Question

Just curious about something. While converting HTML colors (whose individual color components are represented via 2-digit hexadecimal values) to floats between 0.0 and 1.0 so we can use them with OpenGL, I became curious about something. We have to divide the hex values by 255 to give us their OpenGL counterparts, but we can’t simply use the hex values as-is because that produces integer division.

Now I know these all work around this issue (of course)…

float r = 0xFD / (float)0xFF; // Works because of the cast to float

float r = 0xFD / 255.0f;      // Works because of the explicit float 

float d = 0xFF;
float r = 0xFD / d;           // Works because 'd' is a float 

…but I was wondering if there’s any way to just decorate a hex value so it’s interpreted as a float (like you do with the ‘f’ in 1.0f) without having to do casting, calculations or interim variables.

These of course don’t work…

float r = 0xFD / 0xFF;   // Integer division yields an integer, not float

float r = 0xFD / 0xFFf;  // Interprets 'f' as part of the hex value

Again, not trying to find out how to achieve my needed results as my code works just fine. I’m just wondering if I can make the code cleaner via decorating the hex value with something similar to how ‘f’ works with decimal values instead of using the above-three methods that do work.

Answer 1

I’m afraid you have to use preprocessor definition in order to achieve the best look. And you need also casting to perform your computations.

The best solution I can think is

#define COMPONENT8(value) ((float)(value) / 255.0f))

Floating point values cannot be specified as hexadecimal (integer) values.