Tutorials
Make a bubble in Houdini 16
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part 2: SHADING
01The Classic Shader Author Joshua Matthews Joshua Matthews is currently interning at SideFX in Toronto, where he is improving his skills with Houdini each and every day! www.joshuamatthews.com/
In this example, we will be using the Classic Shader, which was previously known as the Mantra Surface. The Classic Shader settings will need to be tweaked to give a proper base for reflections and refractions. I first enabled Coat Reflections to give the illusion of having a reflective layer on top. Then I enabled Refractions and increased the Intensity to 1.5. After changing these settings, the shader should look like a thin glass.
Dispersion and GGX 02 Using
Dispersion is a parameter in the new Houdini 16 shaders that changes the colour of the refraction based on the frequency of the
02 wavelengths in your lights. This creates the rainbow effect that you see in diamonds or caustics from glasses. This feature is only available with GGX refractions, so be sure to change the refraction model from Phong before rendering.
03 Faux Fresnel
Bubbles tend to have more reflections and distortions around the outer edge of the bubble, while the inside tends to be mostly transparent. This is due to fresnel reflections, which are when a material has two differing indexes of refraction. Opacity Falloff can emulate this effect inexpensively,
and is how I got my bubble to stay transparent on the inside, while maintaining the reflections and refractions on the outside.
04 Curl Noise
To push the bubble’s colours, add Curl Noise to the base colour of the shader to emulate an oily sheen on the surface. Because Curl Noise is a 3D noise, it will translate to RGB when added to the shader. Inside of the Material Network, place a Global Variables, Transform, and Curl Noise vop. Connect the nodes as in image 04 and ensure that the Transform is changing from current to world space.Â
Rendering tip
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For the best rendering results, use an HDRI image in an Environment Light to create nice crisp reflections on your created objects.
04 SideFX Houdini
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