auto merge of #5695 : bstrie/rust/noise, r=thestinger

With --opt-level=3, this version runs in 0.014s on my machine, compared to 0.252s for the previous version. Mostly due to the #[inline] on get().

src/test/bench/noise.rs

 // Perlin noise benchmark from https://gist.github.com/1170424
 
-use core::rand::RngUtil;
+use core::rand::{Rng, RngUtil};
 
 struct Vec2 {
     x: f32,
     y: f32,
 }
 
-fn lerp(a: f32, b: f32, v: f32) -> f32  { a * (1.0 - v) + b * v }
-fn smooth(v: f32) -> f32                { v * v * (3.0 - 2.0 * v) }
+#[inline(always)]
+fn lerp(a: f32, b: f32, v: f32) -> f32 { a * (1.0 - v) + b * v }
 
-fn random_gradient(r: @rand::Rng) -> Vec2 {
+#[inline(always)]
+fn smooth(v: f32) -> f32 { v * v * (3.0 - 2.0 * v) }
+
+fn random_gradient(r: @Rng) -> Vec2 {
     let v = r.gen_float() * float::consts::pi * 2.0;
-    Vec2{
+    Vec2 {
         x: float::cos(v) as f32,
         y: float::sin(v) as f32,
     }
 }
 
 fn gradient(orig: Vec2, grad: Vec2, p: Vec2) -> f32 {
-    let sp = Vec2{x: p.x - orig.x, y: p.y - orig.y};
+    let sp = Vec2 {x: p.x - orig.x, y: p.y - orig.y};
     grad.x * sp.x + grad.y + sp.y
 }
 
@@ -28,28 +31,28 @@ struct Noise2DContext {
     permutations: [int, ..256],
 }
 
-fn Noise2DContext() -> ~Noise2DContext {
-    let r = rand::Rng();
-    let mut rgradients = [ Vec2 { x: 0.0, y: 0.0 }, ..256 ];
-    for int::range(0, 256) |i| { rgradients[i] = random_gradient(r); }
-    let mut permutations = [ 0, ..256 ];
-    for int::range(0, 256) |i| { permutations[i] = i; }
-    r.shuffle_mut(permutations);
-
-    ~Noise2DContext{
-        rgradients: rgradients,
-        permutations: permutations,
+pub impl Noise2DContext {
+    fn new() -> Noise2DContext {
+        let r = rand::Rng();
+        let mut rgradients = [ Vec2 { x: 0.0, y: 0.0 }, ..256 ];
+        for int::range(0, 256) |i| { rgradients[i] = random_gradient(r); }
+        let mut permutations = [ 0, ..256 ];
+        for int::range(0, 256) |i| { permutations[i] = i; }
+        r.shuffle_mut(permutations);
+
+        Noise2DContext {
+            rgradients: rgradients,
+            permutations: permutations,
+        }
     }
-}
 
-pub impl Noise2DContext {
     #[inline(always)]
     fn get_gradient(&self, x: int, y: int) -> Vec2 {
         let idx = self.permutations[x & 255] + self.permutations[y & 255];
         self.rgradients[idx & 255]
     }
 
-    #[inline(always)]
+    #[inline]
     fn get_gradients(&self, gradients: &mut [Vec2, ..4], origins: &mut [Vec2, ..4], x: f32, y: f32) {
         let x0f = f32::floor(x);
         let y0f = f32::floor(y);
@@ -63,14 +66,15 @@ fn get_gradients(&self, gradients: &mut [Vec2, ..4], origins: &mut [Vec2, ..4],
         gradients[2] = self.get_gradient(x0, y1);
         gradients[3] = self.get_gradient(x1, y1);
 
-        origins[0] = Vec2{x: x0f + 0.0, y: y0f + 0.0};
-        origins[1] = Vec2{x: x0f + 1.0, y: y0f + 0.0};
-        origins[2] = Vec2{x: x0f + 0.0, y: y0f + 1.0};
-        origins[3] = Vec2{x: x0f + 1.0, y: y0f + 1.0};
+        origins[0] = Vec2 {x: x0f + 0.0, y: y0f + 0.0};
+        origins[1] = Vec2 {x: x0f + 1.0, y: y0f + 0.0};
+        origins[2] = Vec2 {x: x0f + 0.0, y: y0f + 1.0};
+        origins[3] = Vec2 {x: x0f + 1.0, y: y0f + 1.0};
     }
 
+    #[inline]
     fn get(&self, x: f32, y: f32) -> f32 {
-        let p = Vec2{x: x, y: y};
+        let p = Vec2 {x: x, y: y};
         let mut gradients = [ Vec2 { x: 0.0, y: 0.0 }, ..4 ];
         let mut origins = [ Vec2 { x: 0.0, y: 0.0 }, ..4 ];
         self.get_gradients(&mut gradients, &mut origins, x, y);
@@ -88,9 +92,9 @@ fn get(&self, x: f32, y: f32) -> f32 {
 
 fn main() {
     let symbols = [" ", "░", "▒", "▓", "█", "█"];
-    let mut pixels = vec::from_elem(256*256, 0f32);
-    let n2d = Noise2DContext();
-    for int::range(0, 100) |_| {
+    let mut pixels = [0f32, ..256*256];
+    let n2d = ~Noise2DContext::new();
+    for 100.times {
         for int::range(0, 256) |y| {
             for int::range(0, 256) |x| {
                 let v = n2d.get(
@@ -109,4 +113,3 @@ fn main() {
         io::println("");
     }*/
 }
-