Added optimizations

Author: TimGoTheCreator

src/struct/particle.h

@@ -1,51 +1,44 @@
-#pragma once
-#include <immintrin.h>
-#include "floatdef.h"
-#include <cmath>
-#include <string>
-
-struct alignas(32) Particle {
-    real x, y, z;
-    real vx, vy, vz;
-    real m;
-};
-
-inline void Gravity(Particle& a, Particle& b, real dt)
-{
-    constexpr real G = real(1.0);
-    real dx = b.x - a.x;
-    real dy = b.y - a.y;
-    real dz = b.z - a.z;
-
-    real distSq0 = dx*dx + dy*dy + dz*dz;
-    real dist0   = std::sqrt(distSq0);
-
-    // adaptive softening = 1% of separation
-    real eps = dist0 * real(0.01);
-
-    real distSq = distSq0 + eps*eps;
-    real dist   = std::sqrt(distSq);
-
-    real invDist = real(1) / dist;
-    real invDist3 = invDist * invDist * invDist;
-
-    real ax = G * b.m * dx * invDist3;
-    real ay = G * b.m * dy * invDist3;
-    real az = G * b.m * dz * invDist3;
-
-    real bx = -G * a.m * dx * invDist3;
-    real by = -G * a.m * dy * invDist3;
-    real bz = -G * a.m * dz * invDist3;
-
-    
-
-    a.vx += ax * dt;
-    a.vy += ay * dt;
-    a.vz += az * dt;
-
-    b.vx += bx * dt;
-    b.vy += by * dt;
-    b.vz += bz * dt;
-}
-
-
+#pragma once
+#include <cmath>
+#include "floatdef.h"
+
+struct alignas(32) Particle {
+    real x, y, z;
+    real vx, vy, vz;
+    real m;
+};
+
+inline void Gravity(Particle& a, Particle& b, real dt)
+{
+    constexpr real G    = real(1.0);
+    constexpr real eps2 = real(1e-4);
+
+    // Relative position
+    real dx = b.x - a.x;
+    real dy = b.y - a.y;
+    real dz = b.z - a.z;
+
+    // Softened squared distance
+    real r2 = dx*dx + dy*dy + dz*dz + eps2;
+
+    // Inverse distance and inverse distance cubed
+    real invR = std::sqrt(real(1.0) / r2);
+    real invR3 = invR * invR * invR;
+
+    // Accelerations (pairwise, symmetric)
+    real ax = G * b.m * dx * invR3;
+    real ay = G * b.m * dy * invR3;
+    real az = G * b.m * dz * invR3;
+
+    real bx = -G * a.m * dx * invR3;
+    real by = -G * a.m * dy * invR3;
+    real bz = -G * a.m * dz * invR3;
+
+    a.vx += ax * dt;
+    a.vy += ay * dt;
+    a.vz += az * dt;
+
+    b.vx += bx * dt;
+    b.vy += by * dt;
+    b.vz += bz * dt;
+}