how to assign data in Byte type array

Question

This is segment of code of 3dcpptutorials ray tracing. Can someone explain me how this lines of code works ?

As I understand it, if it's less than 0, it stores 0 and if it's greater than 1, then 255 and if it's between, then value * 255, something like that. Am I correct ?

colorbuffer[2] = Color.r <= 0.0f ? 0 : Color.r >= 1.0 ? 255 : (BYTE)(Color.r * 255);
colorbuffer[1] = Color.g <= 0.0f ? 0 : Color.g >= 1.0 ? 255 : (BYTE)(Color.g * 255);
colorbuffer[0] = Color.b <= 0.0f ? 0 : Color.b >= 1.0 ? 255 : (BYTE)(Color.b * 255);

The code convert each color component from floating-point value in a range of 0.0 to 1.0 to an integer value between 0 and 255. — Some programmer dude
– Some programmer dude, Commented Jan 2, 2020 at 13:05

Evg · Accepted Answer · 2020-01-02 13:19:32Z

1

Correct. Due to right-to-left associativity of the ?: operator, the line

colorbuffer[2] = Color.r <= 0.0f ? 
    0 : Color.r >= 1.0 ? 255 : (BYTE)(Color.r * 255);

is equivalent to this one:

colorbuffer[2] = Color.r <= 0.0f ? 
    0 : (Color.r >= 1.0 ? 255 : (BYTE)(Color.r * 255));

which in turn is equivalent to the following if-else block:

if (Color.r <= 0.0f) 
    colorbuffer[2] = 0;
else {
    if (Color.r >= 1.0) 
        colorbuffer[2] = 255;
    else
        colorbuffer[2] = (BYTE)(Color.r * 255);
}

There is the std::clamp function in the standard library to do this kind of job:

colorbuffer[2] = (BYTE)(std::clamp(Color.r, 0.f, 1.f) * 255);

edited Jan 2, 2020 at 13:19

answered Jan 2, 2020 at 13:06

Evg

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