Watermarble simulator based on Mathematical Marbling

User manual:

1. Left click to add new drop of color
2. Hold right click and drag it to the direction desired
3. Customization window:

• Layer: choose the drop, layer 0 for first drop, layer 1 for second drop, and so on
• Radius: drop radius
• Center: the drop center x, and center y. Use this to re-position the drop
• Color: change drop's color, floating point from 0 to 1 is used
• Marble selection: select the marbling type, please refer to Mathematical Marbling by Shufang Lu et al.