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more fixes

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This commit is contained in:
David Rose 2007-10-16 19:46:22 +00:00
parent 26a1985992
commit b97325c1cc
1 changed files with 15 additions and 2 deletions
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15
panda/src/mathutil/plane_src.cxx
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@ -136,10 +136,23 @@ intersects_parabola(FLOATTYPE &t1, FLOATTYPE &t2,
FLOATTYPE c = normal.dot(parabola.get_c()) + _v.v._3; FLOATTYPE c = normal.dot(parabola.get_c()) + _v.v._3;
if (IS_NEARLY_ZERO(a)) { if (IS_NEARLY_ZERO(a)) {
// No intersection. // It's not quadratic. The equation is actually:
// b * t + c == 0.
// Which means:
// t = -c / b.
if (IS_NEARLY_ZERO(b)) {
// It's not even linear. The parabola must be completely
// parallel to the plane, or if c == 0, it's completely within
// the plane. In both cases, we'll call it no intersection.
return false; return false;
} }
t1 = -c / b;
t2 = t1;
return true;
}
// Now use the quadratic equation to solve for t. // Now use the quadratic equation to solve for t.
FLOATTYPE discriminant = b * b - 4.0 * a * c; FLOATTYPE discriminant = b * b - 4.0 * a * c;
if (discriminant < 0.0f) { if (discriminant < 0.0f) {