X-Git-Url: https://git.ucc.asn.au/?p=ipdf%2Fdocuments.git;a=blobdiff_plain;f=irc%2F%23ipdf.log;h=c8c17c93ac4160223f5f0864c18104ac0dc633d1;hp=0be461e0473978631046f965c841e420ee406549;hb=b63206e3974de26097a2c9f0e1dedeec06ea66fb;hpb=1af0c07c5cecd52e17e29d8ff0f4aff5e67b2f39

diff --git a/irc/#ipdf.log b/irc/#ipdf.log
index 0be461e..c8c17c9 100644
--- a/irc/#ipdf.log
+++ b/irc/#ipdf.log
@@ -3813,3 +3813,338 @@
 21:15 < matches> I hope that's not the conference abstract
 21:15 < matches> I also really hope we're allowed to use our own computer and things in the conference
 21:16 < matches> Also I really hope that if I can use my own computer it doesn't decide to shit itself anyway just to spite me
+--- Day changed Mon Aug 18 2014
+17:06 < matches> Good news and bad news!
+17:07 < matches> The kerning now appears to kern in the right direction
+17:07 < matches> But this means "BleedingCowboys.ttf" works
+20:30 < sulix> It's a pain to look up clipping of beziers, because there's a separate technique for doing something else called "bézier clipping"
+20:40 < matches> Baha
+20:41 < matches> I'm basically just procrastinating with Qt
+20:41 < matches> I mean
+20:41 < matches> Doing *awesome* things with Qt
+20:48 < sulix> I am looking with considerable envy at SolveQuadratic().
+20:49 < sulix> SolveCubic() will get very ugly.
+20:49 < sulix> Assuming I don't just sample the cubic at 100 points and look for roots.
+20:49 < matches> Haha
+20:49 < matches> Newton Raphson?
+20:50 < sulix> Very tempting.
+20:50 < matches> Then you can solve any bezier!
+20:50 < matches> Then we can put in Quintics!
+20:50 < sulix> Solving cubics exactly is not fun.
+20:50 < sulix> Dear god no.
+20:50 < matches> Imagine how many loops a quintic could have...
+20:51  * sulix cries quietly in the corner.
+20:53 < matches> So I'm calling AddText with sane values and nothing is happening :(
+20:56 < sulix> With or without quadtree?
+20:56 < sulix> With quadtree, everything is broken if you try adding things.
+20:56 < sulix> Because they won't be added to a node.
+20:57 < matches> No quad trees I think
+20:57 < matches> Yeah no quad tree
+21:00 < matches> Wait I think we need to rebuild the buffers or something
+21:07 < matches> Ah, ForceRenderDirty()
+21:14 < matches> I don't think the scale of our text is quite right?
+21:14 < sulix> Well, the scale of everything is wrong, but it's entirely possible that the text is _extra wrong_
+21:16 < sulix> In theory, the "scale" input to addText is the "height" of a character.
+21:19 < matches> Mmm
+21:19 < matches> I'm trying to add text relative to the current view
+21:19 < matches> But it isn't consistent
+21:19 < matches> When I go to a different view it is definitely not adding it in the same relative place
+21:20 < matches> The scale and positions aren't *already* relative are they?
+21:22 < sulix> Not to the view...
+21:24 < matches> What are they relative to?
+21:24 < matches> Anyway instead of fixing that bug I'm adding more
+21:25 < sulix> Umm... The bounding box maybe?
+21:25  * sulix investigates.
+21:26 < sulix> Scale and position should (I think) be normal, document coordinates.
+21:26 < matches> Odd
+21:26 < matches> Oh well
+21:26 < matches> Having Qt is totally worth it by the way
+21:27 < matches> Although it is still slightly embarrassing that it has its own SVG parser
+21:27 < matches> Ours is better!
+21:27 < matches> It has Reals everywhere!
+21:27 < matches> Except where it constructs Real from floats...
