Patch #1121337 (CGA rendering in early LEC titles).

Differences against patch:
  o Updated documentation
  o Fixed text colors
  o Implemented Hercules dithering

Ditherers are based on loom ega and monkey ega, so for zak and mm they're
wrong, i.e. these games look better than with original ditherers.

TODO:
  Proper ditherers for zak & MM
  EGA ditherers for VGA SCUMM v5 games

svn-id: r16816

18 files changed, 333 insertions, 10 deletions

diff --git a/NEWS b/NEWS
index 428b806165..0cb4b231e8 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,7 @@ For a more comprehensive changelog for the latest experimental CVS code, see:
  SCUMM
    - Added support for Mac Humongous Entertainment titles
    - Added support for multiple filenames/versions using a single target
+   - Implemeted CGA and Hercules render modes in early LEC titles
 
  <PORT #1 NEWS>
    - ...
diff --git a/README b/README
index 652672a471..91f5832ebb 100644
--- a/README
+++ b/README
@@ -364,6 +364,7 @@ arguments - see the next section.
   --native-mt32            True Roland MT-32 (disable GM emulation)
   --output-rate=RATE       Select output sample rate in Hz (e.g. 22050)
   --aspect-ratio           Enable aspect ratio correction
+  --render-mode=MODE       Enable additional render modes (cga, ega, hercules)
 
   --alt-intro              Use alternative intro for CD versions of Beneath a
                            Steel Sky and Flight of the Amazon Queen
diff --git a/base/gameDetector.cpp b/base/gameDetector.cpp
index 44e823ef65..cd3b599460 100644
--- a/base/gameDetector.cpp
+++ b/base/gameDetector.cpp
@@ -96,6 +96,7 @@ static const char USAGE_STRING[] =
 	"  --native-mt32            True Roland MT-32 (disable GM emulation)\n"
 	"  --output-rate=RATE       Select output sample rate in Hz (e.g. 22050)\n"
 	"  --aspect-ratio           Enable aspect ratio correction\n"
+	"  --render-mode=MODE       Enable additional render modes (cga, ega, hercules)\n"
 	"\n"
 #if !defined(DISABLE_SKY) || !defined(DISABLE_QUEEN)
 	"  --alt-intro              Use alternative intro for CD versions of Beneath a\n"
@@ -122,6 +123,7 @@ GameDetector::GameDetector() {
 	ConfMan.registerDefault("fullscreen", false);
 	ConfMan.registerDefault("aspect_ratio", false);
 	ConfMan.registerDefault("gfx_mode", "normal");
+	ConfMan.registerDefault("render_mode", "default");
 
 	// Sound & Music
 	ConfMan.registerDefault("music_volume", 192);
@@ -478,6 +480,14 @@ void GameDetector::parseCommandLine(int argc, char **argv) {
 				ConfMan.set("aspect_ratio", cmdValue, kTransientDomain);
 			END_OPTION
 
+			DO_LONG_OPTION("render-mode")
+				int renderMode = Common::parseRenderMode(option);
+				if (renderMode == Common::kRenderDefault)
+					goto ShowHelpAndExit;
+
+				ConfMan.set("render_mode", option, kTransientDomain);
+			END_OPTION
+
 			DO_LONG_OPTION("savepath")
 				// TODO: Verify whether the path is valid
 				ConfMan.set("savepath", option, kTransientDomain);
diff --git a/common/util.cpp b/common/util.cpp
index eb63e16a68..f4d5c91779 100644
--- a/common/util.cpp
+++ b/common/util.cpp
@@ -219,5 +219,47 @@ const char *getPlatformDescription(Platform id) {
 }
 
 
+#pragma mark -
+
+
+const RenderModeDescription g_renderModes[] = {
+	{"hercules", "Hercules", kRenderHerc},
+	{"cga", "CGA", kRenderCGA},
+	{"ega", "EGA", kRenderEGA},
+	{0, 0, kRenderDefault}
+};
+
+RenderMode parseRenderMode(const String &str) {
+	if (str.isEmpty())
+		return kRenderDefault;
+
+	const char *s = str.c_str();
+	const RenderModeDescription *l = g_renderModes;
+	for (; l->code; ++l) {
+		if (!scumm_stricmp(l->code, s))
+			return l->id;
+	}
+
+	return kRenderDefault;
+}
+
+const char *getRenderModeCode(RenderMode id) {
+	const RenderModeDescription *l = g_renderModes;
+	for (; l->code; ++l) {
+		if (l->id == id)
+			return l->code;
+	}
+	return 0;
+}
+
+const char *getRenderModeDescription(RenderMode id) {
+	const RenderModeDescription *l = g_renderModes;
+	for (; l->code; ++l) {
+		if (l->id == id)
+			return l->description;
+	}
+	return 0;
+}
+
 
 }	// End of namespace Common
diff --git a/common/util.h b/common/util.h
index 8813fc9d8b..173f2bf835 100644
--- a/common/util.h
+++ b/common/util.h
@@ -147,12 +147,42 @@ struct PlatformDescription {
 
 extern const PlatformDescription g_platforms[];
 
-
 /** Convert a string containing a platform name into a Platform enum value. */
 extern Platform parsePlatform(const String &str);
 extern const char *getPlatformCode(Platform id);
 extern const char *getPlatformDescription(Platform id);
 
+/** 
+ * List of render modes. It specifies which original graphics mode
+ * to use. Some targets used postprocessing dithering routines for
+ * reducing color depth of final image which let it to be rendered on
+ * such low-level adapters as CGA or Hercules.
+ */
+enum RenderMode {
+	kRenderDefault = -1,
+	kRenderEGA = 1,
+	kRenderCGA = 2,
+	kRenderHerc = 3
+};
+
+enum HerculesDimesnions {
+	kHercW = 720,
+	kHercH = 350
+};
+
+struct RenderModeDescription {
+	const char *code;
+	const char *description;
+	Common::RenderMode id;
+};
+
+extern const RenderModeDescription g_renderModes[];
+
+/** Convert a string containing a render mode name into a RenderingMode enum value. */
+extern RenderMode parseRenderMode(const String &str);
+extern const char *getRenderModeCode(RenderMode id);
+extern const char *getRenderModeDescription(RenderMode id);
+
 }	// End of namespace Common
 
 
diff --git a/doc/05_01.tex b/doc/05_01.tex
index ca15fa915f..93bb87a7d4 100644
--- a/doc/05_01.tex
+++ b/doc/05_01.tex
@@ -39,6 +39,7 @@ Usage: scummvm [OPTIONS]... [GAME]\\
   --native-mt32           &True Roland MT-32 (disable GM emulation)\\
   --output-rate=RATE      &Select output sample rate in Hz (e.g. 22050)\\
   --aspect-ratio          &Enable aspect ratio correction\\
+  --render-mode=MODE      &Enable additional render modes (cga, ega, hercules)\\
 \\
   --alt-intro             &Use alternative intro for CD versions of Beneath a\\
                           &Steel Sky and Flight of the Amazon Queen\\
diff --git a/gui/options.cpp b/gui/options.cpp
index da2fc3c084..41dbcae9ea 100644
--- a/gui/options.cpp
+++ b/gui/options.cpp
@@ -75,7 +75,7 @@ OptionsDialog::OptionsDialog(const String &domain, int x, int y, int w, int h)
 	: Dialog(x, y, w, h),
 	_domain(domain),
 	_enableGraphicSettings(false),
-	_gfxPopUp(0), _fullscreenCheckbox(0), _aspectCheckbox(0),
+	_gfxPopUp(0), _renderModePopUp(0), _fullscreenCheckbox(0), _aspectCheckbox(0),
 	_enableAudioSettings(false),
 	_multiMidiCheckbox(0), _mt32Checkbox(0), _subCheckbox(0),
 	_enableVolumeSettings(false),
@@ -108,6 +108,19 @@ void OptionsDialog::open() {
 			}
 		}
 
+		_renderModePopUp->setSelected(0);
+
+		if (ConfMan.hasKey("render_mode", _domain)) {
+			const Common::RenderModeDescription *p = Common::g_renderModes;
+			const Common::RenderMode renderMode = Common::parseRenderMode(ConfMan.get("render_mode", _domain));
+			int sel = 0;
+			for (int i = 0; p->code; ++p, ++i) {
+				if (renderMode == p->id)
+					sel = i + 2;
+			}
+			_renderModePopUp->setSelected(sel);
+		}
+
 #ifndef _WIN32_WCE
 		// Fullscreen setting
 		_fullscreenCheckbox->setState(ConfMan.getBool("fullscreen", _domain));
@@ -167,10 +180,14 @@ void OptionsDialog::close() {
 
 				if ((int32)_gfxPopUp->getSelectedTag() >= 0)
 					ConfMan.set("gfx_mode", _gfxPopUp->getSelectedString(), _domain);
+
+				if ((int32)_renderModePopUp->getSelectedTag() >= 0)
+					ConfMan.set("render_mode", _renderModePopUp->getSelectedString(), _domain);
 			} else {
 				ConfMan.removeKey("fullscreen", _domain);
 				ConfMan.removeKey("aspect_ratio", _domain);
 				ConfMan.removeKey("gfx_mode", _domain);
+				ConfMan.removeKey("render_mode", _domain);
 			}
 		}
 
@@ -240,6 +257,7 @@ void OptionsDialog::setGraphicSettingsState(bool enabled) {
 	_enableGraphicSettings = enabled;
 
 	_gfxPopUp->setEnabled(enabled);
+	_renderModePopUp->setEnabled(enabled);
 #ifndef _WIN32_WCE
 	_fullscreenCheckbox->setEnabled(enabled);
 	_aspectCheckbox->setEnabled(enabled);
@@ -282,6 +300,16 @@ int OptionsDialog::addGraphicControls(GuiObject *boss, int yoffset) {
 		gm++;
 	}
 
+	// RenderMode popup
+	_renderModePopUp = new PopUpWidget(boss, x-5, yoffset, w+5, kLineHeight, "Render mode: ", 100);
+	yoffset += 16;
+	_renderModePopUp->appendEntry("<default>");
+	_renderModePopUp->appendEntry("");
+	const Common::RenderModeDescription *rm = Common::g_renderModes;
+	for (; rm->code; ++rm) {
+		_renderModePopUp->appendEntry(rm->description, rm->id);
+	}
+
 	// Fullscreen checkbox
 	_fullscreenCheckbox = new CheckboxWidget(boss, x, yoffset, w, 16, "Fullscreen mode");
 	yoffset += 16;
diff --git a/gui/options.h b/gui/options.h
index 5b2e34ccea..497e216ed5 100644
--- a/gui/options.h
+++ b/gui/options.h
@@ -71,6 +71,7 @@ private:
 	PopUpWidget *_gfxPopUp;
 	CheckboxWidget *_fullscreenCheckbox;
 	CheckboxWidget *_aspectCheckbox;
+	PopUpWidget *_renderModePopUp;
 
 	//
 	// Audio controls
diff --git a/scumm/actor.cpp b/scumm/actor.cpp
index 316a3a116d..95b43a5d31 100644
--- a/scumm/actor.cpp
+++ b/scumm/actor.cpp
@@ -1400,6 +1400,12 @@ void Actor::setActorCostume(int c) {
 	} else if (_vm->_features & GF_OLD_BUNDLE) {
 		for (i = 0; i < 16; i++)
 			palette[i] = i;
+
+		// Make stuff more visible on CGA. Based on disassembly
+		if (_vm->_renderMode == Common::kRenderCGA) {
+			palette[6] = 5;
+			palette[7] = 15;
+		}
 	} else {
 		for (i = 0; i < 32; i++)
 			palette[i] = 0xFF;
diff --git a/scumm/charset.cpp b/scumm/charset.cpp
index 7b34acc7ab..818c1b16d4 100644
--- a/scumm/charset.cpp
+++ b/scumm/charset.cpp
@@ -1160,6 +1160,8 @@ void CharsetRendererV3::setColor(byte color)
 		_color &= 0x7f;
 	} else
 		_dropShadow = false;
+
+	translateColor();
 }
 
 void CharsetRendererV3::printChar(int chr) {
@@ -1253,6 +1255,21 @@ void CharsetRendererV3::drawChar(int chr, const Graphics::Surface &s, int x, int
 	drawBits1(s, dst, charPtr, y, width, height);
 }
 
