As far as I know, there are three samples at Custom Visuals Gallery. To view source code, you may click GitHub as shown below.
- https://app.powerbi.com/visuals/show/PBI_CV_94E55AB3_5D45_4B62_A49D_19E2109AA028
- https://app.powerbi.com/visuals/show/PBI_CV_9053509D_D461_463A_B485_CE9F6AB0F13C
- https://app.powerbi.com/visuals/show/ForceGraph1449359463895
