assets/blender/gleis/rail_verticals.blend

/*
Minetest
Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>

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 "content_mapblock.h"
#include "util/numeric.h"
#include "util/directiontables.h"
#include "mapblock_mesh.h"
#include "settings.h"
#include "nodedef.h"
#include "client/tile.h"
#include "mesh.h"
#include <IMeshManipulator.h>
#include "client/meshgen/collector.h"
#include "client/renderingengine.h"
#include "client.h"
#include "noise.h"

// Distance of light extrapolation (for oversized nodes)
// After this distance, it gives up and considers light level constant
#define SMOOTH_LIGHTING_OVERSIZE 1.0

// Node edge count (for glasslike-framed)
#define FRAMED_EDGE_COUNT 12

// Node neighbor count, including edge-connected, but not vertex-connected
// (for glasslike-framed)
// Corresponding offsets are listed in g_27dirs
#define FRAMED_NEIGHBOR_COUNT 18

static const v3s16 light_dirs[8] = {
	v3s16(-1, -1, -1),
	v3s16(-1, -1,  1),
	v3s16(-1,  1, -1),
	v3s16(-1,  1,  1),
	v3s16( 1, -1, -1),
	v3s16( 1, -1,  1),
	v3s16( 1,  1, -1),
	v3s16( 1,  1,  1),
};

// Standard index set to make a quad on 4 vertices
static constexpr u16 quad_indices[] = {0, 1, 2, 2, 3, 0};

const std::string MapblockMeshGenerator::raillike_groupname = "connect_to_raillike";

MapblockMeshGenerator::MapblockMeshGenerator(MeshMakeData *input, MeshCollector *output)
{
	data      = input;
	collector = output;

	nodedef   = data->m_client->ndef();
	meshmanip = RenderingEngine::get_scene_manager()->getMeshManipulator();

	enable_mesh_cache = g_settings->getBool("enable_mesh_cache") &&
		!data->m_smooth_lighting; // Mesh cache is not supported with smooth lighting

	blockpos_nodes = data->m_blockpos * MAP_BLOCKSIZE;
}

void MapblockMeshGenerator::useTile(int index, u8 set_flags, u8 reset_flags, bool special)
{
	if (special)
		getSpecialTile(index, &tile, p == data->m_crack_pos_relative);
	else
		getTile(index, &tile);
	if (!data->m_smooth_lighting)
		color = encode_light(light, f->light_source);

	for (auto &layer : tile.layers) {
		layer.material_flags |= set_flags;
		layer.material_flags &= ~reset_flags;
	}
}

// Returns a tile, ready for use, non-rotated.
void MapblockMeshGenerator::getTile(int index, TileSpec *tile)
{
	getNodeTileN(n, p, index, data, *tile);
}

// Returns a tile, ready for use, rotated according to the node facedir.
void MapblockMeshGenerator::getTile(v3s16 direction, TileSpec *tile)
{
	getNodeTile(n, p, direction, data, *tile);
}

// Returns a special tile, ready for use, non-rotated.
void MapblockMeshGenerator::getSpecialTile(int index, TileSpec *tile, bool apply_crack)
{
	*tile = f->special_tiles[index];
	TileLayer *top_layer = nullptr;

	for (auto &layernum : tile->layers) {
		TileLayer *layer = &layernum;
		if (layer->texture_id == 0)
			continue;
		top_layer = layer;
		if (!layer->has_color)
			n.getColor(*f, &layer->color);
	}

	if (apply_crack)
		top_layer->material_flags |= MATERIAL_FLAG_CRACK;
}

void MapblockMeshGenerator::drawQuad(v3f *coords, const v3s16 &normal,
	float vertical_tiling)
{
	const v2f tcoords[4] = {v2f(0.0, 0.0), v2f(1.0, 0.0),
		v2f(1.0, vertical_tiling), v2f(0.0, vertical_tiling)};
	video::S3DVertex vertices[4];
	bool shade_face = !f->light_source && (normal != v3s16(0, 0, 0));
	v3f normal2(normal.X, normal.Y, normal.Z);
	for (int j = 0; j < 4; j++) {
		vertices[j].Pos = coords[j] + origin;
		vertices[j].Normal = normal2;
		if (data->m_smooth_lighting)
			vertices[j].Color = blendLightColor(coords[j]);
		else
			vertices[j].Color = color;
		if (shade_face)
			applyFacesShading(vertices[j].Color, normal2);
		vertices[j].TCoords = tcoords[j];
	}
	collector->append(tile, vertices, 4, quad_indices, 6);
}

