Added a helper void Frustum::SetWorldMatrix to easily specify the pos…

…, front and up vectors of a camera.

src/Geometry/Frustum.cpp

@@ -89,6 +89,18 @@ Plane Frustum::BottomPlane() const
 	return Plane(pos, bottomSideNormal);
 }
 
+void Frustum::SetWorldMatrix(const float3x4 &worldTransform)
+{
+	pos = worldTransform.TranslatePart();
+	front = -worldTransform.Col(2); // The camera looks towards -Z axis of the given transform.
+	up = worldTransform.Col(1); // The camera up points towards +Y of the given transform.
+	assume(pos.IsFinite());
+	assume(front.IsNormalized());
+	assume(up.IsNormalized());
+	assume(worldTransform.IsColOrthogonal3()); // Front and up must be orthogonal to each other.
+	assume(EqualAbs(worldTransform.Determinant(), 1.f)); // The matrix cannot contain mirroring.
+}
+
 float3x4 Frustum::WorldMatrix() const
 {
 	assume(up.IsNormalized());

src/Geometry/Frustum.h

@@ -155,6 +155,12 @@ class Frustum
 		@see CornerPoint(). */
 	float3 ExtremePoint(const float3 &direction) const;
 
+	/// Sets the pos, front and up members of this frustum from the given world transform.
+	/** This function sets the 'front' parameter of this Frustum to look towards the -Z axis of the given matrix, 
+		and the 'up' parameter of this Frustum to point towards the +Y axis of the given matrix.
+		@param worldTransform An orthonormalized matrix with determinant of +1 (no mirroring). */
+	void SetWorldMatrix(const float3x4 &worldTransform);
+
 	/// Computes the matrix that transforms from the view space to the world (global) space of this Frustum.
 	/** @note The returned matrix is the inverse of the matrix returned by ViewMatrix().
 		@return An orthonormal affine matrix that performs the view->world transformation. The returned