1 files changed, 22 insertions, 22 deletions

diff --git a/src/intersect.h b/src/intersect.h
index e6566f3..bfde782 100644
--- a/src/intersect.h
+++ b/src/intersect.h
@@ -44,7 +44,7 @@ __device__ bool intersect_triangle(const float3 &origin, const float3 &direction
 		    (m.a01*m.a20 - m.a00*m.a21)*b.y +
 		    (m.a00*m.a11 - m.a01*m.a10)*b.z)/determinant;
 
-	if (u3 < 0.0f || (1.0f-u1-u2) < 0.0f)
+	if (u3 <= 0.0f || (1.0f-u1-u2) < 0.0f)
 		return false;
 
 	distance = u3;
@@ -84,32 +84,34 @@ __device__ bool intersect_box(const float3 &origin, const float3 &direction, con
 {
 	float kmin, kmax, kymin, kymax, kzmin, kzmax;
 
-	if (direction.x >= 0.0f)
+	float divx = 1.0f/direction.x;
+	if (divx >= 0.0f)
 	{
-		kmin = (lower_bound.x - origin.x)/direction.x;
-		kmax = (upper_bound.x - origin.x)/direction.x;
+		kmin = (lower_bound.x - origin.x)*divx;
+		kmax = (upper_bound.x - origin.x)*divx;
 	}
 	else
 	{
-		kmin = (upper_bound.x - origin.x)/direction.x;
-		kmax = (lower_bound.x - origin.x)/direction.x;
+		kmin = (upper_bound.x - origin.x)*divx;
+		kmax = (lower_bound.x - origin.x)*divx;
 	}
 
-	if (kmax < kmin)
+	if (kmax < 0.0f)
 		return false;
 
-	if (direction.y >= 0.0f)
+	float divy = 1.0f/direction.y;
+	if (divy >= 0.0f)
 	{
-		kymin = (lower_bound.y - origin.y)/direction.y;
-		kymax = (upper_bound.y - origin.y)/direction.y;
+		kymin = (lower_bound.y - origin.y)*divy;
+		kymax = (upper_bound.y - origin.y)*divy;
 	}
 	else
 	{
-		kymin = (upper_bound.y - origin.y)/direction.y;
-		kymax = (lower_bound.y - origin.y)/direction.y;
+		kymin = (upper_bound.y - origin.y)*divy;
+		kymax = (lower_bound.y - origin.y)*divy;
 	}
 
-	if (kymax < kymin)
+	if (kymax < 0.0f)
 		return false;
 
 	if (kymin > kmin)
@@ -121,18 +123,19 @@ __device__ bool intersect_box(const float3 &origin, const float3 &direction, con
 	if (kmin > kmax)
 		return false;
 
-	if (direction.z >= 0.0f)
+	float divz = 1.0f/direction.z;
+	if (divz >= 0.0f)
 	{
-		kzmin = (lower_bound.z - origin.z)/direction.z;
-		kzmax = (upper_bound.z - origin.z)/direction.z;
+		kzmin = (lower_bound.z - origin.z)*divz;
+		kzmax = (upper_bound.z - origin.z)*divz;
 	}
 	else
 	{
-		kzmin = (upper_bound.z - origin.z)/direction.z;
-		kzmax = (lower_bound.z - origin.z)/direction.z;
+		kzmin = (upper_bound.z - origin.z)*divz;
+		kzmax = (lower_bound.z - origin.z)*divz;
 	}
 
-	if (kzmax < kzmin)
+	if (kzmax < 0.0f)
 		return false;
 
 	if (kzmin > kmin)
@@ -144,9 +147,6 @@ __device__ bool intersect_box(const float3 &origin, const float3 &direction, con
 	if (kmin > kmax)
 		return false;
 
-	if (kmax < 0.0f)
-		return false;
-
 	return true;
 }