Gradient

#1 Or perhaps a way to limit the steepness a player can walk up?

#2 Gradient?

#3 Daniel Brown

Quote:
Or perhaps a way to limit the steepness a player can walk up?

This is already in the playerdata block.

#4 Assuming poly list is not empty, and looping through it.

runSurfaceCos = mCos(mDegToRad(runSurfaceAngle));
 ...
      F32 bestVd = -1;
      ...
      F32 vd = poly->plane.z;       // i.e.  mDot(Point3F(0,0,1), poly->plane);
         if (vd > bestVd) {
            bestVd = vd;
            *contactNormal = poly->plane;
         }
      
      *run  = bestVd > mDataBlock->runSurfaceCos;
...

#5 In the player datablock, located in player.cs, look for:


runSurfaceAngle =

and

jumpSurfaceAngle =

alter those and it will limit what someone can run and jump up.

#6 He is asking how you get the angle the player is standing on, not limiting what he can stand on.

#7 Oh, sorry im 1/2 asleep, my eyes seemed to have totally missed the second post.

#8 Can someone please explain what the above code does

sorry my math is rusty, i cant figure out what the value of bestVd is.

Why do we compare bestVd > mDatablock->runSurfaceCos. (i know why, i.e to restrict the player from moving uphill) but i cant figure out what bestVd represents or why that variable name was chosen. Is it best vertical distance?

If someone could explain it in detail I would apreciate it.

Thanks!

#9 If the "gradient" means "the most upwards-pointing vector which is on the surface",
and assuming you've got the normal to the surface,
then the cross-product is your friend!

vNorm  = normal to the surface
vUp    = the "up" vector. in torque this would be (0, 0, 1).

vLevel = vUp   CROSS vNorm.  - vLevel is now horizontal.
vGrad  = vNorm CROSS vLevel. - vGrad is now pointing uphill.

note that vGrad becomes (logically) undefined as your surface gets closer to horizontal.

#10 Thanks but were you answering my question or the original one? That was a year old question, perhaps i should have started a new thread but i figured why not keep the information in one place.

#11 Oh, hah. sorry, i answered the original Q.

i believe that clip of code you're asking about chooses the most horizontal surface in a list of surfaces, and tests to see if it's more horizontal than runSurfaceAngle.

bestVd in that code looks to me like the z-component of the surface normal,
which larger ones mean a more horizontal surface.

#12 Thanks that makes sense, I thought that it was the Z component of the plane. Which I was right and if i am correct a plane in vector form is described by the normal and the distance as the 4th vector component.


So the possible values for Z would range from -1 to 1 and when compared to the Cos(SomeAngle) which also ranges from -1 to 1, that should return true if the Z value is larger than Cos(SomeAngle).

Did I understand that correct?