Lighting and Shadow System

[argh]

Update: 2014/02/02 I am going to change to add an additive lighting system

Update: 2014/02/03 Working subtractive lighting system

https://gist.github.com/seanpackham/8727943

Original Post

Hi all, first post here. I want to start by saying Love2D is by far the easiest and quickest 2D framework I have encountered and it is due to the great community and authors. Thank you for all that you have done!

I have been implementing lighting and shadows for a prototype I am making http://forums.tigsource.com/index.php?topic=38448.0 but have hit a wall. I am not too clued up on blend modes, stencils and cavanses and this is currently where I am:



I have been following these great resources:

1. http://forums.tigsource.com/index.php?topic=8803.0
2. http://experimentalized.blogspot.com/20 ... sting.html
3. http://lwjgl.org/forum/index.php/topic,5203.0.html
4. https://github.com/DrAgonmoray/BasicLighting/

trying to emulate these looks:

1. http://www.youtube.com/watch?v=nSf1MpsWKig
2. http://www.youtube.com/watch?v=Gy9tvA9AlSg (user oysi93 implemented his lighting in love2d)

I also saw that löve user styves http://love2d.org/forums/memberlist.php ... e&u=134530 is working on a lighting system http://love2d.org/forums/viewtopic.php? ... 90#p161226.

I have completed the shadow generation, and in the code have drawn the shadow polygons with an alpha to demonstrate multiple shadows overlapping but generally they should be opaque. I have included a port, with some minor changes, of the fragment shader from resource link 4 above.

I have not been able to correctly blend the various states (geometry/background, shadows, lights).

I was wondering if any lövers out there could give me some advice? Perhaps a lightmask solution is easier than using a shader...

Here is a gist of the code https://gist.github.com/seanpackham/8727943

Thanks

[argh]

Updated 2014/02/03 Removed embeeded code and added link to gist.

Thanks to the reddit user http://www.reddit.com/user/naughty who answered my question http://www.reddit.com/r/love2d/comments ... hting_and/ with an algorithm and updated code sample, I now have a finished lighting prototype



Here's a link to the devlog post http://forums.tigsource.com/index.php?t ... #msg990401

Code in a gist https://gist.github.com/seanpackham/8727943

[Ranguna259]

Shadows should stop when they find another object, in your code shadows just keep on going until they hit a wall.

[verilog]

Hi argh!
Just wanted to say that your prototype is looking sweet, man! Thanks for the links and keep it up!

[argh]

Shadows should stop when they find another object, in your code shadows just keep on going until they hit a wall.

Yip to be more realistic they should stop when hitting objects. The problem is the performance plummets if you need to think of each shadow behaving like a light, potentially being split into many sub shadows. Any thoughts or suggestions how this could be done efficiently?

[argh]

Hi argh!
Just wanted to say that your prototype is looking sweet, man! Thanks for the links and keep it up!

Thanks for the encouragement

[Ranguna259]

Yip to be more realistic they should stop when hitting objects. The problem is the performance plummets if you need to think of each shadow behaving like a light, potentially being split into many sub shadows. Any thoughts or suggestions how this could be done efficiently?

I haven't seen how your code works but could you tell me really quickly how yur algorithem works ? is it additive (do you draw the light) or subtractive (do you draw the shadows) ? Here's an exemple of an additive like light.

Oh and nice work so far

[argh]

Thanks, it's subtractive. I see the additive approach will have more realistic results. Thanks for the link, I'll try and implement it. I also found this approach http://www.catalinzima.com/2010/07/my-t ... d-shadows/

[Ranguna259]

That's a similar aproach to this one. I'm actually trying to reproduce that effect and I'm currently looking for a rectangle to polar and a polar to rectangle shader.
Since you draw the shadows how do you set their limit ? Do they stop once they reach a certain distance from the light source or when they hit the screen borders ?

[Germanunkol]

Here's an exemple of an additive like light.

That's an amazing post, thanks for sharing! I love the interacitve examples... really neat!