From: bones_was_here <bones_was_here@xonotic.au>
Date: Sun, 2 Oct 2022 22:05:54 +0000 (+1000)
Subject: Work around float precision problems with scaled model-based bboxes
X-Git-Tag: xonotic-v0.8.6~290^2
X-Git-Url: https://git.rm.cloudns.org/?a=commitdiff_plain;h=73a168a2cc80f8c36602f0558f71fe93fc89e849;p=xonotic%2Fxonotic-data.pk3dir.git

Work around float precision problems with scaled model-based bboxes

Fixes #2742
---

diff --git a/qcsrc/common/mapobjects/subs.qc b/qcsrc/common/mapobjects/subs.qc
index c0b137404..afe3f9399 100644
--- a/qcsrc/common/mapobjects/subs.qc
+++ b/qcsrc/common/mapobjects/subs.qc
@@ -396,7 +396,7 @@ void ApplyMinMaxScaleAngles(entity e)
 		e.mins_y = -e.maxs.x;
 	}
 	if(e.scale)
-		setsize(e, e.mins * e.scale, e.maxs * e.scale);
+		setsize(e, RoundPerfectVector(e.mins * e.scale), RoundPerfectVector(e.maxs * e.scale));
 	else
 		setsize(e, e.mins, e.maxs);
 }
diff --git a/qcsrc/common/monsters/sv_monsters.qc b/qcsrc/common/monsters/sv_monsters.qc
index fc1681a91..e88b35f45 100644
--- a/qcsrc/common/monsters/sv_monsters.qc
+++ b/qcsrc/common/monsters/sv_monsters.qc
@@ -1428,7 +1428,7 @@ bool Monster_Spawn(entity this, bool check_appear, Monster mon)
 	if((mon.spawnflags & MONSTER_SIZE_QUAKE) && autocvar_g_monsters_quake_resize && !(this.spawnflags & MONSTERFLAG_RESPAWNED))
 		this.scale *= 1.3;
 
-	setsize(this, mon.m_mins * this.scale, mon.m_maxs * this.scale);
+	setsize(this, RoundPerfectVector(mon.m_mins * this.scale), RoundPerfectVector(mon.m_maxs * this.scale));
 	this.view_ofs			= '0 0 0.7' * (this.maxs_z * 0.5);
 
 	this.ticrate = bound(sys_frametime, ((!this.ticrate) ? autocvar_g_monsters_think_delay : this.ticrate), 60);
diff --git a/qcsrc/common/mutators/mutator/sandbox/sv_sandbox.qc b/qcsrc/common/mutators/mutator/sandbox/sv_sandbox.qc
index 7188ae329..f3bf39f73 100644
--- a/qcsrc/common/mutators/mutator/sandbox/sv_sandbox.qc
+++ b/qcsrc/common/mutators/mutator/sandbox/sv_sandbox.qc
@@ -122,7 +122,8 @@ void sandbox_ObjectEdit_Scale(entity e, float f)
 	{
 		e.scale = bound(autocvar_g_sandbox_object_scale_min, e.scale, autocvar_g_sandbox_object_scale_max);
 		_setmodel(e, e.model); // reset mins and maxs based on mesh
-		setsize(e, e.mins * e.scale, e.maxs * e.scale); // adapt bounding box size to model size
+		// apply object scaling and prevent any float precision issues like #2742
+		setsize(e, RoundPerfectVector(e.mins * e.scale), RoundPerfectVector(e.maxs * e.scale));
 	}
 }
 
diff --git a/qcsrc/lib/vector.qh b/qcsrc/lib/vector.qh
index 23bfdf055..d2d83ff65 100644
--- a/qcsrc/lib/vector.qh
+++ b/qcsrc/lib/vector.qh
@@ -196,4 +196,17 @@ vector NearestPointOnBoundingBox(vector mi, vector ma, vector org)
 		bound(mi.z, org.z, ma.z)
 	);
 }
+
+// bones_was_here: rounding bbox to nearest perfect floats prevents obscure collision bugs like #2742
+// FIXME: QC shouldn't need to work around tracebox potentially returning a tiny trace_fraction when the move should have been blocked.
+// Tiny values are valid in some situations and can't simply be ignored.
+#define PFLOAT (1/1024) // 1/32 1/64 etc also work
+#define RPFLOAT(a) (a=rint(a/PFLOAT)*PFLOAT)
+ERASEABLE
+vector RoundPerfectVector(vector v)
+{
+	RPFLOAT(v.x); RPFLOAT(v.y); RPFLOAT(v.z);
+	return v;
+}
+
 #endif