From 363f67a56e012c2f55ba1225e58c4a956da41f41 Mon Sep 17 00:00:00 2001
From: Thomas Perl <m@thp.io>
Date: Tue, 7 Aug 2012 16:21:31 +0200
Subject: [PATCH] Tracker: Environment variable to choose camera

---
 README                   | 12 ++++++++++++
 include/psmove_tracker.h |  4 ++++
 src/psmove_tracker.c     | 13 +++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/README b/README
index eb9c038f..ed4ea404 100644
--- a/README
+++ b/README
@@ -19,6 +19,18 @@ Advanced features:
  * Orientation: Rotation tracking using gyro and accelerometer
 
 
+Environment variables:
+
+ PSMOVE_TRACKER_CAMERA
+
+     If set, this is the camera that will be used when using
+     psmove_tracker_new() instead of using auto-detection
+
+   Example: export PSMOVE_TRACKER_CAMERA=2  # Will use the 3rd camera
+
+
+
+
  |- Windows notes ----------- -- -  -
  | If you are using MinGW from the Qt SDK, you have to replace the file
  | libbthprops.a in mingw\lib\ with the file of the same name from the
diff --git a/include/psmove_tracker.h b/include/psmove_tracker.h
index 96f41d9d..0d1ae0cb 100644
--- a/include/psmove_tracker.h
+++ b/include/psmove_tracker.h
@@ -42,6 +42,10 @@ extern "C" {
 /* For now, we only allow 1 controller to be tracked */
 #define PSMOVE_TRACKER_MAX_CONTROLLERS 2
 
+/* Name of the environment variable used to pick a camera */
+#define PSMOVE_TRACKER_CAMERA_ENV "PSMOVE_TRACKER_CAMERA"
+
+
 /* Opaque data structure, defined only in psmove_tracker.c */
 struct _PSMoveTracker;
 typedef struct _PSMoveTracker PSMoveTracker;
diff --git a/src/psmove_tracker.c b/src/psmove_tracker.c
index 529fe7d6..c199e5fc 100644
--- a/src/psmove_tracker.c
+++ b/src/psmove_tracker.c
@@ -263,6 +263,19 @@ PSMoveTracker *psmove_tracker_new() {
     }
 #endif
 
+    char *camera_env = getenv(PSMOVE_TRACKER_CAMERA_ENV);
+    if (camera_env) {
+        char *end;
+        long camera_env_id = strtol(camera_env, &end, 10);
+        if (*end == '\0' && *camera_env != '\0') {
+            camera = (int)camera_env_id;
+#ifdef PSMOVE_DEBUG
+            fprintf(stderr, "[PSMOVE] Using camera %d (%s is set)\n",
+                    camera, PSMOVE_TRACKER_CAMERA_ENV);
+#endif
+        }
+    }
+
     return psmove_tracker_new_with_camera(camera);
 }