Enhance Tunnel Screensaver

gallery/tunnel/tunnel.sh

@@ -32,46 +32,60 @@ animate() {
     height=$(tput lines)
     local center_x=$((width / 2))
     local center_y=$((height / 2))
-    local max_radius=$(( (height > width ? height : width) / 2 + 1 ))
+    local max_radius=$(( (height > width ? height : width) / 2 + 2 ))
+    local ribbon_spacing=7
+    local -a radii=()
+    local frame_counter=0
 
     while true; do
-        for ((r=1; r < max_radius; r++)); do
-            local frame_buffer=""
-            local color=${COLORS[$((r % ${#COLORS[@]}))]}
-            local char=${CHARS[$((r % ${#CHARS[@]}))]}
+        local frame_buffer=""
+        # Add a new ribbon every few frames
+        if (( frame_counter % ribbon_spacing == 0 )); then
+            radii+=(1)
+        fi
 
-            # Erase the previous shape
-            if [ $r -gt 1 ]; then
+        local -a next_radii=()
+        for r in "${radii[@]}"; do
+            if [ $r -gt 0 ]; then
                 local prev_r=$((r-1))
+                # Erase the previous shape
                 for ((i=0; i < prev_r; i++)); do
                     x1=$((center_x + i)); y1=$((center_y - prev_r + i))
                     x2=$((center_x + prev_r - i)); y2=$((center_y + i))
                     x3=$((center_x - i)); y3=$((center_y + prev_r - i))
                     x4=$((center_x - prev_r + i)); y4=$((center_y - i))
-                    if (( y1 >= 0 && y1 < height && x1 >= 0 && x1 < width )); then frame_buffer+="\e[$((y1 + 1));$((x1 + 1))H "; fi
-                    if (( y2 >= 0 && y2 < height && x2 >= 0 && x2 < width )); then frame_buffer+="\e[$((y2 + 1));$((x2 + 1))H "; fi
-                    if (( y3 >= 0 && y3 < height && x3 >= 0 && x3 < width )); then frame_buffer+="\e[$((y3 + 1));$((x3 + 1))H "; fi
-                    if (( y4 >= 0 && y4 < height && x4 >= 0 && x4 < width )); then frame_buffer+="\e[$((y4 + 1));$((x4 + 1))H "; fi
+                    frame_buffer+="\e[$((y1 + 1));$((x1 + 1))H "
+                    frame_buffer+="\e[$((y2 + 1));$((x2 + 1))H "
+                    frame_buffer+="\e[$((y3 + 1));$((x3 + 1))H "
+                    frame_buffer+="\e[$((y4 + 1));$((x4 + 1))H "
                 done
             fi
 
+            local color=${COLORS[$((r % ${#COLORS[@]}))]}
+            local char=${CHARS[$((r % ${#CHARS[@]}))]}
             # Draw a square/diamond shape
             for ((i=0; i < r; i++)); do
                 x1=$((center_x + i)); y1=$((center_y - r + i))
                 x2=$((center_x + r - i)); y2=$((center_y + i))
                 x3=$((center_x - i)); y3=$((center_y + r - i))
                 x4=$((center_x - r + i)); y4=$((center_y - i))
-                if (( y1 >= 0 && y1 < height && x1 >= 0 && x1 < width )); then frame_buffer+="\e[$((y1 + 1));$((x1 + 1))H${color}${char}"; fi
-                if (( y2 >= 0 && y2 < height && x2 >= 0 && x2 < width )); then frame_buffer+="\e[$((y2 + 1));$((x2 + 1))H${color}${char}"; fi
-                if (( y3 >= 0 && y3 < height && x3 >= 0 && x3 < width )); then frame_buffer+="\e[$((y3 + 1));$((x3 + 1))H${color}${char}"; fi
-                if (( y4 >= 0 && y4 < height && x4 >= 0 && x4 < width )); then frame_buffer+="\e[$((y4 + 1));$((x4 + 1))H${color}${char}"; fi
+                frame_buffer+="\e[$((y1 + 1));$((x1 + 1))H${color}${char}"
+                frame_buffer+="\e[$((y2 + 1));$((x2 + 1))H${color}${char}"
+                frame_buffer+="\e[$((y3 + 1));$((x3 + 1))H${color}${char}"
+                frame_buffer+="\e[$((y4 + 1));$((x4 + 1))H${color}${char}"
             done
 
-            printf '%b' "$frame_buffer"
-            sleep $DELAY
+            # Increment radius for the next frame, and keep it if it's not too large
+            local next_r=$((r + 1))
+            if (( next_r < max_radius )); then
+                next_radii+=($next_r)
+            fi
         done
-        # Clear the center after a full cycle
-        printf "\e[$((center_y + 1));$((center_x + 1))H "
+
+        radii=("${next_radii[@]}")
+        printf '%b' "$frame_buffer"
+        sleep $DELAY
+        ((frame_counter++))
     done
 }