+21:27 < matches> And converts them to floats...
+21:28 < sulix> Thesis title should be "Keepin' it real: Staying afloat on the sea of document precision"
+21:31 < matches> Bahaha
+21:31 < matches> That is brilliant
+21:32 < matches> The Qt stuff is never deleting anything
+21:32 < matches> I suppose I should fix that at some point
+21:33 < matches> So basically it is a state machine and you use the menu to change the state
+21:33 < matches> Pressing OK does something depending on the state
+21:34 < matches> And there is a single text edit you can type stuff into
+21:34 < matches> In theory it can hide/show different widgets depending on the state
+21:34 < matches> I feel like I should add a "Generate Thesis Title" widget now...
+21:35 < matches> Also I can sort of see the appeal of lambdas for GUI programming now
+21:35 < matches> But I have a feeling they would totally break Qt anyway
+21:49 < matches> ...
+21:49 < matches> Ok sometimes the text gets added upside down...
+21:49  * sulix disclaims any and all responsibility for that.
+21:51 < matches> Yes!
+21:51 < matches> I finally did that thing I was saying I'd do for like 3 weeks
+21:51 < matches> Zoom in to floating point limit
+21:51 < matches> Add SVG
+21:51 < matches> Watch it explode!
+21:52 < sulix> Oooh...
+21:52 < matches> It is glorious
+21:54 < matches> We need to be a bit careful with thread safety in qt
+21:55 < matches> Really we should be able to request that the qt thread call UpdateAll itself
+21:55 < matches> Rather than calling it directly from the viewer thread
+21:55 < matches> But I'm not sure how that's done
+21:55 < matches> There's all this stuff about "Cross thread signals" on the internet
+21:56 < matches> It seems you can hide/show things but not much else
+22:47 < matches> Bah you pushed things!
+22:55  * sulix proclaims the new features as excellent and promptly goes to bed.
+--- Day changed Tue Aug 19 2014
+18:08 < matches> My conference is in the week starting 13th October
+18:08 < matches> Is Tim back then?
+18:08 < matches> "your supervisor will be invited to attend and mark your presentation"
+18:09 < matches> So if he can't go... I don't get a mark?
+18:12 < matches> It sounds suspiciously like they are going to get everyone's supervisors to mark them and then just scale everyone :S
+18:13 < matches> Surely at least one other person is going to read the final report...
+18:13 < matches> I've heard bad things about the engineering scaling system
+18:14 < matches> Your mark becomes inversely proportional to how well your supervisor's students did the previous year or something like that
+18:15 < matches> Anyway, two months left to accomplish something!
+20:05 < sulix> Worked out why the font bounds were weird.
+20:06 < sulix> AddText takes (msg, scale, x, y) not (msg, x, y, scale), so the coordinates were all bunk.
+20:09 < sulix> Fonts looks _amazing_ with floating pt errors, too.
+20:09 < sulix> http://davidgow.net/stuff/ipdf-i-think-you-mean-comic-fail.png
+20:29 < sulix> The Art of Computer Programming briefly mentions the Stern-Brocot tree, btw.
+20:29 < sulix> I can't see it being really useful, though.
+21:06 < sulix> My difficulty clipping bézier paths may be because it is actually impossible.
+21:06 < sulix> I think I've just found a paper saying that it is only possible for béziers which happen to be straight lines.
+22:55 < sulix> Never mind, it is possible, it's just very nasty.
+23:15 < sulix> Also C++14, because we need more lambdas: https://isocpp.org/blog/2014/08/we-have-cpp14
+--- Day changed Wed Aug 20 2014
+12:05 < matches> I guess we've accomplished the goals for this week's meeting then!
+12:05 < matches> (That shading algorithm totally counts as a "first attempt")
+12:07 < sulix> I'm about 2/3rds of the way through deriving the reparametrisation of béziers.
