[PATCH libinput 3/5] filter: drop constant acceleration

[Peter Hutterer]

This just moves a decimal point around, at the expense of making the approach
harder to understand. The only time the const acceleration matters is when
applied to the velocity but it only matters in relation to the threshold which
is a fixed number.

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 src/filter.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/filter.c b/src/filter.c
index 141b4a9..9e605d3 100644
--- a/src/filter.c
+++ b/src/filter.c
@@ -51,8 +51,7 @@ filter_destroy(struct motion_filter *filter)
  * Default parameters for pointer acceleration profiles.
  */
 
-#define DEFAULT_CONSTANT_ACCELERATION 10.0	/* unitless factor */
-#define DEFAULT_THRESHOLD 4.0			/* in units/ms */
+#define DEFAULT_THRESHOLD 0.4			/* in units/ms */
 #define DEFAULT_ACCELERATION 2.0		/* unitless factor */
 
 /*
@@ -337,12 +336,11 @@ pointer_accel_profile_smooth_simple(struct motion_filter *filter,
 	double smooth_accel_coefficient; /* unitless factor */
 	double factor; /* unitless factor */
 
-	if (threshold < 1.0)
-		threshold = 1.0;
+	if (threshold < 0.1)
+		threshold = 0.1;
 	if (accel < 1.0)
 		accel = 1.0;
 
-	velocity *= DEFAULT_CONSTANT_ACCELERATION;
 
 	if (velocity < (threshold / 2.0))
 		return calc_penumbral_gradient(0.5 + velocity / threshold) * 2.0 - 1.0;
-- 
1.9.3