Testing a level surface for room for a decal

[gopostal]

Is this possible? Meaning if I want to apply a random scorch to a wall is there a way to pre-test it to see if there is enough flat wall space to handle the decal?

[Bleeder91[NL]]

Projectors perhaps. Or do you mean through code?

[gopostal]

I'm spawning a set of persistent decal graffiti across the level at map start. It uses random playerstarts and random direction to find a spot on the wall close by. In practice it works nicely about 60% of the time. On the rest the graffiti is over a corner, 2 sprays will end up overlapping, or the texture is applied in a spot that's just not flat and large enough.

Ferali mentioned that a trace done in four directions (U,D,L,R) from the point of application which are then traced down to find if they all share the same HitNormal would weed out a good chunk of the problem areas. I have done normal tracing but this math is seriously confusing to me, not to mention there is just not a lot of good tutorials on how to work out the proper tracing math on a more complex issue like this.

If anyone can spare the time to explain I'd be a very attentive audience. I run a private teamspeak if you'd rather just talk it out, whatever is easiest on you and your time. I'd like to get this bulletproof because the graffiti is all from active and retired Unreal people and groups and I admire them all. They deserve it to be perfect.

[yrex .]

Code: Select all

GetAxes( rotator(surfNormal), unused, Y, Z );

Now Y and Z are parallel to the surface...

[gopostal]

Just a follow-up in case anyone else wants to use the code. I worked this out as a series of traces and it functions very well. The source code for the checks will be included in the battle royale game mode but here is the function that is used:

Code: Select all

//Contains a series of traces to find if the area is clear, flat, and continuous. If it passes
//all the checks then it spawns the graffiti there. The checks are hard coded to 128X128 but you 
//can easily change the default and have it check for other size decals.
function SpawnGraffiti()
{
   local int PointCount;
   local NavigationPoint NP;
   local rotator newRot;
      local vector HitLocation, HitNormal, FireDir, X, Y, Z, Origin, StartTrace, EndTrace;
   local actor HitActor, Other;
   local int i, j, N, M, SpriteX, SpriteY;
   local float yOffset, zOffset;
   local cpanel Spawnedcpanel;
   local GraffitiLight b, q;
   local bool AreaClear;
   local bool FireAway;

   NavPoint = int(RandRange(0,NumNodes));
   FireAway = False;
   for (NP = Level.NavigationPointList; NP != None; NP = NP.NextNavigationPoint)
   {
      if (NP.IsA('PathNode'))
      {
         if (PointCount == NavPoint)
         {
                        newRot.Yaw = Rand(65535); //360 degrees around
                        newRot.Pitch = Rand(1820); //from 0 to roughly 10 degrees upward angle
                        newRot.Roll = 0;
                        FireDir = vector(newRot);
                        HitActor = Trace(HitLocation, HitNormal, location + FireDir * 1500, Location, false);
                        if(( HitActor == Level) && ( HitNormal.Z < 0.03 ) && ( HitNormal.Z > -0.03 ))
                        {
                            GetAxes( rotator(-HitNormal), X, Y, Z);
                           Origin = HitLocation + HitNormal;
                              //Pass 1
                              StartTrace = Origin;
                              EndTrace =  Origin + Y * 64 + Z * 64;
                              Other = Trace(HitLocation, HitNormal, EndTrace, StartTrace, true);
                              if (Other != none)
                                 return;
                              else
                              {
                                 StartTrace = Origin + Y * 64 + Z * 64;
                                 EndTrace = StartTrace + X * 3;
                                 Other = Trace(HitLocation, HitNormal, EndTrace, StartTrace, true);
                                    if (Other != none)
                                    {
                     //Pass 2
                     StartTrace = Origin;
                                          EndTrace =  Origin + Y * -64 + Z * 64;
                                          Other = Trace(HitLocation, HitNormal, EndTrace, StartTrace, true);
                                          if (Other != none)
                                             return;
                                          else
                                          {
                                             StartTrace = Origin + Y * -64 + Z * 64;
                                             EndTrace = StartTrace + X * 3;
                                             Other = Trace(HitLocation, HitNormal, EndTrace, StartTrace, true);
                                                if (Other != none)
                                                {
                                                      //Pass 3
                                                      StartTrace = Origin;
                                                      EndTrace =  Origin + Y * 64 + Z * -64;
                                                      Other = Trace(HitLocation, HitNormal, EndTrace, StartTrace, true);
                                                      if (Other != none)
                                                         return;
                                                      else
                                                      {
                                                         StartTrace = Origin + Y * 64 + Z * -64;
                                                         EndTrace = StartTrace + X * 3;
                                                         Other = Trace(HitLocation, HitNormal, EndTrace, StartTrace, true);
                                                            if (Other != none)
                                                            {
                                                                  //Pass4
                                                                  StartTrace = Origin;
                                                                  EndTrace =  Origin + Y * -64 + Z * -64;
                                                                  Other = Trace(HitLocation, HitNormal, EndTrace, StartTrace, true);
                                                                  if (Other != none)
                                                                     return;
                                                                  else
                                                                  {
                                                                     StartTrace = Origin + Y * -64 + Z * -64;
                                                                     EndTrace = StartTrace + X * 3;
                                                                     Other = Trace(HitLocation, HitNormal, EndTrace, StartTrace, true);
                                                                        if (Other != none)
                                                                              FireAway = True;
                                                         }
                                                   }  else return;
                                             }
                                       } else return;
                                 }
                           } else return;
                     }
               } else return;
                    } PointCount++;
      }
   }
   if(FireAway)
   {
      AreaClear = True;
      //Check the local area for existing sprays, skip if there are any
          foreach RadiusActors(class 'GraffitiLight', q, 256, Origin)
             if( Q != none)
                AreaClear = False;
            if(AreaClear)
            {
                  b = Spawn(class'GraffitiLight',self,,Origin + HitNormal*32);
              b.remoterole=ROLE_simulatedproxy;
                        
                  Spawnedcpanel = Spawn(class'cpanel',,, Origin,  rotator(HitNormal));
      }
   }
}

cpanel is simply panel subclassed to use random textures. GraffitiLight is a small light used to illuminate the panel very lightly and it also allows an easy check for existing graffiti so there's no overlap.

Thank you guys for your help!