User:LindaB Helendale/meshLODanalyzer

Mesh LOD and Land Impact analyzer (c) Lindab Helendale. Permission to use this script in any way granted.

The script is combination of mesh asset server size script https://wiki.secondlife.com/wiki/User:LindaB_Helendale/getMeshLODsize and mesh land impact script https://wiki.secondlife.com/wiki/User:LindaB_Helendale/meshLODschemeCalculator

Drop the script in a mesh to see the contribution of LODs on the Land Impact and the effect of the scale of the mesh on the Land Impact.

<lsl> // Drop this script in a mesh object to see how the streaming (download) cost component of land impact // is calculated for that mesh. The script also shows how the download cost changes when the size of // the mesh is changed, with breakdown of the cost to each LOD. // // To test the performance of different LOD reduction schemes, see // http://wiki.secondlife.com/wiki/User:LindaB_Helendale/meshLODschemeCalculator // // The script is activated by dropping it in an object, resetting the script, rezzing the object, // or touching the object. // // (c) LindaB Helendale, permission to use this script in any way granted.

float getObjectStreamingCost() {

   return llList2Float(llGetObjectDetails(llGetKey(),[OBJECT_STREAMING_COST]),0);

}

float getRadius() {

   return llVecMag(llGetScale())/2.0 ;

}

setRadius(float R) {

   llSetScale(llGetScale()*R/getRadius());
   if (llFabs(getRadius()-R)>0.01)
       llOwnerSay("Warning: failed to set radius to " + (string)R + " The result was " + (string)getRadius());

}

list getLODtriangles() {

   // Measure the triangle count for mesh LODs used in calculating the Streaming Cost/Download Cost
   // component of the mesh Land Impact. Permission to use this script in any way granted.
   // (c) LindaB Helendale
   // See http://wiki.secondlife.com/wiki/User:LindaB_Helendale/getMeshLODsize for more info
   vector S=llGetScale();
   llSetScale(<1,1,1>); // we set equal scales to make sure the biggest radius is reached
   float MeshTriangleBudgetScaler=50.0/3.0; // = MeshTriangleBudget(250000)/15000
   list radius=[43.4422,   10.8605,    5.43027,    0.01];    
   list C;
   integer i;
   for(i=0;i<4;i++) {
       setRadius(llList2Float(radius,i));
       C += getObjectStreamingCost() * MeshTriangleBudgetScaler;
   }
   list tri;
   tri = [ llList2Float(C,0), 
           16.0/15.0*llList2Float(C,1) - 1.0/15.0*llList2Float(C,0),
             4.0/3.0*llList2Float(C,2) -  1.0/3.0*llList2Float(C,1),
           llList2Float(C,3)
         ];
   llSetScale(S);
   return tri;

}

float getLODbytesize(float triangles) {

   float MeshBytesPerTriangle=16;
   float MeshMetaDataDiscount=384;
   return triangles*MeshBytesPerTriangle + MeshMetaDataDiscount;

}

list LODdistances(float r) {

   float max_distance = 512;
   float dlowest = min(r/0.03, max_distance);
   float dlow = min(r/0.06, max_distance);
   float dmid = min(r/0.24, max_distance);
   return [dlowest, dlow, dmid];

}

list LODweigths(float r) {

   float max_distance = 512;
   float dlowest = min(r/0.03, max_distance);
   float dlow = min(r/0.06, max_distance);
   float dmid = min(r/0.24, max_distance);

   float max_area = 102932;
   float min_area = 1;

   float high_area = min(PI*dmid*dmid, max_area);
   float mid_area = min(PI*dlow*dlow, max_area);
   float low_area = min(PI*dlowest*dlowest, max_area);
   float lowest_area = max_area;

   lowest_area = lowest_area - low_area;
   low_area = low_area - mid_area;
   mid_area = mid_area - high_area;

   high_area = llclamp(high_area, min_area, max_area);
   mid_area = llclamp(mid_area, min_area, max_area);
   low_area = llclamp(low_area, min_area, max_area);
   lowest_area = llclamp(lowest_area, min_area, max_area);

   float total_area = high_area + mid_area + low_area + lowest_area;
   high_area = high_area / total_area;
   mid_area = mid_area / total_area;
   low_area = low_area / total_area;
   lowest_area = lowest_area / total_area;

   list weights=[high_area, mid_area, low_area, lowest_area];
   return weights ;

}

float min(float a, float b) {

   if (a<b) return a;
   else     return b;

} float llclamp(float b,float bmin,float bmax) {

   if (b<bmin) b=bmin;
   if (b>bmax) b=bmax;
   return b;    