+void CharsetRenderer::translateColor() {
+	// Based on disassembly
+	if (_vm->_renderMode == Common::kRenderCGA) {
+		static byte CGAtextColorMap[16] = {0,  3, 3, 3, 5, 5, 5,  15, 
+										   15, 3, 3, 3, 5, 5, 15, 15};
+		_color = CGAtextColorMap[_color & 0x0f];
+	}
+
+	if (_vm->_renderMode == Common::kRenderHerc) {
+		static byte HercTextColorMap[16] = {0, 15,  2, 15, 15,  5, 15,  15, 
+										   8, 15, 15, 15, 15, 15, 15, 15};
+		_color = HercTextColorMap[_color & 0x0f];
+	}
+}
+
 
 void CharsetRendererClassic::printChar(int chr) {
 	int width, height, origWidth, origHeight;
@@ -1269,6 +1286,8 @@ void CharsetRendererClassic::printChar(int chr) {
 	if (chr == '@')
 		return;
 
+	translateColor();
+
 	_vm->_charsetColorMap[1] = _color;
 
 	int type = *_fontPtr;
diff --git a/scumm/charset.h b/scumm/charset.h
index e546d16b73..dbadc1a2c3 100644
--- a/scumm/charset.h
+++ b/scumm/charset.h
@@ -92,6 +92,7 @@ public:
 
 	int getStringWidth(int a, const byte *str);
 	void addLinebreaks(int a, byte *str, int pos, int maxwidth);
+	void translateColor();
 	
 	virtual void setCurID(byte id) = 0;
 	int getCurID() { return _curId; }
@@ -99,7 +100,7 @@ public:
 	virtual int getFontHeight() = 0;
 	virtual int getCharWidth(byte chr) = 0;
 	
-	virtual void setColor(byte color) { _color = color; }
+	virtual void setColor(byte color) { _color = color; translateColor(); }
 };
 
 class CharsetRendererCommon : public CharsetRenderer {
diff --git a/scumm/gfx.cpp b/scumm/gfx.cpp
index 1156f16688..3709f2cbe5 100644
--- a/scumm/gfx.cpp
+++ b/scumm/gfx.cpp
@@ -188,6 +188,7 @@ Gdi::Gdi(ScummEngine *vm) {
 	
 	_compositeBuf = 0;
 	_textSurface.pixels = 0;
+	_herculesBuf = 0;
 }
 
 void ScummEngine::initScreens(int b, int h) {
@@ -225,11 +226,17 @@ void Gdi::init() {
 	const int size = _vm->_screenWidth * _vm->_screenHeight;
 	free(_compositeBuf);
 	free(_textSurface.pixels);
+	free(_herculesBuf);
 	_compositeBuf = (byte *)malloc(size);
 	_textSurface.pixels = malloc(size);
 	memset(_compositeBuf, CHARSET_MASK_TRANSPARENCY, size);
 	memset(_textSurface.pixels, CHARSET_MASK_TRANSPARENCY, size);
 
+	if (_vm->_renderMode == Common::kRenderHerc) {
+		_herculesBuf = (byte *)malloc(Common::kHercW * Common::kHercH);
+		memset(_herculesBuf, CHARSET_MASK_TRANSPARENCY, Common::kHercW * Common::kHercH);
+	}
+
 	_textSurface.w = _vm->_screenWidth;
 	_textSurface.h = _vm->_screenHeight;
 	_textSurface.pitch = _vm->_screenWidth;
@@ -474,8 +481,8 @@ void Gdi::drawStripToScreen(VirtScreen *vs, int x, int width, int top, int botto
 		bottom = _vm->_screenTop + _vm->_screenHeight;
 
 	// Convert the vertical coordinates to real screen coords
-	const int y = vs->topline + top - _vm->_screenTop;
-	const int height = bottom - top;
+	int y = vs->topline + top - _vm->_screenTop;
+	int height = bottom - top;
 	
