Add function to calculate transmitted vector after refraction [skip ci]
Change the name of function to refraction_angle and fix a typo [skip ci]
Make refraction_angle compatible with Ray3D and plane. [skip ci]
Add test_util
Add deviation [skip ci]
Fix a bug in deviation while using plane. [skip ci]
Add tests for refraction_angle and deviation
Remove unused imports
UnXFAIL a failing test
Merge pull request #7626 from debugger22/snell

Calculate transmitted vector after refraction