(ctx: *mut ffi::c_void) {
+    unsafe {
+        let ctx: *mut Context = ctx as *mut Context;
+        (*ctx).update();
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn ctx_draw(ctx: *mut ffi::c_void) {
+    unsafe {
+        let ctx: *mut Context = ctx as *mut Context;
+        (*ctx).draw();
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn ctx_resize_event_callback(ctx: *mut ffi::c_void, width: ffi::c_int, height: ffi::c_int) {
+    unsafe {
+        let ctx: *mut Context = ctx as *mut Context;
+        (*ctx).resize_event_callback(width, height);
+    }
+}
+
+struct Context {
+}
+
+impl Context {
+    pub fn new() -> Self {
+        Self {
+        }
+    }
+
+    pub fn ems_new() -> *mut ffi::c_void {
+        let ctx_box: Box<Context> = Box::new(Context::new());
+        Box::<Context>::leak(ctx_box) as *mut Context as *mut ffi::c_void
+    }
+
+    pub fn update(&mut self) {
+        println!("update called.");
+    }
+
+    pub fn draw(&mut self) {
+        println!("draw called.");
+    }
+
+    pub fn resize_event_callback(&mut self, width: ffi::c_int, height: ffi::c_int) {
+        println!("Resize event: {}, {}", width, height);
+    }
+}

src/.gitignore

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+*.c.o

src/main.c

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+#include <emscripten.h>
+#include <emscripten/html5.h>
+
+#include <rust_src.h>
+
+EM_JS(int, canvas_get_width, (), {
+  return document.getElementById("canvas").clientWidth;
+});
+EM_JS(int, canvas_get_height, (), {
+  return document.getElementById("canvas").clientHeight;
+});
+
+void *main_init(void) {
+  return get_main_ctx();
+}
+
+EM_BOOL resize_event_callback(int event_type, const EmscriptenUiEvent *event, void *ud) {
+  if (event_type == EMSCRIPTEN_EVENT_RESIZE) {
+      ctx_resize_event_callback(ud, canvas_get_width(), canvas_get_height());
+  }
+  return false;
+}
+
+void main_loop_update(void *ud) {
+    ctx_update(ud);
+    ctx_draw(ud);
+}
+
+int main(void) {
+  void *ctx = main_init();
+
+  emscripten_set_resize_callback(
+    EMSCRIPTEN_EVENT_TARGET_WINDOW, NULL, false, resize_event_callback);
+
+  // This function never returns.
+  emscripten_set_main_loop_arg(main_loop_update, ctx, 0, 1);
+
+  return 0;
+}