From ff33a19b85f7f741c24ec6993903e29f423b55fa Mon Sep 17 00:00:00 2001
From: Kawe Mazidjatari <48657826+Mauler125@users.noreply.github.com>
Date: Wed, 6 Nov 2024 21:37:07 +0100
Subject: [PATCH] Recast: move triangle intersection code to shared

Light cleanup and reusability.
---
 src/naveditor/InputGeom.cpp                   | 52 ++-----------------
 .../recast/Shared/Include/SharedCommon.h      |  3 ++
 .../recast/Shared/Source/SharedCommon.cpp     | 44 ++++++++++++++++
 3 files changed, 51 insertions(+), 48 deletions(-)

diff --git a/src/naveditor/InputGeom.cpp b/src/naveditor/InputGeom.cpp
index 8ba67f1d..e69e9e02 100644
--- a/src/naveditor/InputGeom.cpp
+++ b/src/naveditor/InputGeom.cpp
@@ -27,50 +27,6 @@
 #include "NavEditor/Include/Editor.h"
 #include <naveditor/include/GameUtils.h>
 
-// note(amos): based on the Möller–Trumbore algorithm, see:
-// https://en.wikipedia.org/wiki/M%C3%B6ller%E2%80%93Trumbore_intersection_algorithm
-static inline bool intersectSegmentTriangle(const float* sp, const float* sq,
-											const float* a, const float* b, const float* c, float& t)
-{
-	float ab[3], ac[3], qp[3];
-	rdVsub(ab, b, a);
-	rdVsub(ac, c, a);
-	rdVsub(qp, sq, sp);
-
-	float h[3];
-	rdVcross(h, qp, ac);
-
-	const float d = rdVdot(ab, h);
-
-	if (d > -RD_EPS && d < RD_EPS)
-		return false; // Ray is parallel to the triangle plane
-
-	float s[3];
-	rdVsub(s, sp, a);
-
-	const float id = 1.0f/d;
-	const float u = rdVdot(s, h)*id;
-
-	if (u < 0.0f || u > 1.0f)
-		return false;
-
-	float q[3];
-	rdVcross(q, s, ab);
-
-	const float v = rdVdot(qp, q)*id;
-
-	if (v < 0.0f || u+v > 1.0f)
-		return false;
-
-	t = rdVdot(ac, q)*id;
-
-	if (t < 0.0f || t > 1.0f)
-		return false;
-
-	// Segment/ray intersects triangle
-	return true;
-}
-
 static char* parseRow(char* buf, char* bufEnd, char* row, int len)
 {
 	bool start = true;
@@ -598,10 +554,10 @@ bool InputGeom::raycastMesh(const float* src, const float* dst, const unsigned i
 		for (int j = 0; j < ntris*3; j += 3)
 		{
 			float t = 1;
-			if (intersectSegmentTriangle(src, dst,
-										 &verts[tris[j]*3],
-										 &verts[tris[j+1]*3],
-										 &verts[tris[j+2]*3], t))
+			if (rdIntersectSegmentTriangle(src, dst,
+										   &verts[tris[j]*3],
+										   &verts[tris[j+1]*3],
+										   &verts[tris[j+2]*3], t))
 			{
 				// Caller isn't interested in finding the closest intersection; return out.
 				if (!tmin)
diff --git a/src/thirdparty/recast/Shared/Include/SharedCommon.h b/src/thirdparty/recast/Shared/Include/SharedCommon.h
index 0f5316c6..9dff27e9 100644
--- a/src/thirdparty/recast/Shared/Include/SharedCommon.h
+++ b/src/thirdparty/recast/Shared/Include/SharedCommon.h
@@ -473,6 +473,9 @@ void rdClosestPtPointTriangle(float* closest, const float* p,
 ///  @param[out]	h		The resulting height.
 bool rdClosestHeightPointTriangle(const float* p, const float* a, const float* b, const float* c, float& h);
 
+bool rdIntersectSegmentTriangle(const float* sp, const float* sq,
+								const float* a, const float* b, const float* c, float& t);
+
 bool rdIntersectSegmentPoly2D(const float* p0, const float* p1,
 							  const float* verts, int nverts,
 							  float& tmin, float& tmax,
diff --git a/src/thirdparty/recast/Shared/Source/SharedCommon.cpp b/src/thirdparty/recast/Shared/Source/SharedCommon.cpp
index f2fed543..d98f7057 100644
--- a/src/thirdparty/recast/Shared/Source/SharedCommon.cpp
+++ b/src/thirdparty/recast/Shared/Source/SharedCommon.cpp
@@ -120,6 +120,50 @@ void rdClosestPtPointTriangle(float* closest, const float* p,
 	closest[2] = a[2] + ab[2] * v + ac[2] * w;
 }
 
+// note(amos): based on the Möller–Trumbore algorithm, see:
+// https://en.wikipedia.org/wiki/M%C3%B6ller%E2%80%93Trumbore_intersection_algorithm
+bool rdIntersectSegmentTriangle(const float* sp, const float* sq,
+								const float* a, const float* b, const float* c, float& t)
+{
+	float ab[3], ac[3], qp[3];
+	rdVsub(ab, b, a);
+	rdVsub(ac, c, a);
+	rdVsub(qp, sq, sp);
+
+	float h[3];
+	rdVcross(h, qp, ac);
+
+	const float d = rdVdot(ab, h);
+
+	if (d > -RD_EPS && d < RD_EPS)
+		return false; // Ray is parallel to the triangle plane
+
+	float s[3];
+	rdVsub(s, sp, a);
+
+	const float id = 1.0f / d;
+	const float u = rdVdot(s, h) * id;
+
+	if (u < 0.0f || u > 1.0f)
+		return false;
+
+	float q[3];
+	rdVcross(q, s, ab);
+
+	const float v = rdVdot(qp, q) * id;
+
+	if (v < 0.0f || u+v > 1.0f)
+		return false;
+
+	t = rdVdot(ac, q)*id;
+
+	if (t < 0.0f || t > 1.0f)
+		return false;
+
+	// Segment/ray intersects triangle
+	return true;
+}
+
 bool rdIntersectSegmentPoly2D(const float* p0, const float* p1,
 							  const float* verts, int nverts,
 							  float& tmin, float& tmax,