// Create a cuboid.
//  tiles     - the tiles (materials) to use (for all 6 faces)
//  tilecount - number of entries in tiles, 1<=tilecount<=6
//  lights    - vertex light levels. The order is the same as in light_dirs.
//              NULL may be passed if smooth lighting is disabled.
//  txc       - texture coordinates - this is a list of texture coordinates
//              for the opposite corners of each face - therefore, there
//              should be (2+2)*6=24 values in the list. The order of
//              the faces in the list is up-down-right-left-back-front
//              (compatible with ContentFeatures).
void MapblockMeshGenerator::drawCuboid(const aabb3f &box,
	TileSpec *tiles, int tilecount, const LightInfo *lights, const f32 *txc)
{
	assert(tilecount >= 1 && tilecount <= 6); // pre-condition

	v3f min = box.MinEdge;
	v3f max = box.MaxEdge;

	video::SColor colors[6];
	if (!data->m_smooth_lighting) {
		for (int face = 0; face != 6; ++face) {
			colors[face] = encode_light(light, f->light_source);
		}
		if (!f->light_source) {
			applyFacesShading(colors[0], v3f(0, 1, 0));
			applyFacesShading(colors[1], v3f(0, -1, 0));
			applyFacesShading(colors[2], v3f(1, 0, 0));
			applyFacesShading(colors[3], v3f(-1, 0, 0));
			applyFacesShading(colors[4], v3f(0, 0, 1));
			applyFacesShading(colors[5], v3f(0, 0, -1));
		}
	}

	video::S3DVertex vertices[24] = {
		// top
		video::S3DVertex(min.X, max.Y, max.Z, 0, 1, 0, colors[0], txc[0], txc[1]),
		video::S3DVertex(max.X, max.Y, max.Z, 0, 1, 0, colors[0], txc[2], txc[1]),
		video::S3DVertex(max.X, max.Y, min.Z, 0, 1, 0, colors[0], txc[2], txc[3]),
		video::S3DVertex(min.X, max.Y, min.Z, 0, 1, 0, colors[0], txc[0], txc[3]),
		// bottom
		video::S3DVertex(min.X, min.Y, min.Z, 0, -1, 0, colors[1], txc[4], txc[5]),
		video::S3DVertex(max.X, min.Y, min.Z, 0, -1, 0, colors[1], txc[6], txc[5]),
		video::S3DVertex(max.X, min.Y, max.Z, 0, -1, 0, colors[1], txc[6], txc[7]),
		video::S3DVertex(min.X, min.Y, max.Z, 0, -1, 0, colors[1], txc[4], txc[7]),
		// right
		video::S3DVertex(max.X, max.Y, min.Z, 1, 0, 0, colors[2], txc[ 8], txc[9]),
		video::S3DVertex(max.X, max.Y, max.Z, 1, 0, 0, colors[2], txc[10], txc[9]),
		video::S3DVertex(max.X, min.Y, max.Z, 1, 0, 0, colors[2], txc[10], txc[11]),
		video::S3DVertex(max.X, min.Y, min.Z, 1, 0, 0, colors[2], txc[ 8], txc[11]),
		// left
		video::S3DVertex(min.X, max.Y, max.Z, -1, 0, 0, colors[3], txc[12], txc[13]),
		video::S3DVertex(min.X, max.Y, min.Z, -1, 0, 0, colors[3], txc[14], txc[13]),
		video::S3DVertex(min.X, min.Y, min.Z, -1, 0, 0, colors[3], txc[14], txc[15]),
		video::S3DVertex(min.X, min.Y, max.Z, -1, 0, 0, colors[3], txc[12], txc[15]),
		// back
		video::S3DVertex(max.X, max.Y, max.Z, 0, 0, 1, colors[4], txc[16], txc[17]),
		video::S3DVertex(min.X, max.Y, max.Z, 0, 0, 1, colors[4], txc[18], txc[17]),
		video::S3DVertex(min.X, min.Y, max.Z, 0, 0, 1, colors[4], txc[18], txc[19]),
		video::S3DVertex(max.X, min.Y, max.Z, 0, 0, 1, colors[4], txc[16], txc[19]),
		// front
		video::S3DVertex(min.X, max.Y, min.Z, 0, 0, -1, colors[5], txc[20], txc[21]),
		video::S3DVertex(max.X, max.Y, min.Z, 0, 0, -1, colors[5], txc[22], txc[21]),
		video::S3DVertex(max.X, min.Y, min.Z, 0, 0, -1, colors[5], txc[22], txc[23]),
		video::S3DVertex(min.X, min.Y, min.Z, 0, 0, -1, colors[5], txc[20], txc[23]),
	};

