Rewrite rendering engine (#6253)

* Clean draw_*() arguments

* Split rendering core

* Add anaglyph 3D

* Interlaced 3D

* Drop obsolete methods

16 files changed, 910 insertions, 0 deletions

diff --git a/src/client/render/anaglyph.cpp b/src/client/render/anaglyph.cpp
new file mode 100644
index 000000000..1fad9e8d3
--- /dev/null
+++ b/src/client/render/anaglyph.cpp
@@ -0,0 +1,51 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "anaglyph.h"
+
+void RenderingCoreAnaglyph::drawAll()
+{
+	renderBothImages();
+	drawPostFx();
+	drawHUD();
+}
+
+void RenderingCoreAnaglyph::setupMaterial(int color_mask)
+{
+	video::SOverrideMaterial &mat = driver->getOverrideMaterial();
+	mat.Material.ColorMask = color_mask;
+	mat.EnableFlags = video::EMF_COLOR_MASK;
+	mat.EnablePasses = scene::ESNRP_SKY_BOX | scene::ESNRP_SOLID |
+			   scene::ESNRP_TRANSPARENT | scene::ESNRP_TRANSPARENT_EFFECT |
+			   scene::ESNRP_SHADOW;
+}
+
+void RenderingCoreAnaglyph::useEye(bool right)
+{
+	RenderingCoreStereo::useEye(right);
+	driver->clearZBuffer();
+	setupMaterial(right ? video::ECP_GREEN | video::ECP_BLUE : video::ECP_RED);
+}
+
+void RenderingCoreAnaglyph::resetEye()
+{
+	setupMaterial(video::ECP_ALL);
+	RenderingCoreStereo::resetEye();
+}
diff --git a/src/client/render/anaglyph.h b/src/client/render/anaglyph.h
new file mode 100644
index 000000000..6305efb90
--- /dev/null
+++ b/src/client/render/anaglyph.h
@@ -0,0 +1,34 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+#include "stereo.h"
+
+class RenderingCoreAnaglyph : public RenderingCoreStereo
+{
+protected:
+	void setupMaterial(int color_mask);
+	void useEye(bool right) override;
+	void resetEye() override;
+
+public:
+	using RenderingCoreStereo::RenderingCoreStereo;
+	void drawAll() override;
+};
diff --git a/src/client/render/core.cpp b/src/client/render/core.cpp
new file mode 100644
index 000000000..7a4230c84
--- /dev/null
+++ b/src/client/render/core.cpp
@@ -0,0 +1,101 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "core.h"
+#include "camera.h"
+#include "client.h"
+#include "clientmap.h"
+#include "hud.h"
+#include "minimap.h"
+
+RenderingCore::RenderingCore(IrrlichtDevice *_device, Client *_client, Hud *_hud)
+    : device(_device), driver(device->getVideoDriver()), smgr(device->getSceneManager()),
+      guienv(device->getGUIEnvironment()), client(_client), camera(client->getCamera()),
+      mapper(client->getMinimap()), hud(_hud)
+{
+	screensize = driver->getScreenSize();
+	virtual_size = screensize;
+}
+
+RenderingCore::~RenderingCore()
+{
+	clearTextures();
+}
+
+void RenderingCore::initialize()
+{
+	// have to be called late as the VMT is not ready in the constructor:
+	initTextures();
+}
+
+void RenderingCore::updateScreenSize()
+{
+	virtual_size = screensize;
+	clearTextures();
+	initTextures();
+}
+
+void RenderingCore::draw(video::SColor _skycolor, bool _show_hud, bool _show_minimap,
+		bool _draw_wield_tool, bool _draw_crosshair)
+{
+	v2u32 ss = driver->getScreenSize();
+	if (screensize != ss) {
+		screensize = ss;
+		updateScreenSize();
+	}
+	skycolor = _skycolor;
+	show_hud = _show_hud;
+	show_minimap = _show_minimap;
+	draw_wield_tool = _draw_wield_tool;
