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authorDavid Fioramonti2017-08-12 19:49:14 -0700
committerDavid Fioramonti2017-08-12 20:31:16 -0700
commitba128368e8e7c4c4369db48c0f024bd40e8dad80 (patch)
treec7f5f5eb7eb224ed4718bbbffae7363553425a88
parent18e52ef1ea6f2fea5ea311c8d0307a1a65f15ece (diff)
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TITANIC: star control dvector work, replace fn3 with getAnglesAsVect also replace atan2 implementation
fn3 in dvector returns a vector that stores a magnitude, and 2 angles. The second angle (the z component of the returned vector) was the angle that the internal vector was between its z and x axis. This angle was obtained by doing a poor man 4-quadrant atan implementation and it gave large values for negative x. This has been replaced with the atan2 standard function.
-rw-r--r--engines/titanic/star_control/dvector.cpp48
-rw-r--r--engines/titanic/star_control/dvector.h8
2 files changed, 26 insertions, 30 deletions
diff --git a/engines/titanic/star_control/dvector.cpp b/engines/titanic/star_control/dvector.cpp
index 728c94e5f0..86396c9945 100644
--- a/engines/titanic/star_control/dvector.cpp
+++ b/engines/titanic/star_control/dvector.cpp
@@ -26,6 +26,9 @@
namespace Titanic {
+const double Rad2Deg = 180.0 / M_PI;
+const double Deg2Rad = 1.0 / Rad2Deg;
+
double DVector::normalize() {
double hyp = sqrt(_x * _x + _y * _y + _z * _z);
assert(hyp);
@@ -61,9 +64,8 @@ DVector DVector::DAffMatrixProdVec(const DAffine &m) {
}
void DVector::RotVectAxisY(double angle_deg) {
- const double FACTOR = 2 * M_PI / 360.0;
- double sinVal = sin(angle_deg * FACTOR);
- double cosVal = cos(angle_deg * FACTOR);
+ double sinVal = sin(angle_deg * Deg2Rad);
+ double cosVal = cos(angle_deg * Deg2Rad);
double x = cosVal * _x - sinVal * _z;
double z = cosVal * _z + sinVal * _x;
@@ -71,51 +73,39 @@ void DVector::RotVectAxisY(double angle_deg) {
_z = z;
}
-DVector DVector::fn3() const {
+DVector DVector::getAnglesAsVect() const {
DVector vector = *this;
DVector dest;
- dest._x = vector.normalize();
- dest._y = acos(vector._y);
-
- if (ABS(vector._z) < 0.00001) {
- if (vector._x < 0.0) {
- dest._z = 2 * M_PI - (M_PI / 2.0);
- } else {
- dest._z = M_PI / 2.0;
- }
- } else {
- dest._z = atan(vector._x / vector._z);
- if (vector._x < 0.0)
- dest._z += 2 * M_PI;
- }
+ dest._x = vector.normalize(); // scale that makes this vector have magnitude=1, also does the scaling
+ dest._y = acos(vector._y); // radian distance/angle that this vector's y component is from the +y axis,
+ // result is restricted to [0,pi]
+ dest._z = atan2(vector._x,vector._z); // result is restricted to [-pi,pi]
return dest;
}
DAffine DVector::fn4(const DVector &v) {
- const double FACTOR = 180.0 / M_PI;
DAffine matrix1, matrix2, matrix3, matrix4;
- DVector vector1 = fn3();
- matrix1.setRotationMatrix(X_AXIS, vector1._y * FACTOR);
- matrix2.setRotationMatrix(Y_AXIS, -(vector1._z * FACTOR));
+ DVector vector1 = getAnglesAsVect();
+ matrix1.setRotationMatrix(X_AXIS, vector1._y * Rad2Deg);
+ matrix2.setRotationMatrix(Y_AXIS, -(vector1._z * Rad2Deg));
matrix3 = matrix1.compose(matrix2);
matrix4 = matrix3.inverseTransform();
- vector1 = v.fn3();
- matrix1.setRotationMatrix(X_AXIS, vector1._y * FACTOR);
- matrix2.setRotationMatrix(Y_AXIS, -(vector1._z * FACTOR));
+ vector1 = v.getAnglesAsVect();
+ matrix1.setRotationMatrix(X_AXIS, vector1._y * Rad2Deg);
+ matrix2.setRotationMatrix(Y_AXIS, -(vector1._z * Rad2Deg));
matrix3 = matrix1.compose(matrix2);
return matrix4.compose(matrix3);
}
DAffine DVector::fn5() const {
- const double FACTOR = 180.0 / M_PI;
- DVector v1 = fn3();
+ DVector v1 = getAnglesAsVect();
DAffine m1, m2;
- m1.setRotationMatrix(X_AXIS, v1._y * FACTOR);
- m2.setRotationMatrix(Y_AXIS, -(v1._z * FACTOR));
+ m1.setRotationMatrix(X_AXIS, v1._y * Rad2Deg);
+ m2.setRotationMatrix(Y_AXIS, -(v1._z * Rad2Deg));
return m1.compose(m2);
}
diff --git a/engines/titanic/star_control/dvector.h b/engines/titanic/star_control/dvector.h
index 7daeda71aa..b37c8bb851 100644
--- a/engines/titanic/star_control/dvector.h
+++ b/engines/titanic/star_control/dvector.h
@@ -60,7 +60,13 @@ public:
*/
void RotVectAxisY(double angle_deg);
- DVector fn3() const;
+ /**
+ * Returns a vector, v, that represents a magnitude, and two angles in radians
+ * 1. Scale this vector to be unit magnitude and store scale in x component of v
+ * 2. X rotation angle from +y axis of this vector is put in y component of v
+ * 3. z component output of v is the 4-quadrant angle that z makes with x (Y axis rotation)
+ */
+ DVector getAnglesAsVect() const;
DAffine fn4(const DVector &v);
DAffine fn5() const;