+--- Day changed Thu Aug 14 2014
+09:50 < matches> cool
+10:37 < matches> I'm beginning to suspect whoever said to use the Newton Raphson method to find Bezier bounding boxes was right
+10:43 < matches> I love how the sites I looked up said "Obviously there is a problem if a = 0 or b^2 - 4ac < 0, but we can just make sure we always pick beziers that don't cause those problems
+10:44 < matches> Ok
+10:44 < matches> I have at least got an algorithm that returns finite sized bounding boxes now
+10:45 < matches> I think it even works!
+10:45 < matches> But only on the CPU
+10:45 < matches> Presumably the GPU does something to cope with the fact that the bounding boxes were totally wrong before?
+10:53 < matches> Oh it wasn't doing anything because they were {0,0,1,1}
+10:54 < matches> I have to transform the Bezier coefficients before they are uploaded to the GPU
+10:54 < matches> Blergh
+10:55 < matches> What I've basically done is change it to be the opposite of how it was designed
+10:55 < matches> -_-
+10:56 < matches> So before, the Bezier control points were relative to some bounding rectangle but when I parsed the SVG I just made it always {0,0,1,1} so the coordinates were absolute
+10:56 < matches> Now I have changed the Bezier control points to be absolute and then calculated a bounding rectangle from them
+10:56 < matches> I can maths
+10:57 < matches> So I could make the Beziers still have the {0,0,1,1} bounds which will fix the GPU renderer without having to transform the coefficients
+10:57 < matches> And just leave this "SolveBounds" function in for actually getting the bounds
+10:58 < matches> Except SolveBounds is disgusting
+10:58 < matches> And slow
+10:58 < matches> So I could add a Bounds member variable to the Beziers
+10:58 < matches> And then we have two bounds
+10:58 < matches> I seem to have coded myself into a catch 22 "No matter what you do it is terrible" situation
+10:59 < matches> Adding a Bounds member variable to the Bezier struct sort of defeats the whole point of the "Object of Arrays" idea
+10:59 < matches> You know what
+11:00 < matches> I think the "Object of Arrays" approach has caused more problems than it solved :P
+11:02 < matches> (Probably not actually)
+11:09 < matches> Spaghetti
+11:09 < matches> I'm going to transform the coordinates before uploading to the GPU shaders
+11:09 < matches> Because I think that is the least objectionable?
+11:09 < matches> I don't know
+11:09 < matches> I still don't like any of the solutions
+11:10 < matches> But having more than one bounding rectangle definitely seems dumb
+11:10 < matches> Especially if the other is *always* {0,0,1,1}
+11:11 < matches> I hope this doesn't totally break your quad tree
+11:15 < matches> Actually looking at the quad tree it seems that is the best way to make it more likely to work
+11:21 < matches> I feel like we should use SVGMatrix more and Rect less
+11:21 < matches> But oh well
+11:29 < sulix> Ah: so the Quadtree kinda relies on the Bézier coordinates being relative to the bounding rectangle.
+11:29 < matches> Yep
+11:29 < matches> I'll do that
+11:29 < matches> It's easier to do the transform when the coordinates are uploaded to the GPU
+11:29 < matches> Although probably less efficient
+11:30 < matches> On the other hand, the CPU renderer relies on having absolute coordinates
+11:30 < matches> Two renderers
+11:30 < matches> TWICE the matrices
+11:30 < matches> TWICE the confusion
+11:31 < matches> And Rects are not really convenient because they aren't a proper transformation matrix
+11:31 < matches> I can't just multiply some Rects together
+11:31 < matches> Or calculate an inverse
+11:32 < sulix> Yeah, there are problems there.
+11:34 < matches> Hmm
+11:34 < matches> I *almost* fixed it
+11:34 < sulix> Rects are really good for the QuadTree, though.
+11:34 < matches> We should leave it as rects
+11:34 < matches> You just manually work out what it needs to be anyway
+11:35 < matches> I think the inverse of the equivelant matrix will always work as a rect
+11:35 < matches> So there are random lines missing from the beziers now
+11:35 < matches> But the ones that are there are in the right spot!
+11:36 < matches> (On the GPU)
+11:36 < sulix> So, I looked at that. I see random missing lines on Intel, not on nVidia.
+11:37 < matches> Oh were they missing before?
