Reintroduce autojump code

3 files changed, 155 insertions, 2 deletions

diff --git a/src/autojump.c b/src/autojump.c
new file mode 100644
index 0000000..fa0f4b5
--- /dev/null
+++ b/src/autojump.c
@@ -0,0 +1,124 @@
+/*
+ * Copyright © 2021 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 <stdbool.h>
+
+#include "con_.h"
+#include "factory.h"
+#include "gamedata.h"
+#include "intdefs.h"
+#include "hook.h"
+#include "mem.h"
+#include "os.h"
+#include "vcall.h"
+
+DEF_CVAR(sst_autojump, "Jump upon hitting the group while holding space", "0",
+		CON_REPLICATE | CON_DEMO | CON_HIDDEN)
+
+struct vec3f { float x, y, z; };
+struct CMoveData {
+	bool firstrun : 1;
+	bool gamecodemoved : 1;
+	ulong playerhandle;
+	int impulse;
+	struct vec3f viewangles;
+	struct vec3f absviewangles;
+	int buttons;
+	int oldbuttons;
+	float mv_forward;
+	float mv_side;
+	float mv_up;
+	float maxspeed;
+	float clientmaxspeed;
+	struct vec3f vel;
+	struct vec3f angles;
+	struct vec3f oldangles;
+	float out_stepheight;
+	struct vec3f out_wishvel;
+	struct vec3f out_jumpvel;
+	struct vec3f constraint_center;
+	float constraint_radius;
+	float constraint_width;
+	float constraint_speedfactor;
+	struct vec3f origin;
+};
+
+#define IN_JUMP 2
+#define NIDX 256 // *completely* arbitrary lol
+static bool justjumped[NIDX] = {0};
+static inline int handleidx(ulong h) { return h & (1 << 11) - 1; }
+
+static void *gmsv = 0, *gmcl = 0;
+typedef bool (VCALLCONV *CheckJumpButton_f)(void *);
+static CheckJumpButton_f origsv, origcl;
+
+static bool VCALLCONV hook(void *this) {
+	struct CMoveData **mvp = mem_offset(this, gamedata_off_mv), *mv = *mvp;
+	// use 0 idx for client side, as server indices start at 1
+	// FIXME: does this account for splitscreen???
+	int i = this == gmsv ? handleidx(mv->playerhandle) : 0;
+	if (con_getvari(sst_autojump) && !justjumped[i]) mv->oldbuttons &= ~IN_JUMP;
+	return justjumped[i] = (this == gmsv ? origsv : origcl)(this);
+}
+
+static bool unprot(void *gm) {
+	void **vtable = *(void ***)gm;
+	bool ret = os_mprot(vtable + gamedata_vtidx_CheckJumpButton,
+			sizeof(void *), PAGE_EXECUTE_READWRITE);
+	if (!ret) con_warn("autojump: couldn't make memory writeable\n");
+	return ret;
+}
+
+bool autojump_init(void) {
+	// TODO(featgen): auto-check these factories
+	if (!factory_client || !factory_server) {
+		con_warn("autojump: missing required interfaces\n");
+		return false;
+	}
+	if (!gamedata_has_vtidx_CheckJumpButton || !gamedata_has_off_mv) {
+		con_warn("autojump: missing gamedata entries for this engine\n");
+		return false;
+	}
+
+	gmsv = factory_server("GameMovement001", 0);
+	if (!gmsv) {
+		con_warn("autojump: couldn't get server-side game movement interface\n");
+		return false;
+	}
+	if (!unprot(gmsv)) return false;
+	gmcl = factory_client("GameMovement001", 0);
+	if (!gmcl) {
+		con_warn("autojump: couldn't get client-side game movement interface\n");
+		return false;
+	}
+	if (!unprot(gmcl)) return false;
+	origsv = (CheckJumpButton_f)hook_vtable(*(void ***)gmsv,
+			gamedata_vtidx_CheckJumpButton, (void *)&hook);
+	origcl = (CheckJumpButton_f)hook_vtable(*(void ***)gmcl,
+			gamedata_vtidx_CheckJumpButton, (void *)&hook);
+
+	sst_autojump->base.flags &= ~CON_HIDDEN;
+	return true;
+}
+
+void autojump_end(void) {
+	unhook_vtable(*(void ***)gmsv, gamedata_vtidx_CheckJumpButton,
+			(void *)origsv);
+	unhook_vtable(*(void ***)gmcl, gamedata_vtidx_CheckJumpButton,
+			(void *)origcl);
+}
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/autojump.h b/src/autojump.h
new file mode 100644
index 0000000..efcde2e
--- /dev/null
+++ b/src/autojump.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright © 2021 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.
+ */
+
+#ifndef INC_AUTOJUMP_H
+#define INC_AUTOJUMP_H
+
+#include <stdbool.h>
+
+bool autojump_init(void);
+void autojump_end(void);
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/sst.c b/src/sst.c
index d13ba5d..183a73a 100644
--- a/src/sst.c
+++ b/src/sst.c
@@ -17,6 +17,7 @@
 #include <stdbool.h>
 #include <string.h>
 
+#include "autojump.h"
 #include "con_.h"
 #include "demorec.h"
 #include "factory.h"
@@ -65,6 +66,7 @@ ifacefactory factory_client = 0, factory_server = 0, factory_engine = 0;
 // figures out the dependencies at build time and generates all the init glue
 // but we want to actually release the plugin this decade so for now I'm just
 // plonking ~~some bools~~ one bool here and worrying about it later. :^)
+static bool has_autojump = false;
 static bool has_demorec = false;
 
 // HACK: later versions of L4D2 show an annoying dialog on every plugin_load.
@@ -122,7 +124,7 @@ static bool do_load(ifacefactory enginef, ifacefactory serverf) {
 	}
 
 nc:	gamedata_init();
-	// TODO(autojump): we'd init that here
+	has_autojump = autojump_init();
 	has_demorec = demorec_init();
 	fixes_apply();
 
@@ -164,7 +166,7 @@ e:	con_colourmsg(RGBA(64, 255, 64, 255),
 }
 
 static void do_unload(void) {
-	// TODO(autojump): we'd end that here
+	if (has_autojump) autojump_end();
 	if (has_demorec) demorec_end();
 
 #ifdef __linux__