In this tutorial I will show you how to use our advanced patch editing tools to create nice looking blended terrain.

In this tutorial we will be creating a simple strip of terrain that blends from grass to dirt. To do this we will be creating three patches of terrain. To do this, create a brush the size of the first patch of terrain (we will make it square). Once you have the brush created and selected go to the "Patch" menu and select "Simple Terrain Mesh". You will then be prompted to enter a terrain density, we will use the default values of 3/3 in this tutorial so click OK.

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So now that we have created the first patch we can just copy it to create the others. Select it and press the space bar to make a copy and position it next to the original patch. Copy it again and position it on the opposite side creating 3 patches in a row.

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Now we need to apply textures to the patches. In order to do alpha blending on the terrain patches you need to use a texture that has been set up to do blending and contains an alpha channel. In this turoial we will use a grass texture found in the normany folder. Go to the "textures" menu of CoDRadiant and go to Normandy -> Ground. This will load all textures from textures/normany/ground into the texture viewer. We'll use the first one in this list which is called "a_grass1". Apply the grass texture to the middle patch and one of the end patches.

One the third patch (should be on one of the ends) apply one of the dirt textures from the same location. Just scroll down the textures a ways until you find one you like. I chose "dirt@earth_2" in this tutorial.

You might notice that the textures tile badly so you'll want to cap them and put them in world coords. To do this, hilight all three patches and press "S". This will open the Surface Inspector window. Click "CAP" then "Cancel" since we dont want to apply any of the other settings in that window. You should now have something like this...

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Now in order for us to blend the grass into the dirt we need to create another patch that we will blend. Select the middle patch and make a copy (space bar) and move it down to a temperary spot for now (or hide it if you know how to use the hide stuff). In this tutorial I'm just going to move the copy down out of my way for now and select the middle patch like this...

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Now we have the middle patch selected. This is the patch with grass that should blend into the dirt patch next to it. To do this we need to paint alpha to the patch. While the middle patch is selected press "Y". This will open the Advanced Patch Editing Options. As you can see there are several options in here. This tutorial will cover the alpha features. I might write tutorials for the other features in the near future. Select the "Flatten" option and the "Alpha" option. Also uncheck the "Allow soft selection on unhighlighted patches" option because we only want to paint on the selected patch. We will use the 3d view for the next section. You should have something like this...

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You'll notice that you get a paint brush in the 3d view on the selected terrain. You can change your brush size and amplitude in the dialog but the default values will work fine in this tutorial. Now, the fun part. Hold down Alt and click and hold the left mouse button. This will start to paint vertex alpha on the verts of the patch. As you click and drag around you'll continue to paint alpha transparency on the patch of terrain. You can only paint on the verticies of the patch (the dots). If you want to undo the alpha you can use the same method with the right mouse button. We want to make the patch blend from full grass to no grass. The side of the patch that has the dirt next to it will need to completely be transparent. Here's what it should look like once you've finished painting the alpha to the patch...

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Once to get to this point the rest is easy. Close the Advanced Patch Editing Options window by pressing "Y" again. Then select that patch we created before that was moved out of the way. Apply the dirt texture to that patch as well (the same one you already used) and move that patch to the same location as the patch you were just painting alpha onto. You should then have 2 patches in the middle in the exact same spot (one with dirt and one that has the alpha blend) and one on each side of those. By default the new dirt patch in the middles texture won't line up with the dirt texture of the patch next to it so be sure to "CAP" the new dirt patch you just placed into the middle (You could also select all patches again, press "S" and click "CAP", then click "Cancel" if you dont want to do it individually). You should now have a nicly blended row of patches that blends from grass to dirt.

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