Animation Store 
Real Rainbow
Rainbows that follow the physics
Real Rainbow puts a rainbow in your scene the way the sky makes one. The colours, the width of the bands, the bright sky inside the bow, the dark band between the two bows and the much fainter secondary bow are all computed from how sunlight passes through drops of water. The bow is then lit by your own sun lamp, so it has the right brightness and colour for your shot without hand tuning.
Features
• 24 rainbow and halo types in a thumbnail gallery: everyday bows, rare bows, ice halos and glories, halos around lights, and stylised looks.
• Physical colours. A spectral model of light in water drops (Airy theory), checked against exact Mie scattering. Change the drop size and the bow changes the way a real one does: extra fringes for small, even raindrops, a broad white fogbow for fog.
• Lit by your sun lamp. The bow takes its brightness and colour from the scene's sun, so a low, warm sun gives a warm bow. Link the sun and the bow stays exactly opposite it, even when you animate the sun
• Light Halos. Select lamps or glowing objects and add rainbow rings around them: the halo your eyes see around street lights at night, coronas in mist and thin cloud, and the 22° ice halo. Their brightness follows the light live.
• Animation. Grow the bow along its arc with Reveal (one click sets the keyframes), break it into patches of rain with Breakup, and let the patches drift with Shimmer.
• Looks and Artistic mode. Four one-click Looks (Natural, the physical default, plus Vivid, Dreamy and Bold), with hue, saturation, bloom and opacity in either mode. Artistic mode paints the bands from an editable colour ramp with 12 palettes, for stylised and cartoon work.
• Seven demo scenes, built procedurally in a new scene so your own scene is never touched.
• Viewport HUD. Floating windows drawn over the 3D view (Gallery, Quick, Shape, Bows, Colour, Atmosphere, Animation, Sun & Render) with live sliders that you can undo. Show or hide it
• Your own presets, saved with a thumbnail under My Presets.
Comparison with a real rainbow and the one in the add-on
