Add VGUI HUD overlay drawing feature

Currently only supports Orange Box and Left 4 Dead branches. There's
quite a large amount of gamedata involved in making this work, and
figuring it out for the likes of Portal 2 doesn't seem like a major
priority at the moment.

2 files changed, 266 insertions, 0 deletions

diff --git a/src/hud.c b/src/hud.c
new file mode 100644
index 0000000..8176d63
--- /dev/null
+++ b/src/hud.c
@@ -0,0 +1,194 @@
+/*
+ * Copyright © 2022 Matthew Wozniak <sirtomato999@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 "event.h"
+#include "feature.h"
+#include "gamedata.h"
+#include "gametype.h"
+#include "hook.h"
+#include "hud.h"
+#include "intdefs.h"
+#include "mem.h"
+#include "os.h"
+#include "sst.h"
+#include "vcall.h"
+#include "x86.h"
+#include "x86util.h"
+
+FEATURE()
+REQUIRE_GLOBAL(factory_engine)
+REQUIRE_GLOBAL(vgui)
+// ISurface
+REQUIRE_GAMEDATA(vtidx_DrawSetColor)
+REQUIRE_GAMEDATA(vtidx_DrawFilledRect)
+REQUIRE_GAMEDATA(vtidx_DrawOutlinedRect)
+REQUIRE_GAMEDATA(vtidx_DrawLine)
+REQUIRE_GAMEDATA(vtidx_DrawPolyLine)
+REQUIRE_GAMEDATA(vtidx_DrawSetTextFont)
+REQUIRE_GAMEDATA(vtidx_DrawSetTextColor)
+REQUIRE_GAMEDATA(vtidx_DrawSetTextPos)
+REQUIRE_GAMEDATA(vtidx_DrawPrintText)
+REQUIRE_GAMEDATA(vtidx_GetScreenSize)
+REQUIRE_GAMEDATA(vtidx_GetFontTall)
+REQUIRE_GAMEDATA(vtidx_GetCharacterWidth)
+// CEngineVGui
+REQUIRE_GAMEDATA(vtidx_GetPanel)
+// vgui::Panel
+REQUIRE_GAMEDATA(vtidx_SetPaintEnabled)
+REQUIRE_GAMEDATA(vtidx_Paint)
+// ISchemeManager
+REQUIRE_GAMEDATA(vtidx_GetIScheme)
+// IScheme
+REQUIRE_GAMEDATA(vtidx_GetFont)
+
+DEF_EVENT(HudPaint, void)
+
+// we just use ulongs for API, but keep a struct for vcalls to ensure we get the
+// right calling convention (x86 Windows/MSVC is funny about passing structs...)
+struct handlewrap { ulong x; };
+
+// CEngineVGui
+DECL_VFUNC_DYN(unsigned int, GetPanel, int)
+
+// vgui::ISchemeManager
+DECL_VFUNC_DYN(void *, GetIScheme, struct handlewrap)
+// vgui::IScheme
+DECL_VFUNC_DYN(struct handlewrap, GetFont, const char *, bool)
+
+// vgui::ISurface
+DECL_VFUNC_DYN(void, DrawSetColor, struct rgba)
+DECL_VFUNC_DYN(void, DrawFilledRect, int, int, int, int)
+DECL_VFUNC_DYN(void, DrawOutlinedRect, int, int, int, int)
+DECL_VFUNC_DYN(void, DrawLine, int, int, int, int)
+DECL_VFUNC_DYN(void, DrawPolyLine, int *, int *, int)
+DECL_VFUNC_DYN(void, DrawSetTextFont, struct handlewrap)
+DECL_VFUNC_DYN(void, DrawSetTextColor, struct rgba)
+DECL_VFUNC_DYN(void, DrawSetTextPos, int, int)
+DECL_VFUNC_DYN(void, DrawPrintText, ushort *, int, int)
+DECL_VFUNC_DYN(void, GetScreenSize, int *, int *)
+DECL_VFUNC_DYN(int, GetFontTall, struct handlewrap)
+DECL_VFUNC_DYN(int, GetCharacterWidth, struct handlewrap, int)
+
+// vgui::Panel
+DECL_VFUNC_DYN(void, SetPaintEnabled, bool)
+
+static void *matsurf, *toolspanel, *scheme;
+
+typedef void (*VCALLCONV Paint_func)(void *);
+static Paint_func orig_Paint;
+void VCALLCONV hook_Paint(void *this) {
+	if (this == toolspanel) EMIT_HudPaint();
+	orig_Paint(this);
+}
+
+ulong hud_getfont(const char *name, bool proportional) {
+	return GetFont(scheme, name, proportional).x;
+}
+
+void hud_drawrect(int x0, int y0, int x1, int y1, struct rgba colour,
+		bool fill) {
+	DrawSetColor(matsurf, colour);
+	if (fill) DrawFilledRect(matsurf, x0, y0, x1, y1);
+	else DrawOutlinedRect(matsurf, x0, y0, x1, y1);
+}
+
+void hud_drawline(int x0, int y0, int x1, int y1, struct rgba colour) {
+	DrawSetColor(matsurf, colour);
+	DrawLine(matsurf, x0, y0, x1, y1);
+}
+
+void hud_drawpolyline(int *x, int *y, int npoints, struct rgba colour) {
+	DrawSetColor(matsurf, colour);
+	DrawPolyLine(matsurf, x, y, npoints);
+}
+
+void hud_drawtext(ulong font, int x, int y, struct rgba colour, ushort *str,
+		int len) {
+	DrawSetTextFont(matsurf, (struct handlewrap){font});
+	DrawSetTextPos(matsurf, x, y);
+	DrawSetTextColor(matsurf, colour);
+	DrawPrintText(matsurf, str, len, /*FONT_DRAW_DEFAULT*/ 0);
+}
+
+void hud_screensize(int *width, int *height) {
