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engine/3d/src/Plane.cpp

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+/**
+ @file Plane.cpp
+
+ @maintainer Morgan McGuire, http://graphics.cs.williams.edu
+
+ @created 2003-02-06
+ @edited  2006-01-29
+ */
+
+#include "platform.hpp"
+#include "Plane.hpp"
+#include "stringutils.hpp"
+
+namespace G3D
+{
+
+Plane::Plane(Vector4 point0, Vector4 point1, Vector4 point2)
+{
+
+    debugAssertM(point0.w != 0 || point1.w != 0 || point2.w != 0, "At least one point must be finite.");
+
+    // Rotate the points around so that the finite points come first.
+
+    while ((point0.w == 0) && ((point1.w == 0) || (point2.w != 0)))
+    {
+        Vector4 temp = point0;
+        point0 = point1;
+        point1 = point2;
+        point2 = temp;
+    }
+
+    Vector3 dir1;
+    Vector3 dir2;
+
+    if (point1.w == 0)
+    {
+        // 1 finite, 2 infinite points; the plane must contain
+        // the direction of the two direcitons
+        dir1 = point1.xyz();
+        dir2 = point2.xyz();
+    }
+    else if (point2.w != 0)
+    {
+        // 3 finite points, the plane must contain the directions
+        // betwseen the points.
+        dir1 = point1.xyz() - point0.xyz();
+        dir2 = point2.xyz() - point0.xyz();
+    }
+    else
+    {
+        // 2 finite, 1 infinite point; the plane must contain
+        // the direction between the first two points and the
+        // direction of the third point.
+        dir1 = point1.xyz() - point0.xyz();
+        dir2 = point2.xyz();
+    }
+
+    _normal = dir1.cross(dir2).direction();
+    _distance = _normal.dot(point0.xyz());
+}
+
+
+Plane::Plane(const Vector3& point0, const Vector3& point1, const Vector3& point2)
+{
+
+    _normal = (point1 - point0).cross(point2 - point0).direction();
+    _distance = _normal.dot(point0);
+}
+
+
+Plane::Plane(const Vector3& __normal, const Vector3& point)
+{
+
+    _normal = __normal.direction();
+    _distance = _normal.dot(point);
+}
+
+
+Plane Plane::fromEquation(float a, float b, float c, float d)
+{
+    Vector3 n(a, b, c);
+    float magnitude = n.magnitude();
+    d /= magnitude;
+    n /= magnitude;
+    return Plane(n, -d);
+}
+
+
+void Plane::flip()
+{
+    _normal = -_normal;
+    _distance = -_distance;
+}
+
+
+void Plane::getEquation(Vector3& n, float& d) const
+{
+    double _d;
+    getEquation(n, _d);
+    d = (float)_d;
+}
+
+void Plane::getEquation(Vector3& n, double& d) const
+{
+    n = _normal;
+    d = -_distance;
+}
+
+
+void Plane::getEquation(float& a, float& b, float& c, float& d) const
+{
+    double _a, _b, _c, _d;
+    getEquation(_a, _b, _c, _d);
+    a = (float)_a;
+    b = (float)_b;
+    c = (float)_c;
+    d = (float)_d;
+}
+
+void Plane::getEquation(double& a, double& b, double& c, double& d) const
+{
+    a = _normal.x;
+    b = _normal.y;
+    c = _normal.z;
+    d = -_distance;
+}
+
+
+std::string Plane::toString() const
+{
+    return format("Plane(%g, %g, %g, %g)", _normal.x, _normal.y, _normal.z, _distance);
+}
+
+} // namespace G3D