Tessellating a BSpline patch using a triangle list (OpenGL)

Question

As the title describes I am trying to tessellate a BSpline patch using a triangle list.

Here is an image of my patch from the front, which looks exactly how it should.

My problem is the rear of the patch, which gives this effect:

As you can see the previous row of triangles are connecting to the new row that is being drawn. I have tried various ways of trying to avoid this such as increasing the index value by 1 when it reaches the end of the row. The only quick fix I could find is putting each row in a separate loop (with the loop range because the size of that row), which is not intuitive at all.

Here is the code for the drawing of my patch:

void drawBSplinePatch1(std::vector<int>& sample_elements_out, const int samples)
{
    for(int i = 0; i <= 379; i++)
    {
        // first triangle
        sample_elements_out.push_back(i);
        sample_elements_out.push_back(i + 1);
        sample_elements_out.push_back(i + samples);

        // second triangle
        sample_elements_out.push_back(i  + samples);
        sample_elements_out.push_back(i + 1);
        sample_elements_out.push_back(i + samples + 1);
    }
}

Answer 1

Skip a quad for each row, e.g. like this.

for(int i = 0; i <= 379; i++)
{
    if (i % ROW_LENGTH != ROW_LENGTH - 1) {
      // first triangle
      sample_elements_out.push_back(i);
      sample_elements_out.push_back(i + 1);
      sample_elements_out.push_back(i + samples);

      // second triangle
      sample_elements_out.push_back(i  + samples);
      sample_elements_out.push_back(i + 1);
      sample_elements_out.push_back(i + samples + 1);
    }
}

Two nested loops would probably be more readable, though.