# How To Use {% hint style="warning" %} Unreal Engine 4.22 to 4.27 have Tutorial Blueprints built into the product. {% endhint %} ## Placing and Extending the River {% hint style="info" %} It's best to carve a river using the Landscape Editor Mode first. {% endhint %} Start by placing the `BP_FlowmapRiverSystem` Actor into the world. To extend the river out, select the end spline point `(1)` hold `ALT` on your keyboard and `LEFT CLICK` with your mouse to drag out the point, this will create a new spline point for the river.
## Branching the River For this tutorial we have a basic river shape created with the Landscape Editor Mode and built with a single `BP_FlowmapRiverSystem`.
Once the first river is placed, navigate to the *Details Panel* of the Actor and press the `Update River` button.
This will fill the `River Splits` array with all of the river's Spline Points. {% hint style="info" %} You should update your river each time you add additional Spline Points. {% endhint %} ### Branching Into Within the `River Splits` array, find the closest Spline Point at which you want to have your river branch. In this example, we're branching into Spline Point `(1)` so we will select the option `Right End`, which will split the river at the end of Spline Mesh `(1)`.
{% hint style="info" %} You can check the Spline Index Number by enabling `Show Spline Visualizers` and `Show Spline Number`. {% endhint %} Next we place down another `BP_FlowmapRiverSystem`. this will be used as the river branching into the previous one. Within the *Details Panel* of the newly placed river, navigate to the `AttachEnd` input. Select the original river for this input, and then under the `AttachEndIndex` set this to the visually split river Spline Number. {% hint style="info" %} You can use the eyedropper tool to select this river. {% endhint %}
Press the `Update River` button on the newly placed river and it should snap into location. We now want to make sure the new river has the right river split to reduce mesh overlap. In this example, `Left End` is the correct choice for `Index [2]`.
{% hint style="info" %} If you get strange results, try altering the tangents of the spline points. {% endhint %} ### Branching Out Branching out of a river is similar to branching into. In this example we branch out of `Index [3]` on the main river using the `Left Start` option.
From there we place down another `BP_FlowmapRiverSystem` into the scene. This river will be used as the river branching out the main one. We then set the `AttachBeginning` and `AttachBeginningIndex` to the main river and Spline Point `(3)`.
Next we press the `Update River` button and set the river split `Index [0]` to the `Right Start` option.
{% hint style="warning" %} Currently the river will snap into place for branching out which makes it not possible to change the tangents on that point. Doing some light landscape editing and moving the splines can fix this. {% endhint %} You should now have a branched river!
## Vertex Painting {% hint style="success" %} Vertex Painting is available in versions UE4.22-4.27, UE5.0-5.1 and UE5.5+. This includes Water Warping and Foam Painting. {% endhint %} {% hint style="danger" %} Vertex Painting is not available in versions UE5.2-5.4, as Epic removed the feature of Vertex Painting on Spline Meshes. {% endhint %} This system uses Epic's built-in `Mesh Paint` Mode for Vertex Painting. We currently have no up-to-date tutorial on using this feature, but Epic's documentation can be found here: .