Disclaimer: This could apply to any programming langage but I am using C++, so I’m using the C++ tag.
I have an array of an xyz structure:
struct xyz {
float x, y, z;
};
In the array I create, at first I only initialize the x and y as I know the z value only later in the code like this:
size = Width * Height;
Cloud = new xyz[size];
// Remplissage des indices de Pixels
for (int i = 0; i < size; i++)
{
Cloud[i].x = i % Width;
Cloud[i].y = i / Width;
}
};
This results in an array that looks like that:
x; y; z
0; 0; 0
1; 0; 0
2; 0; 0
3; 0; 0
0; 1; 0
1; 1; 0
2; 1; 0
3; 1; 0
0; 2; 0
1; 2; 0
2; 2; 0
3; 2; 0
So after that, I want to set a z value for such x and y values but I don’t know how to do that in an effective way (I don’t want to use a loop that goes through my whole array until I find the right x and y set).
My problem I guess is how to do the inverse math of Cloud[i].x = i % Width and Cloud[i].y = i / Width into something to do Cloud[??].z = someValue.
Thank you in advance!
>Solution :
That is simple mathematics. If you have x and y and want to know the index to address the z-value later, then you may calculate "y * width + x".
So:
Cloud[y * Width + x].z = zValue;