+	draw_crosshair = _draw_crosshair;
+
+	beforeDraw();
+	drawAll();
+}
+
+void RenderingCore::draw3D()
+{
+	smgr->drawAll();
+	driver->setTransform(video::ETS_WORLD, core::IdentityMatrix);
+	if (!show_hud)
+		return;
+	hud->drawSelectionMesh();
+	if (draw_wield_tool)
+		camera->drawWieldedTool();
+}
+
+void RenderingCore::drawHUD()
+{
+	if (show_hud) {
+		if (draw_crosshair)
+			hud->drawCrosshair();
+		hud->drawHotbar(client->getPlayerItem());
+		hud->drawLuaElements(camera->getOffset());
+		camera->drawNametags();
+		if (mapper && show_minimap)
+			mapper->drawMinimap();
+	}
+	guienv->drawAll();
+}
+
+void RenderingCore::drawPostFx()
+{
+	client->getEnv().getClientMap().renderPostFx(camera->getCameraMode());
+}
diff --git a/src/client/render/core.h b/src/client/render/core.h
new file mode 100644
index 000000000..35def7f20
--- /dev/null
+++ b/src/client/render/core.h
@@ -0,0 +1,75 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+#include "irrlichttypes_extrabloated.h"
+
+class Camera;
+class Client;
+class Hud;
+class Minimap;
+
+class RenderingCore
+{
+protected:
+	v2u32 screensize;
+	v2u32 virtual_size;
+	video::SColor skycolor;
+	bool show_hud;
+	bool show_minimap;
+	bool draw_wield_tool;
+	bool draw_crosshair;
+
+	IrrlichtDevice *device;
+	video::IVideoDriver *driver;
+	scene::ISceneManager *smgr;
+	gui::IGUIEnvironment *guienv;
+
+	Client *client;
+	Camera *camera;
+	Minimap *mapper;
+	Hud *hud;
+
+	void updateScreenSize();
+	virtual void initTextures() {}
+	virtual void clearTextures() {}
+
+	virtual void beforeDraw() {}
+	virtual void drawAll() = 0;
+
+	void draw3D();
+	void drawHUD();
+	void drawPostFx();
+
+public:
+	RenderingCore(IrrlichtDevice *_device, Client *_client, Hud *_hud);
+	RenderingCore(const RenderingCore &) = delete;
+	RenderingCore(RenderingCore &&) = delete;
+	virtual ~RenderingCore();
+
+	RenderingCore &operator=(const RenderingCore &) = delete;
+	RenderingCore &operator=(RenderingCore &&) = delete;
+
+	void initialize();
+	void draw(video::SColor _skycolor, bool _show_hud, bool _show_minimap,
+			bool _draw_wield_tool, bool _draw_crosshair);
+
+	inline v2u32 getVirtualSize() const { return virtual_size; }
+};
diff --git a/src/client/render/factory.cpp b/src/client/render/factory.cpp
new file mode 100644
index 000000000..c2c3f341e
--- /dev/null
+++ b/src/client/render/factory.cpp
@@ -0,0 +1,45 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "factory.h"
+#include <stdexcept>
+#include "plain.h"
+#include "anaglyph.h"
+#include "interlaced.h"
+#include "pageflip.h"
+#include "sidebyside.h"
+
+RenderingCore *createRenderingCore(const std::string &stereo_mode, IrrlichtDevice *device,
+		Client *client, Hud *hud)
+{
+	if (stereo_mode == "none")
+		return new RenderingCorePlain(device, client, hud);
+	if (stereo_mode == "anaglyph")
+		return new RenderingCoreAnaglyph(device, client, hud);
+	if (stereo_mode == "interlaced")
+		return new RenderingCoreInterlaced(device, client, hud);
+	if (stereo_mode == "pageflip")
+		return new RenderingCorePageflip(device, client, hud);
+	if (stereo_mode == "sidebyside")
+		return new RenderingCoreSideBySide(device, client, hud);
+	if (stereo_mode == "topbottom")
+		return new RenderingCoreSideBySide(device, client, hud, true);
+	throw std::invalid_argument("Invalid rendering mode: " + stereo_mode);
+}
diff --git a/src/client/render/factory.h b/src/client/render/factory.h
new file mode 100644
index 000000000..c7c5cdc1e
--- /dev/null
+++ b/src/client/render/factory.h
@@ -0,0 +1,25 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <string>
+#include "core.h"
+
+RenderingCore *createRenderingCore(const std::string &stereo_mode, IrrlichtDevice *device,
+		Client *client, Hud *hud);
diff --git a/src/client/render/interlaced.cpp b/src/client/render/interlaced.cpp
new file mode 100644
index 000000000..ccd4e60cf
--- /dev/null
+++ b/src/client/render/interlaced.cpp
@@ -0,0 +1,116 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "interlaced.h"
+#include "client.h"
+#include "shader.h"
+#include "client/tile.h"
+
+RenderingCoreInterlaced::RenderingCoreInterlaced(
+		IrrlichtDevice *_device, Client *_client, Hud *_hud)
+    : RenderingCoreStereo(_device, _client, _hud)
+{
+	initMaterial();
+}
+
+void RenderingCoreInterlaced::initMaterial()
+{
+	IShaderSource *s = client->getShaderSource();
+	mat.UseMipMaps = false;
+	mat.ZBuffer = false;
+	mat.ZWriteEnable = false;
+	u32 shader = s->getShader("3d_interlaced_merge", TILE_MATERIAL_BASIC, 0);
+	mat.MaterialType = s->getShaderInfo(shader).material;
+	for (int k = 0; k < 3; ++k) {
+		mat.TextureLayer[k].AnisotropicFilter = false;
+		mat.TextureLayer[k].BilinearFilter = false;
+		mat.TextureLayer[k].TrilinearFilter = false;
+		mat.TextureLayer[k].TextureWrapU = video::ETC_CLAMP_TO_EDGE;
+		mat.TextureLayer[k].TextureWrapV = video::ETC_CLAMP_TO_EDGE;
+	}
+}
+
+void RenderingCoreInterlaced::initTextures()
+{
+	v2u32 image_size{screensize.X, screensize.Y / 2};
+	left = driver->addRenderTargetTexture(
+			image_size, "3d_render_left", video::ECF_A8R8G8B8);
+	right = driver->addRenderTargetTexture(
+			image_size, "3d_render_right", video::ECF_A8R8G8B8);
+	mask = driver->addTexture(screensize, "3d_render_mask", video::ECF_A8R8G8B8);
+	initMask();
+	mat.TextureLayer[0].Texture = left;
+	mat.TextureLayer[1].Texture = right;
+	mat.TextureLayer[2].Texture = mask;
+}
+
+void RenderingCoreInterlaced::clearTextures()
+{
+	driver->removeTexture(left);
+	driver->removeTexture(right);
+	driver->removeTexture(mask);
+}
+
+void RenderingCoreInterlaced::initMask()
+{
+	u8 *data = reinterpret_cast<u8 *>(mask->lock());
+	for (u32 j = 0; j < screensize.Y; j++) {
+		u8 val = j % 2 ? 0xff : 0x00;
+		memset(data, val, 4 * screensize.X);
+		data += 4 * screensize.X;
+	}
+	mask->unlock();
+}
+
+void RenderingCoreInterlaced::drawAll()
+{
+	renderBothImages();
+	merge();
+	drawHUD();
+}
+
+void RenderingCoreInterlaced::merge()
+{
+	static const video::S3DVertex vertices[4] = {
+			video::S3DVertex(1.0, -1.0, 0.0, 0.0, 0.0, -1.0,
+					video::SColor(255, 0, 255, 255), 1.0, 0.0),
+			video::S3DVertex(-1.0, -1.0, 0.0, 0.0, 0.0, -1.0,
+					video::SColor(255, 255, 0, 255), 0.0, 0.0),
+			video::S3DVertex(-1.0, 1.0, 0.0, 0.0, 0.0, -1.0,
+					video::SColor(255, 255, 255, 0), 0.0, 1.0),
