improvements to cat animation

build.rs

@@ -3,7 +3,6 @@ use std::{env, fs::File, io::Write, path::Path};
 use bitvec::{order::Msb0, vec::BitVec};
 use image::{GenericImageView, ImageReader};
 
-// Example custom build script.
 fn main() {
     println!("cargo::rerun-if-changed=build.rs");
 

src/lib.rs

@@ -5,7 +5,11 @@ const HEIGHT: i32 = 38;
 
 #[no_mangle]
 pub extern "C" fn next_frame(frame: u16, ptr: *mut u8) -> u8 {
-    let out = unsafe { std::slice::from_raw_parts_mut(ptr, 456) }.view_bits_mut::<Msb0>();
+    let out = unsafe { std::slice::from_raw_parts_mut(ptr, 456) };
+    out.fill(0);
+    let out = out.view_bits_mut::<Msb0>();
+
+    let frame: i32 = frame.into();
 
     if frame > 100 {
         return 1;
@@ -14,34 +18,50 @@ pub extern "C" fn next_frame(frame: u16, ptr: *mut u8) -> u8 {
     let cat = include_bytes!(concat!(env!("OUT_DIR"), "/cat.bin")).view_bits::<Msb0>();
     let meow = include_bytes!(concat!(env!("OUT_DIR"), "/meow.bin")).view_bits::<Msb0>();
 
-    let thres = WIDTH / 4;
+    let thres = WIDTH / 3;
 
-    let dx = (frame as i32 * 4 - thres).min(thres);
+    let dx = if frame <= 10 {
+        frame * 6 - thres
+    } else if frame > 87 {
+        (frame - 77) * 6 - thres
+    } else {
+        if frame / 7 % 2 == 0 {
+            // make meow flash on and off every 7 frames for the remaining time
 
-    for x in 0..96 {
-        for y in 0..38 {
-            let out_idx = index(x, y);
-            let in_idx = index(x - dx, y);
+            for x in 0..96 {
+                for y in 0..38 {
+                    let idx = index(x, y);
 
-            out.set(out_idx, cat[in_idx]);
+                    out.set(idx, meow[idx]);
+                }
+            }
         }
-    }
 
-    if dx == thres && frame / 7 % 2 == 0 {
-        // make meow flash on and off every 4 frames for the remaining time
+        60 - thres
+    };
 
-        for x in 0..96 {
-            for y in 0..38 {
-                let idx = index(x, y);
+    for x in 0..96 {
+        for y in 0..38 {
+            let out_idx = index(x, y);
+            let in_idx = index(x - dx, y + cat_height(frame));
 
-                out.set(idx, meow[idx] || out[idx]);
-            }
+            out.set(out_idx, cat[in_idx] || out[out_idx]);
         }
     }
 
     0
 }
 
+fn cat_height(frame: i32) -> i32 {
+    match frame % 4 {
+        0 => 0,
+        1 => 1,
+        2 => 2,
+        3 => 1,
+        _ => unreachable!(),
+    }
+}
+
 fn index(x: i32, y: i32) -> usize {
     if x < 0 || y < 0 || x >= WIDTH || y >= HEIGHT {
         return 0;

src/main.rs

@@ -29,6 +29,7 @@ fn main() {
         }
 
         draw_frame(&frame);
+        println!("Frame: {}", i);
     }
 }