Is there an easy way to draw a triangular grid in C++?

[iamjaved]

I want to draw a grid of equilateral triangle using C++. Output suppose to be consist of multiple triangles.

Not like this type:
1
1 2
1 2 3

How do I proceed to make it from scratch?

My first priority is built from scratch, then the library.

Thank you in advance.

[againtry]

Output suppose to be consist of multiple triangles.
Not like this type:
1
1 2
1 2 3

So, like this then?

1
1 2
1 2 3

1
1 2
1 2 3

1
1 2
1 2 3

[jonnin]

start with the math or the geometry.
you immediately see 3 or 4 useful ideas that might help:
3 series of lines will make such a grid. One sloped up, one down, and one flat.
a equilateral hexagon is made of 6 such triangles
the hexagon with 2 more triangles is a simple rhombus with 2 opposite 120 degree angles and 2 opposite 60 degree angles.
so you can cookie-cutter place any of {hexes, rhombi, or triangles} to make such a grid or you can draw a bunch of lines. The lines is the easy way. But any of it will work.
a slightly more advanced graphics approach can twist a pile of boxes into it.

[iamjaved]

@againtry, Yes it'll be lined.