+12:08 < sulix> It basically just boils down to pages and pages of rearranging polynomials.
+12:38 < sulix> I managed to get the qt4/qt5 monstrosity compiling on my laptop.
+12:38 < sulix> It has a "moc-qt4" program, which works, whereas "moc" is qt5.
+16:28 < matches> I think I need to stop adding this log to git...
+23:08 < sulix> matches: But then, how would history record that I've finally got a maybe-correct derivation for cubic bézier reparametrisation: http://davidgow.net/stuff/cubic_bezier_reparam.pdf
+23:08 < sulix> (Code is in git)
+--- Day changed Thu Aug 21 2014
+12:57 < sulix> So it turns out that quadtrees are hard, and reparametrising béziers is why.
+13:03 < matches> I don't seem to see anything anymore with the quad tree enabled
+13:10 < sulix> The quadtree doesn't let you add things in realtime.
+13:10 < sulix> Quadtree nodes are immutable once created.
+13:12 < matches> Ah
+13:35 < sulix> debug: ReParametrise (bezier.h:190) - (0.000000,0.000000),(1.000000,1.000000),(1.000000,1.000000),(1.000000,1.000000) -> (-nan,-nan),(-nan,-nan),(-nan,-nan),(-nan,-nan)
+13:36 < sulix> Looking good!
+13:54 < sulix> Clearly, the quadtree rendering is now perfect: http://davidgow.net/stuff/ipdf-this-is-definitely-a-fox.png
+--- Day changed Sun Aug 24 2014
+17:51 < matches> ...
+17:51 < matches> I am parsing CSS in the SVGs
+17:51 < matches> WHAT HAVE I DONE
+17:52 < matches> Blame inkscape for always using css to control the properties
+17:57 < matches> http://szmoore.net/ipdf/death-by-shading.png
+17:59 < matches> Anyway there is a proper "Group" data type like with the Beziers
+18:00 < matches> So if you want to cache things related to groups you can put them in that I guess
+18:02 < matches> Really it should be called "PATH" not "GROUP" but I vaguely thought it might be able to be used as either
+--- Day changed Mon Aug 25 2014
+10:39 < matches> I was thinking about how to do shading more
+10:40 < matches> And I basically arrived at the idea Loop and Blinn have that you kept talking about
+10:40 < matches> Except I didn't realise it at first because my version was all using rectangles instead of triangles
+10:40 < matches> I think I will try to get my scanline fill to work first though
+13:03 < matches> It sort of works
+13:15 < matches> ... or not
+--- Day changed Tue Aug 26 2014
+14:25 < matches> I wonder if I'm going to end up just reverse engineering an algorithm that I was too lazy to understand properly
+14:26 < matches> I really like the idea of flood fill better than doing insane triangulation maths
+14:26 < matches> Surely GPUs can flood fill
+14:28 < sulix> I think they can, but either very slowly or only on very new hardware...
+14:28 < sulix> I think you'd need to do it in several passes, maybe?
+14:28 < matches> The problem I had with flood fill was working out where to start
+14:28 < matches> I have something that almost works
+14:28 < matches> That requires no clever maths...
+14:29 < matches> But it is CPU only
+14:29 < matches> And probably breaks in a bunch of special cases
+14:30 < matches> It doesn't have precision problems though (once you've drawn the boundary that is)
+14:31 < matches> It would still be cool to go through the Loop/Blinn algorithm on CPU and GPU
+14:31 < matches> Because that is going to have floating point maths in it
+14:31 < matches> flood fill has no floats
+14:31 < matches> Therefore it is infinite precision
+14:31 < matches> Objective complete
+14:32 < matches> Actually I don't think my algorithm is proper flood fill, it's sort of scanline flood fill but not?
+14:32 < matches> When in doubt write random code
+14:34 < sulix> How are you handling the case where, due to a path being half offscreen it becomes two paths?
