Add basic Portal crosshair colour customisation

Currently only works in 3420 and 5135 and uses hardcoded offsets with a
byte pattern sanity check. Future work includes making it more widely
compatible, and also doing the crazy thing I wanted to do but gave up on
wherein the actual textures and stuff get patched in memory to sync up
all the colours.

Oh also, a couple of vtables were erroneously made executable, so I went
ahead and fixed that while I was at it.

1 files changed, 147 insertions, 0 deletions

diff --git a/src/portalcolours.c b/src/portalcolours.c
new file mode 100644
index 0000000..6030bb8
--- /dev/null
+++ b/src/portalcolours.c
@@ -0,0 +1,147 @@
+/*
+ * Copyright © 2022 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 <string.h>
+
+#include "con_.h"
+#include "engineapi.h"
+#include "extmalloc.h"
+#include "gametype.h"
+#include "hook.h"
+#include "intdefs.h"
+#include "mem.h"
+#include "os.h"
+#include "ppmagic.h"
+#include "vcall.h"
+
+// It's like the thing Portal Tools does, but at runtime!
+
+DEF_CVAR(sst_portal_colour0, "Crosshair colour for gravity beam (hex)",
+		"F2CAA7", CON_ARCHIVE | CON_HIDDEN)
+DEF_CVAR(sst_portal_colour1, "Crosshair colour for left portal (hex)",
+		"40A0FF", CON_ARCHIVE | CON_HIDDEN)
+DEF_CVAR(sst_portal_colour2, "Crosshair colour for right portal (hex)",
+		"FFA020", CON_ARCHIVE | CON_HIDDEN)
+// XXX: bit weird that this is still con_colour. should we move it back out to
+// engineapi as a general colour struct??
+static struct con_colour colours[3] = {
+		{242, 202, 167, 255}, {64, 160, 255, 255}, {255, 160, 32, 255}};
+
+static void hexparse(uchar out[static 4], const char *s) {
+	const char *p = s;
+	for (uchar *q = out; q - out < 3; ++q) {
+		if (*p >= '0' && *p <= '9') {
+			*q = *p++ - '0' << 4;
+		}
+		else if ((*p | 32) >= 'a' && (*p | 32) <= 'f') {
+			*q = 10 + (*p++ | 32) - 'a' << 4;
+		}
+		else {
+			// screw it, just fall back on white, I guess.
+			// note: this also handles *p == '\0' so we don't overrun the string
+			memset(out, 255, 4); // write 4 rather than 3, prolly faster?
+			return;
+		}
+		// repetitive unrolled nonsense
+		if (*p >= '0' && *p <= '9') {
+			*q |= *p++ - '0';
+		}
+		else if ((*p | 32) >= 'a' && (*p | 32) <= 'f') {
+			*q |= 10 + (*p++ | 32) - 'a';
+		}
+		else {
+			memset(out, 255, 4);
+			return;
+		}
+	}
+	//out[3] = 255; // never changes!
+}
+
+static void colourcb(struct con_var *v) {
+	// this is stupid and ugly and has no friends, too bad!
+	if (v == sst_portal_colour0) {
+		hexparse(colours[0].bytes, con_getvarstr(v));
+	}
+	else if (v == sst_portal_colour1) {
+		hexparse(colours[1].bytes, con_getvarstr(v));
+	}
+	else /* sst_portal_colour2 */ {
+		hexparse(colours[2].bytes, con_getvarstr(v));
+	}
+}
+
+// Original sig is the following but we wanna avoid calling convention weirdness
+//typedef struct con_colour (*UTIL_Portal_Color_func)(int);
+typedef void (*UTIL_Portal_Color_func)(struct con_colour *out, int portal);
+static UTIL_Portal_Color_func orig_UTIL_Portal_Color;
+static void hook_UTIL_Portal_Color(struct con_colour *out, int portal) {
+	if (portal < 0 || portal > 2) *out = (struct con_colour){255, 255, 255, 255};
+	else *out = colours[portal];
+}
+
+// TODO(compat): would like to do the usual pointer-chasing business instead of
+// using hardcoded offsets, but that's pretty hard here. Would probably have to
+// do the entprops stuff for ClientClass, get at the portalgun factory, get a
+// vtable, find ViewModelDrawn or something, chase through another 4 or 5 call
+// offsets to find something that calls UTIL_Portal_Color... that or dig through
+// vgui/hud entries, find the crosshair drawing...
+//
+// For now we do this!
+
+static bool find_UTIL_Portal_Color(void *base) {
+	static const uchar x[] = HEXBYTES(8B, 44, 24, 08, 83, E8, 00, 74, 37, 83,
+			E8, 01, B1, FF, 74, 1E, 83, E8, 01, 8B, 44, 24, 04, 88);
+	// 5135
+	orig_UTIL_Portal_Color = (UTIL_Portal_Color_func)mem_offset(base, 0x1BF090);
+	if (!memcmp((void *)orig_UTIL_Portal_Color, x, sizeof(x))) return true;
+	// 3420
+	orig_UTIL_Portal_Color = (UTIL_Portal_Color_func)mem_offset(base, 0x1AA810);
+	if (!memcmp((void *)orig_UTIL_Portal_Color, x, sizeof(x))) return true;
+	return false;
+}
+
+bool portalcolours_init(void *clientlib) { // ... should libs be globals?
+	if (!GAMETYPE_MATCHES(Portal)) return false;
+#ifdef _WIN32
+	if (!find_UTIL_Portal_Color(clientlib)) {
+		con_warn("portalcolours: error: couldn't find UTIL_Portal_Color\n");
+		return false;
+	}
+	orig_UTIL_Portal_Color = (UTIL_Portal_Color_func)hook_inline(
+			(void *)orig_UTIL_Portal_Color, (void *)&hook_UTIL_Portal_Color);
+	if (!orig_UTIL_Portal_Color) {
+		con_warn("portalcolours: error: couldn't hook UTIL_Portal_Color\n");
+		return false;
+	}
+	sst_portal_colour0->base.flags &= ~CON_HIDDEN;
+	sst_portal_colour0->cb = &colourcb;
+	sst_portal_colour1->base.flags &= ~CON_HIDDEN;
+	sst_portal_colour1->cb = &colourcb;
+	sst_portal_colour2->base.flags &= ~CON_HIDDEN;
+	sst_portal_colour2->cb = &colourcb;
+	return true;
+#else
+#warning TODO(linux): yet more stuff!
+	return false;
+#endif
+}
+
+void portalcolours_end(void) {
+	unhook_inline((void *)orig_UTIL_Portal_Color);
+}
+
+// vi: sw=4 ts=4 noet tw=80 cc=80