gistfile1.txt

    float totalArea = 0;


    for( int i = 0; i < triBuffer.triangles.Length/3; i++ ){
      int tri0 = i * 3;
      int tri1 = tri0 + 1;
      int tri2 = tri0 + 2;
      tri0 = triBuffer.triangles[tri0];
      tri1 = triBuffer.triangles[tri1];
      tri2 = triBuffer.triangles[tri2];
      float area = AreaOfTriangle( vertBuffer.vertices[tri0] , vertBuffer.vertices[tri1] , vertBuffer.vertices[tri2] );
      triAreas[i] = area;
      totalArea += area;
    }

    print( totalArea );

    for( int i = 0; i < triAreas.Length; i++ ){
      triAreas[i] /= totalArea;
    }




// Then later
getTri( Random.value );



Where: 


  int getTri(float randomVal){


    int triID = 0;
    float totalTest = 0;
    for( int i = 0; i < triAreas.Length; i++ ){

      totalTest += triAreas[i];
      if( randomVal <= totalTest){
        triID = i;
        break;
      }

    }

    return triID;


  }