TITANIC: daffine refactor, call clear before setting rot matrix

The previous code wasn't reseting all the other elements to zero
when setting up a rotation matrix. This would of left other values
in the not set elements leading to a matrix not quite what the caller
wanted. This should lead to the function getFrameTransform returning
a different Daffine matrix.

Also added lots of todos

2 files changed, 29 insertions, 2 deletions

diff --git a/engines/titanic/star_control/daffine.cpp b/engines/titanic/star_control/daffine.cpp
index 56c705b6a5..8c956da9dd 100644
--- a/engines/titanic/star_control/daffine.cpp
+++ b/engines/titanic/star_control/daffine.cpp
@@ -65,6 +65,7 @@ DAffine::DAffine(const FMatrix &src) {
 	_col3 = src._row3;
 }
 
+//TODO: What is _static_ for?
 void DAffine::init() {
 	_static = nullptr;
 }
@@ -74,7 +75,24 @@ void DAffine::deinit() {
 	_static = nullptr;
 }
 
+void DAffine::clear() {
+	_col1._x = 0.0;
+	_col1._y = 0.0;
+	_col1._z = 0.0;
+	_col2._x = 0.0;
+	_col2._y = 0.0;
+	_col2._z = 0.0;
+	_col3._x = 0.0;
+	_col3._y = 0.0;
+	_col3._z = 0.0;
+	_col4._x = 0.0;
+	_col4._y = 0.0;
+	_col4._z = 0.0;
+}
+
 void DAffine::setRotationMatrix(Axis axis, double angleDeg) {
+        clear();
+
 	double sinVal = sin(angleDeg * Deg2Rad);
 	double cosVal = cos(angleDeg * Deg2Rad);
 
@@ -108,6 +126,7 @@ void DAffine::setRotationMatrix(Axis axis, double angleDeg) {
 	}
 }
 
+//TODO: Check math and provide source
 DAffine DAffine::inverseTransform() const {
 	double val1 = _col1._x * _col3._z * _col2._y;
 	double val2 = 0.0;
@@ -173,6 +192,7 @@ DAffine DAffine::inverseTransform() const {
 	return m;
 }
 
+//TODO: Check math and provide source
 void DAffine::loadTransform(const CMatrixTransform &src) {
 	double total = src.fn1();
 	double factor = (total <= 0.0) ? 0.0 : 2.0 / total;
@@ -200,6 +220,7 @@ void DAffine::loadTransform(const CMatrixTransform &src) {
 	_col4._z = 0;
 }
 
+//TODO: Check math and provide source
 DAffine DAffine::compose(const DAffine &m) {
 	DAffine dm;
 	dm._col1._x = m._col3._x * _col1._z + m._col2._x * _col1._y
diff --git a/engines/titanic/star_control/daffine.h b/engines/titanic/star_control/daffine.h
index 50450b9427..dda87323c6 100644
--- a/engines/titanic/star_control/daffine.h
+++ b/engines/titanic/star_control/daffine.h
@@ -55,6 +55,11 @@ public:
 	DAffine(const FMatrix &src);
 
 	/**
+	 * Sets all elements to zero
+	 */
+	void clear();
+
+	/**
 	 * Sets up an affine matrix for rotating on a given axis by an amount in degrees
 	 */
 	void setRotationMatrix(Axis axis, double angleDeg);
@@ -65,8 +70,9 @@ public:
 	DAffine inverseTransform() const;
 
 	/**
-	 * Change this Daffine to have its first three columns be the src matrix
-         * and the 4rth column to be (three) zeros
+	 * Change this Daffine to have its first three columns be some mapping from src matrix
+         * and the 4rth column to be (three) zeros. The mapping is not as simple as replacing
+         * matching row/colmn indices
 	 */
 	void loadTransform(const CMatrixTransform &src);