Triangle Softer Rounded Shape Instead Sharp

Design a new image featuring a triangle with a softer, rounded shape instead of sharp edges. Change the color of the triangle to a gradient of cool hues, like blues and purples. Instead of a solid white light beam entering the triangle, use a light ray depicted in pastel colors. Modify the output rainbow by displaying it as a series of gentle swirls rather than stripes, blending the colors together seamlessly. Set the background to a deep navy rather than black for a more tranquil feel.