Return value of c_trace?

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Return value of c_trace? #416813 02/05/13 01:33 02/05/13 01:33
Joined: Jan 2013 Posts: 63 Loremaster OP Junior Member
Loremaster OP Junior Member Joined: Jan 2013 Posts: 63	I use the following line of code to evaluate whether there is a line of sight between player and NPC. Code: if (c_trace( my.x, player.x, IGNORE_ME\|IGNORE_PASSENTS\|IGNORE_PASSABLE\|IGNORE_SPRITES) == 0) { FancyNPCFunction() } I assumed if the trace hits the player unhindered, the return value would be 0. My if-statement therefore triggers the NPC-action if it is 0. It does not trigger it. What do I do wrong? Design Diary

Re: Return value of c_trace? [Re: Loremaster] #416814 02/05/13 02:30 02/05/13 02:30
Joined: Apr 2007 Posts: 3,751 Canada WretchedSid Expert
WretchedSid Expert Joined: Apr 2007 Posts: 3,751 Canada	c_trace returns 0 when nothing is hit, otherwise the return value is non-zero. Note though that hit could mean that anything was hit, not just the player, so you should check wether you is equal to the player. Shitlord by trade and passion. Graphics programmer at Laminar Research. I write blog posts at feresignum.com

Re: Return value of c_trace? [Re: WretchedSid] #416815 02/05/13 02:43 02/05/13 02:43
Joined: Jan 2013 Posts: 63 Loremaster OP Junior Member
Loremaster OP Junior Member Joined: Jan 2013 Posts: 63	Got it. There is a me, there is a you. The latter was unknown to me. Design Diary

Re: Return value of c_trace? [Re: Loremaster] #416816 02/05/13 06:15 02/05/13 06:15
Joined: Jul 2008 Posts: 2,107 Germany rayp X
rayp X Joined: Jul 2008 Posts: 2,107 Germany	BTW.: To avoid "empty pointer" errors please check YOU before using it fex.: Code: c_trace if (you) if (you == player) Acknex umgibt uns...zwischen Dir, mir, dem Stein dort... "Hey Griswold ... where u gonna put a tree that big ?" 1998 i married my loved wife ... Sheeva from Mortal Kombat, not Evil-Lyn as might have been expected rayp.flags \|= UNTOUCHABLE;

Re: Return value of c_trace? [Re: rayp] #416817 02/05/13 06:36 02/05/13 06:36
Joined: Apr 2007 Posts: 3,751 Canada WretchedSid Expert
WretchedSid Expert Joined: Apr 2007 Posts: 3,751 Canada	That's not needed Rayp, you can compare a nullpointer to any other pointer just fine, you just can't dereference it. Shitlord by trade and passion. Graphics programmer at Laminar Research. I write blog posts at feresignum.com

Re: Return value of c_trace? [Re: WretchedSid] #416818 02/05/13 06:42 02/05/13 06:42
Joined: Jul 2008 Posts: 2,107 Germany rayp X
rayp X Joined: Jul 2008 Posts: 2,107 Germany	Ah ok. so this is ok: Code: if (you == player) and the check is only needed here Code: if (you) you.health -= 10; Acknex umgibt uns...zwischen Dir, mir, dem Stein dort... "Hey Griswold ... where u gonna put a tree that big ?" 1998 i married my loved wife ... Sheeva from Mortal Kombat, not Evil-Lyn as might have been expected rayp.flags \|= UNTOUCHABLE;

Re: Return value of c_trace? [Re: rayp] #416819 02/05/13 06:56 02/05/13 06:56
Joined: Apr 2007 Posts: 3,751 Canada WretchedSid Expert
WretchedSid Expert Joined: Apr 2007 Posts: 3,751 Canada	If you can guarantee that player is always unequal to NULL, you can omit the second check and just access you directly (given that both if() are related obviously). This would also work if you don't know wether player is NULL or not: Code: if(you && you == player) { you->health -= 10; } Shitlord by trade and passion. Graphics programmer at Laminar Research. I write blog posts at feresignum.com

Re: Return value of c_trace? [Re: WretchedSid] #416820 02/05/13 07:07 02/05/13 07:07
Joined: Jul 2008 Posts: 2,107 Germany rayp X
rayp X Joined: Jul 2008 Posts: 2,107 Germany	Code: if (you) if (you == player) you.health-=10; This is how i use to make it (almost ever). Guess its the most secured way. Acknex umgibt uns...zwischen Dir, mir, dem Stein dort... "Hey Griswold ... where u gonna put a tree that big ?" 1998 i married my loved wife ... Sheeva from Mortal Kombat, not Evil-Lyn as might have been expected rayp.flags \|= UNTOUCHABLE;

Re: Return value of c_trace? [Re: rayp] #416821 02/05/13 07:09 02/05/13 07:09
Joined: Apr 2007 Posts: 3,751 Canada WretchedSid Expert
WretchedSid Expert Joined: Apr 2007 Posts: 3,751 Canada	It's not though. Like I said, if you know that player is always unequal to NULL, you can simply remove the check wether you is NULL or not, because if it is equal to player, it's definitely not NULL. If you don't know if player is NULL or not, you can put the check wether you is NULL or not together into the same if and make your code cleaner and easier to read Shitlord by trade and passion. Graphics programmer at Laminar Research. I write blog posts at feresignum.com

Re: Return value of c_trace? [Re: WretchedSid] #416822 02/05/13 07:24 02/05/13 07:24
Joined: Jul 2008 Posts: 2,107 Germany rayp X
rayp X Joined: Jul 2008 Posts: 2,107 Germany	I just wanted to say if hes not sure if you != 0 he should check it before. But i got your points, thank you. Acknex umgibt uns...zwischen Dir, mir, dem Stein dort... "Hey Griswold ... where u gonna put a tree that big ?" 1998 i married my loved wife ... Sheeva from Mortal Kombat, not Evil-Lyn as might have been expected rayp.flags \|= UNTOUCHABLE;