+11:37 < matches> Well I don't recall them being missing before
+11:37 < matches> Oh
+11:37 < matches> I know what it is
+11:38 < matches> When the bounding rectangle has width or height of zero
+11:38 < matches> Sigh
+11:38 < matches> Wait that can't be it
+11:38 < matches> Most of the missing lines aren't straight horizontal or vertical
+11:38 < matches> :S
+11:39 < sulix> I think it's just dodgy rounding on the GPU.
+11:40 < matches> I will push what I have I guess
+11:40 < matches> I have nice pretty debug rectangles (in *colour*) around the beziers when they are rendered on the CPU
+11:40 < matches> Somehow I don't think that is going to be sufficiently impressive progress in the meeting
+11:41 < sulix> Oooh... I'm looking forward to trying that.
+11:41 < sulix> I have an impressive Quadtree demo to do!
+11:41 < sulix> Assuming the bezier stuff doesn't suddenly break.
+11:41 < matches> ... it might
+11:41 < matches> Ok, I will `git stash` and then `git pull` as opposed to merging
+11:42 < matches> Yes, there are definitely not randomly missing beziers in your code
+11:44 < matches> Wait, was your quad tree working with beziers before?
+11:44 < matches> It wouldn't have been?
+11:44 < matches> All the bounds were wrong
+11:48 < matches> Ooh
+11:48 < matches> H and V
+11:48 < matches> What are they
+11:49 < sulix> Horizontal and Vertical lines
+11:49 < matches> Ah
+11:50 < sulix> The QuadTree works with beziers, but doesn't increase precision.
+11:52 < matches> Hmm, now to work out which of the 5 or 6 edge cases is breaking the Bezier bounds algorithm
+11:53 < matches> It's kind of hard to debug
+11:53 < matches> The edge cases apply seperately to the y and x directions
+11:53 < matches> So you can't tell just by looking at a curve that it is an edge case
+11:54 < matches> Unless you are a mathemagician I guess
+11:55 < matches> I don't understand
+11:55 < matches> The bounds for the beziers that disappear look right
+11:59 < matches> Maybe I'm not uploading the data correctly anymore
+12:03 < matches> Ok now it only breaks for the horizontal and vertical lines which I at least understand
+12:03 < matches> I was iterating over the object bounds and uploading the ones that had a type of BEZIER
+12:03 < matches> Oh
+12:03 < matches> Oh
+12:04 < matches> Yeah because I added a GROUP as well
+12:04 < matches> And every <path> gets a GROUP now
+12:04 < matches> So the order of indexes must be off
+12:14 < matches> Face palm
+12:14 < matches> This is why we have objects.data_indices
+12:19 < matches> I wish I'd added the SVG stuff earlier
+12:19 < matches> It makes it a lot easier to do stuff when you can mess around with actual documents
+12:42 < matches> I have pushed some stuff
+12:43 < matches> Mostly it just looks like I added a bunch of colourful rectangles to the CPU rendering
+12:43 < matches> I think I broke the Quad tree too
+12:43 < matches> Go team
+12:43 < matches> Oh and there are a bunch of not so colourful GPU rectangles
+12:43 < matches> Due to the "GROUP" object just using the outline rectangle shaders
+12:44 < matches> So part of the quad tree seems to work on the GPU but not all of it
+12:44 < matches> And none of it seems to work on the CPU?
+12:48 < matches> Also instead of rendering a slightly broken fox it now renders a segfault
+12:48 < matches> Similarly for the koch snowflake
+12:48 < matches> It's alright we can still draw Humphrey
+12:53 < matches> Oh
+12:53 < matches> It's just the quad tree that segfaults on the more complicated svgs
+13:38 < sulix> I have returned from the committee meeting, and that stupid 2/3rds majority thing has been revoked!
+13:38 < matches> Hooray!
+13:39 < matches> I should head towards University for the project meeting
+13:39 < matches> It is tempting to just stay home
+13:40 < matches> But that would probably not be wise
+13:41 < sulix> You should come.
+13:41 < sulix> I'm going to see if I can fix the Quadtree, but it looks like your changes have thoroughly broken it.
+13:41 < matches> Sorry!
