A new window will pop up in which we can select a material for this layer. We'll navigate to materials -> terrain and select grass_4:
Pic3: Navigating to grass_4 material
Click Open to confirm. This material will now be assigned to the "Default" layer.
Right now, if we would start to paint the grass, not much would change, except the grass that's already there would get a slightly more grey hue. Let's change the color so it's a nice and fairly dark green, as grass usually is. To do this, in the Terrain Editor, we go to the bottom section of the tool and click on the white square next to Filter Color. A window opens in which you can select a color for the currently selected layer:
Pic4: Select Color window
We'll choose a fairly dark green, like the one in the first row, third column from the left. If you think this is too dark, you can make it a bit lighter with the vertical bar on the right. When you're happy with the color, click anywhere outside the Select Color window.
Grass only grows up to a certain height and as our level is in the mountains, we'll certainly reach that height. Also, it doesn't grow on slopes that are steeper than a certain angle. To make sure our grass doesn't grow on any surface that it wouldn't be seen in nature, we'll set a few rules. In the Terrain Editor, below the Layers window, you'll see a number of Layer options:
Pic5: Layer options in Terrain Editor
In our level, there's a lake, and the edge of this lake will be covered in mud up to a certain height. We'll do that in the next step, but as the grass will start where the mud ends, we'll have to set the Min Height to 19. This will be the Max Height of the Mud layer later on. Also, we'll set the Max Height to 26, because like we said before, grass doesn't grow above a certain height.
To make sure our grass isn't painted on slopes that are too steep, we'll also set the Max Angle to 50 degrees. 0 degrees means a flat surface, and we definitely want the grass to grow there, so we can leave the Min Angle as it is.
Now we're ready to paint. Click the large Paint button in the bottom section of the Terrain Editor:
Pic6: Paint button
You'll see that some new options appear for the size of the brush. Adjust the size to something you feel comfortable with and click and drag the brush over the level to paint the ground.
To add a texture, we'll choose one in the same way as we chose the Material: by using the Browse button next to Texture in the bottom of the Terrain Editor and navigating to the texture that we want:
Pic7: Texture browse button
The grey.dds texture that's already set is located in Assets\textures\defaults, which should already be open.
Now that you've added all these layers, the level should look a bit like this:
Pic8: All layers implemented
That doesn't look too bad at all, does it?