added refresh interval in ms for animations

res/config.ini

@@ -35,6 +35,14 @@
 # matrix -> CMatrix
 animation = none
 
+# The minimum time between animation frames
+# 32 -> ~30fps
+# 16 -> ~60fps
+# 8  -> ~120fps
+# 6  -> ~144fps
+# 4  -> ~240fps
+animation_refresh_ms = 16
+
 # Stop the animation after some time
 # 0 -> Run forever
 # 1..2e12 -> Stop the animation after this many seconds

src/animations/Doom.zig

@@ -50,35 +50,57 @@ pub fn realloc(self: *Doom) !void {
     self.buffer = buffer;
 }
 
-pub fn draw(self: Doom) void {
+pub fn drawWithUpdate(self: Doom) void {
     for (0..self.terminal_buffer.width) |x| {
         for (1..self.terminal_buffer.height) |y| {
+            // get source index
             const source = y * self.terminal_buffer.width + x;
+
+            // random number between 0 and 3 inclusive
             const random = (self.terminal_buffer.random.int(u16) % 7) & 3;
 
+            // adjust destination index based on random value
             var dest = (source - @min(source, random)) + 1;
             if (self.terminal_buffer.width > dest) dest = 0 else dest -= self.terminal_buffer.width;
 
+            // get source intensity and destination offset
             const buffer_source = self.buffer[source];
             const buffer_dest_offset = random & 1;
 
             if (buffer_source < buffer_dest_offset) continue;
 
+            // calculate  the destination intensity
             var buffer_dest = buffer_source - buffer_dest_offset;
             if (buffer_dest > 12) buffer_dest = 0;
             self.buffer[dest] = @intCast(buffer_dest);
 
+            // update terminal
             self.terminal_buffer.buffer[dest] = toTermboxCell(FIRE[buffer_dest]);
             self.terminal_buffer.buffer[source] = toTermboxCell(FIRE[buffer_source]);
         }
     }
 }
 
+pub fn draw(self: Doom) void {
+    for (0..self.terminal_buffer.width) |x| {
+        for (1..self.terminal_buffer.height) |y| {
+            // get source index
+            const source = y * self.terminal_buffer.width + x;
+
+            // get intensity from buffer
+            const buffer_source = self.buffer[source];
+
+            // set cell to correct fire char
+            self.terminal_buffer.buffer[source] = toTermboxCell(FIRE[buffer_source]);
+        }
+    }
+}
+
 fn initBuffer(buffer: []u8, width: usize) void {
-    const length = buffer.len - width;
-    const slice_start = buffer[0..length];
-    const slice_end = buffer[length..];
+    const slice_start = buffer[0..buffer.len];
+    const slice_end = buffer[buffer.len - width .. buffer.len];
 
+    // set cell initial values to 0, set bottom row to be fire sources
     @memset(slice_start, 0);
     @memset(slice_end, STEPS - 1);
 }

src/animations/Matrix.zig

@@ -68,80 +68,83 @@ pub fn realloc(self: *Matrix) !void {
     self.lines = lines;
 }
 
-pub fn draw(self: *Matrix) void {
+pub fn drawWithUpdate(self: *Matrix) void {
     const buf_height = self.terminal_buffer.height;
     const buf_width = self.terminal_buffer.width;
-    self.count += 1;
-    if (self.count > FRAME_DELAY) {
-        self.frame += 1;
-        if (self.frame > 4) self.frame = 1;
-        self.count = 0;
 
-        var x: usize = 0;
-        while (x < self.terminal_buffer.width) : (x += 2) {
-            var tail: usize = 0;
-            var line = &self.lines[x];
-            if (self.frame <= line.update) continue;
-
-            if (self.dots[x].value == -1 and self.dots[self.terminal_buffer.width + x].value == ' ') {
-                if (line.space > 0) {
-                    line.space -= 1;
-                } else {
-                    const randint = self.terminal_buffer.random.int(i16);
-                    const h: isize = @intCast(self.terminal_buffer.height);
-                    line.length = @mod(randint, h - 3) + 3;
-                    self.dots[x].value = @mod(randint, MAX_CODEPOINT) + MIN_CODEPOINT;
-                    line.space = @mod(randint, h + 1);
-                }
-            }
+    self.frame += 1;
+    if (self.frame > 4) self.frame = 1;
 
-            var y: usize = 0;
-            var first_col = true;
-            var seg_len: u64 = 0;
-            height_it: while (y <= buf_height) : (y += 1) {
-                var dot = &self.dots[buf_width * y + x];
-                // Skip over spaces
-                while (y <= buf_height and (dot.value == ' ' or dot.value == -1)) {
-                    y += 1;
-                    if (y > buf_height) break :height_it;
-                    dot = &self.dots[buf_width * y + x];
-                }
+    var x: usize = 0;
+    while (x < self.terminal_buffer.width) : (x += 2) {
+        var tail: usize = 0;
+        var line = &self.lines[x];
+        if (self.frame <= line.update) continue;
+
+        if (self.dots[x].value == -1 and self.dots[self.terminal_buffer.width + x].value == ' ') {
+            if (line.space > 0) {
+                line.space -= 1;
+            } else {
+                const randint = self.terminal_buffer.random.int(i16);
+                const h: isize = @intCast(self.terminal_buffer.height);
+                line.length = @mod(randint, h - 3) + 3;
+                self.dots[x].value = @mod(randint, MAX_CODEPOINT) + MIN_CODEPOINT;
+                line.space = @mod(randint, h + 1);
+            }
+        }
 
