Implement random seeds under wasm

dose-response.js

@@ -118,6 +118,7 @@ fetch('target/wasm32-unknown-unknown/release/dose-response.wasm')
 
   .then(bytes => WebAssembly.instantiate(bytes, {
     env: {
+      random: Math.random,
       draw: function(ptr, len) {
         if(len % 6 != 0) {
           throw new Error("The drawcalls vector must have a multiple of 6 elements!");

src/main.rs

@@ -376,6 +376,7 @@ pub fn initialise() -> *mut State {
 
 extern {
     fn draw(nums: *const u8, len: usize);
+    fn random() -> f32;
 }
 
 

src/state.rs

@@ -1,11 +1,10 @@
-
-
 use animation::{AreaOfEffect, ScreenFade};
 use engine::Mouse;
 use keys::Keys;
 use monster;
 use player::Player;
 use point::Point;
+use util;
 use rand::{self, IsaacRng, SeedableRng};
 
 use stats::Stats;
@@ -203,8 +202,7 @@ impl State {
     ) -> State {
         let commands = VecDeque::new();
         let verifications = VecDeque::new();
-        //let seed = rand::random::<u32>();
-        let seed = 1234;
+        let seed = util::random_seed();
         let mut writer: Box<Write> = if let Some(replay_path) = replay_path {
             match File::create(&replay_path) {
                 Ok(f) => {

src/util.rs

@@ -1,5 +1,7 @@
 use std::time::Duration;
 
+use rand;
+
 
 /// The number of nanoseconds in a microsecond.
 const NANOS_PER_MICRO: u32 = 1000;
@@ -26,3 +28,17 @@ pub fn num_microseconds(duration: Duration) -> Option<u64> {
     }
     None
 }
+
+
+#[cfg(not(feature = "web"))]
+pub fn random_seed() -> u32 {
+    rand::random::<u32>()
+}
+
+#[cfg(feature = "web")]
+pub fn random_seed() -> u32 {
+    #[allow(unsafe_code)]
+    // NOTE: this comes from `Math.random` and returns a float in the <0, 1> range:
+    let random_float = unsafe { ::random() };
+    (random_float * ::std::u32::MAX as f32) as u32
+}