How to do a light effect?

MikeHart · February 2012

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 · February 2012

You mean as in Helsing's Fire?

MikeHart · February 2012

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 · February 2012

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 · February 2012

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 · February 2012

Would that work with several layered sprites under it?

atilim · February 2012

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 · February 2012

Thanks, will give it a try.

ar2rsawseen · February 2012

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

atilim · February 2012

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

ar2rsawseen · February 2012

Yes you are right, still it's possible

atilim · February 2012

ohhh great

mykyl66 · February 2012

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 · February 2012

@ar2rsawseen - is this within Gideros?

OZApps · February 2012

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 · February 2012

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

OZApps · February 2012

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

keszegh · February 2017

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

totebo · February 2017

Yeah, raycasting and queryAABB work great.

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

SinisterSoft · February 2017

Is there a demo of this?

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