From 36b9b1cbb79a0998ea3c0ec74475c0654c11ed8f Mon Sep 17 00:00:00 2001 From: Benjamin Tissoires Date: Fri, 19 Jan 2018 17:55:48 +0100 Subject: [PATCH] README: add note about the sensor orientation The coordinates are provided from the top-left position, but the sensor is effectively turned. So on the Spark and the Slate, X goes down, and Y is reversed and goes left. --- README.md | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index 8140889..e18cfa4 100644 --- a/README.md +++ b/README.md @@ -19,8 +19,10 @@ Devices tested and known to be supported: Units used by this interface ---------------------------- -* Physical distances for x/y axes are in µm from the sensor's top-right - position. +* Physical distances for x/y axes are in µm from the sensor's top-left + position. (Note that on the Spark and on the Slate at least, the sensor + is turned 90 degrees clockwise, so (0,0) is at the 'natural' top-right + corner) * Stylus pressure is normalized to a range of [0, 0xffff], inclusive. * Timestamps are in seconds in unix epoch, time offsets are in ms after the most recent timestamp.