	static const u8 light_indices[24] = {
		3, 7, 6, 2,
		0, 4, 5, 1,
		6, 7, 5, 4,
		3, 2, 0, 1,
		7, 3, 1, 5,
		2, 6, 4, 0
	};

	for (int face = 0; face < 6; face++) {
		int tileindex = MYMIN(face, tilecount - 1);
		const TileSpec &tile = tiles[tileindex];
		for (int j = 0; j < 4; j++) {
			video::S3DVertex &vertex = vertices[face * 4 + j];
			v2f &tcoords = vertex.TCoords;
			switch (tile.rotation) {
			case 0:
				break;
			case 1: // R90
				tcoords.rotateBy(90, irr::core::vector2df(0, 0));
				break;
			case 2: // R180
				tcoords.rotateBy(180, irr::core::vector2df(0, 0));
				break;
			case 3: // R270
				tcoords.rotateBy(270, irr::core::vector2df(0, 0));
				break;
			case 4: // FXR90
				tcoords.X = 1.0 - tcoords.X;
				tcoords.rotateBy(90, irr::core::vector2df(0, 0));
				break;
			case 5: // FXR270
				tcoords.X = 1.0 - tcoords.X;
				tcoords.rotateBy(270, irr::core::vector2df(0, 0));
				break;
			case 6: // FYR90
				tcoords.Y = 1.0 - tcoords.Y;
				tcoords.rotateBy(90, irr::core::vector2df(0, 0));
				break;
			case 7: // FYR270
				tcoords.Y = 1.0 - tcoords.Y;
				tcoords.rotateBy(270, irr::core::vector2df(0, 0));
				break;
			case 8: // FX
				tcoords.X = 1.0 - tcoords.X;
				break;
			case 9: // FY
				tcoords.Y = 1.0 - tcoords.Y;
				break;
			default:
				break;
			}
		}
	}

	if (data->m_smooth_lighting) {
		for (int j = 0; j < 24; ++j) {
			video::S3DVertex &vertex = vertices[j];
			vertex.Color = encode_light(
				lights[light_indices[j]].getPair(MYMAX(0.0f, vertex.Normal.Y)),
				f->light_source);
			if (!f->light_source)
				applyFacesShading(vertex.Color, vertex.Normal);
		}
	}

	// Add to mesh collector
	for (int k = 0; k < 6; ++k) {
		int tileindex = MYMIN(k, tilecount - 1);
		collector->append(tiles[tileindex], vertices + 4 * k, 4, quad_indices, 6);
	}
}

