View source for An Advanced Terrain and Megatexture

This guide will show you step by step, on how to create a detailed Megatextured Terrain.
[[Image:AdvMega_Intro.jpg|right]]

= Introduction =
'''For this tutorial you must:'''
* Have a modelling package that can export as LWO, ASE or OBJ
* Have basic modelling skills
* Have basic mapping skills, as in [[A Simple First Map]]

'''This tutorial covers:'''
* Steps to create a detailed terrain mesh.
* How to assign the Megatexture
* How to add the terrain mesh to a map
* How to make a Megatexture
* How to compile a Megatexture
* How to add Water to a map

'''Programs used in this tutorial are:'''
* Mudbox
* World Machine
* Lightwave
* Maya (only used briefly)
Other similar programs can be used instead of these, but wont be covered in this tutorial.

'''This tutorial does not cover in detail:'''
* How to use Mudbox / ZBrush / World Machine / Blender / Lightwave / Maya / 3DSMax

'''If you already have a terrain mesh''', and do not want to use Mudbox and World Machine, skip to [[#Prepare Terrain for Megatexture|Prepare Terrain for Megatexture]] .


= Mudbox: Shape the Terrain =
[[Image:AdvMega_Mudbox.jpg|thumb|128px|right|Mudbox Layers]]
These are the basic steps for sculpting a terrain in Mudbox.
* Create a plane, and subdivide (but still keep a low tessellation).
* Change any tools you use to have the edit ''Direction'' set to ''Y'' axis.
* Create a new Layer, and sculpt the rough layout for the terrain.
* Subdivide again to as detailed as you want (or can).
* Create another layer, and sculpt more details into the terrain.
* Export to OBJ.







= Convert Mesh to Heightmap =
This step is needed  if you want to import your current terrain mesh into World Machine.
* Firstly, rotate the terrain mesh. In Lightwave, rotate -90° around the X axis. For 3ds Max & Maya, rotate +90° around the X axis.
* Cap any holes in the mesh, and triangulate. Using a machine with an nVidia graphics card, run the following command in the ETQW console to get the heightmap (where [model] is pointing to the relative path of the ''.lwo'', ''.obj'' or ''.ase'' mesh):
 ''RenderBumpFlat –floatHeightmap -size 2048 2048 [model]''
* An .r32 (raw 32-bit) heightmap will be saved into the same folder as your model, and this heightmap can be used in World Machine.


= World Machine: Adding Flow =
[[Image:AdvMega_WorldMachine.jpg|thumb|320px|left|World Machine Device View]]
[[Image:AdvMega_WM_Output.jpg|thumb|150px|right|World Machine Heightmap]]
[[Image:AdvMega_WM_Flow.jpg|thumb|100px|right|Flow Map]]
[http://www.world-machine.com World Machine] ([http://world-machine.com/blog/ World Machine Blog]) is used to add erosion flow lines to the terrain.  It's also useful as the flow maps can be exported to help create masks for texture distribution later in [[Terrain_Editor|Terrain Editor]].  These are the basic steps made to build the World Machine device nodes.
* Blend the heightmap made from the Mudbox mesh with perlin Noise to help the Erosion filters.
* Use a snow filter around the rocks (mask used), so rocks look like they are sitting in soil.
* Pass the heightmap through two Erosion nodes, which are set up differently, and combined give a natural flowing look.  Both Erosion nodes are masked around the rocks, so they will keep their shape.  The first Erosion node is setup as ''Channeled Erosion'' with an ''Inverse Filter'', calving large flow lines into the terrain.  The Second is a ''Channeled Erosion'' set with ''No Filter'' , adding finer detailed flow lines.
* The heightmap output of the erosion is split so the heightmap can be saved (and later used to create a mesh), and further filters created (sediment and normal map) to help make masks for texture distribution later.
* ''Flow'' and ''Deposition'' maps from the Erosion nodes are passed through ''Simple Transformation'' nodes that brighten the output saved.
* The heightmap saved above is imported and rendered at a lower (usable) resolution to the ''Mesh Output'' node creating an OBJ mesh.





