cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   jingato
   Member

   Hi guys,

   I need a little math help again. I'm trying to spawn some pickups along an arc that will follow roughly the players path when he jumps between 2 objects. I'm using box2D for the physics.

   Here's the code I am using now. dir starts in the direction the pickups will begin spawning.

   int maxCount = 10;
       int count = 0;
       bool continueSpawning = YES;
   
       float a = TIMESTEP * GRAVITY;
   
       while (continueSpawning)
       {
           Pickup *pickup = [Pickup spriteWithBox2dBody:self atPosition:spawnPos];
           [self addChild:pickup];
   
           dir = ccp(dir.x + a * PICKUP_SPACING, dir.y + a *  PICKUP_SPACING);
           dirNorm = ccpNormalize(dir);
   
           spawnPos = ccp(spawnPos.x + PICKUP_SPACING * dirNorm.x, spawnPos.y + PICKUP_SPACING * dirNorm.y);
   
           count++;
   
           float endObjectSize = [endObject scaledSize].width / 2;
   
           if(ccpDistance(spawnPos, endObject.position) < PICKUP_PADDING + endObjectSize / 2|| count >= maxCount)
               continueSpawning = NO;
   
       }

   I don't know if my math is close or not. I'm going off some stuff I found in other forums. But it seems to give me good results as long as the endObject is at the same height or below the beginning object. If its at a higher hight (the end object can be quite a bit higher) then the pickups seem to spawn almost in a straight line with barley any arc.

   What can I do to fix this? I'm sure my math is not right ;/

   Thanks again!

   Posted 7 months ago #
2. 

   zaaroth
   Member

   If you are going to spawn the objects while the player is jumping you could tie the spawning to the player to leverage box2d physics.

   Unless you need the objects in front of the player (i.e. in positions box2d will lead the player later on), in that case you may need some bezier (or another kind of curve, I like bezier because you can simulate anything with it) in order to approximate the curve.

   Clarify your question so I can understand it correctly.

   Posted 7 months ago #
3. 

   jingato
   Member

   No, I want to spawn the pickups in advance so the player can collect them when he jumps from one object to another

   Thanks

   Posted 7 months ago #

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