// Gets the base lighting values for a node
void MapblockMeshGenerator::getSmoothLightFrame()
{
	for (int k = 0; k < 8; ++k)
		frame.sunlight[k] = false;
	for (int k = 0; k < 8; ++k) {
		LightPair light(getSmoothLightTransparent(blockpos_nodes + p, light_dirs[k], data));
		frame.lightsDay[k] = light.lightDay;
		frame.lightsNight[k] = light.lightNight;
		// If there is direct sunlight and no ambient occlusion at some corner,
		// mark the vertical edge (top and bottom corners) containing it.
		if (light.lightDay == 255) {
			frame.sunlight[k] = true;
			frame.sunlight[k ^ 2] = true;
		}
	}
}

// Calculates vertex light level
//  vertex_pos - vertex position in the node (coordinates are clamped to [0.0, 1.0] or so)
LightInfo MapblockMeshGenerator::blendLight(const v3f &vertex_pos)
{
	// Light levels at (logical) node corners are known. Here,
	// trilinear interpolation is used to calculate light level
	// at a given point in the node.
	f32 x = core::clamp(vertex_pos.X / BS + 0.5, 0.0 - SMOOTH_LIGHTING_OVERSIZE, 1.0 + SMOOTH_LIGHTING_OVERSIZE);
	f32 y = core::clamp(vertex_pos.Y / BS + 0.5, 0.0 - SMOOTH_LIGHTING_OVERSIZE, 1.0 + SMOOTH_LIGHTING_OVERSIZE);
	f32 z = core::clamp(vertex_pos.Z / BS + 0.5, 0.0 - SMOOTH_LIGHTING_OVERSIZE, 1.0 + SMOOTH_LIGHTING_OVERSIZE);
	f32 lightDay = 0.0; // daylight
	f32 lightNight = 0.0;
	f32 lightBoosted = 0.0; // daylight + direct sunlight, if any
	for (int k = 0; k < 8; ++k) {
		f32 dx = (k & 4) ? x : 1 - x;
		f32 dy = (k & 2) ? y : 1 - y;
		f32 dz = (k & 1) ? z : 1 - z;
		// Use direct sunlight (255), if any; use daylight otherwise.
		f32 light_boosted = frame.sunlight[k] ? 255 : frame.lightsDay[k];
		lightDay += dx * dy * dz * frame.lightsDay[k];
		lightNight += dx * dy * dz * frame.lightsNight[k];
		lightBoosted += dx * dy * dz * light_boosted;
	}
	return LightInfo{lightDay, lightNight, lightBoosted};
}

// Calculates vertex color to be used in mapblock mesh
//  vertex_pos - vertex position in the node (coordinates are clamped to [0.0, 1.0] or so)
//  tile_color - node's tile color
video::SColor MapblockMeshGenerator::blendLightColor(const v3f &vertex_pos)
{
	LightInfo light = blendLight(vertex_pos);
	return encode_light(light.getPair(), f->light_source);
}

video::SColor MapblockMeshGenerator::blendLightColor(const v3f &vertex_pos,
	const v3f &vertex_normal)
{
	LightInfo light = blendLight(vertex_pos);
	video::SColor color = encode_light(light.getPair(MYMAX(0.0f, vertex_normal.Y)), f->light_source);
	if (!f->light_source)
		applyFacesShading(color, vertex_normal);
	return color;
}

void MapblockMeshGenerator::generateCuboidTextureCoords(const aabb3f &box, f32 *coords)
{
	f32 tx1 = (box.MinEdge.X / BS) + 0.5;
	f32 ty1 = (box.MinEdge.Y / BS) + 0.5;
	f32 tz1 = (box.MinEdge.Z / BS) + 0.5;
	f32 tx2 = (box.MaxEdge.X / BS) + 0.5;
	f32 ty2 = (box.MaxEdge.Y / BS) + 0.5;
	f32 tz2 = (box.MaxEdge.Z / BS) + 0.5;
	f32 txc[24] = {
		    tx1, 1 - tz2,     tx2, 1 - tz1, // up
		    tx1,     tz1,     tx2,     tz2, // down
		    tz1, 1 - ty2,     tz2, 1 - ty1, // right
		1 - tz2, 1 - ty2, 1 - tz1, 1 - ty1, // left
		1 - tx2, 1 - ty2, 1 - tx1, 1 - ty1, // back
		    tx1, 1 - ty2,     tx2, 1 - ty1, // front
	};
	for (int i = 0; i != 24; ++i)
		coords[i] = txc[i];
}