+13:41 < sulix> By which I mean, it probably was only working if everything had bounds (0,0)-(1,1)
+13:41 < matches> Haha
+13:42 < matches> You can just undo my changes to demonstrate it if you want
+13:42 < matches> To the bus
+13:43 < sulix> I may yet do that...
+14:54 * sulix -> CSSE
+19:08 < matches> So shading on the CPU sort of totally breaks
+19:08 < matches> But it exists
+19:08 < matches> Progress!
+19:10 < matches> Bezier bounds are not as good as I'd hoped
+19:10 < matches> I think they only work if the end points form the bounds
+19:17 < sulix> Ah...
+19:21 < sulix> Btw, in the default "c" glyph, there are _two_ curves with bounds (0,0)-(1,1)
+19:21 < sulix> Numbers 9 and 18
+19:22 < matches> Yeah I found the wierd ebounds
+19:22 < matches> It's in the font code
+19:22 < matches> There is an AddBezierData with (0,0,1,1) instead of AddBezier (which automatically works out the bounds)
+19:22 < matches> For vlines
+19:22 < sulix> That'd do it.
+19:23 < matches> shape.svg seems to lose part of the curve now
+19:23 < matches> I've made the bezier control points relative
+19:23 < matches> Things mostly sort of work
+19:23 < matches> But the quad tree still looks fantastically broken
+19:25 < sulix> It always looks broken if you pan around or zoom out: it's my ugly baby.
+19:28 < matches> http://szmoore.net/ipdf/brokenbeziers.png
+19:28 < matches> To be fair the beziers are actually fine
+19:28 < matches> It's just the bounding rectangles that are broken
+19:28 < matches> Also shading should probably not be turned on unless it is actually a closed path
+19:29 < sulix> Hmm...
+19:29 < matches> Wait
+19:29 < matches> The beziers are rendering fine
+19:29 < matches> But the bounding rectangles are wrong
+19:29 < matches> Does this mean
+19:29 < matches> If I *fix* the bounding rectangles
+19:29 < matches> It will break something
+19:29 < matches> :-(
+19:29 * matches forges ahead nevertheless
+19:30 < matches> It does look suspiciously like it is only ever using P0 and P3 for the bounds
+19:30 < matches> Despite all that horrible solving for the turning points
+19:31 < sulix> Yeah.
+19:31 < matches> Oh
+19:32 < matches> I suspect if I fix this it will totally break the absolute to relative bezier transform then
+19:35 < matches> The file for those beziers is kind of interesting
+19:35 < matches> inkscape has used absolute commands for all except one of the beziers
+19:35 < matches> Why?
+19:35 < matches> The first one was copied and pasted with the control points moved
+19:35 < matches> Also for some reason random "translate" applied to the whole group
+19:36 < matches> It might make some sense if it caused the coordinates of the actual paths to come out as integers maybe
+19:36 < matches> But they don't
+19:37 < matches> There is translate and then the initial "moveto" is not 0,0
+19:37 < matches> I guess we shouldn't be trusting an svg editor that segfaults if you try recursion anyway
+19:59 < matches> Ok, high school maths:1, 5th year science/engineering student:0
+20:15 < matches> Also my amazingly clever shading algorithm has
+20:15 < matches> ...
+20:15 < matches> issues
+20:15 < matches> When the paths are not in the view
+20:16 < sulix> Ah...
+20:18 < matches> In fact it has many issues in many cases
+20:27 < matches> Hmm
+20:27 < matches> I wonder if this is what causes problems with evince/atril
+20:27 < matches> Ok not this
+20:28 < matches> I mean, if they use a similarly terrible except actually working shading algorithm
+20:28 < matches> And just draw everything to a really big texture so they can use it
+20:28 < matches> As opposed to clipping things
+20:28 < matches> That seems a little unbelievable though
+20:29 < matches> Surely that would crash long before you even got to >1600%
+20:30 < matches> I suppose what I should really do is look up some papers on shading
+20:30 < matches> Blergh
+20:35 < matches> Things are pushed
+20:37 < matches> Ah crap
+20:38 < matches> Things will be pushed in 8 hours according to my clock
+20:38 < matches> Just don't do anything until after 4am tomorrow and everything will be in the right order
+20:38 < matches> :P
+20:39 < sulix> That shading is _amazing_
+20:40 < matches> Try replacing the colour with rand()%255 for even more amazingness
+20:40 < sulix> If you zoom in _just_ the right amount, all hell breaks loose. I love it!
