AppleSeed#2 · Google Code-in · Zulip Chat Archive

Stream: Google Code-in

Topic: AppleSeed#2

Mitesh (Jan 04 2018 at 13:16):

What does the drawing out PPM in this task means?

Jeff Sieu (Jan 04 2018 at 14:45):

It means drawing an output image in the PPM format.

Jeff Sieu (Jan 04 2018 at 14:46):

https://www.wikiwand.com/en/Netpbm_format

Mitesh (Jan 04 2018 at 15:26):

okk got that

Mitesh (Jan 04 2018 at 15:28):

I mean the task says that it should be black and white surrounded by misses(black). I successfully build this

http://brlcad.org/wiki/Example_Application

So am i suppose to program it in such a way that rays passes through the sphere and shows that...

Lucas Prieels (Jan 04 2018 at 15:37):

I mean the task says that it should be black and white surrounded by misses(black). I successfully build this

http://brlcad.org/wiki/Example_Application

So am i suppose to program it in such a way that rays passes through the sphere and shows that...

You have to somehow draw a black pixel if you hit and a white one if you miss

Mitesh (Jan 04 2018 at 15:40):

okk...thank you so much

Lucas Prieels (Jan 04 2018 at 15:49):

okk...thank you so much

Good luck! I didn’t know the ppm images before but it is very useful and extremely simple to use!

Sean (Jan 04 2018 at 17:29):

they're a great debugging format since they're a simple text header followed by binary image data just like it's held in memory

Mitesh (Jan 06 2018 at 16:55):

i am wondering how to shoot rays horizontaly....for vertically what i thought was to use for loop and add cout<<endl; once the function is executed...Am i going in right direction?

Lucas Prieels (Jan 07 2018 at 01:00):

i am wondering how to shoot rays horizontaly....for vertically what i thought was to use for loop and add cout<<endl; once the function is executed...Am i going in right direction?

You only have to shoot a grid of rays in 2D. Imagine it like this: take a sphere, hold it in front of you and light it up with a flashlight, the shadow on the wall will be a circle. That's exactly what you need to do: given a sphere, light it up by shooting rays (like light rays) and output the circle, the shadow on the wall. I don't want to give a too big clue, but you'll need a couple of loops to do it.

Mitesh (Jan 09 2018 at 08:06):

what does this function VSET(ap.a_ray.r_dir, 0.0, 0.0, -1.0) do?

Jeff Sieu (Jan 09 2018 at 08:45):

Set the ray direction of ap.a_ray to 0.0, 0.0, -1.0

Mitesh (Jan 09 2018 at 09:13):

okk

Mitesh (Jan 09 2018 at 10:31):

is it ok if write out the image in .pgm format?

Jeff Sieu (Jan 09 2018 at 10:40):

I suppose any image format is fine as long as you can see the image.

Mitesh (Jan 09 2018 at 10:41):

Mitesh (Jan 09 2018 at 11:56):

i am getting circular file but not circular image...cicle.PNG

Mitesh (Jan 09 2018 at 11:58):

any ideas?

Jeff Sieu (Jan 09 2018 at 16:11):

Read up on how the format works

Mitesh (Jan 09 2018 at 16:30):

okk

Mitesh (Jan 09 2018 at 16:52):

anyone completed this task?

Mitesh (Jan 09 2018 at 17:00):

The usage seems to be correct @Jeff Sieu ....usage.PNG

Jeff Sieu (Jan 09 2018 at 17:01):

Did you put the P2 in your file

Jeff Sieu (Jan 09 2018 at 17:01):

And the width and height of the image on the next line

Jeff Sieu (Jan 09 2018 at 17:02):

Or P<whatever>*

Mitesh (Jan 09 2018 at 17:02):

yes..I did

Lucas Prieels (Jan 09 2018 at 17:03):

I'm not sure you can put comments in a PPM file, try to erase it

Lucas Prieels (Jan 09 2018 at 17:12):

Ah I had not seen that the second one was working, but since it writes an image I suppose that's your code which is wrong... Maybe it doesn't print a black pixel when it should

Jeff Sieu (Jan 09 2018 at 17:12):

You may be printing too many per line

Jeff Sieu (Jan 09 2018 at 17:13):

Is the number of numbers per line = width

Jeff Sieu (Jan 09 2018 at 17:13):

Can you send over the whole file's contents

Lucas Prieels (Jan 09 2018 at 17:13):

@Mitesh Can you send the whole file?

Lucas Prieels (Jan 09 2018 at 17:14):

Oups didn't see you just asked :)

Jeff Sieu (Jan 09 2018 at 17:16):

I think I know the problem here

Lucas Prieels (Jan 09 2018 at 17:16):

Also, are you sure you put three numbers for each pixel? I see that in the last line, there are 7 times the number 15

Jeff Sieu (Jan 09 2018 at 17:17):

The number of columns may be smaller than the specified width

Jeff Sieu (Jan 09 2018 at 17:18):

Causing the image to look like a sort of "staircase", as some of the pixels from the second row are treated as that of the first

Jeff Sieu (Jan 09 2018 at 17:18):

Just my guess though

Mitesh (Jan 09 2018 at 17:43):

sorry my computer has shutdown... there is some power problem and i don't have that file in my laptop....i will send the file tom asap....Thank you so much

Mitesh (Jan 09 2018 at 18:02):

wait it has started... i will send in few moments

Mitesh (Jan 09 2018 at 18:03):

color.pgm

Mitesh (Jan 09 2018 at 18:04):

here is the file @Jeff Sieu , @Lucas Prieels

Lucas Prieels (Jan 09 2018 at 19:07):

I've already seen that there are approximately 61-62 numbers per line and 61 lines, so I think there should be more numbers (I'm not certain because it's not easy to count them :)

Lucas Prieels (Jan 09 2018 at 19:07):

But there's definitely a problem with number of 15, it should be a multiple of 3 on each line, and it's not

Lucas Prieels (Jan 09 2018 at 19:12):

Forget what I said, I didn't see it was a .pgm file, I used a .ppm one

Lucas Prieels (Jan 09 2018 at 19:29):

I found out: re-check you have the right numbers of rows and columns :)

Lucas Prieels (Jan 09 2018 at 19:35):

But otherwise, you effectively have a sphere. Just a thing, I don't know if it's important for the task but you should take a bigger resolution and fire more rays