Finds a Character based on distance and health





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$begingroup$


I need to improve the efficiency of my program and, using the profiler, have narrowed the problem down to 2 key areas, but I am having trouble coming up with ways to make the program run better.



Based on my profiler's report, it seems to be telling me that my if functions are inefficient. Whats a better way to achieve a better result?



Character* FindAttackTarget() const
{
float weakestHp = FLT_MAX;
Character* weakestEnemy = nullptr;
uint64_t weakestCharId = INT64_MAX;

//Only attack characters that are within attack range
auto& gameChars = m_pGame->m_gameCharacters;


for (size_t i = 0; i < gameChars.size(); ++i)
{
auto& c = gameChars[i];
if (Location.Dist(c.GetLocation()) <= AttackRange &&
c.HP > 0 &&
c.Team != Team)
{
//We want the weakest with the lowest ID number - this keeps consistent results when re-playing the same part of the game (eg. after a load game)
if (c.HP < weakestHp || (c.HP == weakestHp && c.ID < weakestCharId))
{
weakestEnemy = &gameChars[i];
weakestHp = c.HP;
weakestCharId = c.ID;
}
}
}

return weakestEnemy;
}









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  • $begingroup$
    Which lines are the ones being flagged by the profiler as slow?
    $endgroup$
    – 1201ProgramAlarm
    1 hour ago


















1












$begingroup$


I need to improve the efficiency of my program and, using the profiler, have narrowed the problem down to 2 key areas, but I am having trouble coming up with ways to make the program run better.



Based on my profiler's report, it seems to be telling me that my if functions are inefficient. Whats a better way to achieve a better result?



Character* FindAttackTarget() const
{
float weakestHp = FLT_MAX;
Character* weakestEnemy = nullptr;
uint64_t weakestCharId = INT64_MAX;

//Only attack characters that are within attack range
auto& gameChars = m_pGame->m_gameCharacters;


for (size_t i = 0; i < gameChars.size(); ++i)
{
auto& c = gameChars[i];
if (Location.Dist(c.GetLocation()) <= AttackRange &&
c.HP > 0 &&
c.Team != Team)
{
//We want the weakest with the lowest ID number - this keeps consistent results when re-playing the same part of the game (eg. after a load game)
if (c.HP < weakestHp || (c.HP == weakestHp && c.ID < weakestCharId))
{
weakestEnemy = &gameChars[i];
weakestHp = c.HP;
weakestCharId = c.ID;
}
}
}

return weakestEnemy;
}









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New contributor




Atazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







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  • $begingroup$
    Which lines are the ones being flagged by the profiler as slow?
    $endgroup$
    – 1201ProgramAlarm
    1 hour ago














1












1








1





$begingroup$


I need to improve the efficiency of my program and, using the profiler, have narrowed the problem down to 2 key areas, but I am having trouble coming up with ways to make the program run better.



Based on my profiler's report, it seems to be telling me that my if functions are inefficient. Whats a better way to achieve a better result?



Character* FindAttackTarget() const
{
float weakestHp = FLT_MAX;
Character* weakestEnemy = nullptr;
uint64_t weakestCharId = INT64_MAX;

//Only attack characters that are within attack range
auto& gameChars = m_pGame->m_gameCharacters;


for (size_t i = 0; i < gameChars.size(); ++i)
{
auto& c = gameChars[i];
if (Location.Dist(c.GetLocation()) <= AttackRange &&
c.HP > 0 &&
c.Team != Team)
{
//We want the weakest with the lowest ID number - this keeps consistent results when re-playing the same part of the game (eg. after a load game)
if (c.HP < weakestHp || (c.HP == weakestHp && c.ID < weakestCharId))
{
weakestEnemy = &gameChars[i];
weakestHp = c.HP;
weakestCharId = c.ID;
}
}
}

return weakestEnemy;
}









share|improve this question







New contributor




Atazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




I need to improve the efficiency of my program and, using the profiler, have narrowed the problem down to 2 key areas, but I am having trouble coming up with ways to make the program run better.



