void DrawPolygon(POLYGON *p )
{
    // Your code here
int i;
int top_vertex = 0;
int current_left;
int current_right;
int next_left;
int next_right;
float x_start;
float x_end;
float y_start;
float y_end;
float slope_right;
float slope_left;
int y_top;
int y_bottom;

float x_slope; //slope for x
float y_slope; //slope for y

bool change_left;

top_vertex = 0;

for(i = 1; i < p->nv; i++)
{
    if(p->vert[i].y < p->vert[top_vertex].y)
    {
        top_vertex = i;
    }
}

current_left = top_vertex;
current_right = top_vertex;

next_left = (current_left - 1 + p->nv) % p->nv;
next_right = (current_right + 1) % p->nv;

x_slope = p->vert[current_left].x - p->vert[next_left].x;
y_slope = p->vert[current_left].y - p->vert[next_left].y;

if(x_slope != y_slope)
{
    slope_left = x_slope/y_slope;
}

x_slope = p->vert[current_right].x - p->vert[next_right].x;
y_slope = p->vert[current_right].y - p->vert[next_right].y;

if(x_slope != y_slope)
{
    slope_right = x_slope/y_slope;
}

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

y_top = p->vert[top_vertex].y;
x_start = p->vert[current_left].x;
x_end = p->vert[current_right].x;

DrawTrapezium(p->colour, &x_end, slope_right, slope_left, &x_start, y_bottom, y_top);

do
    {
        if(change_left == true)
        {
            current_left = next_left;
            next_left = (current_left - 1 + p->nv) % p->nv;


            x_slope = p->vert[next_left].x - p->vert[current_left].x;
            y_slope = p->vert[next_left].y - p->vert[current_left].y;

            if(y_slope != 0)
            {
                slope_left = x_slope/y_slope;
            }

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

        }
        else
        {
            current_right = next_right;
            next_right = (current_right + 1) % p->nv;

                x_slope = p->vert[next_right].x - p->vert[current_right].x;
                y_slope = p->vert[next_right].y - p->vert[current_right].y;

                if(y_slope != 0)
                {
                    slope_right = x_slope/y_slope;
                }

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

        }

        y_top = y_bottom;

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

        DrawTrapezium(p->colour, &x_end, slope_right, slope_left, &x_start, y_bottom, y_top);

    }while(next_left != next_right);
}