I'd be willing to give it a shot.
On Tuesday, October 4, 2016 at 9:03:57 AM UTC-5, Benjamin Moran wrote:
> Thanks for your insite with regards to DrawArrays/DrawElements. There is a
> lot of old bickering online about how one or the other is "better", but not
> so much recent discussion.
> I think having the separate implementation of these things is a good idea
> for a start. I don't think anyone would want to have two seperate
> implementations side by side in the long run, but it's nice to compare side
> by side. I think you've already worked out most of the messy stuff, so it
> would be a matter of seeing if this implementation is feasable if we add in
> some fallbacks to keep things simple. For example, pyglet is really fast if
> you use a batch, and rely on the resources module to load your images. It
> still works fine, however more slowly, if you are ignorant of that and load
> all of your textures manually.
> I have other things on my plate at the moment, but if you're keen to help
> make this happen we could open a new branch to experiment in. Let me know
> what you think.
> On Tuesday, October 4, 2016 at 5:17:08 AM UTC+9, Josh wrote:
>> I have the code with some bug fixes from after I sent it to you. It's not
>> in a public repository right now but I can put it somewhere. It's still not
>> thoroughly tested, it just worked for my project.
>> Call for call, I think there isn't much difference between DrawArrays and
>> DrawElements (or if there is, it's on the GPU side). The huge advantage of
>> DrawElements is that you can render your entire game with just the one
>> call, and do it in whatever order you want. In current pyglet, when you
>> call batch.draw(), pyglet makes a separate DrawArrays call for each
>> separate texture that needs to be rendered.
>> What if we subclass VertexDomain with OrderedVertexDomain, create a
>> ZSpriteGroup class, and create a ZSprite class? That keeps backwards
>> compatibility. ZSprites would be initialized with a fixed ZSpriteGroup.
>> Unlike normal groups, ZSpriteGroups would maintain a TextureAtlas, a sorted
>> list of indices, and an OrderedVertexDomain, and would not allow children.
>> Batch methods would be modified so the batch always associates a ZGroup's
>> domain, and only that domain, with that group. This requires changes to
>> Batch.migrate, Batch._get_domain, Batch._add_group that explicitly check if
>> a group is a ZSpriteGroup.
>> On Monday, October 3, 2016 at 5:02:59 AM UTC-5, Benjamin Moran wrote:
>>> Thanks for the lengthy writeup, Josh. It seems like this is one of those
>>> issues that has no "perfect" solution. I was able to find the code you
>>> shared before, and it looks like a nice bit of work. Do you still have an
>>> active branch of this somewhere?
>>> I'm also curious what your experience with glDrawArrays vs
>>> glDrawElements is, performance wise. Most of the talk on the subject is
>>> pretty old, so I'm wondering just what the differnce really is.
>>> Not breaking code would be ideal. I think as long as there are fallbacks
>>> (even if slow fallbacks) would be a requirement, so as not to regress in
>>> functionality. Additionally, not to impose any behaviour that would
>>> negatively affect people who don't even use the sprite class at all.
>>> On Monday, October 3, 2016 at 4:30:07 AM UTC+9, Josh wrote:
>>>> Hi all,
>>>> Been a while since I dealt with this, but here is the core of the
>>>> solution I came up with. Currently VertexDomain uses glDrawArrays to
>>>> sprites. This requires the correct texture for each sprite has to be bound
>>>> before it can be rendered. So if you have, say, 100 distinct images being
>>>> rendered as sprites, that's (usually) 100 glDrawArrays calls per frame.
>>>> Also, all sprites sharing a texture are always rendered simultaneously if
>>>> they belong to the same batch.
>>>> To solve this problem, I created a new method draw_ordered for
>>>> VertexDomain that uses glDrawElements. This allows you to pass a list of
>>>> indices that specifies the order the elements will be rendered in.
>>>> because you have to choose one texture to have bound before calling
>>>> DrawElements, everything in the domain still has to have a common texture.
>>>> So to make this solution work,* all sprites in a batch must take their
>>>> textures as regions from a single master textur**e *(in pyglet,
>>>> TextureAtlas was convenient for this; it automatically sets the texture
>>>> coordinates for the sprite vertices correctly).
>>>> I still think the huge gains in efficiency make it worth changing to
>>>> glDrawArrays. To make it work with the existing pyglet framework, I
>>>> a new rendering hierarchy in parallel with the existing pyglet methods:
>>>> OrderedBatch, OrderedSprite, AtlasAnimation, AnimationRegion. But a better
>>>> solution would be to have a singleton TextureAtlas. Getting images through
>>>> the pyglet resource tools would automatically enter them in the singleton,
>>>> and most users would not have to worry about the change in rendering
>>>> method. But definitely some code would break.
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