From 001c74ba6a20ddf5f027fa6a6bd2f5e3a31da62c Mon Sep 17 00:00:00 2001
From: Mark <mark@betalupi.com>
Date: Thu, 4 Jan 2024 21:41:15 -0800
Subject: [PATCH] Added reverse animation

---
 content/sprite.toml                        |  4 +--
 crates/content/src/part/sprite.rs          |  9 +++++--
 crates/render/shaders/include/animate.wgsl | 29 +++++++++++++++++-----
 3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/content/sprite.toml b/content/sprite.toml
index 17f07fa..7ce88b8 100644
--- a/content/sprite.toml
+++ b/content/sprite.toml
@@ -20,8 +20,8 @@ file = "projectile/blaster.png"
 file = "ship/gypsum.png"
 
 [sprite."ship::peregrine"]
-duration = 1
-repeat = "repeat"
+duration = 1.3
+repeat = "reverse"
 frames = [
 	"ship/peregrine/01.png",
 	"ship/peregrine/02.png",
diff --git a/crates/content/src/part/sprite.rs b/crates/content/src/part/sprite.rs
index 060cf09..2b901d8 100644
--- a/crates/content/src/part/sprite.rs
+++ b/crates/content/src/part/sprite.rs
@@ -44,6 +44,10 @@ pub enum RepeatMode {
 	/// After the first frame, jump to the last frame
 	#[serde(rename = "repeat")]
 	Repeat,
+
+	/// Play this animation in reverse after the last frame
+	#[serde(rename = "reverse")]
+	Reverse,
 }
 
 impl RepeatMode {
@@ -51,8 +55,9 @@ impl RepeatMode {
 	/// Used to pass this enum into shaders
 	pub fn as_int(&self) -> u32 {
 		match self {
-			Self::Once => 0,
-			Self::Repeat => 1,
+			Self::Repeat => 0,
+			Self::Once => 1,
+			Self::Reverse => 2,
 		}
 	}
 }
diff --git a/crates/render/shaders/include/animate.wgsl b/crates/render/shaders/include/animate.wgsl
index 58f86df..507ae79 100644
--- a/crates/render/shaders/include/animate.wgsl
+++ b/crates/render/shaders/include/animate.wgsl
@@ -10,16 +10,33 @@ fn animate(instance: InstanceInput, age: f32) -> u32 {
 	let fps = sprites.data[idx].fps;
 	var frame: u32 = u32(0);
 
-	if rep == u32(1) { // Repeat
-		let x = age / fps;
-		let m = f32(len);
-		// x fmod m
-		frame = u32(x - floor(x / m) * m);
-	} else { // Once
+
+	// Repeat
+	if rep == u32(1) {
+
 		frame = u32(min(
 			(age / fps),
 			f32(len) - 1.0
 		));
+
+	// Reverse
+	} else if rep == u32(2) {
+		let x = age / fps;
+		let m = f32(len) * 2.0 - 1.0;
+		// x fmod m
+		frame = u32(x - floor(x / m) * m);
+
+		if frame >= len {
+			frame = len + len - frame - u32(1);
+		}
+
+	// Repeat (default)
+	} else {
+		let x = age / fps;
+		let m = f32(len);
+		// x fmod m
+		frame = u32(x - floor(x / m) * m);
+
 	}
 	
 	return frame + sprites.data[idx].first_frame;