-                // Find the head of this column
-                tail = y;
-                seg_len = 0;
-                while (y <= buf_height and dot.value != ' ' and dot.value != -1) {
-                    dot.is_head = false;
-                    if (MID_SCROLL_CHANGE) {
-                        const randint = self.terminal_buffer.random.int(i16);
-                        if (@mod(randint, 8) == 0) {
-                            dot.value = @mod(randint, MAX_CODEPOINT) + MIN_CODEPOINT;
-                        }
-                    }
+        var y: usize = 0;
+        var first_col = true;
+        var seg_len: u64 = 0;
+        height_it: while (y <= buf_height) : (y += 1) {
+            var dot = &self.dots[buf_width * y + x];
+            // Skip over spaces
+            while (y <= buf_height and (dot.value == ' ' or dot.value == -1)) {
+                y += 1;
+                if (y > buf_height) break :height_it;
+                dot = &self.dots[buf_width * y + x];
+            }
 
-                    y += 1;
-                    seg_len += 1;
-                    // Head's down offscreen
-                    if (y > buf_height) {
-                        self.dots[buf_width * tail + x].value = ' ';
-                        break :height_it;
+            // Find the head of this column
+            tail = y;
+            seg_len = 0;
+            while (y <= buf_height and dot.value != ' ' and dot.value != -1) {
+                dot.is_head = false;
+                if (MID_SCROLL_CHANGE) {
+                    const randint = self.terminal_buffer.random.int(i16);
+                    if (@mod(randint, 8) == 0) {
+                        dot.value = @mod(randint, MAX_CODEPOINT) + MIN_CODEPOINT;
                     }
-                    dot = &self.dots[buf_width * y + x];
                 }
 
-                const randint = self.terminal_buffer.random.int(i16);
-                dot.value = @mod(randint, MAX_CODEPOINT) + MIN_CODEPOINT;
-                dot.is_head = true;
-
-                if (seg_len > line.length or !first_col) {
+                y += 1;
+                seg_len += 1;
+                // Head's down offscreen
+                if (y > buf_height) {
                     self.dots[buf_width * tail + x].value = ' ';
-                    self.dots[x].value = -1;
+                    break :height_it;
                 }
-                first_col = false;
+                dot = &self.dots[buf_width * y + x];
+            }
+
+            const randint = self.terminal_buffer.random.int(i16);
+            dot.value = @mod(randint, MAX_CODEPOINT) + MIN_CODEPOINT;
+            dot.is_head = true;
+
+            if (seg_len > line.length or !first_col) {
+                self.dots[buf_width * tail + x].value = ' ';
+                self.dots[x].value = -1;
             }
+            first_col = false;
         }
     }
 
+    self.draw();
+}
+
+pub fn draw(self: *Matrix) void {
+    const buf_width = self.terminal_buffer.width;
+
     var x: usize = 0;
     while (x < buf_width) : (x += 2) {
         var y: usize = 1;

src/config/Config.zig

@@ -8,6 +8,7 @@ const Bigclock = enums.Bigclock;
 
 animation: Animation = .none,
 animation_timeout_sec: u12 = 0,
+animation_refresh_ms: u16 = 16,
 asterisk: ?u8 = '*',
 auth_fails: u64 = 10,
 bg: u16 = 0,

src/main.zig

@@ -317,6 +317,11 @@ pub fn main() !void {
         }
     }
 
+    var animation_timer = switch (config.animation) {
+        .none => undefined,
+        else => try std.time.Timer.start(),
+    };
+
     const animate = config.animation != .none;
     const shutdown_key = try std.fmt.parseInt(u8, config.shutdown_key[1..], 10);
     const shutdown_len = try utils.strWidth(lang.shutdown);
@@ -380,8 +385,22 @@ pub fn main() !void {
                 if (!animation_timed_out) {
                     switch (config.animation) {
                         .none => {},
-                        .doom => doom.draw(),
-                        .matrix => matrix.draw(),
+                        .doom => {
+                            if (animation_timer.read() / std.time.ns_per_ms > config.animation_refresh_ms) {
+                                animation_timer.reset();
+                                doom.drawWithUpdate();
+                            } else {
+                                doom.draw();
+                            }
+                        },
+                        .matrix => {
+                            if (animation_timer.read() / std.time.ns_per_ms > config.animation_refresh_ms) {
+                                animation_timer.reset();
+                                matrix.drawWithUpdate();
+                            } else {
+                                matrix.draw();
+                            }
+                        },
                     }
                 }
 
@@ -685,7 +704,7 @@ pub fn main() !void {
                     const password_text = try allocator.dupeZ(u8, password.text.items);
                     defer allocator.free(password_text);
 
-                    // Give up control on the TTY
+                    // Give up TTY
                     _ = termbox.tb_shutdown();
 
                     session_pid = try std.posix.fork();
@@ -702,10 +721,13 @@ pub fn main() !void {
                     session_pid = -1;
                 }
 
-                // Take back control of the TTY
+                // Take back TTY
                 _ = termbox.tb_init();
                 _ = termbox.tb_set_output_mode(termbox.TB_OUTPUT_NORMAL);
 
+                // Reinitialise buffer to avoid use after free
+                buffer = TerminalBuffer.init(config, labels_max_length, random);
+
                 const auth_err = shared_err.readError();
                 if (auth_err) |err| {
                     auth_fails += 1;