Psychedelic - Op-Art

Optical effects with animations of textures.

The cyclic animation of textures
Besides of the camera and geometric objects, also textures can be animated. We can achieve by this op art like psychedelic and nearly hypnotic effects.
Here the phase of the "normal" component of a texture is modulated:

normal { onion sine_wave phase -1/4*pi*clock }

For this effect the pattern "spiral1" was used twice: once in a "color_map" the second time in the "normal" component and the texture is rotated continuously around:

Another nice effect using the pattern "gradient y" with stripes from red to yellow and "turbulence" modified with clock: