public E3DViewFrustum2D(
E3DEngine engine,
E3DViewport viewport,
E3DVector2F minMin,
E3DVector2F minMax,
E3DVector2F maxMax,
E3DVector2F maxMin) {
super(engine);
setA(minMin);
setB(minMax);
setC(maxMax);
setD(maxMin);
setViewport(viewport);
triOne =
new E3DTriangle(
getEngine(),
new E3DVector3F(a.getX(), a.getY(), 0.0),
new E3DVector3F(b.getX(), b.getY(), 0.0),
new E3DVector3F(c.getX(), c.getY(), 0.0));
triTwo =
new E3DTriangle(
getEngine(),
new E3DVector3F(a.getX(), a.getY(), 0.0),
new E3DVector3F(c.getX(), c.getY(), 0.0),
new E3DVector3F(d.getX(), d.getY(), 0.0));
}
/**
* Get the intersection pt of two 2d lines made of A->B and C->D. TODO: This is a misplaced
* method, but its only used currently by this frustum.
*
* @param ptA First point of segment1
* @param ptB Second point of segment1
* @param ptC First point of segment2
* @param ptD Second point of segment2
* @return
*/
public E3DVector3F get2DLineIntersectionPt(
E3DVector2F ptA, E3DVector2F ptB, E3DVector3F ptC, E3DVector3F ptD) {
// First, put into y = mx+b form
boolean vertical1 = false;
double m1 = 0.0;
double b1;
if (ptB.getX() != ptA.getX()) {
m1 = (ptB.getY() - ptA.getY()) / (ptB.getX() - ptA.getX()); // rise
b1 = ptA.getY() - (m1 * ptA.getX()); // Solve for B we now have m and b
} else {
vertical1 = true;
b1 = ptA.getX();
}
// Segment 2 in y=mx+b form
boolean vertical2 = false;
double m2 = 0.0;
double b2;
if (ptD.getX() != ptC.getX()) // denominator of 0 means vertical line
{
m2 = (ptD.getY() - ptC.getY()) / (ptD.getX() - ptC.getX()); // rise
b2 = ptC.getY() - (m2 * ptC.getX());
} else {
vertical2 = true;
b2 = ptC.getX();
}
// If both are vertical see if the two segments intersect
if (vertical1 && vertical2) {
if (b1 != b2) // parallel lines, no intersection
return null;
else // equal means they are the same line, see if the segments intersect
{
// check if either pt of segment 2 is withing segment 1. If so, return that point (since
// there can be multiple intersection pts when they're in the same line, it doesn't matter
// exactly what pt)
if ((ptD.getY() >= ptA.getY() && ptD.getY() <= ptB.getY())
|| // D is between A and B
(ptD.getY() <= ptA.getY() && ptD.getY() >= ptB.getY())) return ptD;
else if ((ptC.getY() >= ptA.getY() && ptC.getY() <= ptB.getY())
|| // C is between A and B
(ptC.getY() <= ptA.getY() && ptC.getY() >= ptB.getY())) return ptC;
else // don't intersect
return null;
}
} else if (vertical1) // if one is vertical, find out if an x value of the vertical yields a Y
// value on the line is between the pts of the vertical line
{
double intX = b1;
double intY = (m2 * intX) + b2;
if (((intY >= ptD.getY() && intY <= ptC.getY()) || (intY >= ptC.getY() && intY <= ptD.getY()))
&& (intX >= ptD.getX() && intX <= ptC.getX())
|| (intX >= ptC.getX() && intX <= ptD.getX())) return new E3DVector3F(intX, intY, 0.0);
else return null;
} else if (vertical2) // C->D is vertical
{
double intX = b2;
double intY = (m1 * intX) + b1;
if (((intY >= ptA.getY() && intY <= ptB.getY()) || (intY >= ptB.getY() && intY <= ptA.getY()))
&& (intX >= ptA.getX() && intX <= ptB.getX())
|| (intX >= ptB.getX() && intX <= ptA.getX())) return new E3DVector3F(intX, intY, 0.0);
else return null;
} else {
// Now set the Y's equal to each other to solve for X, then replace X in one of the equations
// to get Y. That is the intersection pt of the lines
// m1x + b1 = m2x + b2
// = m1x = m2x + b2 - b1 =
// = m1x - m2x = b2 - b1
// = (m1-m2)x = (b2 - b1)
// = x = (b2 - b1) / (m1 - m2)
double intX = 0.0;
if (m1 - m2 != 0.0) intX = (b2 - b1) / (m1 - m2);
else intX = (b2 - b1);
double intY = (m1 * intX) + b1; // get Y from that X
if (intY == 0) intY = (m2 * intX) + b2;
// Now determine if intX and intY lie on both lines ptA->ptB and ptC->ptD
if (((intX >= ptA.getX() && intX <= ptB.getX()) || (intX >= ptB.getX() && intX <= ptA.getX()))
&& ((intX >= ptC.getX() && intX <= ptD.getX())
|| (intX >= ptD.getX() && intX <= ptC.getX()))
&& ((intY >= ptA.getY() && intY <= ptB.getY())
|| (intY >= ptB.getY() && intY <= ptA.getY()))
&& ((intY >= ptC.getY() && intY <= ptD.getY())
|| (intY >= ptD.getY() && intY <= ptC.getY())))
return new E3DVector3F(intX, intY, 0.0);
else return null;
}
}