+14:34 < matches> ... I am not
+14:35 < matches> If part of the path is offscreen it is annoying
+14:36 < sulix> Hopefully, once some of the quadtree code is more functional, the path clipping code can be used to clip paths to the screen.
+14:39 < matches> Compositing is also totally broken because the fill just looks for black pixels
+14:40 < matches> But if I can get it doing fonts then that's sort of not totally useless
+18:35 < matches> I am very tempted to implement a "Please click on the location to fill this path from" interface at the moment
+18:39 < matches> Alright, I have shading somewhat stack overflowing
+18:39 < matches> I mean
+18:39 < matches> Working
+18:39 < matches> *
+18:39 < matches> ********
+18:49 < matches> http://szmoore.net/ipdf/shading-the-only-svg-that-doesnt-segfault.png
+20:43 < matches> Argh
+20:43  * matches stabs coordinate transforms
+20:43 < matches> stab stab stab
+20:44 < matches> My filling algorithm is to find the 4 extrema of the path
+20:44 < matches> And try and flood fill inwards from each one
+20:45 < matches> But the extrema pixel coordinates keep transforming to *outside* of the path
+20:45 < matches> By one pixel
+20:45  * matches stabs
+21:52 < matches> I guess I should just actually implement loop and blinn shading
+21:52 < matches> Flood fill is not as easy as I had hoped
+21:53 < matches> I have to start doing annoying geometry maths to work out what point I can start the flood fill at
+21:55 < matches> Sigh
+--- Day changed Wed Aug 27 2014
+22:33 < sulix> Suddenly: ToAbsolute on ToRelative does not give original Bezier
+22:34 < sulix> I may need to rethink what my quadtree code is doing to those poor curves.
+22:51 < sulix> Never mind, that assertion happens _whenever_ trying to load cubicbeziers.svg.
+23:03 < sulix> Oh wow: you should see what happens if you start splitting and reparametrising beziers with bad precision.
+23:03 < sulix> 'tis "whacked"
+23:08 < sulix> http://davidgow.net/stuff/ipdf-a-slight-curve.png
+23:15 < sulix> And the Quadtree infinite precision for béziers now works*
+23:15 < sulix> *for some beziers.
+23:15 < sulix> * for some large finite value of "infinite"
+--- Day changed Thu Aug 28 2014
+11:35 < sulix> What time is it? It's NaN time!
+11:44 < sulix> Ah, so... horizontal lines have a height of zero in their bounds. This makes divides by zero happen in places.
+11:48  * sulix apologieses profusely for his latest "break absolutely everything" commit.
+11:57 < sulix> Yeah, making divide by zero crash rather than generating NaNs breaks a lot of things.
+11:57 < sulix> You'd be surprised by how often we divide by zero.
+11:57 < sulix> Mostly in the Quadtree code.
+11:58 < sulix> Because, damnit, mathematics can't beat me.
+12:20 < matches> Yes, lines have zero width... stupid lines
+12:21 < matches> I stopped the segfaults in shading by adding a depth counter to FloodFillOnCPU
+12:21 < matches> Which makes interesting shading patterns...
+12:22 < matches> I think it's time to fall back to the "Use the second algorithm on Wikipedia" approach
+12:23 < matches> I can still use a Flood Fill but hopefully a less segfaulty one
+12:29 < matches> I'm not sure about ToAbsolute and ToRelative...
+12:29 < matches> I thought they should be inverses but they seem not to be
+12:29 < matches> Oh wait, the divide by zero would do that
+12:30 < matches> That curve looks cool
+12:30 < matches> You should talk about it lots in the meeting
+12:31 < matches> For the whole meeting
+12:31 < matches> Nothing else
+12:31 < matches> Don't mention the total lack of progress I made...
+12:32 < matches> How much can I trust SolveCubic?