}

list get_LI_per_LOD(list triangles, float r) {

   integer i;
   list W=LODweigths(r); 
   list LI;
   for(i=0;i<4;i++) {
       LI += llList2Float(triangles,i)*llList2Float(W,i) * 3.0/50.0;   // = 15000/MeshTriangleBudget
   }
   return LI;

}

print_LODs(list triangles, float r, integer percentage, integer showByteCounts) {

   integer i;
   float LItotal;

   list LI = get_LI_per_LOD(triangles,r);
   LItotal = llListStatistics(LIST_STAT_SUM, LI);
   string txt;
   for(i=0;i<4;i++) {
       float li = llList2Float(LI,i);
       if (percentage) li *= 100.0/LItotal;
       txt +=  "      " + llGetSubString((string)li,0,7) ;
   }
   llOwnerSay(llGetSubString((string)r,0,7) + "    " + llGetSubString((string)LItotal,0,7) + txt);
   if (showByteCounts) {
       llOwnerSay(" ");
       txt="";
       for(i=0;i<4;i++) {
           float tri = llList2Float(triangles,i);
           txt += "       " + llGetSubString("        " + (string)llRound(tri),-8,-1) ;
       }
       llOwnerSay("LOD sizes in triangles:"  + txt);
       txt="";
       for(i=0;i<4;i++) {
           float byt = getLODbytesize(llList2Float(triangles,i));
           txt += "       " + llGetSubString("        " + (string)llRound(byt),-8,-1) ;
       }
       llOwnerSay("LOD sizes in bytes:  "  + txt);
       llOwnerSay(" ");
       llOwnerSay("Note that the 'size in triangles' is lower than the actual triangle count, due to gzip compression of the data in asset server.");
   }

}

show_landimpact_table() {

   integer percentage = FALSE;
   if (llGetNumberOfPrims()>1) {
       llOwnerSay("Use this script with an unlinked mesh.");
       return;
   }
   float radius=getRadius();
   list triangles=getLODtriangles();
   list LIcosts = llGetObjectDetails(llGetKey(),[OBJECT_SERVER_COST, OBJECT_STREAMING_COST,OBJECT_PHYSICS_COST]);
   llOwnerSay("Mesh land impact analysis");
   llOwnerSay("====================");
   llOwnerSay("Server cost: " + (string)llList2Float(LIcosts,0));
   llOwnerSay("Physics cost: " + (string)llList2Float(LIcosts,2));
   llOwnerSay("Streaming (download) cost: " + (string)llList2Float(LIcosts,1));
   float LIestimate =  llListStatistics(LIST_STAT_SUM,get_LI_per_LOD(triangles,radius));
   llOwnerSay("        Estimated DL cost:   " + (string)LIestimate);
   llOwnerSay("        Error of this model: " + (string)(llList2Float(LIcosts,1)-LIestimate));
   llOwnerSay(" ");
   llOwnerSay("LOD switch distances at the currect radius of " + (string)radius + " m with the default renderVolumeLODfactor debug settings:");
   list LODdist=LODdistances(radius);
   llOwnerSay("  Lowest to low: " + (string)llList2Float(LODdist,0) + " m");
   llOwnerSay("  Low to mid: " + (string)llList2Float(LODdist,1) + " m");
   llOwnerSay("  Mid to high: " + (string)llList2Float(LODdist,2) + " m");
   llOwnerSay(" ");
   llOwnerSay("Contribution of each LOD on the download cost:");
   llOwnerSay("Radius       Total LI        highest LOD   mid LOD     low LOD     lowest LOD");
   print_LODs(triangles,radius,percentage,TRUE);
   
   llOwnerSay(" ");
   llOwnerSay("Effect of the mesh bounding sphere radius on the download cost:");
   llOwnerSay("Radius       Total LI        highest LOD   mid LOD     low LOD     lowest LOD");
   print_LODs(triangles,0.1,percentage,FALSE);
   print_LODs(triangles,0.25,percentage,FALSE);
   print_LODs(triangles,0.5,percentage,FALSE);
   for(radius=1;radius<20;radius++) print_LODs(triangles,radius,percentage,FALSE);
   for(radius=20;radius<=55;radius+=5) print_LODs(triangles,radius,percentage,FALSE);

}

default {

   state_entry()
   {
       show_landimpact_table();
   }

   on_rez(integer p) 
   {
       show_landimpact_table();
   }

   touch_start(integer num) {
       show_landimpact_table();
   }

} </lsl>