1 files changed, 75 insertions, 0 deletions
diff --git a/bowshock/source/lgc/grv.cxx b/bowshock/source/lgc/grv.cxx
new file mode 100644
index 0000000..1eceae5
--- /dev/null
+++ b/bowshock/source/lgc/grv.cxx
@@ -0,0 +1,75 @@
+// Copyright 2022-2023 Gabriel Jensen.
+
+#include <bow/lgc.hxx>
+
+#include <cmath>
+
+namespace bow {
+	static auto grav1(::bow::obj & obj,::bow::obj const & par) noexcept -> void {
+		double const distx = par.pos.x-obj.pos.x;
+		double const disty = par.pos.y-obj.pos.y;
+		double const distz = par.pos.z-obj.pos.z;
+		double const dist  = ::std::sqrt(distx*distx+disty*disty+distz*distz);
+
+		double const angy  = ::std::atan2(disty,distx);
+		double const angz  = ::std::atan2(distz,distx);
+
+		double       acc   = par.mas/(dist*dist)*::bow::grvval;
+
+		double const vx    = ::std::cos(angy)*acc;
+		double const vy    = ::std::sin(angy)*acc;
+		double const vz    = ::std::sin(angz)*acc;
+
+		obj.posVel.x += vx;
+		obj.posVel.y += vy;
+		obj.posVel.z += vz;
+	}
+
+	static void grav2(::bow::obj & obj0,::bow::obj & obj1) noexcept {
+		double const distx  = obj1.pos.x-obj0.pos.x;
+		double const disty  = obj1.pos.y-obj0.pos.y;
+		double const distz  = obj1.pos.z-obj0.pos.z;
+		double const dist   = ::std::sqrt(distx*distx+disty*disty+distz*distz);
+
+		double const angy   = ::std::atan2(disty,distx);
+		double const angz   = ::std::atan2(distz,distx);
+
+		double       acc0   = ::bow::grvval/(dist*dist);
+		double const acc1   = acc0*obj0.mas; // This is negative.
+		             acc0  *= obj1.mas;
+
+		double       vx0    = ::std::cos(angy);
+		double       vy0    = ::std::sin(angy);
+		double       vz0    = ::std::sin(angz);
+		double const vx1    = vx0*acc1;
+		double const vy1    = vy0*acc1;
+		double const vz1    = vz0*acc1;
+		             vx0   *= acc0;
+		             vy0   *= acc0;
+		             vz0   *= acc0;
+
+		obj0.posVel.x += vx0;
+		obj0.posVel.y += vy0;
+		obj0.posVel.z += vz0;
+
+		obj1.posVel.x -= vx1;
+		obj1.posVel.y -= vy1;
+		obj1.posVel.z -= vz1;
+	}
+}
+	
+auto ::bow::grv(::bow::objroot & sys) noexcept -> void {
+	for (::bow::obj * obj0 = sys.objs;obj0 != nullptr;obj0 = obj0->nxt) {
+		for (::bow::obj * obj1 = obj0->nxt;obj1 != nullptr;obj1 = obj1->nxt) {
+			::bow::grav2(*obj0,*obj1);
+		}
+	}
+}
+
+auto ::bow::grv(::bow::objroot & objs,::bow::objroot const & sys) noexcept -> void {
+	for (::bow::obj * obj = objs.objs;obj != nullptr;obj = obj->nxt) {
+		for (::bow::obj * par = sys.objs;par != nullptr;par = par->nxt) {
+			::bow::grav1(*obj,*par);
+		}
+	}
+}