+	GetScreenSize(matsurf, width, height);
+}
+
+int hud_fontheight(ulong font) {
+	return GetFontTall(matsurf, (struct handlewrap){font});
+}
+
+int hud_charwidth(ulong font, int ch) {
+	return GetCharacterWidth(matsurf, (struct handlewrap){font}, ch);
+}
+
+static bool find_toolspanel(void *enginevgui) {
+	const uchar *insns = (const uchar *)VFUNC(enginevgui, GetPanel);
+	for (const uchar *p = insns; p - insns < 16;) {
+		// first CALL instruction in GetPanel calls GetRootPanel, which gives a
+		// pointer to the specified panel
+		if (p[0] == X86_CALL) {
+			typedef void *(*VCALLCONV GetRootPanel_func)(void *this, int);
+			int off = mem_load32(p + 1);
+			GetRootPanel_func GetRootPanel = (GetRootPanel_func)(p + 5 + off);
+			toolspanel = GetRootPanel(enginevgui, /*PANEL_TOOLS*/ 3);
+			return true;
+		}
+		NEXT_INSN(p, "GetRootPanel function");
+	}
+	return false;
+}
+
+INIT {
+	matsurf = factory_engine("MatSystemSurface006", 0);
+	if (!matsurf) {
+		errmsg_errorx("couldn't get MatSystemSurface006 interface");
+		return false;
+	}
+	void *schememgr = factory_engine("VGUI_Scheme010", 0);
+	if (!schememgr) {
+		errmsg_errorx("couldn't get VGUI_Scheme010 interface");
+		return false;
+	}
+	if (!find_toolspanel(vgui)) {
+		errmsg_errorx("couldn't find engine tools panel");
+		return false;
+	}
+	void **vtable = *(void ***)toolspanel;
+	if (!os_mprot(vtable + vtidx_Paint, sizeof(void *),
+			PAGE_READWRITE)) {
+		errmsg_errorsys("couldn't make virtual table writable");
+		return false;
+	}
+	orig_Paint = (Paint_func)hook_vtable(vtable, vtidx_Paint,
+			(void *)&hook_Paint);
+	SetPaintEnabled(toolspanel, true);
+	// 1 is the default, first loaded scheme. should always be sourcescheme.res
+	scheme = GetIScheme(schememgr, (struct handlewrap){1});
+	return true;
+}
+
+END {
+	// don't unhook toolspanel if exiting, it's already long gone!
+	if (sst_userunloaded) {
+		unhook_vtable(*(void ***)toolspanel, vtidx_Paint, (void *)orig_Paint);
+		SetPaintEnabled(toolspanel, false);
+	}
+}
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/hud.h b/src/hud.h
new file mode 100644
index 0000000..8ea0877
--- /dev/null
+++ b/src/hud.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright © 2022 Matthew Wozniak <sirtomato999@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_HUD_H
+#define INC_HUD_H
+
+#include "event.h"
+#include "engineapi.h"
+#include "intdefs.h"
+
+/*
+ * Emitted when the game HUD is being drawn. Allows features to draw their own
+ * additional overlays atop the game's standard HUD.
+ */
+DECL_EVENT(HudPaint, void)
+
+/* Font style flags */
+#define HUD_FONT_ITALIC 1
+#define HUD_FONT_UNDERLINE 2
+#define HUD_FONT_STRIKE 4
+#define HUD_FONT_SYMBOL 8
+#define HUD_FONT_AA 16
+#define HUD_FONT_GAUSSBLUR 32
+#define HUD_FONT_ROTARY 64
+#define HUD_FONT_DROPSHADOW 128
+#define HUD_FONT_ADDITIVE 256
+#define HUD_FONT_OUTLINE 512
+#define HUD_FONT_CUSTOM 1024
+#define HUD_FONT_BITMAP 2048
+
+/* Gets a font handle by its name in sourcescheme.res. */
+ulong hud_getfont(const char *name, bool proportional);
+
+/* Sets the drawing pen colour for subsequent HUD drawing calls (below). */
+void hud_setcolour(struct rgba colour);
+
+/* Draws a rectangle on top of the HUD. */
+void hud_drawrect(int x0, int y0, int x1, int y1, struct rgba colour, bool fill);
+
+/* Draws a line on top of the HUD. */
+void hud_drawline(int x0, int y0, int x1, int y1, struct rgba colour);
+
+/* Draws an arbitrary series of lines between an array of points. */
+void hud_drawpolyline(int *xs, int *ys, int npoints, struct rgba colour);
+
+/* Draws text using a given font handle. */
+void hud_drawtext(ulong font, int x, int y, struct rgba colour, ushort *str,
+		int len);
+
+/* Returns the width and height of the game window in pixels. */
+void hud_screensize(int *width, int *height);
+
+/* Returns the height of a font, in pixels. */
+int hud_fontheight(ulong font);
+
+/* Returns the width of a font character, in pixels. */
+int hud_getcharwidth(ulong font, int ch);
+
+#endif