Guide: Procedural Plant Growth in Houdini
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Those animations look amazing!! Great job!

Very cool review of the making of Spellbreak. Would be even more cool to see some videos inside UE4 showing how they do a few very specific things unique to them.

This was so helpful for me. I'm hoping to adapt your tutorial to pull off something similar comparing modern satellite imagery with historical maps. No topo, so my steps should be simpler, but I'm a novice with Blender and you've really helped. Thanks!

Guide: Procedural Plant Growth in Houdini
24 October, 2017

Houdini has always been about the procedural approach. Set up some nodes and a few expressions to realistic results — just like that. The thing is that many artists believe the tool is to complex to master. The times they are a changin’. Houdini now provides a new interface and all sorts of helpers that make it easier to use the tool. 

Creative Bloq has shared a tutorial that gives an overview of the tool. Start with some basic modeling techniques for leaves and grass to see how easy it can be to get started. The guide covers sampling VDB volumes to distribute plant growth and the use of VEX code and wrangle nodes to generate geometry on the fly.

01. Get organised

Make life easier for your future self by giving your shapes meaningful names

Start with a model of a ruin you want to cover in foliage. Make sure you name your shapes in a meaningful way. This allows easy grouping of the geometry for different purposes later. Split it up into walls, planks, bricks, windows and glass. Houdini alembic import will set a path attribute on import. You can then easily use a split or blast node to select the pieces you want.

02. Create the leaves

Make your leaves single-sided with a low poly count

With the ruin in place, it’s time to begin creating individual leaves to use later for instancing. Always work with reference images from nature if you want more realistic results. We need the leaves to be single-sided and of fairly low poly count. Start off by making a curve to resemble the outer leaf shape. Use a remesh node to add some surface tessellation. With a soft transform, slightly lift out the centre at the stem. Also add a colour attribute with different shades of green.

03. Grass strands

Put as much variety into your grass strands as you can

We also need individual strands of grass to cover the floor. Again, simple one-sided polygonal strands with varying width are sufficient. Generally speaking, more variation is always better. But even with just five different shapes, you will achieve quite realistic results. As our setup is procedural, more can easily be added later. It’s important to make sure all meshes are centred at the origin with the pivot at their foot. This way we can use them as instances straight away.

Creative Bloq 

You can find the full guide here

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