/* Intersect the given trapezoidal line with
* all other lines in this shape. */
public float intersect(TrapezoidLine t, float max)
{
float min = max;
foreach (TDPoint pt in points)
{
if (points.IndexOf(pt) > 0)
{
TDPoint prevpt = points[points.IndexOf(pt) - 1];
if (consider(t.getStart(), pt, prevpt))
{
min = Mathf.Min(min, (float )(pt.y - prevpt.y) / (pt.x - prevpt.x) * (t.getStart().x - prevpt.x) + prevpt.y);
}
}
}
return(min);
}
public bool equals(TrapezoidLine t)
{
return(t.start.equals(start) &&
t.length == length &&
t.getUp() == up);
}
/*
* Creates trapezoidal maps the "naive" way. More specifically, this
* function iterates through each shape, and each point of each shape,
* creating a TrapezoidLine for each point with an initially long length.
* Then, this length is minimized over all the x intersections for above the
* point. This is repeated for all the lines below the point. This is
* primarily used for drawing the visual lines on the screen (as any time
* savings are already negated when having to draw all objects anyway).
*/
public List <TrapezoidLine> naiveMap(float width, float height)
{
//return all the vertical lines of trapezoid.
//TODO:fix the boundary parameter;
List <TrapezoidLine> trapezoidMap = new List <TrapezoidLine>();
// Add the borders of the window as temporary shapes
TDShape border = new TDShape();
TDShape border2 = new TDShape();
border.getPoints().Add(new TDPoint(-1f * height, 0));
border.getPoints().Add(new TDPoint(height, 0));
border2.getPoints().Add(new TDPoint(0, -1f * width));
border2.getPoints().Add(new TDPoint(0, width));
shapes.Add(border);
shapes.Add(border2);
// Step through each shape
for (int i = 0; i < shapes.Count; i++)
{
//TDShape s = shapes[i];
//TDShape sh = shapes[i + 1];
TDShape sh = shapes[i];
// Ignore the border shapes so their points do not appear as part of
// the trapezoidal map
if (sh.equals(border) || sh.equals(border2))
{
continue;
}
// Step through the points in the current shape
for (int pi = 0; pi < sh.getPoints().Count; pi++)
{
//TDPoint p = sh.getPoints()[pi];
TDPoint pt = sh.getPoints()[pi];
// Generate two trapezoidal lines for each point (up and down)
TrapezoidLine t = new TrapezoidLine(pt, height + 1, true);
TrapezoidLine t2 = new TrapezoidLine(pt, height + 1, false);
bool tu = false;
bool t2u = false;
// Iterate over all shapes, intersecting the trapezoidal lines
// with each of the shapes
for (int s2i = 0; s2i < shapes.Count; s2i++)
{
//TDShape s2 = shapes[s2i];
TDShape sh2 = shapes[s2i];
// if(!sh.equals(sh2)) {
// If the intersection yields a positive difference that is
// smaller than the previous length, update t
// down
if (t.getStart().y - sh2.intersect(t, height + 1) > 0)
{
t.setLength(Mathf.Min((t.getStart().y - sh2
.intersect(t, height + 1)), t.getLength()));
tu = true;
}
// if the intersection yields a negative difference that is
// absolutely smaller than the previous length, update t2
else if (t2.getStart().y - sh2.intersect(t2, height + 1) < 0)
{
t2.setLength(Mathf.Min(Mathf.Abs(t2.getStart().y
- sh2.intersect(t2, height + 1)), t2
.getLength()));
t2u = true;
}
// }
}
// If the lengths have been updated to a reasonable value, Add
// them
if (t.getLength() < height)
{
trapezoidMap.Add(t);
}
if (t2.getLength() < height)
{
trapezoidMap.Add(t2);
}
}
}
// Remove the borders so they are not displayed
shapes.Remove(border);
shapes.Remove(border2);
return(trapezoidMap);
}
