How to do a light effect?

MikeHart

Guess what,

Michael and Mike want to do this in their game=> Imagine a cave area. The character is roaming around, carries a torch with him. We only want the area that is lit up by the torch to be visible. How can we do this in Gideros?

Michael

atilim

You mean as in Helsing's Fire?

MikeHart

Around 20 seconds where you see the creatures and only a circle area aroudn them is visible. Something like this. Not a dynamic 3d light like they show later on.

MikeHart

Here are some images that exlain the effect we are after.

https://www.google.com/search?q=gem+miner&hl=en&client=firefox-a&hs=yFI&rls=org.mozilla:de:official&prmd=imvnsa&source=lnms&tbm=isch&ei=xwBET9qFGsiM4gSWk-XzDw&sa=X&oi=mode_link&ct=mode&cd=2&ved=0CBMQ_AUoAQ&biw=1523&bih=1000

atilim

Sprite:setBlendMode(Sprite.MULTIPLY) should work. For example, add a big polygon with a spotlight image with multiply blending on top of your maze.

MikeHart

Would that work with several layered sprites under it?

atilim

I think it should. First you draw everything normal, then draw a multiply blended layer on top of it. But the top layer should cover all the screen.

MikeHart

Thanks, will give it a try.

ar2rsawseen

I always thought something like that is achieved through Raycast in Box2D.
Will have to try out your method atilim.

atilim

@ar2rsawseen, but I think the effect in Helsing's Fire after ~40 seconds really needs a good geometric algorithm combined with ray casting.

ar2rsawseen

Yes you are right, still it's possible

atilim

ohhh great

mykyl66

looks very nice. That helsings fire is similar to something I thought about a while back. Nice to see it may be possible to develop that idea. hmmm. Lots more to think about.

Mike

chipster123

@ar2rsawseen - is this within Gideros?

OZApps

the video above is from http://www.iforce2d.net and using a software called RUBE available on the same site.

@Atilim, is raytracing an extension to Box2D or part of? If it is part of, then do you think it would be possible to flick that switch to have the wrapper around it?

atilim

@OZApps, yes I can also wrap the ray casting query functions of box2d.

OZApps

that will be nice, I am sure there will be some really wicked cool stuff coming out soon...

keszegh

to resurrect an old topic, can we do such a raycasting with box2d nowadays? was it ever added to gideros?

totebo

Yeah, raycasting and queryAABB work great.

http://docs.giderosmobile.com/reference/physics/b2World/rayCast

SinisterSoft

Is there a demo of this?