int top_vertex = 0;
	int y_top, y_bottom;
	int num_verticies = p->nv;
	float slope_left, slope_right;

	// Find 'top_vertex' by taking the LOWEST y co-or.
	for (int i = 1; i < num_verticies; i++)
	{
		if (p->vert[i].y < p->vert[top_vertex].y)
		{
			top_vertex = i;
		}
	}

	int current_left = top_vertex;
	int current_right = top_vertex;
	int next_left = current_left - 1;
	int next_right = current_right + 1;

	// Test for wrap
	if (next_left < 0)
	{
		next_left = num_verticies - 1;
	}
	if (next_right >= num_verticies)
	{
		next_right = 0;
	}

	// Calculate left and right slopes
	float y_dif_R, y_dif_L;

	y_dif_L = (p->vert[next_left].y - p->vert[current_left].y);
	y_dif_R = (p->vert[next_right].y - p->vert[current_right].y);

	if ( (y_dif_L != 0) || (y_dif_R != 0) )
	{
		slope_left = (p->vert[next_left].x - p->vert[current_left].x) / y_dif_L;
		slope_right = (p->vert[next_right].x - p->vert[current_right].x) / y_dif_R;
	}

	//Check which side the trapezium finishes first

	if (p->vert[next_left].y < p->vert[next_right].y)
	{
		y_bottom = p->vert[next_left].y;
	}
	else
	{
		y_bottom = p->vert[next_right].y;
	}

	// Call Function

	y_top = p->vert[top_vertex].y;

	float x_start = p->vert[current_left].x;
	float x_end = p->vert[current_right].x;

	//DrawSquare(Default_Colour, 100, 200, -0.5, 1.5, 100, 160);
	DrawSquare(p->colour, x_start, x_end, slope_left, slope_right, y_bottom, y_top);