animation of some function

src/lib.rs

@@ -11,11 +11,25 @@ pub fn set_panic_hook() {
 
 #[wasm_bindgen]
 pub struct Universe {
+    width: u32,
+    height: u32,
+    field: Vec<f32>,
+}
+
+#[wasm_bindgen]
+pub struct Drawable {
     width: u32,
     height: u32,
     field: Vec<u8>,
 }
 
+const WAVESPEED: f32 = 1.0;
+
+fn func(x: f32, y: f32, t: f32) -> f32 {
+    use std::f32;
+    (2.0 * f32::consts::PI * (x + y) - WAVESPEED * t).sin()
+}
+
 #[wasm_bindgen]
 impl Universe {
     pub fn new(width: u32, height: u32) -> Self {
@@ -24,20 +38,51 @@ impl Universe {
         Universe {
             width,
             height,
-            field: vec![0u8; width as usize * height as usize],
+            field: vec![0.0; width as usize * height as usize],
         }
     }
 
-    pub fn set_something(&mut self) {
+    pub fn set_initial(&mut self, t: f32) {
         for j in 0..self.height {
             for i in 0..self.width {
-                self.field[(self.width * j + i) as usize] =
-                    ((10 * i + 100 * j) % (u8::max_value() as u32)) as u8;
+                let x = i as f32 / self.width as f32;
+                let y = j as f32 / self.height as f32;
+                self.field[(self.width * j + i) as usize] = func(x, y, t);
             }
         }
     }
 
-    pub fn get_field(&mut self) -> *mut u8 {
-        self.field.as_mut_ptr()
+    pub fn get_drawable(&self) -> Drawable {
+        // let fmin = self.field.iter().fold(0.0f32, |acc, x| acc.min(*x));
+        let fmin = -1.0;
+        // let fmax = self.field.iter().fold(0.0f32, |acc, x| acc.max(*x));
+        let fmax = 1.0;
+
+        let field = self
+            .field
+            .iter()
+            .map(|x| (u8::max_value() as f32 * (x - fmin) / (fmax - fmin)) as u8)
+            .collect::<Vec<_>>();
+
+        Drawable {
+            width: self.width,
+            height: self.height,
+            field,
+        }
+    }
+}
+
+#[wasm_bindgen]
+impl Drawable {
+    pub fn get_pointer(&mut self) -> *mut u8 {
+        self.field.as_mut_ptr()
+    }
+
+    pub fn width(&self) -> u32 {
+        self.width
+    }
+
+    pub fn height(&self) -> u32 {
+        self.height
     }
 }