+			video::S3DVertex(1.0, 1.0, 0.0, 0.0, 0.0, -1.0,
+					video::SColor(255, 255, 255, 255), 1.0, 1.0),
+	};
+	static const u16 indices[6] = {0, 1, 2, 2, 3, 0};
+	driver->setMaterial(mat);
+	driver->drawVertexPrimitiveList(&vertices, 4, &indices, 2);
+}
+
+void RenderingCoreInterlaced::useEye(bool _right)
+{
+	driver->setRenderTarget(_right ? right : left, true, true, skycolor);
+	RenderingCoreStereo::useEye(_right);
+}
+
+void RenderingCoreInterlaced::resetEye()
+{
+	driver->setRenderTarget(nullptr, false, false, skycolor);
+	RenderingCoreStereo::resetEye();
+}
diff --git a/src/client/render/interlaced.h b/src/client/render/interlaced.h
new file mode 100644
index 000000000..d0c1d9e62
--- /dev/null
+++ b/src/client/render/interlaced.h
@@ -0,0 +1,43 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+#include "stereo.h"
+
+class RenderingCoreInterlaced : public RenderingCoreStereo
+{
+protected:
+	video::ITexture *left = nullptr;
+	video::ITexture *right = nullptr;
+	video::ITexture *mask = nullptr;
+	video::SMaterial mat;
+
+	void initMaterial();
+	void initTextures() override;
+	void clearTextures() override;
+	void initMask();
+	void useEye(bool right) override;
+	void resetEye() override;
+	void merge();
+
+public:
+	RenderingCoreInterlaced(IrrlichtDevice *_device, Client *_client, Hud *_hud);
+	void drawAll() override;
+};
diff --git a/src/client/render/pageflip.cpp b/src/client/render/pageflip.cpp
new file mode 100644
index 000000000..8d6fa7423
--- /dev/null
+++ b/src/client/render/pageflip.cpp
@@ -0,0 +1,55 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "pageflip.h"
+
+void RenderingCorePageflip::initTextures()
+{
+	hud = driver->addRenderTargetTexture(
+			screensize, "3d_render_hud", video::ECF_A8R8G8B8);
+}
+
+void RenderingCorePageflip::clearTextures()
+{
+	driver->removeTexture(hud);
+}
+
+void RenderingCorePageflip::drawAll()
+{
+	driver->setRenderTarget(hud, true, true, video::SColor(0, 0, 0, 0));
+	drawHUD();
+	driver->setRenderTarget(nullptr, false, false, skycolor);
+	renderBothImages();
+}
+
+void RenderingCorePageflip::useEye(bool _right)
+{
+	driver->setRenderTarget(_right ? video::ERT_STEREO_RIGHT_BUFFER
+				       : video::ERT_STEREO_LEFT_BUFFER,
+			true, true, skycolor);
+	RenderingCoreStereo::useEye(_right);
+}
+
+void RenderingCorePageflip::resetEye()
+{
+	driver->draw2DImage(hud, v2s32(0, 0));
+	driver->setRenderTarget(video::ERT_FRAME_BUFFER, false, false, skycolor);
+	RenderingCoreStereo::resetEye();
+}
diff --git a/src/client/render/pageflip.h b/src/client/render/pageflip.h
new file mode 100644
index 000000000..ee4567ac4
--- /dev/null
+++ b/src/client/render/pageflip.h
@@ -0,0 +1,37 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+#include "stereo.h"
+
+class RenderingCorePageflip : public RenderingCoreStereo
+{
+protected:
+	video::ITexture *hud = nullptr;
+
+	void initTextures() override;
+	void clearTextures() override;
+	void useEye(bool right) override;
+	void resetEye() override;
+
+public:
+	using RenderingCoreStereo::RenderingCoreStereo;
+	void drawAll() override;
+};
diff --git a/src/client/render/plain.cpp b/src/client/render/plain.cpp
new file mode 100644
index 000000000..94921245b
