Instead of rendering textured billboards, this technique called “Mega Particles” render spheres to an off-screen texture. This texture is then blurred and randomly displaced using a fractal cube. The final result is carefully blended into the scene, taking depth into account. The result is a volumetric cloud that is lit by lighting and truly look volumetric. The problem is that this technique suffers from the shower-door effect which can make it really annoying to use in practice. It’s also harder for artist to control the final look. Also, going inside the cloud requires special treatment not even mentioned in the slides. But nevertheless, it’s an interesting approach that certainly can be developed furthered. At least one optimization could be to not render actual spheres, but instead billboards holding the sphere info.

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