+12:40 < matches> Basically I'm going with randomly picking points until I find one inside the shape then starting a flood fill from that point
+12:41 < matches> Checking the pixels for the edges is not feasable
+12:42 < matches> If you scan along a bresenham line you could jump over the edge
+12:42 < matches> ... I see an "if false" in SolveCubic
+12:42 < matches> Slightly worrying
+12:43 < matches> Ah
+12:43 < matches> I approve of SolveCubic
+13:31 < matches> So
+13:31 < matches> Did you introduce the floating point exception or did I...
+13:45 < sulix> I just did.
+13:49 < sulix> SolveCubic may have small problems.
+13:50 < matches> Yes I am trying to rewrite it now...
+13:50 < matches> I swear we did this in CQM
+13:52 < sulix> Solvecubic also sometimes tries to take the square root of a negative number.
+13:52 < matches> Yep
+13:54 < sulix> I've pushed slightly less broken code.
+13:55 < sulix> Ny which I mean slightly more broken.
+13:55 < matches> ...
+13:55 < sulix> I'm avoiding divide by zeros by "if (denominator = 0) denominator = 1" style shenanigans.
+13:56 < matches> I'm slightly scared by the change to Rect::TransformRectCoordinates
+13:56 < matches> Oh right
+13:56 < matches> Yeah
+13:56 < matches> That seems...
+13:56 < matches> Scary
+13:56 < sulix> It works, scarily enough.
+13:56 < matches> Anyway I already ifdef'd the thing out of SolveCubic
+13:56 < matches> It's too slow for me though
+13:57 < sulix> And by works, I mean I haven't found any issues yet.
+13:57 < matches> I am brute forcing a point inside the shape
+13:57 < matches> This requires finding the intersections with horizontal and vertical lines for every single bounding bezier
+13:57 < matches> Then the "even or odd" test
+13:57 < matches> You only have to do it once
+14:05 < matches> I think SolveCubic would best be done by doing Newton Raphson or the Shooting Method between the endpoints and the turning points
+14:05 < matches> I'll see
+14:06 < matches> I'll try implement it and see if it's faster
+14:06 < matches> You may have to demonstrate my totally broken shading for me
+14:06 < matches> I haven't committed in a while
+14:41 < matches> Oh
+14:41 < matches> SolveCubic may not have been the bottleneck there...
+14:41 < matches> -_-
+14:41 < matches> The failure to update the variable for a while loop miiiight be more of an issue
+14:44 < sulix> Good, 'cause I'm thinking of "upping the SolveCubic accuracy" a bit.
+14:44 < sulix> Anyway...
+14:44  * sulix -> CS
+14:46 < matches> I've reimplemented SolveCubic
+14:46 < matches> In theory it works
+14:55 < matches> I reckon Binary Search is the only algorithm I am good at implementing :S
+14:57 < sulix> Oooh...
+14:57 < matches> What?
+18:56 < matches> So, the fact that we are not solving cubics analytically is probably important in terms of precision issues
+18:58 < sulix> Yeah, that's why I started trying to solve them analytically and then stopped and cried.
+18:58 < matches> :(
+18:59 < matches> There is a solution, it's just ugly
+18:59 < sulix> Nah: for the Quadtree, it didn't matter much. As long as the error went in the correct direction, you'd just lost a tiny bit of efficiency.
+19:00 < matches> Hmm
+19:00 < matches> I don't expect shading using arbitrary precision arithmetic will be particularly fast anyway...
+19:01 < sulix> Well, ideally most of the work in the shading will be done in screen-space anyway.
+19:01 < matches> Yes
+19:02 < sulix> And, of course, you don't need infinite precision for that because pixels/integers/etc.
+19:03 < sulix> So, fingers crossed, things shouldn't matter too much.
+19:03  * sulix realises that that is a maddeningly vague statement.
+19:03 < matches> Well
+19:04 < matches> I got the fill point to actually be in the correct location by actually solving the intercepts correctly
+19:04 < matches> But
+19:04 < matches> If you zoom *out* far enough, it can end up no longer inside the shape when transformed to screen space
+19:04 < sulix> Okay, new plan.