= High to Low poly =
[[Image:AdvMega Dags.jpg|thumb|320px|right|Polygon Dags to Delete]]
This stage will briefly explain how the high poly mesh exported from World Machine, can be reduced down to the low poly game mesh.
* Load the OBJ exported from [[#World Machine: Adding Flow|World Machine]] into your preferred 3d Application.
* Rotate so it's orientated correctly.
* The outer mesh border will look like it's been dragged down (an artifact from the mesh being built from a heightmap). So remove this by selecting the mesh border polygons and delete.
* Triangulate and save out as OBJ, so it can be loaded into Lightwave.
* In Lightwave use a plug-in called [http://amber.rc.arizona.edu/lw/qemloss3.html qemLOSS3](once installed, found in the Utilities tab) to reduce the polygons to a reasonable amount (Enemy Territory : Quake Wars used around 32,000 polygons for the 32,768 unit width terrain).  If you have trouble running qemLOSS3, apply a different material other than the default.
* Fix edges that are triangulated in the wrong direction.
* Smooth subdivide the mesh, and run your mesh through qemLOSS3 again (to the same polycount as before).  This will give a smoother terrain, easier for gameplay. Reapeat until you're happy with the mesh smoothness.
* Again fix edges that are triangulated in the wrong direction.
* If you plan on having water, cut the mesh along the waterline. So no polygons are both above or below the water.  This is so [[#Water Fog|water fog]] has a clear line where to stop.




[[Image:AdvMega_UV.png|thumb|200px|right|UV Layout]]
=== UV the Terrain ===
This process is written for Maya, other 3d packages will have to modify the process.
* To achieve relaxed UV borders use a mel script called worldSpaceUVLine - it can be found on [http://Highend3d.com/maya/downloads/mel_scripts/modeling/poly_tools/4508.html Highend3D]. Copy the .mel into your ''My Documents\maya\#.#\scripts'' folder and run by typing '''''worldSpaceUVLine;''''' in the Maya command line.
* Snap all 4 corners to the UV 0-1 square.  Select all the edge uv for one side, and in the worldSpaceUVLine tool select the corresponding UV layout direction (U for horizontal, V for vertical), and press the align UV’s on selected line button. Repeat for each side.
* Make sure all holes in the mesh are capped, and run the Relax UVs tool, with the option ''Edge Weights'' set to ''World Space'', and ''Pin UV Border'' selected.  Keep repeating Relax UVs until you see no more UV movement.







[[Image:AdvMega_LowPoly.jpg|thumb|400px|left|Low Poly Mesh with Local Map]]
[[Image:AdvMega_Perturbate.jpg|thumb|200px|right|Perturbate Image (Tangent Space Local Map)]]
=== Perturbate Image (Normal Map) ===
The Perturbate Image is an image that is [[#Construct the Megatexture|applied to the megatexture]], and corrects the low poly mesh normal to match that of the high poly.
* Load the high and low poly mesh into your preferred 3d Application.
* Surface sample the high poly normals onto the low poly, with normals set to tangent space.
* You Probably will need to fix the normal map channels (red and green) as the 3D Application use normals maps differently to the Game.  Make sure the green channel has white facing down, and red has white facing right.

=== Convert World Machine masks to UV space ===
All the masks created created in World Machine (flow, deposition...) wont match the new game mesh UV's
* Load the high and low poly mesh into your preferred 3d Application.
* Duplicate the game mesh and apply a planar UV projection.
* Apply the masks created in World Machine to the planar mapped mesh.
* Surface sample the diffuse from the planar mapped mesh, onto the game UV mesh.
Also render the mesh normals (world space) to an image.  The blue channel will become useful when creating distribution masks, as it represents how vertical a polygon is.


= Prepare Terrain for Megatexture =
Now the mesh is nearly ready for the game, just a couple more steps.

=== Prepare the Mesh ===
* Scale the game mesh to the correct size, as after converting from a heightmap it probably isn't the right size.  This tutorial mesh is a small 8,192 x 8,192 unit mesh (again the Enemy Territory : Quake Wars terrains were 32,768 x 32,768.
* Rename the material to ''megatextures/sdk/terrain_mesh_sdk'' (''megatextures/'''<map_name>'''''). Maya will have problems with this naming convention.
* Set the Mesh normals to be smooth.
* Save the mesh to ''base/models/terrain/sdk/terrain_mesh_sdk.lwo'' ('''''<map_name>'''.lwo'' or ''.obj'' to ''base/models/terrain'').

