sdl-ios-xcode: NOTES annotate

annotate NOTES @ 2218:6cc82cad8b77

1.3 video API design chat

author	Sam Lantinga <slouken@libsdl.org>
date	Tue, 07 Aug 2007 07:08:25 +0000
parents	18bca558f3a1
children	f6099efa3f0b

rev	line source
2217 18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	1
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	2 Sam - Mon Aug 6 23:02:37 PDT 2007
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	3 ------
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	4 Add color modulation to blitting
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	5 Blit convert format X -> format Y (needed for texture upload)
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	6 Blit copy / blend / modulate format X -> format X (needed for software renderer)
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	7
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	8 Create full software renderer for framebuffer interfaces.
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	9
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	10 Create texture for surface, keep surface around as pixel source, allow
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	11 copying / blending / modulating from surface to display (automatically
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	12 generate texture?)
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	13
18bca558f3a1 Some thoughts on 1.3 video written down Sam Lantinga <slouken@libsdl.org> parents: diff changeset	14 At that point, should anyone be using anything besides textures for display?
2218 6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	15
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	16 IRC - Mon Aug 6 23:50:44 PDT 2007
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	17 -----
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	18 [11:07pm] icculus: so we're clear, "textures" replace "surfaces" from 1.2 when you want to get stuff to the screen? So you have a definitely point where it stops being pixels in memory and starts being an object on the graphics card?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	19 [11:07pm] icculus: Upload once, blit many
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	20 [11:07pm] icculus: something like that?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	21 [11:07pm] slouken: That's the idea, yes
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	22 [11:07pm] icculus: ok, just making sure
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	23 [11:08pm] slouken: Many drivers retain the "texture" as a surface and blit to opaque bits which then get copied into a framebuffer.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	24 [11:08pm] slouken: retain -> would retain
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	25 [11:08pm] icculus: yeah, I figured
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	26 [11:08pm] slouken: That's why the features for surface blitting need to match the features for texture display.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	27 [11:08pm] icculus: But it gives an abstraction where the app has to make a conscious action: the upload is slow, but then the blit is fast.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	28 [11:09pm] icculus: This couldn't just map to LockSurface, though?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	29 [11:09pm] slouken: Yes, exactly. I wasn't sure whether to make that clear, e.g. can you display any surface, and automatically generate a texture (if necessary)?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	30 [11:09pm] slouken: If not, it simplifies the framebuffer case.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	31 [11:10pm] slouken: But even the framebuffer case will probably still want to convert the bits to the optimal format.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	32 [11:10pm] slouken: And at that point, the non-optimal bits can be thrown away.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	33 [11:11pm] slouken: e.g. SDL_DisplayFormat()
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	34 [11:10pm] icculus: oh, that's a good point.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	35 [11:10pm] icculus: hmm
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	36 [11:11pm] icculus: yeah, okay
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	37 [11:11pm] icculus: I was thinking about if the separation is really necessary, or if LockSurface would imply a texture creation (and you just have much more strict locking requirements than most 1.2 targets had)
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	38 [11:11pm] slouken: That's also why I separated the conversion blits from the copy / blend / modulate blits.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	39 [11:12pm] icculus: But I like that the app has to be conscious of when that's happening
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	40 [11:12pm] slouken: Yeah, I was really leaning towards making it implicit, but the memory savings is pretty significant for artwork.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	41 [11:12pm] icculus: SDL_compat can wrap the difference for people that can't get their head around it.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	42 [11:13pm] icculus: At the performance cost, that can be a totally external layer that manages it like 1.2's locking.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	43 [11:13pm] slouken: Well, SDL_compat is entirely software on top of a single texture that represents the screen.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	44 [11:14pm] slouken: Yeah, that's the way it's implemented right now.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	45 [11:14pm] slouken: a HWSURFACE is one that is backed by a texture, and lock/unlock is used to synchronize the bits.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	46 [11:14pm] slouken: I'm not sure if that's worth keeping though, if SDL_compat is software only.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	47 [11:15pm] slouken: It would minimize code migration though.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	48 [11:15pm] icculus: yeah
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	49 [11:15pm] icculus: I expect SDL_compat to be a complete cesspool
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	50 [11:15pm] icculus: just a black box that no one touches or looks at more than necessary
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	51 [11:15pm] slouken: more or less, but it's actually pretty clean right now... I think as a side effect of the new API being pretty clean.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	52 [11:15pm] slouken: I'm just unsure how much to use texture vs HWSURFACE
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	53 [11:16pm] icculus: Besides, you'd be surprised how quickly you can get people to move if you flag functions as deprecated so that GCC bitches when you use them.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	54 [11:16pm] slouken:
