How to fix blending?

Newbie & Debugging Questions
#1

So I’ve got this shader:
http://pastebin.com/5iax5iX6

And I render it through a for loop like this:

for(Light light : lights)
[bind shader]
[enable blend: blend function (GL_SRC_ALPHA, GL_ONE)]
[shader uniforms based on light]
[render large quad the size of the display]

for(Entity e : entity)
[enable blend: blend function (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)]
[render entity]
[disable blend]

[bind shader]

I’ve tried other blending methods, and most of them don’t let more than one light… light it.

Image:

MP4 format: http://gyazo.com/ea3b8611e0d746a1f8783db22320a198

#2

I’m sorry, but what is the problem exactly and what behavior are you attempting to achieve?

#3

I’m trying to make the squares not transparent, but also allot multiple shader passes to show.

#4

Is there anyone who can help? I kinda need this to work for my game engine.

#5

What is the behavior you want exactly though? In your GIF, the lights seem to be working fine, however the squares are semi-transparent and show through. You want one square to be completely opaque and on top of the other?

#6

Maybe it’s a Z-ordering problem. Try clearing the depth buffer as well so you can have control over your z positions. This way you won’t have to do any weird render order stuff.

#7

Yes…

I tried clearing the depth buffer, no difference. Is that all you meant, or do I have to do something else?

#8

Perhaps I’m completely wrong, but I still try…

In the algorithm you give, the entities are never completely opaque when rendered.
When the background is black, the blending isn’t a problem. But for the second entity, the background isn’t black into the crossing section and the problem occurs.
This certainly also occurs when the background color isn’t black.
I think the problem is the fact that all rendering (entities and lights) are done in the same loop.

If I would try to achieve this :

  • Fisrt pass : render all the entities with zbuffer + diffuse texture only (no shader, no blending)
  • Second pass : for each entity, loop thru lights and for each light, render entity with light’s informations (shader, no diffuse texture, blending enabled)
  • Third pass : render the lights squares (shader, blending enabled)

The goal of this algorithm is to avoid overdraws and blending between entities.

Hope this will help a little.