+20:40 < matches> Haha
+20:40 < sulix> Slowly panning across it is also magical!
+20:41 < matches> Try it on rabbit_simple.svg
+20:42 < sulix> I think Humphrey might have come down with a case of stripey binary myxomatosis.
+20:43 < matches> So I will have to think about shading a bit more :P
+20:43 * sulix braves the unholy combination of shading and quadtree.
+20:43 < matches> Oh I didn't try that
+20:44 < sulix> It actually doesn't look any different.
+20:44 < sulix> I think the quadtree only breaks w/ the GPU.
+20:44 < matches> Yes
+20:45 < matches> You lose the debug message if the node # > 9 it seems too
+20:46 < matches> At least the quad tree works on the CPU
+20:46 < matches> But why doesn't it work on the GPU they are now using the same bounds
+20:47 < matches> So should I prepare a report for Tim?
+20:47 < matches> Progress Report: Arbitrary precision numbers are unsurprisingly, totally infeasible
+20:47 < matches> Therefore, we implemented random bits of SVG
+20:47 < matches> Figure 1: A totally broken shading algorithm
+20:48 < sulix> You should include this image of the quadtree: http://davidgow.net/stuff/ipdf-humphreys-ghost-face.png
+20:48 < matches> Yes
+20:48 < matches> I wonder if since we're allegedly engineers we should document what bugs go with what images
+20:48 < matches> Hmmm
+20:49 < sulix> That's why I name the screenshots like that, I know this goes with the "Humphrey's Ghost Face" bug.
+20:49 < matches> Haha
+20:49 < matches> So we have the svg-test images
+20:50 < matches> Would it be worth while to have a commit script that automatically drew them and did screnshots
+20:50 < matches> It might be tricky though because you have to test panning and zooming and things
+20:50 < sulix> Yeah... perhaps videos?
+20:51 < matches> We'd need to be able to control the view automatically
+20:51 < matches> Which is actually required for that list of things in the proposal we are supposed to do anyway
+20:52 < sulix> I think we'll want that feature at some point anyway for doing proper performance tests
+20:54 < matches> I kind of want some sort of debug overlay for things like the bounding boxes too
+20:54 < sulix> Hmmm... the bounds look right: http://davidgow.net/stuff/ipdf-humphrey-bounds-ahead.png
+20:54 < matches> And a menu system
+20:54 < matches> And the ability to "insert SVG here"
+20:54 < matches> And open a file browser
+20:54 < matches> And...
+20:54 < matches> And...
+20:54 < matches> Yeah
+20:54 < sulix> I've been seriously considering doing a menu system.
+20:54 < matches> Too bad christmas is after the thesis is due
+20:54 < matches> Do it!
+20:55 < matches> We're running out of mouse buttons to toggle things :P
+20:55 < matches> Are there any SDL based menu systems that we can use easily?
+20:55 < sulix> There are a couple of OpenGL-y ones that might work.
+20:56 < matches> Let's not port the project from SDL -> FreeGlut
+20:56 < sulix> No.
+20:56 < sulix> Let's not.
+20:57 < sulix> (I'm looking for an SDL/OpenGL menu system so that I can replace FreeGLUT in the Graphics project(
+20:57 < matches> Could we use Qt or is that overkill?
+20:57 < sulix> I suspect it's probably overkill.
+20:59 < sulix> I've got a couple of old GUI libraries for SDL/OpenGL I wrote in high school I could dig up as a last resort.
+20:59 < matches> ... I have seen your high school code
+20:59 < matches> :P
+20:59 < sulix> (I think one of them uses a tiny bit of boost, though, so I'd rather avoid it)
+21:03 < matches> I kind of want to look at Qt at some point
+21:03 < matches> Maybe if we have the menu in a seperate window...
+21:03 < matches> Then we need threads...
+21:03 < matches> Then we have two problems...
+21:09 < matches> All the links to SDL libraries are broken
+21:34 < sulix> I'm not sure what changed, but now ipdf crashes my OpenGL debugger.
+21:42 < sulix> The QuadTree/GPU code works again!
+21:42 < sulix> Somehow the bug I fixed last night reappeared, but I've added the needed *2s back in.
git.ucc.asn.au / ipdf / documents.git / commitdiff
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