1 files changed, 52 insertions, 5 deletions

diff --git a/source/blender/blenlib/intern/rct.c b/source/blender/blenlib/intern/rct.c
index cab383b60f3..ee073d5d309 100644
--- a/source/blender/blenlib/intern/rct.c
+++ b/source/blender/blenlib/intern/rct.c
@@ -102,16 +102,28 @@ int BLI_rctf_isect_pt_v(const rctf *rect, const float xy[2])
 }
 
 /* based closely on 'isect_line_line_v2_int', but in modified so corner cases are treated as intersections */
-static int isect_segments(const int v1[2], const int v2[2], const int v3[2], const int v4[2])
+static int isect_segments_i(const int v1[2], const int v2[2], const int v3[2], const int v4[2])
 {
 	const double div = (double)((v2[0] - v1[0]) * (v4[1] - v3[1]) - (v2[1] - v1[1]) * (v4[0] - v3[0]));
-	if (div == 0.0f) {
+	if (div == 0.0) {
 		return 1; /* co-linear */
 	}
 	else {
 		const double labda = (double)((v1[1] - v3[1]) * (v4[0] - v3[0]) - (v1[0] - v3[0]) * (v4[1] - v3[1])) / div;
 		const double mu    = (double)((v1[1] - v3[1]) * (v2[0] - v1[0]) - (v1[0] - v3[0]) * (v2[1] - v1[1])) / div;
-		return (labda >= 0.0f && labda <= 1.0f && mu >= 0.0f && mu <= 1.0f);
+		return (labda >= 0.0 && labda <= 1.0 && mu >= 0.0 && mu <= 1.0);
+	}
+}
+static int isect_segments_fl(const float v1[2], const float v2[2], const float v3[2], const float v4[2])
+{
+	const double div = (double)((v2[0] - v1[0]) * (v4[1] - v3[1]) - (v2[1] - v1[1]) * (v4[0] - v3[0]));
+	if (div == 0.0) {
+		return 1; /* co-linear */
+	}
+	else {
+		const double labda = (double)((v1[1] - v3[1]) * (v4[0] - v3[0]) - (v1[0] - v3[0]) * (v4[1] - v3[1])) / div;
+		const double mu    = (double)((v1[1] - v3[1]) * (v2[0] - v1[0]) - (v1[0] - v3[0]) * (v2[1] - v1[1])) / div;
+		return (labda >= 0.0 && labda <= 1.0 && mu >= 0.0 && mu <= 1.0);
 	}
 }
 
@@ -134,14 +146,49 @@ int BLI_rcti_isect_segment(const rcti *rect, const int s1[2], const int s2[2])
 		/* diagonal: [/] */
 		tvec1[0] = rect->xmin; tvec1[1] = rect->ymin;
 		tvec2[0] = rect->xmin; tvec2[1] = rect->ymax;
-		if (isect_segments(s1, s2, tvec1, tvec2)) {
+		if (isect_segments_i(s1, s2, tvec1, tvec2)) {
+			return 1;
+		}
+
+		/* diagonal: [\] */
+		tvec1[0] = rect->xmin; tvec1[1] = rect->ymax;
+		tvec2[0] = rect->xmax; tvec2[1] = rect->ymin;
+		if (isect_segments_i(s1, s2, tvec1, tvec2)) {
+			return 1;
+		}
+
+		/* no intersection */
+		return 0;
+	}
+}
+
+int BLI_rctf_isect_segment(const rctf *rect, const float s1[2], const float s2[2])
+{
+	/* first do outside-bounds check for both points of the segment */
+	if (s1[0] < rect->xmin && s2[0] < rect->xmin) return 0;
+	if (s1[0] > rect->xmax && s2[0] > rect->xmax) return 0;
+	if (s1[1] < rect->ymin && s2[1] < rect->ymin) return 0;
+	if (s1[1] > rect->ymax && s2[1] > rect->ymax) return 0;
+
+	/* if either points intersect then we definetly intersect */
+	if (BLI_rctf_isect_pt_v(rect, s1) || BLI_rctf_isect_pt_v(rect, s2)) {
+		return 1;
+	}
+	else {
+		/* both points are outside but may insersect the rect */
+		float tvec1[2];
+		float tvec2[2];
+		/* diagonal: [/] */
+		tvec1[0] = rect->xmin; tvec1[1] = rect->ymin;
+		tvec2[0] = rect->xmin; tvec2[1] = rect->ymax;
+		if (isect_segments_fl(s1, s2, tvec1, tvec2)) {
 			return 1;
 		}
 
 		/* diagonal: [\] */
 		tvec1[0] = rect->xmin; tvec1[1] = rect->ymax;
 		tvec2[0] = rect->xmax; tvec2[1] = rect->ymin;
-		if (isect_segments(s1, s2, tvec1, tvec2)) {
+		if (isect_segments_fl(s1, s2, tvec1, tvec2)) {
 			return 1;
 		}