auto merge of #12270 : bstrie/rust/pnoise, r=huonw

Mostly just style fixes, but also remove a heap allocation and switch to using a buffered writer rather than doing 60,000 `println!`s.

1 files changed, 49 insertions, 65 deletions

diff --git a/src/test/bench/noise.rs b/src/test/bench/noise.rs
index e9e59924acc..42918ae5aa0 100644
--- a/src/test/bench/noise.rs
+++ b/src/test/bench/noise.rs
@@ -8,128 +8,112 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// Perlin noise benchmark from https://gist.github.com/1170424
+// Multi-language Perlin noise benchmark.
+// See https://github.com/nsf/pnoise for timings and alternative implementations.
 
-use std::f64;
-use std::rand::Rng;
-use std::rand;
+use std::f32::consts::PI;
+use std::rand::{Rng, StdRng};
 
 struct Vec2 {
     x: f32,
     y: f32,
 }
 
-#[inline(always)]
 fn lerp(a: f32, b: f32, v: f32) -> f32 { a * (1.0 - v) + b * v }
 
-#[inline(always)]
 fn smooth(v: f32) -> f32 { v * v * (3.0 - 2.0 * v) }
 
-fn random_gradient<R:Rng>(r: &mut R) -> Vec2 {
-    let v = 2.0 * f64::consts::PI * r.gen();
-    Vec2 {
-        x: v.cos() as f32,
-        y: v.sin() as f32,
-    }
+fn random_gradient<R: Rng>(r: &mut R) -> Vec2 {
+    let v = PI * 2.0 * r.gen();
+    Vec2 { x: v.cos(), y: v.sin() }
 }
 
 fn gradient(orig: Vec2, grad: Vec2, p: Vec2) -> f32 {
-    let sp = Vec2 {x: p.x - orig.x, y: p.y - orig.y};
-    grad.x * sp.x + grad.y * sp.y
+    (p.x - orig.x) * grad.x + (p.y - orig.y) * grad.y
 }
 
 struct Noise2DContext {
     rgradients: [Vec2, ..256],
-    permutations: [int, ..256],
+    permutations: [i32, ..256],
 }
 
 impl Noise2DContext {
-    pub fn new() -> Noise2DContext {
-        let mut r = rand::rng();
-        let mut rgradients = [ Vec2 { x: 0.0, y: 0.0 }, ..256 ];
-        for i in range(0, 256) {
-            rgradients[i] = random_gradient(&mut r);
-        }
-        let mut permutations = [ 0, ..256 ];
-        for i in range(0, 256) {
-            permutations[i] = i;
+    fn new() -> Noise2DContext {
+        let mut rng = StdRng::new();
+
+        let mut rgradients = [Vec2 { x: 0.0, y: 0.0 }, ..256];
+        for x in rgradients.mut_iter() {
+            *x = random_gradient(&mut rng);
         }
-        r.shuffle_mut(permutations);
 
-        Noise2DContext {
-            rgradients: rgradients,
-            permutations: permutations,
+        let mut permutations = [0i32, ..256];
+        for (i, x) in permutations.mut_iter().enumerate() {
+            *x = i as i32;
         }
+        rng.shuffle_mut(permutations);
+
+        Noise2DContext { rgradients: rgradients, permutations: permutations }
     }
 
-    #[inline(always)]
-    pub fn get_gradient(&self, x: int, y: int) -> Vec2 {
+    fn get_gradient(&self, x: i32, y: i32) -> Vec2 {
         let idx = self.permutations[x & 255] + self.permutations[y & 255];
         self.rgradients[idx & 255]
     }
 
-    #[inline]
-    pub fn get_gradients(&self,
-                         gradients: &mut [Vec2, ..4],
-                         origins: &mut [Vec2, ..4],
-                         x: f32,
-                         y: f32) {
+    fn get_gradients(&self, x: f32, y: f32) -> ([Vec2, ..4], [Vec2, ..4]) {
         let x0f = x.floor();
         let y0f = y.floor();
-        let x0 = x0f as int;
-        let y0 = y0f as int;
+        let x1f = x0f + 1.0;
+        let y1f = y0f + 1.0;
+
+        let x0 = x0f as i32;
+        let y0 = y0f as i32;
         let x1 = x0 + 1;
         let y1 = y0 + 1;
 
-        gradients[0] = self.get_gradient(x0, y0);
-        gradients[1] = self.get_gradient(x1, y0);
-        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};
+        ([self.get_gradient(x0, y0), self.get_gradient(x1, y0),
+          self.get_gradient(x0, y1), self.get_gradient(x1, y1)],
+         [Vec2 { x: x0f, y: y0f }, Vec2 { x: x1f, y: y0f },
+          Vec2 { x: x0f, y: y1f }, Vec2 { x: x1f, y: y1f }])
     }
 
-    #[inline]
-    pub fn get(&self, x: f32, y: f32) -> f32 {
+    fn get(&self, x: f32, y: f32) -> f32 {
         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);
+        let (gradients, origins) = self.get_gradients(x, y);
+
         let v0 = gradient(origins[0], gradients[0], p);
         let v1 = gradient(origins[1], gradients[1], p);
         let v2 = gradient(origins[2], gradients[2], p);
         let v3 = gradient(origins[3], gradients[3], p);
+
         let fx = smooth(x - origins[0].x);
         let vx0 = lerp(v0, v1, fx);
         let vx1 = lerp(v2, v3, fx);
         let fy = smooth(y - origins[0].y);
+
         lerp(vx0, vx1, fy)
     }
 }
 
 fn main() {
-    let symbols = [" ", "░", "▒", "▓", "█", "█"];
+    let symbols = [' ', '░', '▒', '▓', '█', '█'];
     let mut pixels = [0f32, ..256*256];
-    let n2d = ~Noise2DContext::new();
-    for _ in range(0, 100u) {
+    let n2d = Noise2DContext::new();
+
+    for _ in range(0, 100) {
         for y in range(0, 256) {
             for x in range(0, 256) {
-                let v = n2d.get(
-                    x as f32 * 0.1f32,
-                    y as f32 * 0.1f32
-                ) * 0.5f32 + 0.5f32;
-                pixels[y*256+x] = v;
-            };
-        };
-    };
+                let v = n2d.get(x as f32 * 0.1, y as f32 * 0.1);
+                pixels[y*256+x] = v * 0.5 + 0.5;
+            }
+        }
+    }
 
     for y in range(0, 256) {
         for x in range(0, 256) {
-            print!("{}", symbols[(pixels[y*256+x] / 0.2f32) as int]);
+            let idx = (pixels[y*256+x] / 0.2) as uint;
+            print!("{:c}", symbols[idx]);
         }
-        println!("");
+        print!("\n");
     }
 }