Work around float precision problems with scaled model-based bboxes

[xonotic/xonotic-data.pk3dir.git] / qcsrc / lib / vector.qh

diff --git a/qcsrc/lib/vector.qh b/qcsrc/lib/vector.qh
index 23bfdf05593ff178f4f31c35d4319d4985d6626a..d2d83ff6595dca5a2642017702112745527eef1c 100644 (file)
--- 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