Update

3d_rendering.md

@@ -291,13 +291,15 @@ First we need to say what conventions we'll stick to:
 
 - We'll be using ROW VECTORS, i.e. we'll be writing vectors like [x,y,z]. Some people rather use column vectors, which then means their matrices are also transposed and they do multiplication in opposite direction etcetc. Watch out about this, it's quite important to know which convention you're using, because e.g. matrix multiplication is non-commutative (i.e. with matrices A * B does NOT generally equal B * A) and the order you need to multiply in depends on this convention, so be careful.
 - Counterclockwise triangles are front facing, clockwise ones are back facing (invisible).
-- We'll be using LEFT HANDED coordinate systems, i.e X axis goes right, Y goes up, Z goes forward (right handed system would be the same except Z would go the opposite way -- backwards). Watch out: some systems (for example OpenGL) use the other one. I.e. our coordinate system looks like this:
+- We'll be using [LEFT](left_right.md) HANDED coordinate systems, i.e X axis goes right, Y goes up, Z goes forward (right handed system would be the same except Z would go the opposite way -- backwards). Watch out: some systems (for example OpenGL) use the other one. I.e. our coordinate system looks like this:
 
+```
   Y ^     _
     |    _/| Z
     |  _/
     |_/
     '-------> X
+```
 
 Now let's have a simple **3D model data** of a quad. Quad is basically just a square made of four vertices and two triangles, it will look like this: