PolygonClipping: CLIPLINE produces NaN when line to clip is parallel to the maxX of the clip window

[jmarrec]

Issue overview

Here is an example:

    Real64 const minX = 2.0;
    Real64 const maxX = 8.0;
    Real64 const minY = 3.0;
    Real64 const maxY = 6.0;

    Real64 x0 = maxX;
    Real64 x1 = maxX;
    Real64 y0 = 4.5;
    Real64 y1 = 1.0;
    bool visible = false;
    bool rev = false;

    EXPECT_NO_THROW(CLIPLINE(x0, x1, y0, y1, maxX, minX, maxY, minY, visible, rev));

    // y1 is NaN now

Graphically, this looks like this:

Because dx is 0, This is a divide by zero on that line:

EnergyPlus/src/EnergyPlus/SolarShading.cc

Line 3996 in eb6665f

y2 = minY + e / dx;

Details

Some additional details for this issue (if relevant):

• Platform (Operating system, version): all
• Version of EnergyPlus (if using an intermediate build, include SHA): develop, eb6665f
• Found in Fix unit test floating point exceptions so we can enable Floating point exceptions by default in Debug mode (GCC/Clang) #10648

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

• Defect file added (list location of defect file here)
• Ticket added to EnergyPlus Defect Complexity (Github Project)
• Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)