This is a method for enabling UDK to use textures larger than its default limit. Conventional wisdom says that game textures should be highly optimized, but large resolution artwork is always enticing for many designers, and computers are getting better all the time. Performance issues aside, it's a good goal to push the graphic envelope and larger textures allow detail to hold up better on close inspection.
We've provided one really large texture that is 4096x4096 that you may find convenient, intended for use as a Skydome. If you are going to use a large texture it would most likely be on a very important model like a key character always close to the camera or else of a very large model which is always visible, such as a Skydome, or Skybox. A simple tutorial for making a Skybox is at http://www.worldofleveldesign.com/categories/UDK/UDK-how-add-skybox.php but this recipe assumes the use of a provided one.
- With UDK closed, open
C:UDK~UDKGameConfigDefaultEngineUDK.INI. - Press Ctrl + F in ConTEXT and search for Skybox. You should be directed to line 127:
TEXTUREGROUP_Skybox=(MinLODSize=512,MaxLODSize=2048,LODBias=0,MinMagFilter=aniso,MipFilter=point). - Change the value for
MaxLODSize=2048to4096. To really force it, you can also set theMinLODSize=4096too. Doing this for a Skybox is okay, since there's normally only one used in a map, but you'd risk slowing the game down to do this with regular textures. Note, theTEXTUREGROUP_Skyboxwill allow a texture for a Skybox to be large, but not other things like character textures. For that, you can edit the relevant values in the otherTEXTUREGROUPlines. Further down, in the SystemSettingsMobile section, the texture sizes are much smaller, which is due to the relatively limited processing power of mobile devices. - Now save, and next we'll verify this in fact worked by adding a large sky to a scene in UDK.
- Look in the Content Browser and search the Packt folder for Packt_SkyDome, which is a typical mesh for a sky. You can see there is a completed version, and a copy called Packt_SkyDomeStart which has no material.
- Go to the Packt texture group. You will see there is already a provisioned 4096x4096 texture for Packt_SkyDome, but let's import a fresh one.
- Right-click in the Content Browser panel and choose Import, and browse to find Packt_SkydomeStart.PNG which is just a copy of the already existing texture. The reason to import it, is to verify you understand the compression setting.
- In the options you will see a panel that lets you specify the name info, which you should enter as Packt.Texture.SkyDomeTest or something unique. Further down you will see the compression settings. Choose LODGroup and from the expanding list choose TEXTUREGROUP_Skybox, as shown in the next screenshot, since this is what we have set to have 4096x4096 compression enabled in the configuration:
- The file may take some time to process, given its size. Once it is complete you can create a new Material Packt.Material.SkyDomeTest_mat. Open it and in the Material Editor hold T and click to add the highlighted SkyDomeTest texture to the Emissive channel. Skies are self lighting, so in the PreviewMaterial node's properties, set the Lighting Model to MLM_Unlit.
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The mesh Packt_SkyDomeStart is already UV mapped to match the texture, and if you double-click on it you can assign the new Material Packt.Material.SkyDomeTest_mat in the LODGroupInfo by expanding until you access the empty Material channel. Select the Material in the Content Browser then use the assign icon [
] to assign it.
- Then you can save the package and place the mesh in the level. Be sure to access its properties (F4) and under the Lighting turn off Cast Shadow and set the Lighting Channels tick on Skybox and uncheck Static, as shown in the next screenshot:
- You could scale the mesh in the scene to suit, and perhaps drop it down below Z=0 a little. You could also use an Exponential Height Fog to hide the horizon.
- Since there is a specific sun shown in the sky image, you will need to place a Dominant Directional light in the scene and rotate it so its arrow (representing its direction) approximates the direction the sunlight would be coming from. It would be appropriate to tint the light warmly for a sunset.