--- /dev/null
+++ b/src/client/render/plain.cpp
@@ -0,0 +1,76 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "plain.h"
+#include "settings.h"
+
+inline u32 scaledown(u32 coef, u32 size)
+{
+	return (size + coef - 1) / coef;
+}
+
+RenderingCorePlain::RenderingCorePlain(
+		IrrlichtDevice *_device, Client *_client, Hud *_hud)
+    : RenderingCore(_device, _client, _hud)
+{
+	scale = g_settings->getU16("undersampling");
+}
+
+void RenderingCorePlain::initTextures()
+{
+	if (!scale)
+		return;
+	v2u32 size{scaledown(scale, screensize.X), scaledown(scale, screensize.Y)};
+	lowres = driver->addRenderTargetTexture(
+			size, "render_lowres", video::ECF_A8R8G8B8);
+}
+
+void RenderingCorePlain::clearTextures()
+{
+	if (!scale)
+		return;
+	driver->removeTexture(lowres);
+}
+
+void RenderingCorePlain::beforeDraw()
+{
+	if (!scale)
+		return;
+	driver->setRenderTarget(lowres, true, true, skycolor);
+}
+
+void RenderingCorePlain::upscale()
+{
+	if (!scale)
+		return;
+	driver->setRenderTarget(0, true, true);
+	v2u32 size{scaledown(scale, screensize.X), scaledown(scale, screensize.Y)};
+	v2u32 dest_size{scale * size.X, scale * size.Y};
+	driver->draw2DImage(lowres, core::rect<s32>(0, 0, dest_size.X, dest_size.Y),
+			core::rect<s32>(0, 0, size.X, size.Y));
+}
+
+void RenderingCorePlain::drawAll()
+{
+	draw3D();
+	drawPostFx();
+	upscale();
+	drawHUD();
+}
diff --git a/src/client/render/plain.h b/src/client/render/plain.h
new file mode 100644
index 000000000..af9d7036b
--- /dev/null
+++ b/src/client/render/plain.h
@@ -0,0 +1,38 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+#include "core.h"
+
+class RenderingCorePlain : public RenderingCore
+{
+protected:
+	int scale = 0;
+	video::ITexture *lowres = nullptr;
+
+	void initTextures() override;
+	void clearTextures() override;
+	void beforeDraw() override;
+	void upscale();
+
+public:
+	RenderingCorePlain(IrrlichtDevice *_device, Client *_client, Hud *_hud);
+	void drawAll() override;
+};
diff --git a/src/client/render/sidebyside.cpp b/src/client/render/sidebyside.cpp
new file mode 100644
index 000000000..2af09ee33
--- /dev/null
+++ b/src/client/render/sidebyside.cpp
@@ -0,0 +1,74 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "sidebyside.h"
+#include <ICameraSceneNode.h>
+#include "hud.h"
+
+RenderingCoreSideBySide::RenderingCoreSideBySide(
+		IrrlichtDevice *_device, Client *_client, Hud *_hud, bool _horizontal)
+    : RenderingCoreStereo(_device, _client, _hud), horizontal(_horizontal)
+{
+}
+
+void RenderingCoreSideBySide::initTextures()
+{
+	if (horizontal) {
+		image_size = {screensize.X, screensize.Y / 2};
+		rpos = v2s32(0, screensize.Y / 2);
+	} else {
+		image_size = {screensize.X / 2, screensize.Y};
+		rpos = v2s32(screensize.X / 2, 0);
+	}
+	virtual_size = image_size;
+	left = driver->addRenderTargetTexture(
+			image_size, "3d_render_left", video::ECF_A8R8G8B8);
+	right = driver->addRenderTargetTexture(
+			image_size, "3d_render_right", video::ECF_A8R8G8B8);
+}
+
+void RenderingCoreSideBySide::clearTextures()
+{
+	driver->removeTexture(left);
+	driver->removeTexture(right);
+}
+
+void RenderingCoreSideBySide::drawAll()
