1 files changed, 40 insertions, 0 deletions
diff --git a/src/tail.odin b/src/tail.odin
new file mode 100644
index 0000000..2184444
--- /dev/null
+++ b/src/tail.odin
@@ -0,0 +1,40 @@
+package demonchime
+
+import "core:math"
+import "core:math/linalg"
+
+Tail :: struct($N: int) {
+  points: [N]Vec2,
+  point_max_dist: f32,
+  point_rad: f32,
+  color_start: Color,
+  color_end: Color,
+}
+
+set_tail_position :: proc(tail: ^Tail($N), pos: Vec2, dt: f32) {
+  tail.points[0] = pos
+  for i in 1..<len(tail.points) {
+    prev := tail.points[i - 1]
+    cur := &tail.points[i]
+
+    cur.y += 50 * dt
+
+    dist := linalg.length2(prev - cur^)
+    if dist > tail.point_max_dist*tail.point_max_dist {
+      dir := linalg.normalize0(cur^ - prev)
+      cur^ = prev + dir * (tail.point_max_dist - 1)
+    }
+  }
+}
+
+draw_tail :: proc(tail: Tail($N)) {
+  for point, i in tail.points {
+    renderer.tint = linalg.lerp(
+      tail.color_start,
+      tail.color_end,
+      f32(i)/len(tail.points),
+    )
+    draw_circle(point, tail.point_rad)
+  }
+  renderer.tint = {1, 1, 1, 1}
+}