day 9 animation

d09.cc

@@ -2,6 +2,11 @@
 #include <vector>
 #include <unordered_set>
 
+//#define ANIMATE
+#ifdef ANIMATE
+#include <fstream>
+#endif
+
 using namespace std;
 
 enum Dir {
@@ -71,6 +76,50 @@ Input parse()
     return data;
 }
 
+#ifdef ANIMATE
+bool animate;
+int min_x, max_x, min_y, max_y;
+unsigned frame;
+void output_img(const vector<Pos2d> &knot, const unordered_set<Pos2d> &visited)
+{
+    enum Grid {
+        NONE,
+        VISITED,
+        TAIL,
+        HEAD
+    };
+    unsigned width = max_x - min_x;
+    unsigned height = max_y - min_y;
+    auto map = vector<enum Grid>(width * height);
+
+    for (auto i : visited) map[(i.y - min_y) * width + (i.x - min_x)] = VISITED;
+    for (auto i : knot) map[(i.y - min_y) * width + (i.x - min_x)] = TAIL;
+    map[(knot.front().y - min_y) * width + (knot.front().x - min_x)] = HEAD;
+
+    char fname[] = "img/00000.pam";
+    sprintf(fname, "img/%05d.pam", frame++);
+    auto file = ofstream(fname);
+    file << "P7\n";
+    file << "WIDTH " << width << "\n";
+    file << "HEIGHT " << height << "\n";
+    file << "DEPTH 3\n";
+    file << "MAXVAL 255\n";
+    file << "TUPLTYPE RGB\n";
+    file << "ENDHDR\n";
+    for (auto i : map) {
+        uint32_t color = 0;
+        switch (i) {
+        case NONE: color = 0x000000; break;
+        case VISITED: color = 0xFF0000; break;
+        case TAIL: color = 0x00FF00; break;
+        case HEAD: color = 0x0000FF; break;
+        }
+        file.write((char *)&color, 3);
+    }
+    file.close();
+}
+#endif
+
 unsigned p1(const Input &input, unsigned count = 2)
 {
     auto knot = vector<Pos2d>(count);
@@ -90,6 +139,18 @@ unsigned p1(const Input &input, unsigned count = 2)
                 break;
             }
             visited.insert(knot.back());
+#ifdef ANIMATE
+            if (!animate) {
+                for (auto cur : knot) {
+                    if (cur.x < min_x) min_x = cur.x;
+                    if (cur.x > max_x) max_x = cur.x;
+                    if (cur.y < min_y) min_y = cur.y;
+                    if (cur.y > max_y) max_y = cur.y;
+                }
+            } else {
+                output_img(knot, visited);
+            }
+#endif
         }
     }
     return visited.size();
@@ -103,6 +164,13 @@ unsigned p2(const Input &input)
 int main()
 {
     auto input = parse();
+#ifdef ANIMATE
+    animate = false;
+    p1(input, 10);
+    animate = true;
+    p1(input, 10);
+    return 0;
+#endif
     cout << p1(input) << endl;
     cout << p2(input) << endl;
 }

makeanim.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+rm img/*.gif
+waitjobs() {
+    while [ "$(jobs -p | wc -l)" -ge "$1" ]; do wait; done
+}
+for x in img/*.pam; do
+    echo "$x"
+    pamtogif -quiet "$x" > "$x.gif" &
+    waitjobs "$(nproc)"
+done
+wait
+gifsicle -d1 --verbose img/*.gif > anim.gif
+ffmpeg -i anim.gif -filter:v "setpts=0.1*PTS,scale=iw*4:ih*4:flags=neighbor" -r 100 anim.webm