Automatic commit of irc logs

You prefer the company of the opposite sex, but are well liked by your own.

diff --git a/irc/#ipdf.log b/irc/#ipdf.log
index 60fd46c..c8c17c9 100644 (file)
--- a/irc/#ipdf.log
+++ b/irc/#ipdf.log
@@ -4003,3 +4003,148 @@
 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...