SPQuadBatch with motion blur

iosNighthawk

Hey I'm wondering if this is possible to do with SPQuadBatch.

What I'd like to do is render mass bullets flying across the screen and the tail end would fade out. Once the quad goes outside screen bounds I wouldn't render it to the quad batch anymore. I also wouldn't have to reset the batch because quads would fade out.

Would this be possible with a single quad batch.

Shilo

I created a motion blur effect awhile ago for Sparrow 1.1, by alternating between two SPRenderTextures. (See http://wiki.sparrow-framework.org/users/shilo/extensions/shmotionblursprite)

I recently updated the extension for Sparrow 2.0. You can find it here: https://gist.github.com/Shilo/8265850

The above solution isn't perfect, because drawing the objects into the render textures does not alpha blend properly with each other, so crossing blur trails will not look quite right. The performance may also show a drop in frame rate.

What I think would be a great solution is to use GLSL shaders to create a motion blur effect. Unfortunately, Sparrow doesn't have shader/filter support out of the box yet, but there are other forks of Sparrow 2.0 that support shaders, such as Sparrow-S and my fork which combines the latest Sparrow git changes with Sparrow-S filters only.

Anyone know of any good GLSL shader examples for creating a OpenGL ES 2.0 2D motion blur (trails)?

iosNighthawk

Hey Shilo thanks for the reply. I'll take a look at your solution. Honestly I am no OpenGl expert so this kind of stuff is over my head.

So since Sparrow-S supports shaders does that mean the latest Master supports shaders as well? I was using Sparrow-S, but read in a post that MRC changes were merged into Sparrow Master branch so now I am using latest on Master.

I also came across this which someone wrote for Cocos2D. I haven't looked at the src, but it looks like exactly what I need and the overlapping trails looks great.

http://www.cocos2d-iphone.org/forums/topic/new-awmotionstreak-10x-faster-one-draw-call-no-artifacts/

Shilo

As far as I know, currently, the only similarities between Sparrow master and Sparrow-S is MRC. Sparrow master does not have filters or built-in shader support yet.

AWMotionStreak looks interesting, I will need a closer look.

Daniel

Shilo is right, the current master version does not have filters yet -- I currently plan to release a version 2.1 that's pretty much the current master, and then add filters in 2.2.

However, even if you can't use filters, it *is* possible to write shaders -- via custom display objects. There's a tutorial in the wiki.

If what you're looking for is the pink tail of the object in the sample -- than a custom display object would allow you to do that. However, it's definitely not an easy task. :-/

iosNighthawk

Hey guys thanks for the feedback and suggestions. I'll definitely take a look at creating custom shaders because it looks interesting.

I am also looking forward to seeing those in 2.2.

For the bullet trails I ended up going with a simple approach using SPQuads that are scaled and then faded out. It creates a pretty cool effect.

Daniel

Using simple quads for that is definitely a good idea! Simple yet effective. And with Sparrow's automatic batching, it shouldn't be too expensive performance-wise. 🙂

Cheers!