From f4c046a32ac8609cc016307679b22bf2fcca970b Mon Sep 17 00:00:00 2001
From: DeaDDooMER <deaddoomer@deadsoftware.ru>
Date: Sun, 17 Mar 2024 02:43:00 +0300
Subject: [PATCH] geom: simplify sweepAABB (this also will fix crash on ARMv8)

---
 src/game/g_grid.pas  |  2 +-
 src/game/g_panel.pas |  4 ++--
 src/shared/geom.pas  | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+), 3 deletions(-)

diff --git a/src/game/g_grid.pas b/src/game/g_grid.pas
index 0e2876a..f19b11f 100644
--- a/src/game/g_grid.pas
+++ b/src/game/g_grid.pas
@@ -1653,7 +1653,7 @@ begin
           if ((ptag and TagDisabled) = 0) and ((ptag and tagmask) <> 0) and (px.mQueryMark <> lq) then
           begin
             px.mQueryMark := lq; // mark as processed
-            if not sweepAABB(ax0, ay0, aw, ah, dx, dy, px.mX, px.mY, px.mWidth, px.mHeight, @u0) then continue;
+            if not sweepAABB(ax0, ay0, aw, ah, dx, dy, px.mX, px.mY, px.mWidth, px.mHeight, u0) then continue;
             if (minu0 > u0) then
             begin
               hitpx := px;
diff --git a/src/game/g_panel.pas b/src/game/g_panel.pas
index 964a95f..bc121df 100644
--- a/src/game/g_panel.pas
+++ b/src/game/g_panel.pas
@@ -644,7 +644,7 @@ var
         if (szdx < 0) then szdx := 0;
         if (szdy < 0) then szdy := 0;
         // move platform by szd* back, and check for szd* movement
-        if sweepAABB(ox-szdx, oy-szdy, nw, nh, szdx, szdy, px, py, pw, ph, @u0) then
+        if sweepAABB(ox-szdx, oy-szdy, nw, nh, szdx, szdy, px, py, pw, ph, u0) then
         begin
           // yes, platform hits the entity, push the entity in the resizing direction
           u0 := 1.0-u0; // how much path left?
@@ -661,7 +661,7 @@ var
         end;
       end;
       // second, process platform movement, using te* as entity starting point
-      if sweepAABB(ox, oy, nw, nh, pdx, pdy, tex, tey, pw, ph, @u0) then
+      if sweepAABB(ox, oy, nw, nh, pdx, pdy, tex, tey, pw, ph, u0) then
       begin
         //e_LogWritefln('T: platsweep; u0=%s; u1=%s; hedge=%s; sweepAABB(%s, %s, %s, %s, %s, %s, %s, %s, %s, %s)', [u0, u1, hedge, ox, oy, mpw, mph, pdx, pdy, px-1, py-1, pw+2, ph+2]);
         // yes, platform hits the entity, push the entity in the direction of the platform
diff --git a/src/shared/geom.pas b/src/shared/geom.pas
index b19a677..12a6409 100644
--- a/src/shared/geom.pas
+++ b/src/shared/geom.pas
@@ -44,9 +44,13 @@ type
 // enter/exit coords will form non-intersecting configuration (i.e. will be before/after the actual collision)
 // but beware of floating point inexactness; `sweepAABB()` will try to (crudely) compensate for it
 // while calculating `hitx` and `hity`.
+{
 function sweepAABB (mex0, mey0, mew, meh: Integer; medx, medy: Integer; itx0, ity0, itw, ith: Integer;
                     u0: PSingle=nil; hitedge: PSweepEdge=nil; u1: PSingle=nil;
                     hitx: PInteger=nil; hity: PInteger=nil): Boolean;
+}
+function sweepAABB (mex0, mey0, mew, meh: Integer; medx, medy: Integer; itx0, ity0, itw, ith: Integer;
+                    out u0: Single): Boolean;
 
 function distanceSq (x0, y0, x1, y1: Integer): Integer; inline;
 
@@ -170,6 +174,7 @@ end;
 
 
 // ////////////////////////////////////////////////////////////////////////// //
+{
 function sweepAABB (mex0, mey0, mew, meh: Integer; medx, medy: Integer; itx0, ity0, itw, ith: Integer;
                     u0: PSingle=nil; hitedge: PSweepEdge=nil; u1: PSingle=nil;
                     hitx: PInteger=nil; hity: PInteger=nil): Boolean;
@@ -263,6 +268,69 @@ begin
     end;
   end;
 end;
+}
+
+function sweepAABB (mex0, mey0, mew, meh: Integer; medx, medy: Integer; itx0, ity0, itw, ith: Integer;
+                    out u0: Single): Boolean;
+var
+  tin, tout: Single;
+
+  function axisOverlap (me0, me1, it0, it1, d: Integer): Boolean; inline;
+    var t: Single;
+  begin
+    Result := false;
+
+    if me1 < it0 then
+    begin
+      if (d >= 0) then
+        exit; // oops, no hit
+      t := (me1 - it0 + 1) / d;
+      if t > tin then
+        tin := t;
+    end
+    else if it1 < me0 then
+    begin
+      if d <= 0 then
+        exit; // oops, no hit
+      t := (me0 - it1 - 1) / d;
+      if t > tin then
+        tin := t;
+    end;
+
+    if (d < 0) and (it1 > me0) then
+    begin
+      t := (me0 - it1 - 1) / d;
+      if t < tout then
+        tout := t;
+    end
+    else if (d > 0) and (me1 > it0) then
+    begin
+      t := (me1 - it0 + 1) / d;
+      if t < tout then
+        tout := t;
+    end;
+
+    result := true;
+  end;
+
+begin
+  Result := False;
+  u0 := -1;
+
+  if (mew >= 1) and (meh >= 1) and (itw >= 1) and (ith >= 1) and (medx <> 0) and (medy <> 0) then
+  begin
+    tin := -100000000.0;
+    tout := 100000000.0;
+    if axisOverlap(mex0, mex0 + mew - 1, itx0, itx0 + itw - 1, -medx) then
+    begin
+      if not axisOverlap(mey0, mey0 + meh - 1, ity0, ity0 + ith - 1, -medy) then
+      begin
+        u0 := tin;
+        Result := (tin <= tout) and (tin >= 0.0) and (tin <= 1.0);
+      end;
+    end;
+  end;
+end;
 
 
 end.
-- 
2.11.4.GIT