Based on my profiler's report, it seems to be telling me that my if functions are inefficient. Whats a better way to achieve a better result?



Character* FindAttackTarget() const
{
float weakestHp = FLT_MAX;
Character* weakestEnemy = nullptr;
uint64_t weakestCharId = INT64_MAX;

//Only attack characters that are within attack range
auto& gameChars = m_pGame->m_gameCharacters;


for (size_t i = 0; i < gameChars.size(); ++i)
{
auto& c = gameChars[i];
if (Location.Dist(c.GetLocation()) <= AttackRange &&
c.HP > 0 &&
c.Team != Team)
{
//We want the weakest with the lowest ID number - this keeps consistent results when re-playing the same part of the game (eg. after a load game)
if (c.HP < weakestHp || (c.HP == weakestHp && c.ID < weakestCharId))
{
weakestEnemy = &gameChars[i];
weakestHp = c.HP;
weakestCharId = c.ID;
}
}
}

return weakestEnemy;
}






c++ performance






share|improve this question







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Atazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question







New contributor




Atazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









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Check out our Code of Conduct.









asked 4 hours ago









AtazirAtazir

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Check out our Code of Conduct.





New contributor





Atazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






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Check out our Code of Conduct.












  • $begingroup$
    Which lines are the ones being flagged by the profiler as slow?
    $endgroup$
    – 1201ProgramAlarm
    1 hour ago


















  • $begingroup$
    Which lines are the ones being flagged by the profiler as slow?
    $endgroup$
    – 1201ProgramAlarm
    1 hour ago
















$begingroup$
Which lines are the ones being flagged by the profiler as slow?
$endgroup$
– 1201ProgramAlarm
1 hour ago




$begingroup$
Which lines are the ones being flagged by the profiler as slow?
$endgroup$
– 1201ProgramAlarm
1 hour ago










1 Answer
1






active

oldest

votes


















2












$begingroup$

The tests c.HP > 0 and c.Team != Team are probably blazingly fast tests. Location.Dist(c.GetLocation()) <= AttackRange probably involves the square-root of the sum of the squares of the difference of coordinates in two or three dimensions. Plus, GetLocation() may involve memory allocation and/or copying constructors. It is by far the slowest test, yet you are testing it first! Take advantage of the short-circuit logical and operators by reordering the tests so the fastest tests are done first, so the slowest test may not even need to be executed, resulting in faster execution.



Bonus: the square-root can be avoided; simply compute the square distance, and compare against the $AttackRange^2$ (computed outside of the loop) for another speed gain.






share|improve this answer









$endgroup$













  • $begingroup$
    I believe you're on the right track but could expand and systematize your answer: for instance, @Atazir could have gameChars partitioned between enemy and the rest, then have the enemy partition sorted by strength, and last find the first enemy in range: the costly operation is performed on the least number of elements.
    $endgroup$
    – papagaga
    39 mins ago












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1 Answer
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active

oldest

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1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









2












$begingroup$

The tests c.HP > 0 and c.Team != Team are probably blazingly fast tests. Location.Dist(c.GetLocation()) <= AttackRange probably involves the square-root of the sum of the squares of the difference of coordinates in two or three dimensions. Plus, GetLocation() may involve memory allocation and/or copying constructors. It is by far the slowest test, yet you are testing it first! Take advantage of the short-circuit logical and operators by reordering the tests so the fastest tests are done first, so the slowest test may not even need to be executed, resulting in faster execution.



