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Occlusion culling.

Name: cb 2013-05-22 15:31

How would I go about occlusion culling a set of 2.5D rectangles (2D rectangles with 3D transforms applied to them) so that:

1) The quads are rendered in the right order.
2) Quads that intersect other shapes are split into several other shapes that are then ordered.

Essentially, I'm looking to a solution to this (https://bugzilla.mozilla.org/show_bug.cgi?id=689498) but for an unrelated question.

Asked this on SO a while ago but didn't really get a satisfactory answer in terms of an actual, acceptable algorithm: http://stackoverflow.com/questions/16582320/occlusion-culling-3d-transformed-2d-rectangles

Name: Anonymous 2013-05-22 19:58

Yeah, those suggestions aren't too bad: either z-buffering, raycasting or splitting the geometry.
If you don't know 100% what you're doing, I'd recommend against splitting the geometry, though. A naive implementation isn't too complex but as that one guy already pointed out, complexity (time and memory-wise) may be a real problem if you don't have a super-sophisticated-Carmack-grade algorithm.
For raycasting you might also require some more sophisticated stuff.
To get to the point: I'd recommend OpenGL with some sort of z-buffering (``Solution #2''). Even if you don't have HW-Acceleration, most OpenGL-Software-Renderers (Mesa, and even the Win32 fallback renderer) should perform pretty well, even for higher resolutions (where z-buffering and raycasting are usually weak, due to memory speed limits). Unfortunately I can't really give you hints as to how z-buffering works with transparency (how it's actually implemented).
2) Quads that intersect other shapes are split into several other shapes that are then ordered.
...will not happen with z-buffering, though. You just test every pixel for visibility before it's drawn, geometry will stay untouched. Naturally you'll also have some overdraw here.

Maybe I can post something useful tomorrow, it's already 2 am here...

Name: Anonymous 2013-05-22 20:52

2.5D rectangles

what have you been smoking?

Name: Anonymous 2013-05-22 21:13

>>3
your mother's anus

Name: Anonymous 2013-05-22 21:36

>>1
Christina Brooks
Oy vey, we've got a woman here!

Name: Anonymous 2013-05-22 21:42

>I have experience with the following languages:
    * x86 Assembly
    * ARM Assembly

    * C
    * Objective-C
    * C++ (and EC++)


    * Python
    * PHP (Ashamed of it)
    * Perl
    * JavaScript

    * HTML
    * CSS


Typical woman who hasn't read her SICP. Back to Reddit News, please.

Name: Anonymous 2013-05-22 21:43

>>6
I fucked up!

Name: Anonymous 2013-05-22 21:52

You will get an answer only if you post your Gensokyo Citizenship ID with a timestamp.

Name: Anonymous 2013-05-22 21:57

>>8
mad virgin

Name: Anonymous 2013-05-22 22:10

Holy shit, take a course in linear algebra! Honestly, you just want to find an intersecting line and it's causing you all this trouble?

Name: Anonymous 2013-05-22 22:12

>>9
No, I'm a happy virgin willing to help the Touhous.

What are you, a mad non-virgin? Pathetic.

Name: Anonymous 2013-05-22 22:13

>>10
She's a she, give her a break.

Name: Anonymous 2013-05-22 22:23

>>12
She's a it until it learns some linear fucking algebra.

Name: Anonymous 2013-05-22 22:24

>>13
She's a it, give that thing a break.

Name: Anonymous 2013-05-22 22:27

>>5
A transgender woman!

Name: Anonymous 2013-05-22 22:28

>>13
Woman can't do math, silly goy.

Name: Anonymous 2013-05-22 22:38

>>16
No, but females can.

Name: Anonymous 2013-05-22 22:55

>>6
him are*

Name: Anonymous 2013-05-22 23:29

>>17
Females can't do math either, silly gentile.

Only manly male men can do math.

Name: Anonymous 2013-05-22 23:38

>>19
Manly male men can only do minimum wage moving-heavy-boxes-around jobs; their peak of intellectuality of the week occurs as they are comparing the scores of the two teams in the football match they are watching to see which is leading.

Also don't "gentile" me you filthy goy.

Name: Anonymous 2013-05-22 23:42

>>20
Oh, we have different concepts of manly then. A manly male men is someone who's not afraid of monads or lambda calculus. If someone is afraid of those, you can call them faggots.

I "gentile"d you again, goy.

Name: Anonymous 2013-05-23 0:03

>>21
That's like those people who redefine common words like racism.

Name: Anonymous 2013-05-23 0:10

ITT: goys

Name: Anonymous 2013-05-23 0:14

>>23
Goyim is the plural of goy, goy.

Name: Anonymous 2013-05-23 0:14

>>24
Spoken like a true goyela

Name: Anonymous 2013-05-23 0:33

Name: Anonymous 2013-05-23 0:41

>>26
It was real in my mind.

Name: Anonymous 2013-05-23 0:45

>>27
They gassed us hard,
They gassed us long,
They gassed us in our sleep,
They gassed my entire family,
Until there was no peep!
They gassed us day by day by day,
Oy vey, oy vey, oy vey!
Some filthy goyim say,
The shoah was a lie.
But my friend,
I think you’ll find,
It was real in my mind!

Name: Anonymous 2013-05-23 0:57

Name: Anonymous 2013-05-23 1:04

Hate to break it to you Gerald, but christina is a guy who thinks he can get away with passing himself off as a girl.

But that isnt why you helped him is it? No, it is because he is ethnically kosher.

Name: Anonymous 2013-05-23 1:46

>>28
5 star post.

Name: Anonymous 2013-05-23 4:49

http://stackoverflow.com/questions/16582320/occlusion-culling-3d-transformed-2d-rectangles
Soltuion #1 (extremely difficult):
apparently proper spelling is also extremely difficult

>>30
at least he's not a self-hating russian KIKE

Name: Anonymous 2013-05-23 4:57

>>1
Asked this on SO a while ago but didn't really get a satisfactory answer
So instead you turned to the most helpful programming board in the universe, /prog/.

Name: cb 2013-05-23 5:09

>>33
Never hurts to try. Haha, people here are dicks.

Name: (΄◉◞౪◟◉`) 2013-05-23 5:44

<b>( ;⊙´◞౪◟`⊙)</b>

Name: Anonymous 2013-05-23 6:12

>>10
hmm.. how to find those lines in 3d?
Could you use the diagonals..?

Name: Anonymous 2013-05-23 6:21

>>36
There are these funny things called equations.

Name: Anonymous 2013-05-23 6:26

even better if you can quickly check if there is an intersection first..?
seems like you should zero a dimension relative to the given plane, then look for positive/negative crossings in the area =D

Name: Anonymous 2013-05-23 6:44

a plane is defined as a line and a point (not on the line)?
....do polygons that aren't triangles ever get messy? (planar twist?) eg. (0,0,0,/0,1,1/1,0,1/1,1,0)

Name: Anonymous 2013-05-23 6:47

^^ gives co-ords for a tetrahedron....

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