+{
+	driver->OnResize(image_size); // HACK to make GUI smaller
+	renderBothImages();
+	driver->OnResize(screensize);
+	driver->draw2DImage(left, {});
+	driver->draw2DImage(right, rpos);
+}
+
+void RenderingCoreSideBySide::useEye(bool _right)
+{
+	driver->setRenderTarget(_right ? right : left, true, true, skycolor);
+	RenderingCoreStereo::useEye(_right);
+}
+
+void RenderingCoreSideBySide::resetEye()
+{
+	hud->resizeHotbar();
+	drawHUD();
+	driver->setRenderTarget(nullptr, false, false, skycolor);
+	RenderingCoreStereo::resetEye();
+}
diff --git a/src/client/render/sidebyside.h b/src/client/render/sidebyside.h
new file mode 100644
index 000000000..70b2bdcf5
--- /dev/null
+++ b/src/client/render/sidebyside.h
@@ -0,0 +1,42 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+#include "stereo.h"
+
+class RenderingCoreSideBySide : public RenderingCoreStereo
+{
+protected:
+	video::ITexture *left = nullptr;
+	video::ITexture *right = nullptr;
+	bool horizontal = false;
+	core::dimension2du image_size;
+	v2s32 rpos;
+
+	void initTextures() override;
+	void clearTextures() override;
+	void useEye(bool right) override;
+	void resetEye() override;
+
+public:
+	RenderingCoreSideBySide(IrrlichtDevice *_device, Client *_client, Hud *_hud,
+			bool _horizontal = false);
+	void drawAll() override;
+};
diff --git a/src/client/render/stereo.cpp b/src/client/render/stereo.cpp
new file mode 100644
index 000000000..eec9f8ced
--- /dev/null
+++ b/src/client/render/stereo.cpp
@@ -0,0 +1,60 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "stereo.h"
+#include "camera.h"
+#include "constants.h"
+#include "settings.h"
+
+RenderingCoreStereo::RenderingCoreStereo(
+		IrrlichtDevice *_device, Client *_client, Hud *_hud)
+    : RenderingCore(_device, _client, _hud)
+{
+	eye_offset = BS * g_settings->getFloat("3d_paralax_strength");
+}
+
+void RenderingCoreStereo::beforeDraw()
+{
+	cam = camera->getCameraNode();
+	base_transform = cam->getRelativeTransformation();
+}
+
+void RenderingCoreStereo::useEye(bool right)
+{
+	core::matrix4 move;
+	move.setTranslation(
+			core::vector3df(right ? eye_offset : -eye_offset, 0.0f, 0.0f));
+	cam->setPosition((base_transform * move).getTranslation());
+}
+
+void RenderingCoreStereo::resetEye()
+{
+	cam->setPosition(base_transform.getTranslation());
+}
+
+void RenderingCoreStereo::renderBothImages()
+{
+	useEye(false);
+	draw3D();
+	resetEye();
+	useEye(true);
+	draw3D();
+	resetEye();
+}
diff --git a/src/client/render/stereo.h b/src/client/render/stereo.h
new file mode 100644
index 000000000..0b13de376
--- /dev/null
+++ b/src/client/render/stereo.h
@@ -0,0 +1,38 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2017 numzero, Lobachesky Vitaly <numzer0@yandex.ru>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+#include "core.h"
+
+class RenderingCoreStereo : public RenderingCore
+{
+protected:
+	scene::ICameraSceneNode *cam;
+	core::matrix4 base_transform;
+	float eye_offset;
+
+	void beforeDraw() override;
+	virtual void useEye(bool right);
+	virtual void resetEye();
+	void renderBothImages();
+
+public:
+	RenderingCoreStereo(IrrlichtDevice *_device, Client *_client, Hud *_hud);
+};