New 3D Mode: Pageflip

The pageflip mode requires a stereo quadbuffer, and a modern graphic
card. Patch tested with NVidia 3D Vision.

The mini-map is not drawn, but that's what is done for topbottom and
sidebyside modes as well.

Also most of the time the user would prefer the HUD to be off. That's
for the user to decide though, and toggle it manually.

Finally, the interocular distance (aka eye separation) is twice as much
as the "3d_paralax_strength" settings. I find this a strange design
decision. I didn't want to chance this though, since it's how the other
3d modes interpret this settings.

5 files changed, 97 insertions, 2 deletions

diff --git a/builtin/settingtypes.txt b/builtin/settingtypes.txt
index 62f817062..6412ab4f6 100644
--- a/builtin/settingtypes.txt
+++ b/builtin/settingtypes.txt
@@ -454,7 +454,8 @@ fall_bobbing_amount (Fall bobbing) float 0.0
 #    -    interlaced: odd/even line based polarisation screen support.
 #    -    topbottom: split screen top/bottom.
 #    -    sidebyside: split screen side by side.
-3d_mode (3D mode) enum none none,anaglyph,interlaced,topbottom,sidebyside
+#    -    pageflip: quadbuffer based 3d.
+3d_mode (3D mode) enum none none,anaglyph,interlaced,topbottom,sidebyside,pageflip
 
 #    In-game chat console background color (R,G,B).
 console_color (Console color) string (0,0,0)
diff --git a/minetest.conf.example b/minetest.conf.example
index 40456f953..806ce62c2 100644
--- a/minetest.conf.example
+++ b/minetest.conf.example
@@ -518,7 +518,8 @@
 #    -    interlaced: odd/even line based polarisation screen support.
 #    -    topbottom: split screen top/bottom.
 #    -    sidebyside: split screen side by side.
-#    type: enum values: none, anaglyph, interlaced, topbottom, sidebyside
+#    -    pageflip: quadbuffer based 3d.
+#    type: enum values: none, anaglyph, interlaced, topbottom, sidebyside, pageflip
 # 3d_mode = none
 
 #    In-game chat console background color (R,G,B).
diff --git a/src/client/clientlauncher.cpp b/src/client/clientlauncher.cpp
index dfddef34e..be6426627 100644
--- a/src/client/clientlauncher.cpp
+++ b/src/client/clientlauncher.cpp
@@ -512,6 +512,9 @@ bool ClientLauncher::create_engine_device()
 	u16 bits = g_settings->getU16("fullscreen_bpp");
 	u16 fsaa = g_settings->getU16("fsaa");
 
+	// stereo buffer required for pageflip stereo
+	bool stereo_buffer = g_settings->get("3d_mode") == "pageflip";
+
 	// Determine driver
 	video::E_DRIVER_TYPE driverType = video::EDT_OPENGL;
 	std::string driverstring = g_settings->get("video_driver");
@@ -537,6 +540,7 @@ bool ClientLauncher::create_engine_device()
 	params.AntiAlias     = fsaa;
 	params.Fullscreen    = fullscreen;
 	params.Stencilbuffer = false;
+	params.Stereobuffer  = stereo_buffer;
 	params.Vsync         = vsync;
 	params.EventReceiver = receiver;
 	params.HighPrecisionFPU = g_settings->getBool("high_precision_fpu");
diff --git a/src/drawscene.cpp b/src/drawscene.cpp
index 509f341d5..c716ca0d4 100644
--- a/src/drawscene.cpp
+++ b/src/drawscene.cpp
@@ -404,6 +404,84 @@ void draw_top_bottom_3d_mode(Camera& camera, bool show_hud,
 	camera.getCameraNode()->setTarget(oldTarget);
 }
 
