Round a float to a regular grid of predefined points

Question

I want to round a float number to a given precision, for example :

0.051 i want to convert it to 0.1  0.049 i want to convert it to 0.0  0.56 i want to convert it to 0.6  0.54 i want to convert it to 0.5 

I cant explain it better, but the reason for this is to translate a point location (like 0.131f, 0.432f) to the location of tile in a grid (like 0.1f, 0.4f).

Answer 1

As long as your grid is regular, just find a transformation from integers to this grid. So let's say your grid is

0.2  0.4  0.6  ... 

Then you round by

float round(float f) {     return floor(f * 5 + 0.5) / 5;     // return std::round(f * 5) / 5; // C++11 }