Detect whether there is an obstacle between objects
Accepted solution
The line goes through the coboid if it intersects with any of its faces. Each face defines a plane in 3D space. The intersection point of the line with that plane (if not parallel) can be calculated relatively easily. You then have to check whether that point is part of the surface.
The math is summarized pretty well under the following link:
https://www.wikiwand.com/en/Line%E2%80%93plane_intersection
If you take the vectors that define the plane to be equal to the edges of the object (vectors between corner points) then the line intersects the face if 0 <= u <= 1 and 0 <= v <= 1, as mentioned on the linked page.
In the Flexsim the Vec3 Class offers all necessary methods for these calculations. The 'getLocation()' method can be used to get the corner points of the object, serving as p0, p1 and p2.
Depends on how many objects there are. In general, I would recommend to first to a rough check (distance from object center to line) to see if an intersection is possible. Only then do the check above to improve performance.
The distance can be gotten quite easily:
|pxp0| = |p1p0| * sin(α), where p1 and p2 define the line and p0 ist the objects center
In the attached model is the approach listed above as a user command called findIntersectionsBetweenPoints() that takes two points in model space and returns a list of objects it crosses and a list of intersection points. It's called in the onDraw of the cylinder, which then draws the intersection points as green spheres on a line between two flow items that are circulating on the conveyors.
/**Custom Code*/
Vec3 L1=param(1); //The first point of the line in model space
Vec3 L2=param(2); // The second point of the line in model space
Array omit=param(3); //The array of objects to omit from tests.
Vec3 L12 =L2-L1; // The vector between the two points on the line
double lineMag=L12.magnitude; //length of the line
Vec3 L21=L12*-1; // The reverse vector of the line
Vec3 mid=Vec3(0.5,0.5,0.5);
Object o=model().last;
Vec3 oCen;
Vec3 L1toCen;
double dist=0;
string pathstr;
double objDiagLen;
Array objects=[];
Array intersections=[];
forobjecttreeunder(model()){
if (getdatatype(a)==DATATYPE_OBJECT&& omit.indexOf(a)==-1){
pathstr=nodetopath(a,1);
if (not(pathstr.startsWith("MODEL:/Tools"))){
o=a;
oCen=o.getLocation(mid); //get the centre point of the object's oriented bounding box (OBB)
L1toCen=oCen-L1; // the vector from the start of our line to the object centre
dist=L1toCen.cross(L12).magnitude/lineMag; // distance of the centre to out line at the shortest point
objDiagLen=sqrt(sqr(o.size.x)+sqr(o.size.y)+sqr(o.size.z)); // the length of the OBB diagnonal.
int possIntersect=dist<objDiagLen/2; // could it intersect the line 1/0
if (possIntersect){
int intersected=0;
Vec3 pa0=o.getLocation(0,0,0).project(o.up,model());
Vec3 pa1=o.getLocation(1,0,0).project(o.up,model());
Vec3 pa2=o.getLocation(0,1,0).project(o.up,model());
Vec3 pa3=o.getLocation(0,0,1).project(o.up,model());
Vec3 pb0=o.getLocation(1,1,1).project(o.up,model());
Vec3 pb1=o.getLocation(0,1,1).project(o.up,model());
Vec3 pb2=o.getLocation(1,0,1).project(o.up,model());
Vec3 pb3=o.getLocation(1,1,0).project(o.up,model());
Array planes= [[pa0,pa1-pa0,pa2-pa0]
,[pa0,pa1-pa0,pa3-pa0]
,[pa0,pa2-pa0,pa3-pa0]
,[pb0,pb1-pb0,pb2-pb0]
,[pb0,pb1-pb0,pb3-pb0]
,[pb0,pb2-pb0,pb3-pb0]];
for (int n=6;n>0;n--){ // Use n>0&&!intersected if you don't want all the intersection points
Vec3 p0=planes[1]; //common corner point in model space
Vec3 p01=planes[2]; //vector along edge1
Vec3 p02=planes[3]; //vector along edge2
double denom=L21.dot(p01.cross(p02));
if (denom==0) //no solution
continue;
double t=p01.cross(p02).dot(L1-p0)/denom;
double u=p02.cross(L21).dot(L1-p0)/denom;
double v=L21.cross(p01).dot(L1-p0)/denom;
if (u>=0&&u<=1&&v>=0&&v<=1&&t>=0&&t<=1) { //solution is in this plane of the OBB
intersected=1;
objects.push(o);
intersections.push(L1+L12*t);
}
}
}
}
}
}
return [objects, intersections]; 
The OptiX ray tracing engine that is used by RTX Mode is specifically implemented in the Engine to render the 3D view. It isn't accessible generally to a modeler to use for arbitrary calculations.
You could use the Module SDK or DLL Maker to implement a ray tracer to do arbitrary calculations if you wanted, but it's probably simpler to just write a mathematical function to calculate what you want.
Phil BoBo
Sr. Manager, Software Development