Bonus: the square-root can be avoided; simply compute the square distance, and compare against the $AttackRange^2$ (computed outside of the loop) for another speed gain.






share|improve this answer









$endgroup$













  • $begingroup$
    I believe you're on the right track but could expand and systematize your answer: for instance, @Atazir could have gameChars partitioned between enemy and the rest, then have the enemy partition sorted by strength, and last find the first enemy in range: the costly operation is performed on the least number of elements.
    $endgroup$
    – papagaga
    39 mins ago
















2












$begingroup$

The tests c.HP > 0 and c.Team != Team are probably blazingly fast tests. Location.Dist(c.GetLocation()) <= AttackRange probably involves the square-root of the sum of the squares of the difference of coordinates in two or three dimensions. Plus, GetLocation() may involve memory allocation and/or copying constructors. It is by far the slowest test, yet you are testing it first! Take advantage of the short-circuit logical and operators by reordering the tests so the fastest tests are done first, so the slowest test may not even need to be executed, resulting in faster execution.



Bonus: the square-root can be avoided; simply compute the square distance, and compare against the $AttackRange^2$ (computed outside of the loop) for another speed gain.






share|improve this answer









$endgroup$













  • $begingroup$
    I believe you're on the right track but could expand and systematize your answer: for instance, @Atazir could have gameChars partitioned between enemy and the rest, then have the enemy partition sorted by strength, and last find the first enemy in range: the costly operation is performed on the least number of elements.
    $endgroup$
    – papagaga
    39 mins ago














2












2








2





$begingroup$

The tests c.HP > 0 and c.Team != Team are probably blazingly fast tests. Location.Dist(c.GetLocation()) <= AttackRange probably involves the square-root of the sum of the squares of the difference of coordinates in two or three dimensions. Plus, GetLocation() may involve memory allocation and/or copying constructors. It is by far the slowest test, yet you are testing it first! Take advantage of the short-circuit logical and operators by reordering the tests so the fastest tests are done first, so the slowest test may not even need to be executed, resulting in faster execution.



Bonus: the square-root can be avoided; simply compute the square distance, and compare against the $AttackRange^2$ (computed outside of the loop) for another speed gain.






share|improve this answer









$endgroup$



The tests c.HP > 0 and c.Team != Team are probably blazingly fast tests. Location.Dist(c.GetLocation()) <= AttackRange probably involves the square-root of the sum of the squares of the difference of coordinates in two or three dimensions. Plus, GetLocation() may involve memory allocation and/or copying constructors. It is by far the slowest test, yet you are testing it first! Take advantage of the short-circuit logical and operators by reordering the tests so the fastest tests are done first, so the slowest test may not even need to be executed, resulting in faster execution.



Bonus: the square-root can be avoided; simply compute the square distance, and compare against the $AttackRange^2$ (computed outside of the loop) for another speed gain.







share|improve this answer












share|improve this answer



share|improve this answer










answered 1 hour ago









AJNeufeldAJNeufeld

7,0541723




7,0541723












  • $begingroup$
    I believe you're on the right track but could expand and systematize your answer: for instance, @Atazir could have gameChars partitioned between enemy and the rest, then have the enemy partition sorted by strength, and last find the first enemy in range: the costly operation is performed on the least number of elements.
    $endgroup$
    – papagaga
    39 mins ago


















  • $begingroup$
    I believe you're on the right track but could expand and systematize your answer: for instance, @Atazir could have gameChars partitioned between enemy and the rest, then have the enemy partition sorted by strength, and last find the first enemy in range: the costly operation is performed on the least number of elements.
    $endgroup$
    – papagaga
    39 mins ago
















$begingroup$
I believe you're on the right track but could expand and systematize your answer: for instance, @Atazir could have gameChars partitioned between enemy and the rest, then have the enemy partition sorted by strength, and last find the first enemy in range: the costly operation is performed on the least number of elements.
$endgroup$
– papagaga
39 mins ago




$begingroup$
I believe you're on the right track but could expand and systematize your answer: for instance, @Atazir could have gameChars partitioned between enemy and the rest, then have the enemy partition sorted by strength, and last find the first enemy in range: the costly operation is performed on the least number of elements.
$endgroup$
– papagaga
39 mins ago










Atazir is a new contributor. Be nice, and check out our Code of Conduct.










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