Fix crash in Camera::computeFitViewEyePosition with zero view direction

Zoom All could pass a zero view direction (eye equal to view reference
point). The up vector then also became zero, giving a plane with a zero
normal and an assert in Plane::distanceToOrigin. Fall back to the Y axis
when the direction is zero or undefined. Follow-up to the parallel
dir/up fix in #14849.

Call stack:
[5] cvf::AssertHandlerConsole::handleAssert(char const*, int, char const*, char const*) at cvfAssert.cpp:125
[6] cvf::Plane::distanceToOrigin() const at cvfPlane.cpp:313
[7] cvf::Camera::computeFitViewEyePosition(cvf::BoundingBox const&, cvf::Vector3<double> const&, cvf::Vector3<double> const&, double, double, double) at cvfCamera.cpp:361
[8] caf::Viewer::zoomAll() at cafViewer.cpp:992
[9] caf::CmdFeature::actionTriggered(bool) at cafCmdFeature.cpp:176

ApplicationLibCode/UnitTests/CvfCameraCrashTriage-Test.cpp

@@ -85,3 +85,44 @@ TEST( CvfCameraCrashTriageTest, FitViewWithParallelDirAndUpProducesValidViewMatr
     EXPECT_NEAR( c.direction() * c.right(), 0.0, 1e-6 );
     EXPECT_NEAR( c.up() * c.right(), 0.0, 1e-6 );
 }
+
+//--------------------------------------------------------------------------------------------------
+/// A zero view direction (eye == view reference point, as in caf::Viewer::zoomAll()) gave a zero up
+/// vector and a zero-normal plane, which asserted in Plane::distanceToOrigin().
+//--------------------------------------------------------------------------------------------------
+TEST( CvfCameraCrashTriageTest, FitViewEyePositionWithZeroDirDoesNotCrash )
+{
+    Camera c;
+
+    BoundingBox bb;
+    bb.add( Vec3d( 0, 0, 0 ) );
+    bb.add( Vec3d( 1, 1, 1 ) );
+
+    for ( const auto& dir : { Vec3d::ZERO, Vec3d::UNDEFINED } )
+    {
+        Vec3d eye = Camera::computeFitViewEyePosition( bb, dir, Vec3d( 0, 0, 1 ), 0.9, c.fieldOfViewYDeg(), 1.0 );
+
+        EXPECT_FALSE( eye.isUndefined() );
+    }
+}
+
+//--------------------------------------------------------------------------------------------------
+/// fitView() must derive the up vector from the same valid direction as the eye position
+//--------------------------------------------------------------------------------------------------
+TEST( CvfCameraCrashTriageTest, FitViewWithZeroOrUndefinedDirProducesValidViewMatrix )
+{
+    BoundingBox bb;
+    bb.add( Vec3d( 0, 0, 0 ) );
+    bb.add( Vec3d( 1, 1, 1 ) );
+
+    for ( const auto& dir : { Vec3d::ZERO, Vec3d::UNDEFINED } )
+    {
+        Camera c;
+        c.setViewport( 0, 0, 100, 100 );
+        c.fitView( bb, dir, Vec3d( 0, 0, 1 ), 0.9 );
+
+        EXPECT_NEAR( c.direction().length(), 1.0, 1e-6 );
+        EXPECT_NEAR( c.up().length(), 1.0, 1e-6 );
+        EXPECT_NEAR( c.right().length(), 1.0, 1e-6 );
+    }
+}

Fwk/VizFwk/LibRender/cvfCamera.cpp

@@ -43,10 +43,23 @@
 #include "cvfBoundingBox.h"
 #include "cvfGeometryUtils.h"
 
+#include <limits>
+
 namespace cvf {
 
 namespace {
 
+//--------------------------------------------------------------------------------------------------
+/// A zero, undefined or non-finite view direction cannot define a view; fall back to looking along the Y axis
+//--------------------------------------------------------------------------------------------------
+Vec3d validViewDirection(const Vec3d& dir)
+{
+    const double length = dir.length();
+    if (!dir.isUndefined() && length > 0.0 && length < std::numeric_limits<double>::max()) return dir;
+
+    return Vec3d::Y_AXIS;
+}
+
 //--------------------------------------------------------------------------------------------------
 /// Returns an up vector guaranteed to be non-parallel to dir. If the passed up vector is already
 /// non-parallel to dir, it is returned unchanged. Otherwise a corrected, orthogonal up vector is
@@ -310,8 +323,10 @@ void Camera::setProjectionAsPixelExact2D()
 /// the view to. The relativeDistance parameter specifies the distance from the camera to the 
 /// center of the bounding box
 //--------------------------------------------------------------------------------------------------
-void Camera::fitView(const BoundingBox& boundingBox, const Vec3d& dir, const Vec3d& up, double coverageFactor)
+void Camera::fitView(const BoundingBox& boundingBox, const Vec3d& dirIn, const Vec3d& up, double coverageFactor)
 {
+    const cvf::Vec3d dir = validViewDirection(dirIn);
+
     // dir and up may be parallel (degenerate camera orientation); derive a corrected, non-parallel
     // up vector so both the eye computation and the final look-at matrix use a consistent basis.
     cvf::Vec3d correctedUp = nonParallelUpVector(dir, up);
@@ -327,8 +342,10 @@ void Camera::fitView(const BoundingBox& boundingBox, const Vec3d& dir, const Vec
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
-Vec3d Camera::computeFitViewEyePosition(const BoundingBox& boundingBox, const Vec3d& dir, const Vec3d& up, double coverageFactor, double fieldOfViewYDeg, double aspectRatio) 
+Vec3d Camera::computeFitViewEyePosition(const BoundingBox& boundingBox, const Vec3d& dirIn, const Vec3d& up, double coverageFactor, double fieldOfViewYDeg, double aspectRatio) 
 {
+    const cvf::Vec3d dir = validViewDirection(dirIn);
+
     cvf::Vec3d corners[8];
     boundingBox.cornerVertices(corners);