From 701c1e26c481af0502f51e7285ef7302ccef74a6 Mon Sep 17 00:00:00 2001
From: GoldenTails <milestailsprower101n2@gmail.com>
Date: Sat, 18 Jun 2022 23:35:22 -0500
Subject: [PATCH] Implement epicenter and radius support for quakes.

---
 src/p_tick.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/p_tick.c b/src/p_tick.c
index 28ace9288..c8c927ae1 100644
--- a/src/p_tick.c
+++ b/src/p_tick.c
@@ -23,6 +23,7 @@
 #include "lua_hook.h"
 #include "m_perfstats.h"
 #include "i_system.h" // I_GetPreciseTime
+#include "r_main.h"
 
 // Object place
 #include "m_cheat.h"
@@ -740,7 +741,22 @@ void P_Ticker(boolean run)
 		if (quake.time)
 		{
 			fixed_t ir = quake.intensity>>1;
-			/// \todo Calculate distance from epicenter if set and modulate the intensity accordingly based on radius.
+
+			if (quake.epicenter) {
+				// Calculate 3D distance from epicenter, using camera.
+				// Uses only player 1 camera because only one quake variable exists.
+				fixed_t xydist = R_PointToDist2(camera.x, camera.y, quake.epicenter->x, quake.epicenter->y);
+				fixed_t dist = R_PointToDist2(0, camera.z, xydist, quake.epicenter->z);
+
+				CONS_Printf("%d\n", dist / FRACUNIT);
+
+				// More effect closer to epicenter, outside of radius = no effect
+				if (!quake.radius || dist > quake.radius)
+					ir = 0;
+				else
+					ir = FixedMul(ir, FRACUNIT - FixedDiv(dist, quake.radius));
+			}
+
 			quake.x = M_RandomRange(-ir,ir);
 			quake.y = M_RandomRange(-ir,ir);
 			quake.z = M_RandomRange(-ir,ir);