From 35c4867334a9e69d3d7693e26669fbf395d7c642 Mon Sep 17 00:00:00 2001
From: "Michael Cook (mackal)" <mcook@mackal.net>
Date: Sun, 4 Mar 2018 02:19:12 -0500
Subject: [PATCH] Add the Fast trig functions that work with EQ headings

This should match pretty close to the clients LUTs

Also fixed a bug with push
---
 zone/CMakeLists.txt |  2 ++
 zone/attack.cpp     |  8 +++++---
 zone/fastmath.cpp   | 32 ++++++++++++++++++++++++++++++++
 zone/fastmath.h     | 18 ++++++++++++++++++
 4 files changed, 57 insertions(+), 3 deletions(-)
 create mode 100644 zone/fastmath.cpp
 create mode 100644 zone/fastmath.h

diff --git a/zone/CMakeLists.txt b/zone/CMakeLists.txt
index 49644cfcf..b10ab32a0 100644
--- a/zone/CMakeLists.txt
+++ b/zone/CMakeLists.txt
@@ -28,6 +28,7 @@ SET(zone_sources
 	encounter.cpp
 	entity.cpp
 	exp.cpp
+	fastmath.cpp
 	fearpath.cpp
 	forage.cpp
 	groups.cpp
@@ -158,6 +159,7 @@ SET(zone_headers
 	entity.h
 	errmsg.h
 	event_codes.h
+	fastmath.h
 	forage.h
 	global_loot_manager.h
 	groups.h
diff --git a/zone/attack.cpp b/zone/attack.cpp
index 1ae42b168..90a774550 100644
--- a/zone/attack.cpp
+++ b/zone/attack.cpp
@@ -32,6 +32,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 #include "worldserver.h"
 #include "zone.h"
 #include "lua_parser.h"
+#include "fastmath.h"
 
 #include <assert.h>
 #include <stdio.h>
@@ -43,6 +44,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 
 extern QueryServ* QServ;
 extern WorldServer worldserver;
+extern FastMath g_Math;
 
 #ifdef _WINDOWS
 #define snprintf	_snprintf
@@ -3624,9 +3626,9 @@ void Mob::CommonDamage(Mob* attacker, int &damage, const uint16 spell_id, const
 			// update NPC stuff
 			if (a->force != 0.0f) {
 				auto new_pos = glm::vec3(
-				    m_Position.x + (a->force * std::cos(a->hit_heading) + m_Delta.x),
-				    m_Position.y + (a->force * std::sin(a->hit_heading) + m_Delta.y), m_Position.z);
-				if ((IsNPC() && position_update_melee_push_timer.Check()) && zone->zonemap &&
+				    m_Position.x + (a->force * g_Math.FastSin(a->hit_heading) + m_Delta.x),
+				    m_Position.y + (a->force * g_Math.FastCos(a->hit_heading) + m_Delta.y), m_Position.z);
+				if ((!IsNPC() || position_update_melee_push_timer.Check()) && zone->zonemap &&
 				    zone->zonemap->CheckLoS(
 					glm::vec3(m_Position),
 					new_pos)) { // If we have LoS on the new loc it should be reachable.
diff --git a/zone/fastmath.cpp b/zone/fastmath.cpp
new file mode 100644
index 000000000..fb2cef193
--- /dev/null
+++ b/zone/fastmath.cpp
@@ -0,0 +1,32 @@
+#include <cmath>
+#include "fastmath.h"
+
+FastMath g_Math;
+
+// This should match EQ's sin/cos LUTs
+// Some values didn't match on linux, but they were the "same" float :P
+FastMath::FastMath()
+{
+	int ci = 0;
+	int si = 128;
+	float res;
+	do {
+		res = std::cos(static_cast<float>(ci) * M_PI * 2 / 512);
+		lut_cos[ci] = res;
+		if (si == 512)
+			si = 0;
+		lut_sin[si] = res;
+		++ci;
+		++si;
+	} while (ci < 512);
+
+	lut_sin[0] = 0.0f;
+	lut_sin[128] = 1.0f;
+	lut_sin[256] = 0.0f;
+	lut_sin[384] = -1.0f;
+
+	lut_cos[0] = 1.0f;
+	lut_cos[128] = 0.0f;
+	lut_cos[384] = 0.0f;
+}
+
diff --git a/zone/fastmath.h b/zone/fastmath.h
new file mode 100644
index 000000000..083198e48
--- /dev/null
+++ b/zone/fastmath.h
@@ -0,0 +1,18 @@
+#ifndef FASTMATH_H
+#define FASTMATH_H
+
+class FastMath
+{
+private:
+	float lut_cos[512];
+	float lut_sin[512];
+
+public:
+	FastMath();
+
+	inline float FastSin(float a) { return lut_sin[static_cast<int>(a) & 0x1ff]; }
+	inline float FastCos(float a) { return lut_cos[static_cast<int>(a) & 0x1ff]; }
+
+};
+
+#endif /* !FASTMATH_H */