Thank you very much!
On Wed, Mar 7, 2018 at 8:13 PM, Rybec Arethdar <rybecareth...@gmail.com> wrote: > Alright, I wrote the program. I also modified it in a second version, to > eliminate the use of Surface.set_at() as an explanation for the results. I > posted both programs on Github. > > https://github.com/pygame/pygame/issues/410 > > On Fri, Mar 2, 2018 at 10:42 AM, Rybec Arethdar <rybecareth...@gmail.com> > wrote: > >> If my student does not post the information on Github, I will see if I >> can write up a simple program to reproduce it, and I will post it there. >> As it is, I don't have the code, however we worked together on it for half >> an hour yesterday, and while there were some bugs in his code initially, by >> the end we had everything relevant to this worked out. >> >> Once there is more information on Github, I'll drop a note here. >> >> On Fri, Mar 2, 2018 at 1:16 AM, René Dudfield <ren...@gmail.com> wrote: >> >>> ... and replying on the pygame-users mailing list. >>> >>> On Fri, Mar 2, 2018 at 8:38 AM, illume <ren...@gmail.com> wrote: >>> >>>> Hello, >>>> >>>> Thanks for picking up the ball. >>>> It must be muddy and old after five years on the ground. >>>> >>>> It's cool that your students are messing around with >>>> per pixel collision detection.An d even making videos about it. >>>> That's pretty advanced! >>>> >>>> So, what's next for getting this issue fixed? >>>> >>>> >>>> You've already linked to some existing discussion on the issue, >>>> that's a good start! There's even code in there. Brilliant. >>>> >>>> But what even is a mask, and an overlap? >>>> >>>> >>>> Another thing people can do is link to the relevant code in >>>> the pygame source code. This means they don't need to look >>>> themselves, and it helps them get to the task quicker. >>>> >>>> Remember, the person fixing the code might never have seen >>>> or even used the code before. >>>> >>>> Documentation for mask overlap stuff lives here: >>>> https://www.pygame.org/docs/ref/mask.html#pygame.mask.Mask.overlap >>>> >>>> Implementation of bitmask overlap (src/bitmask.c in pygame repo). >>>> https://github.com/pygame/pygame/blob/master/src/bitmask.c#L161 >>>> >>>> The unit test is here (test/mask_test.py in the pygame repo): >>>> https://github.com/pygame/pygame/blob/master/test/mask_test.py#L74 >>>> >>>> >>>> So, now they know where to look for what it does, and where in >>>> the code base they can write a test for it, or change the code. >>>> >>>> >>>> But is it even a bug? Having your students writing a unit test >>>> for their own code will help them check all their assumptions, >>>> and also see if it's a problem with the mask overlap code or >>>> a problem somewhere else. >>>> >>>> Being able to reproduce the issue makes it easier for anyone >>>> coming along to fix it. If not a unit test, then a short script, >>>> or minimal working example pasted into the issue will help with that. >>>> >>>> Sometimes a visual example with an explanation is best. >>>> >>>> Screenshots, screenshots, and more screenshots. >>>> Or a video, are all useful in helping people understand what's >>>> going on. >>>> >>>> >>>> >>>> Mostly people only get a hour or two here and there on weekends >>>> or late nights to mess around with pygame, it really helps the >>>> next person to not drop the ball again. >>>> >>>> Anything to help them see how it's not working correctly will >>>> help the next person fix it. >>>> >>>> >>>> cheers, >>>> >>>> >>>> >>>> >>>> >>>> On Friday, March 2, 2018 at 7:46:13 AM UTC+1, ...@gmail.com wrote: >>>>> >>>>> I just found the Pygame Github repository. I'll make sure the issue >>>>> gets reported there. >>>>> >>>>> On Thursday, March 1, 2018 at 11:42:40 PM UTC-7, rybeca...@gmail.com >>>>> wrote: >>>>>> >>>>>> So, *five years later* this bug still exists. I use Pygame to teach >>>>>> a college video game course, and I have a student having what appears to >>>>>> be >>>>>> this exact same issue. Sadly, the OP never bothered to file that bug >>>>>> report. >>>>>> >>>>>> I don't see any way to post a report at that link, which may be why >>>>>> the bug report was never filed. I will explain what we are seeing >>>>>> though. >>>>>> >>>>>> My student started with a YouTube video, showing how to do pixel >>>>>> perfect collision detection with Pygame masks. Several students have had >>>>>> success with this. This particular student decided that he wanted to >>>>>> recolor one of the images, to display exactly where it is overlapping >>>>>> another image. Unfortunately, the recoloring behavior is totally >>>>>> erratic. >>>>>> The parts of the image that are being recolored based on the overlap mask >>>>>> produced are very inconsistent. Moving the top image even slightly can >>>>>> dramatically change what pixels are marked as colliding. The only >>>>>> consistent thing is that pixels that are *not* colliding are never >>>>>> marked as colliding, however pixels that *are* colliding are not >>>>>> consistently marked as colliding. When the mobile image is stationary, >>>>>> the >>>>>> pixels marked as colliding don't change, but a movement of 1 pixel in any >>>>>> direction can dramatically change what is marked as colliding and what is >>>>>> not. Moving the mobile image rapidly back and forth over the stationary >>>>>> one appears to reveal vertical divisions, where pixels on one side are >>>>>> more >>>>>> likely to be marked as colliding than pixels on the other. I did not >>>>>> observe horizontal divisions like this, though I could have missed them. >>>>>> >>>>>> Anyhow, someone *please* file a report for this bug! It clearly >>>>>> should have been done 5 years ago, but someone obviously dropped the >>>>>> ball. >>>>>> >>>>> >>> -- >>> >>> --- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "pygame mirror on google groups" group. >>> To unsubscribe from this topic, visit https://groups.google.com/d/to >>> pic/pygame-mirror-on-google-groups/8RGH0HIg2o8/unsubscribe. >>> To unsubscribe from this group and all its topics, send an email to >>> pygame-mirror-on-google-groups+unsubscr...@googlegroups.com. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> べん >> > > > > -- > べん > > -- > > --- > You received this message because you are subscribed to the Google Groups > "pygame mirror on google groups" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to pygame-mirror-on-google-groups+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. >