void MapblockMeshGenerator::drawAutoLightedCuboid(aabb3f box, const f32 *txc,
	TileSpec *tiles, int tile_count)
{
	f32 texture_coord_buf[24];
	f32 dx1 = box.MinEdge.X;
	f32 dy1 = box.MinEdge.Y;
	f32 dz1 = box.MinEdge.Z;
	f32 dx2 = box.MaxEdge.X;
	f32 dy2 = box.MaxEdge.Y;
	f32 dz2 = box.MaxEdge.Z;
	box.MinEdge += origin;
	box.MaxEdge += origin;
	if (!txc) {
		generateCuboidTextureCoords(box, texture_coord_buf);
		txc = texture_coord_buf;
	}
	if (!tiles) {
		tiles = &tile;
		tile_count = 1;
	}
	if (data->m_smooth_lighting) {
		LightInfo lights[8];
		for (int j = 0; j < 8; ++j) {
			v3f d;
			d.X = (j & 4) ? dx2 : dx1;
			d.Y = (j & 2) ? dy2 : dy1;
			d.Z = (j & 1) ? dz2 : dz1;
			lights[j] = blendLight(d);
		}
		drawCuboid(box, tiles, tile_count, lights, txc);
	} else {
		drawCuboid(box, tiles, tile_count, nullptr, txc);
	}
}

void MapblockMeshGenerator::prepareLiquidNodeDrawing()
{
	getSpecialTile(0, &tile_liquid_top);
	getSpecialTile(1, &tile_liquid);

	MapNode ntop = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(p.X, p.Y + 1, p.Z));
	MapNode nbottom = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(p.X, p.Y - 1, p.Z));
	c_flowing = nodedef->getId(f->liquid_alternative_flowing);
	c_source = nodedef->getId(f->liquid_alternative_source);
	top_is_same_liquid = (ntop.getContent() == c_flowing) || (ntop.getContent() == c_source);
	draw_liquid_bottom = (nbottom.getContent() != c_flowing) && (nbottom.getContent() != c_source);
	if (draw_liquid_bottom) {
		const ContentFeatures &f2 = nodedef->get(nbottom.getContent());
		if (f2.solidness > 1)
			draw_liquid_bottom = false;
	}

	if (data->m_smooth_lighting)
		return; // don't need to pre-compute anything in this case

	if (f->light_source != 0) {
		// If this liquid emits light and doesn't contain light, draw
		// it at what it emits, for an increased effect
		u8 e = decode_light(f->light_source);
		light = LightPair(std::max(e, light.lightDay), std::max(e, light.lightNight));
	} else if (nodedef->get(ntop).param_type == CPT_LIGHT) {
		// Otherwise, use the light of the node on top if possible
		light = LightPair(getInteriorLight(ntop, 0, nodedef));
	}

	color_liquid_top = encode_light(light, f->light_source);
	color = encode_light(light, f->light_source);
}

void MapblockMeshGenerator::getLiquidNeighborhood()
{
	u8 range = rangelim(nodedef->get(c_flowing).liquid_range, 1, 8);

	for (int w = -1; w <= 1; w++)
	for (int u = -1; u <= 1; u++) {
		NeighborData &neighbor = liquid_neighbors[w + 1][u + 1];
		v3s16 p2 = p + v3s16(u, 0, w);
		MapNode n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
		neighbor.content = n2.getContent();
		neighbor.level = -0.5 * BS;
		neighbor.is_same_liquid = false;
		neighbor.top_is_same_liquid = false;

		if (neighbor.content == CONTENT_IGNORE)
			continue;

		if (neighbor.content == c_source) {
			neighbor.is_same_liquid = true;
			neighbor.level = 0.5 * BS;
		} else if (neighbor.content == c_flowing) {
			neighbor.is_same_liquid = true;
			u8 liquid_level = (n2.param2 & LIQUID_LEVEL_MASK);
			if (liquid_level <= LIQUID_LEVEL_MAX + 1 - range)
				liquid_level = 0;
			else
				liquid_level -= (LIQUID_LEVEL_MAX + 1 - range);
			neighbor.level = (-0.5 + (liquid_level + 0.5) / range) * BS;
		}

