X-Git-Url: http://shamusworld.gotdns.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fvector.cpp;h=fbe45ff70f82b9713ff454b4e8eb432407f66069;hb=HEAD;hp=11ddb6494962b724e8166b05502baa27612c0295;hpb=fd5a80446b2abfdfb9d8951fcc03fb1b55ad707c;p=architektonas diff --git a/src/vector.cpp b/src/vector.cpp index 11ddb64..fbe45ff 100644 --- a/src/vector.cpp +++ b/src/vector.cpp @@ -16,41 +16,48 @@ #include "vector.h" -#include // For sqrt() +#include // For sqrt() #include "mathconstants.h" // Vector implementation -Vector::Vector(double xx/*= 0*/, double yy/*= 0*/, double zz/*= 0*/): x(xx), y(yy), z(zz) +Vector::Vector(double xx/*= 0*/, double yy/*= 0*/, double zz/*= 0*/): x(xx), y(yy), z(zz), b(0) { } +Vector::Vector(Vector tail, Vector head): x(head.x - tail.x), y(head.y - tail.y), z(head.z - tail.z), b(0) +{ +} -Vector::Vector(Vector tail, Vector head): x(head.x - tail.x), y(head.y - tail.y), z(head.z - tail.z) +Vector::Vector(const Vector &v): x(v.x), y(v.y), z(v.z), b(v.b) { } +// Create vector from angle + length (2D; z is set to zero) +void Vector::SetAngleAndLength(double angle, double length) +{ + x = cos(angle) * length; + y = sin(angle) * length; + z = 0; +} Vector Vector::operator=(Vector const v) { - x = v.x, y = v.y, z = v.z; + x = v.x, y = v.y, z = v.z, b = v.b; return *this; } - Vector Vector::operator+(Vector const v) { return Vector(x + v.x, y + v.y, z + v.z); } - Vector Vector::operator-(Vector const v) { return Vector(x - v.x, y - v.y, z - v.z); } - // Unary negation Vector Vector::operator-(void) @@ -58,7 +65,6 @@ Vector Vector::operator-(void) return Vector(-x, -y, -z); } - // Vector x constant Vector Vector::operator*(double const v) @@ -66,7 +72,6 @@ Vector Vector::operator*(double const v) return Vector(x * v, y * v, z * v); } - // Vector x constant Vector Vector::operator*(float const v) @@ -74,7 +79,6 @@ Vector Vector::operator*(float const v) return Vector(x * v, y * v, z * v); } - // Vector / constant Vector Vector::operator/(double const v) @@ -82,7 +86,6 @@ Vector Vector::operator/(double const v) return Vector(x / v, y / v, z / v); } - // Vector / constant Vector Vector::operator/(float const v) @@ -90,7 +93,6 @@ Vector Vector::operator/(float const v) return Vector(x / v, y / v, z / v); } - // Vector (cross) product Vector Vector::operator*(Vector const v) @@ -99,7 +101,6 @@ Vector Vector::operator*(Vector const v) return Vector((y * v.z) - (z * v.y), (z * v.x) - (x * v.z), (x * v.y) - (y * v.x)); } - // Dot product double Vector::Dot(Vector const v) @@ -107,7 +108,6 @@ double Vector::Dot(Vector const v) return (x * v.x) + (y * v.y) + (z * v.z); } - // Vector x constant, self assigned Vector& Vector::operator*=(double const v) @@ -117,7 +117,6 @@ Vector& Vector::operator*=(double const v) return *this; } - // Vector / constant, self assigned Vector& Vector::operator/=(double const v) @@ -136,7 +135,6 @@ Vector& Vector::operator+=(Vector const v) return *this; } - // Vector + constant, self assigned Vector& Vector::operator+=(double const v) @@ -146,7 +144,6 @@ Vector& Vector::operator+=(double const v) return *this; } - // Vector - vector, self assigned Vector& Vector::operator-=(Vector const v) @@ -156,7 +153,6 @@ Vector& Vector::operator-=(Vector const v) return *this; } - // Vector - constant, self assigned Vector& Vector::operator-=(double const v) @@ -166,78 +162,87 @@ Vector& Vector::operator-=(double const v) return *this; } - // Check for equality bool Vector::operator==(Vector const v) { return (x == v.x && y == v.y && z == v.z ? true : false); } - // Check for inequality bool Vector::operator!