At this point I have reached the final instruction for the semester before creating a level from scratch. This entry will involve decals and roads. Decals are visual details that may be placed on the ground or on objects/brushes/assets to proved specific detail, as opposed to texturing a brand new asset for every new detail you want to add. Rollup Bar>Objects>Misc>Decals:
Decals are used frequently on level design after you have created the basic terrain and textures. Rather than place decals as you create terrain, it is more efficient to essentially do a decal-pass after everything else is set up.
Above you can see the red decal. Isn’t that amazing? Don’t you just love bright red squares? Hooray for bright red squares! This is your gizmo for identifying and placing the decal. Also note that follow ground surface option (circled in red) is activated. This ensures that the decal is placed properly on the ground surface. A decal is essential a flat, 2D polygon with a texture that rests on surface. It can be flat, or it can be made to conform to the changes in the surface, for example over a bump, or up the side of a wall. In the same way that splashes and wakes can hide seams transitions from streams to waterfalls over rocks, decals can also hide seams between the ground and other aspects of the environemnt:
In the above image, lower left, is a decal of orange fungus. I enhanced the saturation so that it would be easier to see in this example. Note how the decal is simultaneously on the ground surface as well as on the vertical rock surface.
Decal visibility can be controlled by ViewDistRatio (Rollup Bar, attributes). This is helpful if you are having performance issues and you only want the decal to be visible as the player comes within a certain distance. This means that the engine does not have to process the decal until necessary. This option exists for just about any renderable entity, as a matter of fact.
Important!: Shift + CTRL + ALT left-click enables quick placement of decals that align automatically to surface normals. This way you can quickly copy and place decals rather than needing to place a new decal step-by-step each time. This applies to other brushes,archetypes etc in your level.
As you go through this process you may want to change decals. Simply click on the current material shown in your Rollup Bar, select a new decal, and then press the Assign Item to Selected Objects (circled in red):
As you can see by the list on the right of the Material Editor, the sandbox comes with a large variety of decals to get you started. Once you click inside the list oyu can use the arrow buttons on your keyboard to quickly scroll through the decals and see how they look before applying them (above left).
As with Particles and Boids, Decals provide immense possibilities for detail and level characteristics. What we see here is only a brief introduction.
Roads
Roads are any kind of meandering path that should be defined: street, dirt path, gravel road etc. As with decals, roads are created by Rollup Bar>Objects>Misc>Roads.
Make sure you have Follow Terrain (red circle) activated. From there you just click each new point as you want the road to follow. Easy, right? Note how the road is just red decals that repeat. Double-click to finish the road process. Once again, open Materials and select a material, and below you can see a road with a tiled material:
Once a material is selected, you can control various attributes in the Rollup Bar, such as width and tile length (StepSize). TileLength controls the tiling/stretching and repetition of the texture. Lower values yield more tiling, which is bad. However, values that are too high will stretch the tiles, creating bad artifacts as well. The idea is to find a balance between StepSize (lower StepSize means more polygons, which is generally bad) and TileLength to create a good looking result.
Above you can see an artifact where the road texture has a gap. This is because two points of the tiled texture are too close or are overlapping. Note the purple control points circled in red. These can be easily dragged with instant results to remedy such issues. To activate this mode press Edit (above, right). Also note that CTRL-click on the line defining the road instantly creates another point that can be dragged to alter the path of the road. Shift-double-click on a point deletes it.
An interesting and useful trick is using roads to create terrain.
Above you can see a road form has been built out over the surface of the water. Also note that XY has been activated in the top tool bar. This controls level of the road out over the water. Note on the bottom right, above, in the Rollup Bar, you can click on Align Height Map. This yields the following results:
Pretty cool, right? This technique can be used for advanced control when terrain modelling. The road control points can be raised and lowered to create vertical variation:
One last note on roads is that a road can split into multiple entities, or rejoined (Merge) by the control points. This is useful if you want natural gaps in the road without creating a brand new road from scratch.
Certain areas on the edges of roads can be cleaned up with decals. Rocks and other items can be added to create natural variation, as well.
So, that’s it for now. We have covered a large amount of ground and certainly enough to make a basic level, which is what I will begin now.
Eric Chamberlain 