fix friction

[blobs.git] / src / world / Planet.hpp

diff --git a/src/world/Planet.hpp b/src/world/Planet.hpp
index 2034b8dc4c787b4f30e6a52eb87389402e1c1f95..f7efc585d6dbac8f58bf6ca0b3ae2cbddbcfedc2 100644 (file)
--- a/src/world/Planet.hpp
+++ b/src/world/Planet.hpp
@@ -41,6 +41,8 @@ public:
        double ElevationAt(const glm::dvec3 &p) const noexcept { return glm::length(p) - Radius(); }
        /// distance to planet center
        double DistanceAt(const glm::dvec3 &p) const noexcept { return glm::length(p); }
+       /// acceleration due to gravity at given point
+       glm::dvec3 GravityAt(const glm::dvec3 &p) const noexcept { return NormalAt(p) * (-GravitationalParameter() / glm::length2(p)); }
 
        /// get ground tile
        Tile &TileAt(const glm::dvec3 &) noexcept;