		// Check node above neighbor.
		// NOTE: This doesn't get executed if neighbor
		//       doesn't exist
		p2.Y++;
		n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
		if (n2.getContent() == c_source || n2.getContent() == c_flowing)
			neighbor.top_is_same_liquid = true;
	}
}

void MapblockMeshGenerator::calculateCornerLevels()
{
	for (int k = 0; k < 2; k++)
	for (int i = 0; i < 2; i++)
		corner_levels[k][i] = getCornerLevel(i, k);
}

f32 MapblockMeshGenerator::getCornerLevel(int i, int k)
{
	float sum = 0;
	int count = 0;
	int air_count = 0;
	for (int dk = 0; dk < 2; dk++)
	for (int di = 0; di < 2; di++) {
		NeighborData &neighbor_data = liquid_neighbors[k + dk][i + di];
		content_t content = neighbor_data.content;

		// If top is liquid, draw starting from top of node
		if (neighbor_data.top_is_same_liquid)
			return 0.5 * BS;

		// Source always has the full height
		if (content == c_source)
			return 0.5 * BS;

		// Flowing liquid has level information
		if (content == c_flowing) {
			sum += neighbor_data.level;
			count++;
		} else if (content == CONTENT_AIR) {
			air_count++;
			if (air_count >= 2)
				return -0.5 * BS + 0.2;
		}
	}
	if (count > 0)
		return sum / count;
	return 0;
}

void MapblockMeshGenerator::drawLiquidSides()
{
	struct LiquidFaceDesc {
		v3s16 dir; // XZ
		v3s16 p[2]; // XZ only; 1 means +, 0 means -
	};
	struct UV {
		int u, v;
	};
	static const LiquidFaceDesc base_faces[4] = {
		{v3s16( 1, 0,  0), {v3s16(1, 0, 1), v3s16(1, 0, 0)}},
		{v3s16(-1, 0,  0), {v3s16(0, 0, 0), v3s16(0, 0, 1)}},
		{v3s16( 0, 0,  1), {v3s16(0, 0, 1), v3s16(1, 0, 1)}},
		{v3s16( 0, 0, -1), {v3s16(1, 0, 0), v3s16(0, 0, 0)}},
	};
	static const UV base_vertices[4] = {
		{0, 1},
		{1, 1},
		{1, 0},
		{0, 0}
	};

	for (const auto &face : base_faces) {
		const NeighborData &neighbor = liquid_neighbors[face.dir.Z + 1][face.dir.X + 1];

		// No face between nodes of the same liquid, unless there is node
		// at the top to which it should be connected. Again, unless the face
		// there would be inside the liquid
		if (neighbor.is_same_liquid) {
			if (!top_is_same_liquid)
				continue;
			if (neighbor.top_is_same_liquid)
				continue;
		}

		const ContentFeatures &neighbor_features = nodedef->get(neighbor.content);
		// Don't draw face if neighbor is blocking the view
		if (neighbor_features.solidness == 2)
			continue;