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	55 [11:16pm] icculus: how much to use texture vs HWSURFACE in 1.3, or in SDL_compat?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	56 [11:16pm] slouken: in 1.3
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	57 [11:17pm] icculus: Pick one or the other, I would say.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	58 [11:17pm] icculus: I don't think it's good to confuse people with both terms
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	59 [11:17pm] slouken: yeah
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	60 [11:17pm] icculus: Everything is software until it's a texture.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	61 [11:17pm] slouken: I'm just not sure which
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	62 [11:17pm] slouken: that's certainly cleanest.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	63 [11:18pm] slouken: and what's currently implemented
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	64 [11:18pm] slouken: Let's think through the migration process...
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	65 [11:18pm] icculus: Plus dropping the term HWSURFACE gets the point across that a) this isn't 1.2 and b) this is probably going to a 3D api that you should be using anyhow.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	66 [11:18pm] • slouken nods
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	67 [11:18pm] icculus: I mean, "texture" is what every API calls these things
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	68 [11:18pm] slouken: Yep
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	69 [11:19pm] slouken: So let's work through a migration case...
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	70 [11:19pm] icculus: ok
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	71 [11:19pm] slouken: FooBall loads a big background and a bunch of sprites. They are png, loaded into SDL_Surface with SDL_image, then converted with SDL_DisplayFormat()
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	72 [11:20pm] slouken: Then the background is blitted every frame and the sprites are blended on top.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	73 [11:20pm] slouken: In the compat case:
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	74 [11:21pm] slouken: SDL_SetVideoMode() creates a single lockable texture for the display. DisplayFormat() converts the bits into the optimal format, all blitting is done in software, and SDL_UpdateRects() pushes the bits into the texture and the texture is rendered.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	75 [11:21pm] slouken: In the 1.3 case:
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	76 [11:22pm] slouken: The background and sprites are converted to textures using SDL_CreateTextureFromSurface(), and the appropriate blending flags are set. Each frame copies the textures into place and then the display is presented.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	77 [11:23pm] slouken: compat is software only, 1.3 can be 3D accelerated.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	78 [11:23pm] icculus: wait, why does all blitting have to be done in software in the SDL_compat case?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	79 [11:23pm] icculus: I don't understand why SDL_compat can't move things between surfaces and textures at Lock/Unlock time
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	80 [11:24pm] slouken: Because by default the screen isn't created with HWSURFACE, since apps expect to be able to munge the bits. Therefore, the blits to it have to be done locally.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	81 [11:24pm] icculus: And all the surfaces are flagged HWSURFACE, so ->pixels is NULL until locked.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	82 [11:24pm] icculus: oh
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	83 [11:24pm] icculus: It wasn't possible to have a HWSURFACE screen?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	84 [11:25pm] slouken: Yes, it was, just nobody did it because alpha blending needs to read from video memory, and poking pixels across the bus is slow.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	85 [11:25pm] slouken: Even in 1.3, the Xlib case needs to be software renderer if you want to do any alpha blending.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	86 [11:26pm] icculus: But arguably there's no reason that can't all be HWSURFACE (that is, they need to get moved to a texture, even if that's still a software renderer on the backend)
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	87 [11:26pm] icculus: That sounds like it's only a problem when an app touches SDL_GetVideoSurface()->pixels without checking if they should lock it.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	88 [11:26pm] icculus: Which might be quite common
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	89 [11:27pm] slouken: Yep, in 1.2 the app was able to specify it, and most explicitly don't because it's either not available or bad for alpha blending and direct pixel poking.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	90 [11:27pm] icculus: hmm.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	91 [11:28pm] slouken: You see why I've been going round and round for months on this?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	92 [11:28pm] icculus: Well, we're talking about a compatibility layer; if it's going to crash without LockSurface() on the screen, make them lock it. If that makes it slow, so be it.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	93 [11:29pm] icculus: The options are make small changes and take a performance hit, or make bigger changes and get a big performance win.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	94 [11:29pm] icculus: (if touching the framebuffer directly, that is)
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	95 [11:29pm] slouken: Well, at that point it's a compatibility layer, why not just leave it software? (devil's advocate here)
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	96 [11:29pm] icculus: That's a good point.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	97 [11:30pm] slouken: Unless we leave everything surfaces to get the best of both worlds...
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	98 [11:30pm] • slouken gets dizzy