=(Vector const v) { return (x != v.x || y != v.y || z != v.z ? true : false); } - Vector Vector::Unit(void) { double mag = Magnitude(); - // If the magnitude of the vector is zero, then the Unit vector is undefined... + // If the magnitude of the vector is zero, then the Unit vector is + // undefined... if (mag == 0) return Vector(0, 0, 0); return Vector(x / mag, y / mag, z / mag); } - double Vector::Magnitude(void) { - return sqrt(x * x + y * y + z * z); + return sqrt((x * x) + (y * y) + (z * z)); } - double Vector::Angle(void) { - // acos returns a value between zero and PI, which means we don't know which - // quadrant the angle is in... Though, if the y-coordinate of the vector is - // negative, that means that the angle is in quadrants III - IV. + // acos returns a value between zero and TAU/2, which means we don't know + // which quadrant the angle is in... However, if the y-coordinate of the + // vector is negative, that means that the angle is in quadrants III - IV. double rawAngle = acos(Unit().x); - double correctedAngle = (y < 0 ? (2.0 * PI) - rawAngle : rawAngle); + double correctedAngle = (y < 0 ? TAU - rawAngle : rawAngle); return correctedAngle; } - bool Vector::isZero(double epsilon/*= 1e-6*/) { return (fabs(x) < epsilon && fabs(y) < epsilon && fabs(z) < epsilon ? true : false); } - // Class methods -double Vector::Dot(Vector v1, Vector v2) +/*static*/ double Vector::Dot(Vector v1, Vector v2) { return (v1.x * v2.x) + (v1.y * v2.y) + (v1.z * v2.z); } - -double Vector::Magnitude(Vector v1, Vector v2) +/*static*/ double Vector::Magnitude(Vector v1, Vector v2) { double xx = v1.x - v2.x; double yy = v1.y - v2.y; double zz = v1.z - v2.z; + return sqrt((xx * xx) + (yy * yy) + (zz * zz)); } +// +// Convenience function +// +/*static*/ Vector Vector::Unit(Point p1, Point p2) +{ + return Vector(p1, p2).Unit(); +} + +// +// Convenience function +// +/*static*/ double Vector::Angle(Point p1, Point p2) +{ + return Vector(p1, p2).Angle(); +} // Returns the parameter of a point in space to this vector. If the parameter // is between 0 and 1, the normal of the vector to the point is on the vector. // Note: v1 is the tail, v2 is the head of the line (vector). -double Vector::Parameter(Vector tail, Vector head, Vector p) +/*static*/ double Vector::Parameter(Vector tail, Vector head, Vector p) { // Geometric interpretation: // The parameterized point on the vector lineSegment is where the normal of @@ -249,19 +254,35 @@ double Vector::Parameter(Vector tail, Vector head, Vector p) double magnitude = lineSegment.Magnitude(); Vector pointSegment = p - tail; double t = lineSegment.Dot(pointSegment) / (magnitude * magnitude); + return t; } - -// Return the normal to the linesegment formed by the passed in points. -// (Not sure which is head or tail, or which hand the normal lies) -// [v1 should be the tail, v2 should be the head, in which case the normal should -// rotate anti-clockwise.] -///*static*/ Vector Vector::Normal(Vector v1, Vector v2) +// Return the 2D normal to the linesegment formed by the passed in points. +// The normal thus calculated should rotate anti-clockwise. /*static*/ Vector Vector::Normal(Vector tail, Vector head) { -// Vector v = (v1 - v2).Unit(); Vector v = (head - tail).Unit(); + return Vector(-v.y, v.x); } +/*static*/ double Vector::AngleBetween(Vector a1, Vector a2) +{ + // This is done using the following formula: + // (a . b) = ||a|| ||b|| cos(theta) + // However, have to check for two degenerate cases, where a = cb: + // 1) if c > 0, theta = 0; 2) if c < 0, theta = 180°. + // Also, the vectors a & b have to be non-zero. + // Also, have to check using an epsilon because acos will not return an + // exact value if the vectors are orthogonal. + if (a1.isZero() || a2.isZero()) + return 0; + + return acos(a1.Dot(a2) / (a1.Magnitude() * a2.Magnitude())); +} + +/*static*/ Point Vector::Midpoint(Point p1, Point p2) +{ + return Point((p1.x + p2.x) / 2.0, (p1.y + p2.y) / 2.0); +}