+void draw_pageflip_3d_mode(Camera& camera, bool show_hud,
+		Hud& hud, std::vector<aabb3f> hilightboxes, video::IVideoDriver* driver,
+		scene::ISceneManager* smgr, const v2u32& screensize,
+		bool draw_wield_tool, Client& client, gui::IGUIEnvironment* guienv,
+		video::SColor skycolor)
+{
+	/* preserve old setup*/
+	irr::core::vector3df oldPosition = camera.getCameraNode()->getPosition();
+	irr::core::vector3df oldTarget   = camera.getCameraNode()->getTarget();
+
+	irr::core::matrix4 startMatrix =
+			camera.getCameraNode()->getAbsoluteTransformation();
+	irr::core::vector3df focusPoint = (camera.getCameraNode()->getTarget()
+			- camera.getCameraNode()->getAbsolutePosition()).setLength(1)
+			+ camera.getCameraNode()->getAbsolutePosition();
+
+	//Left eye...
+	driver->setRenderTarget(irr::video::ERT_STEREO_LEFT_BUFFER);
+
+	irr::core::vector3df leftEye;
+	irr::core::matrix4 leftMove;
+	leftMove.setTranslation(
+			irr::core::vector3df(-g_settings->getFloat("3d_paralax_strength"),
+					0.0f, 0.0f));
+	leftEye = (startMatrix * leftMove).getTranslation();
+
+	//clear the depth buffer, and color
+	driver->beginScene(true, true, irr::video::SColor(200, 200, 200, 255));
+	camera.getCameraNode()->setPosition(leftEye);
+	camera.getCameraNode()->setTarget(focusPoint);
+	smgr->drawAll();
+	driver->setTransform(video::ETS_WORLD, core::IdentityMatrix);
+
+	if (show_hud) {
+		draw_selectionbox(driver, hud, hilightboxes, show_hud);
+
+		if (draw_wield_tool)
+			camera.drawWieldedTool(&leftMove);
+
+		hud.drawHotbar(client.getPlayerItem());
+		hud.drawLuaElements(camera.getOffset());
+	}
+
+	guienv->drawAll();
+
+	//Right eye...
+	driver->setRenderTarget(irr::video::ERT_STEREO_RIGHT_BUFFER);
+
+	irr::core::vector3df rightEye;
+	irr::core::matrix4 rightMove;
+	rightMove.setTranslation(
+			irr::core::vector3df(g_settings->getFloat("3d_paralax_strength"),
+					0.0f, 0.0f));
+	rightEye = (startMatrix * rightMove).getTranslation();
+
+	//clear the depth buffer, and color
+	driver->beginScene(true, true, irr::video::SColor(200, 200, 200, 255));
+	camera.getCameraNode()->setPosition(rightEye);
+	camera.getCameraNode()->setTarget(focusPoint);
+	smgr->drawAll();
+	driver->setTransform(video::ETS_WORLD, core::IdentityMatrix);
+
+	if (show_hud) {
+		draw_selectionbox(driver, hud, hilightboxes, show_hud);
+
+		if (draw_wield_tool)
+			camera.drawWieldedTool(&rightMove);
+
+		hud.drawHotbar(client.getPlayerItem());
+		hud.drawLuaElements(camera.getOffset());
+	}
+
+	guienv->drawAll();
+
+	camera.getCameraNode()->setPosition(oldPosition);
+	camera.getCameraNode()->setTarget(oldTarget);
+}
+
 void draw_plain(Camera& camera, bool show_hud, Hud& hud,
 		std::vector<aabb3f> hilightboxes, video::IVideoDriver* driver,
 		bool draw_wield_tool, Client& client, gui::IGUIEnvironment* guienv)
@@ -466,6 +544,13 @@ void draw_scene(video::IVideoDriver *driver, scene::ISceneManager *smgr,
 				smgr, screensize, draw_wield_tool, client, guienv, skycolor);
 		show_hud = false;
 	}
+	else if (draw_mode == "pageflip")
+	{
+		draw_pageflip_3d_mode(camera, show_hud, hud, hilightboxes, driver,
+				smgr, screensize, draw_wield_tool, client, guienv, skycolor);
+		draw_crosshair = false;
+		show_hud = false;
+	}
 	else {
 		draw_plain(camera, show_hud, hud, hilightboxes, driver,
 				draw_wield_tool, client, guienv);
diff --git a/src/game.cpp b/src/game.cpp
index 7ada1791e..92d919931 100644
--- a/src/game.cpp
+++ b/src/game.cpp
@@ -1872,6 +1872,10 @@ void Game::run()
 
 void Game::shutdown()
 {
+	if (g_settings->get("3d_mode") == "pageflip") {
+		driver->setRenderTarget(irr::video::ERT_STEREO_BOTH_BUFFERS);
+	}
+
 	showOverlayMessage(wgettext("Shutting down..."), 0, 0, false);
 
 	if (clouds)