From ea6ecd3579611030c396580f18e771b2eb4e5441 Mon Sep 17 00:00:00 2001
From: Erwin Coumans <erwincoumans@google.com>
Date: Thu, 10 Mar 2016 23:12:22 -0800
Subject: [PATCH] Use higher precision GJK/EPA collision tolerances in
 BT_USE_DOUBLE_PRECISION See
 https://raw.githubusercontent.com/billhoffman/bullet-pod/ac6aae3e3ee8137de484471094a65bfe166898b4/bullet_gjk_accuracy_patch.diff

---
 .../NarrowPhaseCollision/btGjkEpa2.cpp        | 35 ++++++++++++++-----
 .../btGjkPairDetector.cpp                     |  6 +++-
 2 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/src/BulletCollision/NarrowPhaseCollision/btGjkEpa2.cpp b/src/BulletCollision/NarrowPhaseCollision/btGjkEpa2.cpp
index 3268f06c2..e4bbe340e 100644
--- a/src/BulletCollision/NarrowPhaseCollision/btGjkEpa2.cpp
+++ b/src/BulletCollision/NarrowPhaseCollision/btGjkEpa2.cpp
@@ -41,21 +41,38 @@ namespace gjkepa2_impl
 
 	/* GJK	*/ 
 #define GJK_MAX_ITERATIONS	128
-#define GJK_ACCURARY		((btScalar)0.0001)
-#define GJK_MIN_DISTANCE	((btScalar)0.0001)
-#define GJK_DUPLICATED_EPS	((btScalar)0.0001)
+
+#ifdef BT_USE_DOUBLE_PRECISION
+	#define GJK_ACCURARY		((btScalar)1e-12)
+	#define GJK_MIN_DISTANCE	((btScalar)1e-12)
+	#define GJK_DUPLICATED_EPS	((btScalar)1e-12)
+#else
+	#define GJK_ACCURARY		((btScalar)0.0001)
+	#define GJK_MIN_DISTANCE	((btScalar)0.0001)
+	#define GJK_DUPLICATED_EPS	((btScalar)0.0001)
+#endif //BT_USE_DOUBLE_PRECISION
+
+
 #define GJK_SIMPLEX2_EPS	((btScalar)0.0)
 #define GJK_SIMPLEX3_EPS	((btScalar)0.0)
 #define GJK_SIMPLEX4_EPS	((btScalar)0.0)
 
 	/* EPA	*/ 
-#define EPA_MAX_VERTICES	64
-#define EPA_MAX_FACES		(EPA_MAX_VERTICES*2)
+#define EPA_MAX_VERTICES	128
 #define EPA_MAX_ITERATIONS	255
-#define EPA_ACCURACY		((btScalar)0.0001)
-#define EPA_FALLBACK		(10*EPA_ACCURACY)
-#define EPA_PLANE_EPS		((btScalar)0.00001)
-#define EPA_INSIDE_EPS		((btScalar)0.01)
+
+#ifdef BT_USE_DOUBLE_PRECISION
+	#define EPA_ACCURACY		((btScalar)1e-12)
+	#define EPA_FALLBACK		(10*EPA_ACCURACY)
+	#define EPA_PLANE_EPS		((btScalar)1e-14)
+	#define EPA_INSIDE_EPS		((btScalar)1e-9)
+#else
+	#define EPA_ACCURACY		((btScalar)0.0001)
+	#define EPA_PLANE_EPS		((btScalar)0.00001)
+	#define EPA_INSIDE_EPS		((btScalar)0.01)
+#endif
+
+#define EPA_MAX_FACES           (EPA_MAX_VERTICES*2)
 
 
 	// Shorthands
diff --git a/src/BulletCollision/NarrowPhaseCollision/btGjkPairDetector.cpp b/src/BulletCollision/NarrowPhaseCollision/btGjkPairDetector.cpp
index 759443a96..603ad167d 100644
--- a/src/BulletCollision/NarrowPhaseCollision/btGjkPairDetector.cpp
+++ b/src/BulletCollision/NarrowPhaseCollision/btGjkPairDetector.cpp
@@ -30,7 +30,11 @@ subject to the following restrictions:
 #endif
 
 //must be above the machine epsilon
-#define REL_ERROR2 btScalar(1.0e-6)
+#ifdef  BT_USE_DOUBLE_PRECISION
+	#define REL_ERROR2 btScalar(1.0e-12)
+#else
+	#define REL_ERROR2 btScalar(1.0e-6)
+#endif
 
 //temp globals, to improve GJK/EPA/penetration calculations
 int gNumDeepPenetrationChecks = 0;