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	99 [11:30pm] icculus: From a technical elegance viewpoint, I can see a good mapping between HWSURFACE and textures, but realistically, you want to motivate people to move away from old APIs.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	100 [11:31pm] slouken: Yeah probably. There's a certain attraction to retaining the SDL_Surface usage even for hardware surfaces, simply because of code reuse. You don't have to have separate code for your software composition and your rendering. You also get to keep your old image loading code, etc.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	101 [11:31pm] icculus: man, this really is a pain in the ass, I see what you mean.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	102 [11:32pm] slouken: Yeah.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	103 [11:32pm] icculus: hmm, let me think on this awhile.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	104 [11:32pm] slouken: On the other hand, separating the Texture API for rendering is clearer and allows extension in the future.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	105 [11:32pm] slouken: We could potentially allow you to create a software renderer pointed at an SDL surface....
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	106 [11:32pm] slouken: Hmmm
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	107 [11:33pm] icculus: well, that's what you have now for something like Doom
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	108 [11:33pm] icculus: you render to a shadow surface, and throw a hail-mary with SDL_Flip()
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	109 [11:34pm] slouken: Yep. I mean a 1.3 "renderer" with an SDL_Surface or another texture as the target.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	110 [11:34pm] icculus: More or less, that doesn't change. The only important thing there is not generating a new texture every time, but being able to discard what's currently in it for a fresh upload.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	111 [11:34pm] slouken: Yep
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	112 [11:34pm] icculus: oh, I see
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	113 [11:35pm] icculus: render-to-surface
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	114 [11:35pm] slouken: lol
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	115 [11:35pm] slouken: yeah
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	116 [11:36pm] slouken: So... where to draw the line with surface vs texture...
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	117 [11:37pm] icculus: I don't know, I would think that basically you want to get out of surfaces as fast as possible
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	118 [11:37pm] icculus: (disregarding SDL_compat for the moment)
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	119 [11:37pm] slouken: Yeah, I think so.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	120 [11:37pm] slouken: Load the bits up, throw them into a texture, and go
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	121 [11:37pm] icculus: And basically all you really need for that is an "upload" function.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	122 [11:38pm] slouken: Yep
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	123 [11:38pm] icculus: I'd even be inclined to not allow "Locking," so there's no readback.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	124 [11:38pm] icculus: well, I'm sure that would cause a fight
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	125 [11:38pm] • slouken thinks
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	126 [11:40pm] slouken: Let me see where I use SDL_LockTexture() right now.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	127 [11:42pm] slouken: The only time that's useful is to avoid a buffer copy when you're already writing the bits in the correct format.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	128 [11:42pm] slouken: e.g. lock -> software render into bits -> unlock (upload)
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	129 [11:43pm] slouken: that may already be taken care of by the upload though.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	130 [11:43pm] slouken: e.g. software render into bits -> upload
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	131 [11:44pm] slouken: Oh yeah, there's probably a memory copy of the bits though, so it's: upload = copy into cached bits, copy cached bits to video memory as needed. In that case if you lock to get access to the cached bits directly that's a win.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	132 [11:44pm] icculus: ah, okay
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	133 [11:47pm] icculus: I don't know, my head hurts.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	134 [11:47pm] slouken: Yeah, mine too.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	135 [11:47pm] slouken: I was pretty happy with the current setup until I noticed that it's really hard to write a framebuffer driver right now.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	136 [11:49pm] slouken: I think maybe if I clean that up and separate conversion blit and copy / blend / modulate blit, then it may work pretty cleanly.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	137 [11:49pm] icculus: yeah
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	138
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	139 [11:54pm] slouken: So recapping... SDL_Surface is only used for loading and app composition.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	140 [11:55pm] slouken: SDL surface blitting is enhanced to maintain parity with the renderer features, since it's used as the core of the software renderer.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	141 [11:56pm] slouken: The software renderer is adapted to be a standalone module targeting either an SDL_Surface or an SDL_Texture.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	142 [11:56pm] slouken: SDL_HWSURFACE goes away
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	143 [11:57pm] slouken: Anything I'm missing?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	144 [11:58pm] icculus: no, sounds good
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	145 [11:58pm] slouken: This means we have the new 1.3 texture API pretty much as it stands.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	146 [11:59pm] slouken: Right?
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	147 [11:59pm] icculus: yeah, I think so
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	148
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	149 [12:00am] slouken: I was trying to see if it was possible to make a pluggable blit API, but I was going insane with trying to figure out how to make it fast.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	150 [12:01am] slouken: If it were software only I could just say, write your own and register it here, but you'd have to maintain parity with the OpenGL and Direct3D renderers as well.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	151 [12:01am] slouken: At that point you might as well be working in surfaces and uploading to texture.
6cc82cad8b77 1.3 video API design chat Sam Lantinga <slouken@libsdl.org> parents: 2217 diff changeset	152 [12:02am] icculus: yeah

Mercurial > sdl-ios-xcode

annotate NOTES @ 2218:6cc82cad8b77