=== Setup the Material ===
* Create ''base/materials/megatextures_sdk.mtr''
* Add the following text, to create the material, and save:
 ''material megatextures/sdk/terrain_mesh_sdk	{ useTemplate megatextures/default_ambient< "sdk/terrain_mesh_sdk" > }''


= Construct the Megatexture =
This section will cover the step by step creation of the megatexture using Terrain Editor (an inspector tab in EditWorld).  For Detailed explanation on feilds and setting not discussed here, check out the [[Terrain_Editor|Terrain Editor]]

=== Set up the Map ===
* Load EditWorld, and create a new map.
* Bring up the [[Terrain Editor]] inspector.
* {{accelbtn|RMB}} in the left blank (white) area.  In the pop-up menu select ''New'' | ''Tree...''
* On the Root node set the model field to ''base/models/terrain/sdk/terrain_mesh_sdk.lwo'', and also set the ST Model to the same model.  If you have holes in your mesh (holes cut for buildings), you'd need to make a separate ST Model version with no mesh holes.
* Seal the map up by [[A_Simple_First_Terrain#Creating a Caulk Hull|Creating a Caulk Hull]].  Make sure the origin of the terrain mesh is inside this hull.
*For the area to be lit by the sun, create a brush inside the caulk hull, textured with 'editor/outsideportal'.
*To set the atmosphere create an Atmosphere entity and set '''atmospheredecl''' to '''Valley01''' (or what ever atmosphere you're using).

=== Detail Textures ===
Also on the Root node is where the detail textures are assigned. In each of the layers created, you assign which of these 4 detail textures to use. Detail Textures need to be a greyscale 512x512 texture (preferably saved in ''base/textures/detail/'').
{| cellspacing="8" border="0"
|Detail Texture 0
|
|'''textures/detail/temperate_dirt.tga'''
|-
|'''Detail Texture 1'''
|
|'''textures/detail/temperate_grass.tga'''
|-
|'''Detail Texture 2'''
|
|'''textures/detail/temperate_gravel.tga'''
|-
|'''Detail Texture 3'''
|
|'''textures/detail/temperate_rock.tga'''
|}

=== Image Sources ===
Here we'll start to create the texture layers that build up the Megatexture.

;Ground_Base
* Create a '''Group node''', {{accelbtn|RMB}} and  with the pop-up menu select ''New'' | '''Group'''. In the right field you can enter a name for the Group, we'll name this one '''Ground_Base'''.


;Dirt
* Now we'll create a base '''Image Source''' node. {{accelbtn|RMB}} over the Group node, and create an '''Image Source''' node, this should create it as a child to the Group.  If you accidently created the Image node under the Root, don't worry as you can drag and release over the Group node to make it a child.  Name the Layer '''Dirt''', same way as the Group node.
* Apply a Diffuse texture by selecting '''Diffuse''' on the right hand panel of the inspector, then selecting the '''File Name''' field and press the '''...''' button to choose a texture.  For this layer we'll use '''textures/megagen/temperate/dirt_06_d.tga'''
* Repeat the same process for the '''Local''' image by selecting '''Local''' on the right, and applying the texture '''textures/megagen/temperate/dirt_06_local.tga'''
* As this is the base layer, the '''Distribution''' needs to cover the whole map.  So apply a full white image the same way as above but to the '''Distribution'''.
* This layer is a dirt layer so I'll set the the '''Detail Texture Type''' to '''0''', to match the number for the dirt detail texture.
* Also as this layer is dirt I'll set '''Sur Type Properties''' | '''Type''' to dirt. For a full list of usable surface types, check the [[Terrain_Editor#Surface_Type|Surface Type]] section.
* The diffuse texture has the dimensions 1024 x 1024, while the map covers 8192.  To keep the correct texture ratio, set '''Texture Properties''' | '''Scale''' to '''8 8'''.
* '''Texture Properties''' | '''Rotation''' is set to '''270''' to keep the to match the texture lighting to that of the atmosphere.


=== Road Tool ===

=== Projector ===



= Compile the Megatexture =

=== Setup Renderlight ===




= Stamps =


= Add Water =

=== Water Mesh ===

=== Water Volume ===

=== Water Fog ===