+19:04 < sulix> No zooming out.
+19:05 < matches> I wish there were other people in this channel so I could justify putting that in qdb
+19:20 < matches> There is a temptation to not require all those references to be const during rendering
+19:20 < matches> We might want the Path to be able to alter itself based on the view
+19:20 < matches> But I guess we'll take that path when we get to it
+19:22 < matches> It might be worthwhile caching Path's for fonts
+19:22 < matches> But I'd have to change the coordinates to be relative
+19:22 < matches> Too many coord transforms
+19:24 < sulix> Yup, that can be the subtitle of the thesis: "Too many coord transforms"
+19:26 < matches> "A coordinated approach to graphics"
+19:26 < matches> Oh wow
+19:26 < matches> That should be a textbook
+19:26 < sulix> "Transformers: Matrices in disguise"?
+19:30 < sulix> Okay, it turns out (if denominator is zero, make denominator 1) has one flaw.
+19:30 < sulix> Sometimes you should make the denominator... negative 1.
+19:30 < matches> ...
+19:30 < sulix> Somehow, I did not see this coming.
+19:30 < matches> I'm not sure how this maths works
+19:30 < matches> 1/0 != 1/-1
+19:30 < sulix> That's what they want you to think.
+19:31 < sulix> (Or maybe the bug I'm having is unrelated to that, but it seems like a fun guess)
+21:16 < matches> Floating Point Exception in fglrx!
+21:16 < matches> glXDestroyContext
+21:16 < matches> It only happens when the program is about to close
+21:16 < matches> So I'll be fine
+21:18 < sulix> Ah, maybe enabling floating point exceptions was a bad idea.
+21:18 < sulix> ...if it causes lots of "fglrxceptions"!
+21:21 < matches> Well fglrx is exceptional
+21:37 < matches> I'm falling back on just testing a crap tonne of points for "inside" and adding all the ones that are to a vector
+21:37 < matches> I think there are some false negatives in Path::PointInside
+21:37 < matches> Also FloodFill misses some edge pixels which makes no sense
+21:38 < matches> If it's next to a filled pixel it should get filled!
+21:47 < matches> So the disadvantage of using a breadth first search is that when your queue gets really big instead of getting a segfault you just get OOM
+21:48 < matches> segfaults are quick
+21:48 < matches> segfaults are like a pistol and oom is like drowning
+21:54 < sulix> There is no way a BFS floodfill should ever OOM
+21:54 < sulix> How many pixels are there, and how much are you storing per one?
+21:58 < matches> Probably max 256x256 pixels, 4 way fill
+21:58 < matches> It does not like rabbit_simple.svg
+22:04 < matches> Yeah there is *something* causing it to get in a loop
+22:04 < matches> Because obviously my BFS didn't check for loops
+22:14 < matches> -_-
+22:14 < matches> It is in a loop
+22:14 < matches> Because there is a region with fill colour of white
+22:14 < matches> And the flood fill is just "If it isn't white, stop"
+22:14 < matches> Maybe I should set the background to have 0 alpha or something
+22:15 < matches> Alpha seems to not actually do anything at the moment
+22:27 < matches> http://szmoore.net/ipdf/who-the-hell-needs-antialiasing-anyway.png
+22:44 < matches> http://szmoore.net/ipdf/shady-the-fox.png
+22:47 < matches> rabbit_simple.svg actually doesn't work as well as rabbit.svg
+22:48 < matches> I think one of the fill points of the outer ear is inside the inner ear
+22:54 < sulix> Oh my... They're beautiful!
+23:07 < matches> Ah crap
+23:07 < matches> I will be pushing
+23:07 < matches> 8 hours in the future
+23:07 < matches> I really should fix my system clock
+23:07 < matches> One of these days...