How To Use

Previous UE versions have Tutorial Blueprints built in. (UE4.27 and Under)

Placing and Extending the River

It is best to carve a riverbank out using the landscape editor mode first.

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 i have carved out a basic river shape within the landscape editor and built out a single BP_FlowmapRiverSystem down it.

Once you have your main river artery 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 your current river spline points.

You should update your river each time you add additional spline points

Branching Into

Within the River Splits array, find the closest spline point at which you want to have your river branch.

In this example I'm branching into spline point (1) so i will select the option Right End which will split the river at the end of spline mesh (1)

You can check the spline index number by enabling Show Spline Visualizers and Show Spline Number

Next i will place down another BP_FlowmapRiverSystem into the scene, this will be used as the river branching into the previous one.

Within the details panel of the newly placed river system, 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.

You can use the eyedropper tool to select this river.

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]

If you get strange results, try altering the tangents of the spline points.

Branching Out

Branching out of the river system is similar to branching into, in this example i will branch out of Index [3] on the main river using the Left Start option.

From there i will place down another BP_FlowmapRiverSystem into the scene, this river will be used as the river branching out the main one.

I will then set the AttachBeginning and AttachBeginningIndex to the main river and spline point (3)

Next i will press the Update River button and set the river split Index [0] to the Right Start option.

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. (We are working on an update to change this)

You should now have a branched river!

Vertex Painting

This has been disabled in UE5.2+ as epic removed the feature of vertex painting on spline meshes.

We will use epic's built in Mesh Paint mode for vertex painting.

COMING SOON: Vertex Painting Tutorial for UE5.1 and under