Add FindRandomPoint and FindRandomPointAroundCircle to the navigation utilities

Source/Engine/Navigation/NavMeshRuntime.cpp

@@ -4,7 +4,7 @@
 #include "NavigationSettings.h"
 #include "NavMesh.h"
 #include "Engine/Core/Log.h"
-#include "Engine/Core/Math/Matrix.h"
+#include "Engine/Core/Random.h"
 #include "Engine/Profiler/ProfilerCPU.h"
 #include "Engine/Threading/Threading.h"
 #include <ThirdParty/recastnavigation/DetourNavMesh.h>
@@ -231,6 +231,71 @@ bool NavMeshRuntime::ProjectPoint(const Vector3& point, Vector3& result) const
     return true;
 }
 
+bool NavMeshRuntime::FindRandomPoint(Vector3& result) const
+{
+    ScopeLock lock(Locker);
+
+    const auto query = GetNavMeshQuery();
+    if (!query || !_navMesh)
+    {
+        return false;
+    }
+
+    dtQueryFilter filter;
+    InitFilter(filter);
+
+    dtPolyRef randomPoly = 0;
+    query->findRandomPoint(&filter, Random::Rand, &randomPoly, &result.X);
+    if (!randomPoly)
+    {
+        return false;
+    }
+
+    Quaternion invRotation;
+    Quaternion::Invert(Properties.Rotation, invRotation);
+    Vector3::Transform(result, invRotation, result);
+
+    return true;
+}
+
+bool NavMeshRuntime::FindRandomPointAroundCircle(const Vector3& center, float radius, Vector3& result) const
+{
+    ScopeLock lock(Locker);
+
+    const auto query = GetNavMeshQuery();
+    if (!query || !_navMesh)
+    {
+        return false;
+    }
+
+    dtQueryFilter filter;
+    InitFilter(filter);
+    Vector3 extent(DEFAULT_NAV_QUERY_EXTENT_HORIZONTAL, DEFAULT_NAV_QUERY_EXTENT_VERTICAL, DEFAULT_NAV_QUERY_EXTENT_HORIZONTAL);
+
+    Vector3 centerNavMesh;
+    Vector3::Transform(center, Properties.Rotation, centerNavMesh);
+
+    dtPolyRef centerPoly = 0;
+    query->findNearestPoly(&centerNavMesh.X, &extent.X, &filter, &centerPoly, nullptr);
+    if (!centerPoly)
+    {
+        return false;
+    }
+
+    dtPolyRef randomPoly = 0;
+    query->findRandomPointAroundCircle(centerPoly, &centerNavMesh.X, radius, &filter, Random::Rand, &randomPoly, &result.X);
+    if (!randomPoly)
+    {
+        return false;
+    }
+
+    Quaternion invRotation;
+    Quaternion::Invert(Properties.Rotation, invRotation);
+    Vector3::Transform(result, invRotation, result);
+
+    return true;
+}
+
 bool NavMeshRuntime::RayCast(const Vector3& startPosition, const Vector3& endPosition, NavMeshHit& hitInfo) const
 {
     ScopeLock lock(Locker);
@@ -522,6 +587,7 @@ void NavMeshRuntime::RemoveTiles(bool (* prediction)(const NavMeshRuntime* navMe
 #if COMPILE_WITH_DEBUG_DRAW
 
 #include "Engine/Debug/DebugDraw.h"
+#include "Engine/Core/Math/Matrix.h"
 
 void DrawPoly(NavMeshRuntime* navMesh, const Matrix& navMeshToWorld, const dtMeshTile& tile, const dtPoly& poly)
 {

Source/Engine/Navigation/NavMeshRuntime.h

@@ -127,6 +127,22 @@ public:
     /// <returns>True if found valid location on the navmesh, otherwise false.</returns>
     bool ProjectPoint(const Vector3& point, Vector3& result) const;
 
+    /// <summary>
+    /// Finds random location on nav mesh.
+    /// </summary>
+    /// <param name="result">The result position on the navmesh (valid only if method returns true).</param>
+    /// <returns>True if found valid location on the navmesh, otherwise false.</returns>
+    bool FindRandomPoint(Vector3& result) const;
+
+    /// <summary>
+    /// Finds random location on nav mesh within the reach of specified location.
+    /// </summary>
+    /// <param name="center">The source point to find random location around it.</param>
+    /// <param name="radius">The search distance for a random point. Maximum distance for a result point from the center of the circle.</param>
+    /// <param name="result">The result position on the navmesh (valid only if method returns true).</param>
+    /// <returns>True if found valid location on the navmesh, otherwise false.</returns>
+    bool FindRandomPointAroundCircle(const Vector3& center, float radius, Vector3& result) const;
+
     /// <summary>
     /// Casts a 'walkability' ray along the surface of the navigation mesh from the start position toward the end position.
     /// </summary>

Source/Engine/Navigation/Navigation.cpp

@@ -315,6 +315,20 @@ bool Navigation::ProjectPoint(const Vector3& point, Vector3& result)
     return NavMeshes.First()->ProjectPoint(point, result);
 }
 
+bool Navigation::FindRandomPoint(Vector3& result)
+{
+    if (NavMeshes.IsEmpty())
+        return false;
+    return NavMeshes.First()->FindRandomPoint(result);
+}
+
+bool Navigation::FindRandomPointAroundCircle(const Vector3& center, float radius, Vector3& result)
+{
+    if (NavMeshes.IsEmpty())
+        return false;
+    return NavMeshes.First()->FindRandomPointAroundCircle(center, radius, result);
+}
+
 bool Navigation::RayCast(const Vector3& startPosition, const Vector3& endPosition, NavMeshHit& hitInfo)
 {
     if (NavMeshes.IsEmpty())

Source/Engine/Navigation/Navigation.h

@@ -48,6 +48,23 @@ public:
     /// <returns>True if found valid location on the navmesh, otherwise false.</returns>
     API_FUNCTION() static bool ProjectPoint(const Vector3& point, API_PARAM(Out) Vector3& result);
 
+    /// <summary>
+    /// Finds random location on nav mesh.
+    /// </summary>
+    /// <param name="result">The result position on the navmesh (valid only if method returns true).</param>
+    /// <returns>True if found valid location on the navmesh, otherwise false.</returns>
+    API_FUNCTION() static bool FindRandomPoint(API_PARAM(Out) Vector3& result);
+
+    /// <summary>
+    /// Finds random location on nav mesh within the reach of specified location.
+    /// </summary>
+    /// <remarks>If the result location doesn't need to be exactly inside the circle but just in local are aof the navigation mesh polys, then use more optimized <see cref="FindRandomPointAround"/>.</remarks>
+    /// <param name="center">The source point to find random location around it.</param>
+    /// <param name="radius">The search distance for a random point. Maximum distance for a result point from the center of the circle.</param>
+    /// <param name="result">The result position on the navmesh (valid only if method returns true).</param>
+    /// <returns>True if found valid location on the navmesh, otherwise false.</returns>
+    API_FUNCTION() static bool FindRandomPointAroundCircle(const Vector3& center, float radius, API_PARAM(Out) Vector3& result);
+
     /// <summary>
     /// Casts a 'walkability' ray along the surface of the navigation mesh from the start position toward the end position.
     /// </summary>