/** @see Object3D#intersection(Object3D) */
public Object3D intersection(Object3D space) {
double cutxyX = 0.0, cutxzX = 0.0;
if (space instanceof Point3D) {
Point3D other = (Point3D) space;
if ((this.gradeY * other.x + this.offsetY == other.y)
&& (this.gradeZ * other.x + this.offsetZ == other.z)) return (Object3D) other.clone();
else return Object3DVoid;
}
if (space instanceof Line3D) {
Line3D test = (Line3D) space;
// Exclusion of parallel lines which never will intersect each others.
if (test.gradeY == this.gradeY) {
if (this.offsetY != test.offsetY)
return Object3DVoid; // parallel lines in x-y area (they will never touch in this
// dimension)
}
if (test.gradeZ == this.gradeZ) {
if (this.offsetZ != test.offsetZ)
return Object3DVoid; // parallel lines in x-z area (they will never touch in this
// dimension)
}
// mathematical search for the intersection point:
// has to cut in x-y dimension:
cutxyX = (this.offsetY - test.offsetY) / (test.gradeY - this.gradeY);
cutxzX = (this.offsetZ - test.offsetZ) / (test.gradeZ - this.gradeZ);
if (cutxyX == 0.0 / 0.0) {
// Parallel lines are caught above.
// In xy-dimension the lines are matching. (see calculation of cutxyX)
// Now there are two possibilities:
// - The lines are also matching in dimension xz (cutxzX is NaN too): If the x-ranges of
// both lines are overlapping "intersection" is true.
// - The lines have to cross: Check wether cutxzX is in x-range of both lines.
if (cutxzX == 0.0 / 0.0) {
if (!((this.end.x < test.start.x) // start.x is smaller end.x! (constructor)
|| (this.start.x > test.end.x))) {
Point3D startx = (this.start.x > test.start.x) ? this.start : test.start;
Point3D endx = (this.end.x < test.end.x) ? this.end : test.end;
return new Line3D(startx, endx);
} else return Object3DVoid;
} else {
// on zx-area it's not matching, so we have to check wether the intersection of both
// lines of the zx-area is within the x-bounds of both lines.
if ((cutxzX >= this.start.x)
&& (cutxzX <= this.end.x)
&& (cutxzX >= test.start.x)
&& (cutxzX <= test.end.x))
return new Point3D(
cutxzX, this.gradeY * cutxzX + this.offsetY, this.gradeZ * cutxzX + this.offsetZ);
else return Object3DVoid;
}
}
// The lines have an intersection in xy-dimension
else {
// this is the other way round:
// either in xz - dimension the lines are on the same way:
if (cutxzX == 0.0 / 0.0) {
// in zx - area the lines are matching in grade and offset.
// Then we will only have to check, wether the crossing of the lines in
// xy-dimension is within the x-bounds of both lines.
if ((cutxyX >= this.start.x)
&& (cutxyX <= this.end.x)
&& (cutxyX >= test.start.x)
&& (cutxyX <= test.end.x))
return new Point3D(
cutxyX, cutxyX * this.gradeY + this.offsetY, cutxyX * this.gradeZ + this.offsetZ);
else return Object3DVoid;
}
// The lines are crossing in xy and xz dimension:
// only if both x values cutxyX and cutxzX are equal and within the
// x-ranges of both lines this is an intersection:
else {
if ((cutxyX == cutxzX)
&& ((cutxyX >= this.start.x) && (cutxyX <= this.end.x))
&& ((cutxyX >= test.start.x) && (cutxyX <= test.end.x))) {
return new Point3D(
cutxyX, cutxyX * this.gradeY + this.offsetY, cutxyX * this.gradeZ + this.offsetZ);
} else return Object3DVoid;
}
}
}
return space.intersection(this);
}