 	// Compute screen etc. buffer pointers
 	const byte *src = vs->getPixels(x, top);
@@ -508,11 +515,105 @@ void Gdi::drawStripToScreen(VirtScreen *vs, int x, int width, int top, int botto
 		dst += _vm->_screenWidth;
 		text += _textSurface.pitch;
 	}
-	
-	// Finally blit the whole thing to the screen
-	_vm->_system->copyRectToScreen(_compositeBuf + x + y * _vm->_screenWidth, _vm->_screenWidth, x, y, width, height);
+
+	if (_vm->_renderMode == Common::kRenderCGA)
+		ditherCGA(_compositeBuf + x + y * _vm->_screenWidth, _vm->_screenWidth, x, y, width, height);
+
+	if (_vm->_renderMode == Common::kRenderHerc) {
+		ditherHerc(_compositeBuf + x + y * _vm->_screenWidth, _herculesBuf, _vm->_screenWidth, &x, &y, &width, &height);
+		// center image on the screen
+		_vm->_system->copyRectToScreen(_herculesBuf + x + y * Common::kHercW, 
+			Common::kHercW, x + (Common::kHercW - _vm->_screenWidth * 2) / 2, y, width, height);
+	} else {
+		// Finally blit the whole thing to the screen
+		_vm->_system->copyRectToScreen(_compositeBuf + x + y * _vm->_screenWidth, _vm->_screenWidth, x, y, width, height);
+	}
+}
+
+// CGA
+// indy3 loom maniac monkey1 zak
+//
+// Herc (720x350)
+// maniac monkey1 zak
+//
+// EGA
+// monkey2 loom maniac monkey1 atlantis indy3 zak loomcd
+
+// CGA dithers 4x4 square with direct substitutes
+// Odd lines have colors swapped, so there will be checkered patterns.
+// But apparently there is a mistake for 10th color.
+void Gdi::ditherCGA(byte *dst, int dstPitch, int x, int y, int width, int height) const {
+	byte *ptr;
+	int idx1, idx2;
+	static byte cgaDither[2][2][16] = {
+		{{0, 1, 0, 1, 2, 2, 0, 0, 3, 1, 3, 1, 3, 2, 1, 3},
+		 {0, 0, 1, 1, 0, 2, 2, 3, 0, 3, 1, 1, 3, 3, 1, 3}},
+		{{0, 0, 1, 1, 0, 2, 2, 3, 0, 3, 1, 1, 3, 3, 1, 3},
+		 {0, 1, 0, 1, 2, 2, 0, 0, 3, 1, 1, 1, 3, 2, 1, 3}}};
+
+	for (int y1 = 0; y1 < height; y1++) {
+		ptr = dst + y1 * dstPitch;
+
+		idx1 = (y + y1) % 2;
+		for (int x1 = 0; x1 < width; x1++) {
+			idx2 = (x + x1) % 2;
+			*ptr++ = cgaDither[idx1][idx2][*ptr & 0xF];
+		}
+	}
+}
+
+// Hercules dithering. It uses same dithering tables but output is 1bpp and
+// it stretches in this way:
+//         aaaa0
+// aa      aaaa1
+// bb      bbbb0      Here 0 and 1 mean dithering table row number
+// cc -->  bbbb1
+// dd      cccc0
+//         cccc1
+//         dddd0
+void Gdi::ditherHerc(byte *src, byte *hercbuf, int srcPitch, int *x, int *y, int *width, int *height) const {
+	byte *srcptr, *dstptr;
+	int xo = *x, yo = *y, widtho = *width, heighto = *height;
+	int idx1, idx2, dsty = 0;
+	static byte cgaDither[2][2][16] = {
+		{{0, 1, 0, 1, 2, 2, 0, 0, 3, 1, 3, 1, 3, 2, 1, 3},
+		 {0, 0, 1, 1, 0, 2, 2, 3, 0, 3, 1, 1, 3, 3, 1, 3}},
+		{{0, 0, 1, 1, 0, 2, 2, 3, 0, 3, 1, 1, 3, 3, 1, 3},
+		 {0, 1, 0, 1, 2, 2, 0, 0, 3, 1, 1, 1, 3, 2, 1, 3}}};
+
+	// calculate dsty
+	for (int y1 = 0; y1 < yo; y1++) {
+		dsty += 2;
+		if (y1 % 4 == 3)
+			dsty--;
+	}
+	*y = dsty;
+	*x *= 2;
+	*width *= 2;
+	*height = 0;
+
+	for (int y1 = 0; y1 < heighto;) {
+		srcptr = src + y1 * srcPitch;
+		dstptr = hercbuf + dsty * Common::kHercW + xo * 2;
+
+		if (dstptr >= hercbuf + Common::kHercW * Common::kHercH + widtho * 2)
+			debug("Gnaa");
+
+		idx1 = (dsty % 7) % 2;
+		for (int x1 = 0; x1 < widtho; x1++) {
+			idx2 = (xo + x1) % 2;
+			*dstptr++ = cgaDither[idx1][idx2][*srcptr & 0xF] >> 1;
+			*dstptr++ = cgaDither[idx1][idx2][*srcptr & 0xF] & 0x1;
+			srcptr++;
+		}
+		if (idx1 || dsty % 7 == 6)
+			y1++;
+		dsty++;
+		(*height)++;
+	}
 }
 
