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.

1 files changed, 60 insertions, 0 deletions

diff --git a/src/trace.h b/src/trace.h
new file mode 100644
index 0000000..82d2dac
--- /dev/null
+++ b/src/trace.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright © 2023 Willian Henrique <wsimanbrazil@yahoo.com.br>
+ *
+ * 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.
+ */
+
+#ifndef INC_TRACE_H
+#define INC_TRACE_H
+
+#include "intdefs.h"
+#include "engineapi.h"
+
+struct CBaseTrace {
+	struct vec3f startpos, endpos;
+	struct {
+		struct vec3f normal;
+		float dist;
+		u8 type, signbits;
+		//u8 pad[2];
+	} plane; // surface normal at impact
+	float frac;
+	int contents;
+	ushort dispflags;
+	bool allsolid, startsolid;
+};
+
+struct CGameTrace {
+	struct CBaseTrace base;
+	float fracleftsolid;
+	struct {
+		const char *name;
+		short surfprops;
+		ushort flags;
+	} surf;
+	int hitgroup;
+	short physbone;
+	ushort worldsurfidx; // not in every branch, but doesn't break ABI
+	void *ent; // CBaseEntity (C_BaseEntity in client.dll)
+	int hitbox;
+};
+
+struct CGameTrace trace_line(struct vec3f start, struct vec3f end, uint mask,
+		void *filt);
+
+struct CGameTrace trace_hull(struct vec3f start, struct vec3f end,
+		struct vec3f mins, struct vec3f maxs, uint mask, void *filt);
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80