		video::S3DVertex vertices[4];
		for (int j = 0; j < 4; j++) {
			const UV &vertex = base_vertices[j];
			const v3s16 &base = face.p[vertex.u];
			v3f pos;
			pos.X = (base.X - 0.5) * BS;
			pos.Z = (base.Z - 0.5) * BS;
			if (vertex.v)
				pos.Y = neighbor.is_same_liquid ? corner_levels[base.Z][base.X] : -0.5 * BS;
			else
				pos.Y =     !top_is_same_liquid ? corner_levels[base.Z][base.X] :  0.5 * BS;
			if (data->m_smooth_lighting)
				color = blendLightColor(pos);
			pos += origin;
			vertices[j] = video::S3DVertex(pos.X, pos.Y, pos.Z, 0, 0, 0, color, vertex.u, vertex.v);
		};
		collector->append(tile_liquid, vertices, 4, quad_indices, 6);
	}
}

void MapblockMeshGenerator::drawLiquidTop()
{
	// To get backface culling right, the vertices need to go
	// clockwise around the front of the face. And we happened to
	// calculate corner levels in exact reverse order.
	static const int corner_resolve[4][2] = {{0, 1}, {1, 1}, {1, 0}, {0, 0}};

	video::S3DVertex vertices[4] = {
		video::S3DVertex(-BS / 2, 0,  BS / 2, 0, 0, 0, color_liquid_top, 0, 1),
		video::S3DVertex( BS / 2, 0,  BS / 2, 0, 0, 0, color_liquid_top, 1, 1),
		video::S3DVertex( BS / 2, 0, -BS / 2, 0, 0, 0, color_liquid_top, 1, 0),
		video::S3DVertex(-BS / 2, 0, -BS / 2, 0, 0, 0, color_liquid_top, 0, 0),
	};

	for (int i = 0; i < 4; i++) {
		int u = corner_resolve[i][0];
		int w = corner_resolve[i][1];
		vertices[i].Pos.Y += corner_levels[w][u];
		if (data->m_smooth_lighting)
			vertices[i].Color = blendLightColor(vertices[i].Pos);
		vertices[i].Pos += origin;
	}

	// Default downwards-flowing texture animation goes from
	// -Z towards +Z, thus the direction is +Z.
	// Rotate texture to make animation go in flow direction
	// Positive if liquid moves towards +Z
	f32 dz = (corner_levels[0][0] + corner_levels[0][1]) -
	         (corner_levels[1][0] + corner_levels[1][1]);
	// Positive if liquid moves towards +X
	f32 dx = (corner_levels[0][0] + corner_levels[1][0]) -
	         (corner_levels[0][1] + corner_levels[1][1]);
	f32 tcoord_angle = atan2(dz, dx) * core::RADTODEG;
	v2f tcoord_center(0.5, 0.5);
	v2f tcoord_translate(blockpos_nodes.Z + p.Z, blockpos_nodes.X + p.X);
	tcoord_translate.rotateBy(tcoord_angle);
	tcoord_translate.X -= floor(tcoord_translate.X);
	tcoord_translate.Y -= floor(tcoord_translate.Y);

	for (video::S3DVertex &vertex : vertices) {
		vertex.TCoords.rotateBy(tcoord_angle, tcoord_center);
		vertex.TCoords += tcoord_translate;
	}

	std::swap(vertices[0].TCoords, vertices[2].TCoords);

	collector->append(tile_liquid_top, vertices, 4, quad_indices, 6);
}

void MapblockMeshGenerator::drawLiquidBottom()
{
	video::S3DVertex vertices[4] = {
		video::S3DVertex(-BS / 2, -BS / 2, -BS / 2, 0, 0, 0, color_liquid_top, 0, 0),
		video::S3DVertex( BS / 2, -BS / 2, -BS / 2, 0, 0, 0, color_liquid_top, 1, 0),
		video::S3DVertex( BS / 2, -BS / 2,  BS / 2, 0, 0, 0, color_liquid_top, 1, 1),
		video::S3DVertex(-BS / 2, -BS / 2,  BS / 2, 0, 0, 0, color_liquid_top, 0, 1),
	};

	for (int i = 0; i < 4; i++) {
		if (data->m_smooth_lighting)
			vertices[i].Color = blendLightColor(vertices[i].Pos);
		vertices[i].Pos += origin;
	}

	collector->append(tile_liquid_top, vertices, 4, quad_indices, 6);
}