From 7eec9b32f74bd571a5817a293f4edfe58a2c4290 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kristian=20H=C3=B8gsberg?= <krh@bitplanet.net>
Date: Mon, 17 Jun 2013 09:15:22 -0400
Subject: [PATCH] spring: Make clip behavior configurable

When the spring goes outside the envelope, we have a few options for
bringing it back: either just let it overshoot, bounce off the limit or
just clamp it.  Instead of controlling that with #ifdef, let's make it
a part of the spring state.
---
 src/animation.c  | 38 ++++++++++++++++++++++++--------------
 src/compositor.h |  7 +++++++
 2 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/src/animation.c b/src/animation.c
index ed65739a..57d384d2 100644
--- a/src/animation.c
+++ b/src/animation.c
@@ -41,6 +41,7 @@ weston_spring_init(struct weston_spring *spring,
 	spring->current = current;
 	spring->previous = current;
 	spring->target = target;
+	spring->clip = WESTON_SPRING_OVERSHOOT;
 }
 
 WL_EXPORT void
@@ -71,22 +72,31 @@ weston_spring_update(struct weston_spring *spring, uint32_t msec)
 			force * step * step;
 		spring->previous = current;
 
-#if 0
-		if (spring->current >= 1.0) {
-#ifdef TWEENER_BOUNCE
-			spring->current = 2.0 - spring->current;
-			spring->previous = 2.0 - spring->previous;
-#else
-			spring->current = 1.0;
-			spring->previous = 1.0;
-#endif
+		switch (spring->clip) {
+		case WESTON_SPRING_OVERSHOOT:
+			break;
+
+		case WESTON_SPRING_CLAMP:
+			if (spring->current >= 1.0) {
+				spring->current = 1.0;
+				spring->previous = 1.0;
+			} else if (spring->current <= 0.0) {
+				spring->current = 0.0;
+				spring->previous = 0.0;
+			}
+			break;
+
+		case WESTON_SPRING_BOUNCE:
+			if (spring->current >= 1.0) {
+				spring->current = 2.0 - spring->current;
+				spring->previous = 2.0 - spring->previous;
+			} else if (spring->current <= 0.0) {
+				spring->current = -spring->current;
+				spring->previous = -spring->previous;
+			}
+			break;
 		}
 
-		if (spring->current <= 0.0) {
-			spring->current = 0.0;
-			spring->previous = 0.0;
-		}
-#endif
 		spring->timestamp += 4;
 	}
 }
diff --git a/src/compositor.h b/src/compositor.h
index a56bd4de..12ec8e3a 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -113,6 +113,12 @@ struct weston_animation {
 	struct wl_list link;
 };
 
+enum {
+	WESTON_SPRING_OVERSHOOT,
+	WESTON_SPRING_CLAMP,
+	WESTON_SPRING_BOUNCE
+};
+
 struct weston_spring {
 	double k;
 	double friction;
@@ -120,6 +126,7 @@ struct weston_spring {
 	double target;
 	double previous;
 	uint32_t timestamp;
+	uint32_t clip;
 };
 
 enum {