From 455c8b09aaba197476d420e4442f2a5313638259 Mon Sep 17 00:00:00 2001
From: Willian Henrique <wsimanbrazil@yahoo.com.br>
Date: Tue, 27 Aug 2024 16:53:27 +0100
Subject: Add basic server-side tracing functionality

Restricted to L4D for now due to known ABI compatibility issues on other
branches. This should be easy to fix later when needed elsewhere.

Committer's note: I've counted myself as a joint author and added a
copyright notice to the .c file since this code is reasonably
modified from the code bill originally wrote last year.
but June of this year and , so I've gone ahead and
corrected his copyright notice too, with permission.
---
 src/trace.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 src/trace.c

(limited to 'src/trace.c')

diff --git a/src/trace.c b/src/trace.c
new file mode 100644
index 0000000..0a301a7
--- /dev/null
+++ b/src/trace.c
@@ -0,0 +1,101 @@
+/*
+ * Copyright © 2023 Willian Henrique <wsimanbrazil@yahoo.com.br>
+ * Copyright © 2024 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "engineapi.h"
+#include "errmsg.h"
+#include "feature.h"
+#include "gametype.h"
+#include "intdefs.h"
+#include "trace.h"
+
+FEATURE()
+
+struct ray {
+	// these have type VectorAligned in the engine, which occupies 16 bytes
+	struct vec3f _Alignas(16) start, delta, startoff, extents;
+	// align to 16 since "extents" is supposed to occupy 16 bytes.
+    // TODO(compat): this member isn't in every engine branch
+	const float _Alignas(16) (*worldaxistransform)[3][4];
+	bool isray, isswept;
+};
+
+static void *srvtrace;
+
+DECL_VFUNC(void, TraceRay, 5, struct ray *, uint /*mask*/, void */*filter*/,
+		struct CGameTrace *)
+
+static inline bool nonzero(struct vec3f v) {
+	union { struct vec3f v; struct { unsigned int x, y, z; }; } u = {v};
+	return (u.x | u.y | u.z) << 1 != 0; // ignore sign bit
+}
+
+struct CGameTrace trace_line(struct vec3f start, struct vec3f end, uint mask,
+		void *filt) {
+	struct CGameTrace t;
+	struct vec3f delta = {end.x - start.x, end.y - start.y, end.z - start.z};
+	struct ray r = {
+		.isray = true,
+		.isswept = nonzero(delta),
+		.start = start,
+		.delta = delta
+	};
+	TraceRay(srvtrace, &r, mask, filt, &t);
+	return t;
+}
+
+struct CGameTrace trace_hull(struct vec3f start, struct vec3f end,
+		struct vec3f mins, struct vec3f maxs, uint mask, void *filt) {
+	struct CGameTrace t;
+	struct vec3f delta = {end.x - start.x, end.y - start.y, end.z - start.z};
+	struct vec3f extents = {
+		(maxs.x - mins.x) * 0.5f,
+		(maxs.y - mins.y) * 0.5f,
+		(maxs.z - mins.z) * 0.5f
+	};
+	struct ray r = {
+		// NOTE: could maybe hardcode this to false, but we copy engine logic
+		// just on the off chance we're tracing some insanely thin hull
+		.isray = (extents.x * extents.x + r.extents.y * r.extents.y +
+				extents.z * extents.z) < 1e-6,
+		.isswept = nonzero(delta),
+		.start = start,
+		.delta = delta,
+		.extents = extents,
+		.startoff = {
+			(mins.x + maxs.x) * -0.5f,
+			(mins.y + maxs.y) * -0.5f,
+			(mins.z + maxs.z) * -0.5f
+		}
+	};
+	TraceRay(srvtrace, &r, mask, filt, &t);
+	return t;
+}
+
+PREINIT {
+    // TODO(compat): restricting this to tested branches for now
+    return GAMETYPE_MATCHES(L4D);
+}
+
+INIT {
+    if (!(srvtrace = factory_engine("EngineTraceServer003", 0))) {
+		errmsg_errorx("couldn't get server-side tracing interface");
+		return false;
+	}
+    return true;
+}
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
-- 
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