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Creating a Dynamic Wet Map Shader in Houdini

by Jeff Wolverton

This tutorial introduces a new method for simulating wet objects, a shader-based method that first generates a 3D cloud of animated wet points, then by creating a shader that will use this data to shade the wet, previously-wet, or drying parts of the character that were previously in contact with a fluid. Software required: Houdini 14.

What you'll learn

To realistically simulate fluids (water, blood, paint, oil, etc.), often a wet map is required to change the shading of an object where the fluid comes into contact with an object. These need to animate, not only while the fluid is active, but also afterwards to simulate drying. The usual solution, generating a wet map, or fixed set of images for a texture map, has several drawbacks: fixed resolution, color depths, and difficulties applying across objects or to subsequent shots in the film. This tutorial introduces a new method for simulating wet objects, a shader-based method that first generates a 3D cloud of animated wet points, then by creating a shader that will use this data to shade the wet, previously-wet, or drying parts of the character that were previously in contact with a fluid. This will be accomplished without any need to create or rerun the original fluid simulation. Software required: Houdini 14.

About the author

Jeff Wolverton has been working on visual effects for major motion pictures for over 15 years, having created signature effects for Sony Pictures Imageworks, Digital Domain, Rythym & Hues, Framestore, MPC, Disney, and Dreamworks. He specializes in unique and unusual procedural effects, as well as the standards (fire, water, smoke, destruction, dust, fluids and atmospheric effects). He was also the screenwriter for the Academy Award-winning animated short, The ChubbChubbs!

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