+
 #pragma mark -
 #pragma mark --- Background buffers & charset mask ---
 #pragma mark -
diff --git a/scumm/gfx.h b/scumm/gfx.h
index 4762b3678c..6bac0b54fa 100644
--- a/scumm/gfx.h
+++ b/scumm/gfx.h
@@ -216,6 +216,7 @@ public:
 
 protected:
 	byte *_compositeBuf;
+	byte *_herculesBuf;
 
 	byte *_roomPalette;
 	byte _decomp_shr, _decomp_mask;
@@ -256,7 +257,9 @@ protected:
 	/* Misc */
 	void drawStripToScreen(VirtScreen *vs, int x, int w, int t, int b);
 	void updateDirtyScreen(VirtScreen *vs);
-	
+	void ditherCGA(byte *dst, int dstPitch, int x, int y, int width, int height) const;
+	void ditherHerc(byte *src, byte *hercbuf, int srcPitch, int *x, int *y, int *width, int *height) const;
+
 	byte *getMaskBuffer(int x, int y, int z);
 	
 	int getZPlanes(const byte *smap_ptr, const byte *zplane_list[9], bool bmapImage) const;
diff --git a/scumm/input.cpp b/scumm/input.cpp
index f68745ef47..d7d1f1c25c 100644
--- a/scumm/input.cpp
+++ b/scumm/input.cpp
@@ -130,6 +130,12 @@ void ScummEngine::parseEvents() {
 		case OSystem::EVENT_MOUSEMOVE:
 			_mouse.x = event.mouse.x;
 			_mouse.y = event.mouse.y;
+
+			if (_renderMode == Common::kRenderHerc) {
+				_mouse.x -= (Common::kHercW - _screenWidth * 2) / 2;
+				_mouse.x /= 2;
+				_mouse.y = _mouse.y * 4 / 7;
+			}
 			break;
 
 		case OSystem::EVENT_LBUTTONDOWN:
diff --git a/scumm/palette.cpp b/scumm/palette.cpp
index b4f8ab8e43..9f0b0cd445 100644
--- a/scumm/palette.cpp
+++ b/scumm/palette.cpp
@@ -48,6 +48,28 @@ void ScummEngine::setupAmigaPalette() {
 	setPalColor(15, 255, 255, 255);
 }
 
+void ScummEngine::setupHercPalette() {
+	setPalColor( 0,   0,   0,   0);
+	setPalColor( 1, 0xAE, 0x69, 0x38);
+
+	// Setup cursor palette
+	setPalColor( 7, 170, 170, 170);
+	setPalColor( 8,  85,  85,  85);
+	setPalColor(15, 255, 255, 255);
+}
+
+void ScummEngine::setupCGAPalette() {
+	setPalColor( 0,   0,   0,   0);
+	setPalColor( 1,   0, 168, 168);
+	setPalColor( 2, 168,   0, 168);
+	setPalColor( 3, 168, 168, 168);
+
+	// Setup cursor palette
+	setPalColor( 7, 170, 170, 170);
+	setPalColor( 8,  85,  85,  85);
+	setPalColor(15, 255, 255, 255);
+}
+
 void ScummEngine::setupEGAPalette() {
 	setPalColor( 0,   0,   0,   0);
 	setPalColor( 1,   0,   0, 170);
diff --git a/scumm/scumm.cpp b/scumm/scumm.cpp
index 395ae16e89..8fac59868a 100644
--- a/scumm/scumm.cpp
+++ b/scumm/scumm.cpp
@@ -998,6 +998,32 @@ ScummEngine::ScummEngine(GameDetector *detector, OSystem *syst, const ScummGameS
 	}
 	_confirmExit = ConfMan.getBool("confirm_exit");
 
