cocos2d for iPhone

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

1. 

   eoin
   Member

   Am guessing that this is not in Cocos2d at the moment.

   I want to add shadows to sprites, or particles even. I am guessing the only way to do this - unless there is some OpenGL lighting trick - is to replicate a dark shadow of the sprite on the screen at a lower Z order by creatring a dark sprite masked at a black color, it's position dependent on where the light is; and it's opacity, bluriness etc. set by the user of the shadow API.

   The position of the shadow would depend on the position of the light and the z order of the sprite being shadowed, I dont need to deal with shadows on sprites but on the background.

   Thats a bit of work and it has performance implications, so before I do it can anyone think of something simpler?

   Posted 2 years ago #
2. 

   Steve Oldmeadow
   Administrator

   Try setting a sprite's colour to black.

   Posted 2 years ago #
3. 

   Karl
   Member

   Decide if realistic shadows are that critical to the success of your game. Often a simple dark blob under/behind your sprite is plenty good enough.

   Posted 2 years ago #
4. 

   mhussa
   Member

   I've used a shaped feathered shadow sprite underneath each car sprite. The shadow is a child of the car sprite and positioned to the lower right. The framework looks after everything else rotation etc (v0.9), so no matter which way the car is facing the shadow is automagically positioned and rotated. Very easy to implement and I think its much better for it (see image).

   

   Posted 2 years ago #
5. 

   jtbowden
   Member

   I want to do a similar thing, but my problem is that I need the child shadows to always be below ALL non-shadow objects. Simply making a sprite with a shadow child means that when 2 objects are near each other, the shadow from one will be over the other.

   Is there a way to accomplish this easily?

   The new "honor transform" flags are great, but what about this?

   Actually, come to think of it, I'm not sure that the honor transforms will work for my shadows either. I want the shadow to move with the sprite, but rotate around it's own center, so that the shadow is always offset to the lower right.

   Posted 2 years ago #
6. 

   mhussa
   Member

   @jtbowden: sounds like you need to add shadows as children of a world based layer ( a map object maybe) that way you manage shadows like tags e.g have a 'z' enum like mapZ=0, shadowZ = 1, objectZ=2 etc, then [map addchild:object z:shadowZ tag:shadow_tag]. You'll have to update the shadow positions and rotation manually which you can copy from the shadowed object.

   The positioning works well in my case and I am copying the parent rotation to keep the shadow in the right place. Not entirely automagic but partly :)

   Posted 2 years ago #
7. 

   jtbowden
   Member

   @mhussa: yes, that is definitely an option, but I was hoping for something more robust. I don't like the idea of having to animate shadows independently of the main object. I would rather have a child-behavior, where the shadow follows the parent, but doesn't have to be tied within the z-index bounds of the parent. In other words, a link behavior where when X moves, so does Y. I keep toying with coding a SpriteWithShadow object, but it gives me headaches to think about it. :)

   Posted 2 years ago #
8. 

   jtbowden
   Member

   A late follow-up, but it turned out not to be so bad. I simply added an addShadow:offset method to CCNode, and a shadowSprite_ member to the class.

   I also add the shadow to the scene at a low z-index. This means that the scene visits the shadow, but the shadow ends up moving when the parent sprite moves. This is because I added special handling in CCNode, so that if a node has a shadow, it will be moved when the parent does, and rotated too. The key is that it rotates around it's own anchor, not the parent's. That keeps the shadow offset always the same.

   Posted 1 year ago #
9. 

   eoin
   Member

   Ok, so did you use the shadow as a child?

   Posted 1 year ago #
10. 

    jtbowden
    Member

    No, the shadow is not a child of the sprite. It is added directly to the scene or layer I am working on. This means that it can be drawn before all of the objects.

    If it is a child, it a shadow is always grouped with the parent, so the shadow ends up above other objects (i.e. SHADOW1 is above OBJECT2):

    OBJECT1
    SHADOW1
         OBJECT2
         SHADOW2

    With my implementation you get:
    

    OBJECT1
         OBJECT2
    SHADOW1
         SHADOW2

    Or any layering of shadows you desire. So, for drawing purposes, the shadow is a separate object, but by linking it to another object, it will move when it's shadow-parent moves. Does that make sense?

    Posted 1 year ago #
11. 

    eoin
    Member

    Cool, ta.

    Posted 1 year ago #
12. 

    georgeburns
    Member

    In an experiment I added a separate sprite as a shadow and had it offset from its shadow daddy based on the device orientation.
    Also had it match the rotation in the step function.

    I really didn't need any performance out of it, but it looks okay... i used it on the menu in this:
    http://itunes.apple.com/app/awesome-physics-fun-ballz/id366559845?mt=8
    If you want to see it in action... send me a pm...i'll send you a promo code.

    Posted 1 year ago #

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