Blast bubble

Production idea

1 Create an exploding bubble effect in Houdini, split into bubbles and foam

2 The foam portion is reduced to about 5000 using Remesh and Attrubute blur nodes and exported as VAT

3 Bake the bubble part using UV to create a mask map. Use the homemade SDF tool to generate SDF and gradient mask maps

4 Write shader in Unity using gradient mask to make bubble burst animation, with VAT model to achieve the full effect

5 Draw a Flow map in Houdini to simulate bubble surface flow

6 Unity uses Flowmap to perturb the normal map to create a surface flow effect

7 The water in the vacuole will flow from the top down, so the top is thin and the bottom is thick. Then superposition the maximum noise disturbance of the normal, plot the thickness as the X-axis of spectral sampling

8 The Angle is calculated using the normal and line of sight directions as the Y-axis of the spectral sampling

8 Spectrograms are sampled using thickness and Angle

9 Sample the sky box twice in opposite directions, using thickness mixing to simulate double-sided reflection

10 Because the film interference is also obvious where the bubble is reflected, a brightness map is made with the result of the reflected sky box, and the film interference pattern is multiplied

11 Finally, the film interferogram and the sky box are added together

12 Foam is also interfered with film. But the foam is much thicker than the ball, so map the thickness to a thicker range. Finally, a subjective color adjustment: I want the foam to be about the same brightness as the brightest part of the ball, so that the foam becomes the visual center when it explodes.

13 Bubble and foam overlay output

Exploding bubble

Production idea

Reference list