+	if (ConfMan.hasKey("render_mode")) {
+		_renderMode = Common::parseRenderMode(ConfMan.get("render_mode").c_str());
+	} else {
+		_renderMode = Common::kRenderDefault;
+	}
+
+	// Do some render mode restirctions
+	switch (_renderMode) {
+	case Common::kRenderHerc:
+		if (_version > 2 && _gameId != GID_MONKEY_EGA)
+			_renderMode = Common::kRenderDefault;
+		break;
+
+	case Common::kRenderCGA:
+		if (!(_features & GF_16COLOR))
+			_renderMode = Common::kRenderDefault;
+		break;
+
+	case Common::kRenderEGA:
+			_renderMode = Common::kRenderDefault;
+		break;
+
+	default:
+		break;
+	}
+
 	_hexdumpScripts = false;
 	_showStack = false;
 
@@ -1019,6 +1045,11 @@ ScummEngine::ScummEngine(GameDetector *detector, OSystem *syst, const ScummGameS
 	} else if (_features & GF_NES) {
 		_screenWidth = 256;
 		_screenHeight = 240;
+	} else if (_renderMode == Common::kRenderHerc) {
+		_system->setGraphicsMode("1x");
+		_features |= GF_DEFAULT_TO_1X_SCALER;
+		_screenWidth = 320;
+		_screenHeight = 200;
 	} else {
 		_screenWidth = 320;
 		_screenHeight = 200;
@@ -1109,7 +1140,13 @@ int ScummEngine::init(GameDetector &detector) {
 	// Initialize backend
 	_system->beginGFXTransaction();
 		initCommonGFX(detector);
-		_system->initSize(_screenWidth, _screenHeight);
+		if (_renderMode == Common::kRenderHerc) {
+			_system->initSize(Common::kHercW, Common::kHercH);
+			_features |= GF_DEFAULT_TO_1X_SCALER;
+			_system->setGraphicsMode("1x");
+		} else {
+			_system->initSize(_screenWidth, _screenHeight);
+		}
 
 		// FIXME: All this seems a dirty hack to me. We already
 		// have this check in constructor
@@ -1268,6 +1305,10 @@ void ScummEngine::scummInit() {
 			_shadowPalette[i] = i;
 		if ((_features & GF_AMIGA) || (_features & GF_ATARI_ST))
 			setupAmigaPalette();
+		else if (_renderMode == Common::kRenderHerc)
+			setupHercPalette();
+		else if (_renderMode == Common::kRenderCGA)
+			setupCGAPalette();
 		else
 			setupEGAPalette();
 	}
diff --git a/scumm/scumm.h b/scumm/scumm.h
index 091635c8e9..56146d41fa 100644
--- a/scumm/scumm.h
+++ b/scumm/scumm.h
@@ -868,6 +868,8 @@ public:
 	int _screenStartStrip, _screenEndStrip;
 	int _screenTop;
 
+	Common::RenderMode _renderMode;
+
 protected:
 	ColorCycle _colorCycle[16];	// Palette cycles
 
@@ -930,6 +932,8 @@ protected:
 
 	const byte *getPalettePtr(int palindex, int room);
 	void setupAmigaPalette();
+	void setupHercPalette();
+	void setupCGAPalette();
 	void setupEGAPalette();
 	void setupV1ManiacPalette();
 	void setupV1ZakPalette();
diff --git a/scumm/vars.cpp b/scumm/vars.cpp
index 429c153962..4a8ced0de1 100644
--- a/scumm/vars.cpp
+++ b/scumm/vars.cpp
@@ -553,6 +553,12 @@ void ScummEngine::initScummVars() {
 			VAR(VAR_VIDEOMODE) = 50;
 		else if (_gameId == GID_MONKEY2 && (_features & GF_AMIGA))
 			VAR(VAR_VIDEOMODE) = 82;
+		else if (_renderMode == Common::kRenderCGA)
+			VAR(VAR_VIDEOMODE) = 4;
+		else if (_renderMode == Common::kRenderHerc)
+			VAR(VAR_VIDEOMODE) = 30;
+		else if (_renderMode == Common::kRenderEGA)
+			VAR(VAR_VIDEOMODE) = 13;
 		else
 			VAR(VAR_VIDEOMODE) = 19;
 		if (_gameId == GID_LOOM && _features & GF_OLD_BUNDLE) {