Beginners Task #3

[tougo]

Beginners Task #3: Transformations

I thought that it is a very usefull excercise for those that like to go into some mathematical concepts of
game programming. Iam sure it needs a little bit of thought but overall is very simple. The results can very well be just ascii files or just output on the screen, it doesn't really matter.

There are two versions of the task a 2d and 3d one. The 3d might be more difficult so you can just try the 2d

1st version

Write a program that produces a n set of points [xy] that are part of a circle and then calculated the largest
square that can be fitted in the circle and transform the initial coordinates of the cirlce to that of the square's.

INPUT

(P) number of point:
radius:

OUTPUT

(P) coordinates:

2nd version

Write a program that produces a n set of points [xyz] that are part of a sphere and then calculated the largest
cube that can be fitted in the sphere and transform the initial coordinates of the sphere to that of the cube's.

INPUT

(P) number of point:
radius:

OUTPUT

(P) coordinates:

a visual representation would make things easier I think. I did my best . I hope someone like it.

[leas5040]

This looks kind of fun. Could you post a sample output? Is it supposed to show the square in the circle, with the coordinates of each crossing vertex?

[MXP]

I dont understand what you mean.

Write a program that produces a n set of points [xy]

Do you mean "a set of points (x, y)"? If so how does that fit with the example input?

Code: Select all

(P) number of point:
radius:


transform the initial coordinates of the cirlce to that of the square's.

A square is made of 4 coordinates. To which would you like us to transform the circle?

[tomcant]

If I understand correctly, this is quite simple... but I won't give anything away

[RecursiveS]

Stickied for a while, as usual.

[tougo]

If I understand correctly, this is quite simple

Yes it is, that's why It's a Beginners task

A square is made of 4 coordinates. To which would you like us to transform the circle?

each coordinate of the circle corresponds to a coordinate of the square ..if you have a cirlce made from let's say 40 points...then you'll have a square made from the same points...you actually move the circles points in to the corresponding position in the square.

the fitting is quite easy...(can't be easier) the transformation is easy as well but it can be tricky (for the 3d at least)

[Alvaro]

Do you mean you have to project the points on the circle to points on the square? Like, joining a point in the circle with the center of the circle and then finding the intersection with the square? And what is the square, exactly?

Can you give us a sample input and the expected output?

[tougo]

yes exactly that...Alvaro
I'll try to post a screenshot or else just a list of points of an example later this day

[tougo]

i don't know if these screenshots will help ...but here it goes

ignore the programme that displays the points it was designed for another purpose. ignore the red cross as well it just shows the weight of the points

PS. The output can be a lot better (not missing any points in the edges that the screenshots). It was done in a hurry and i tried to maintain equal lengths between points (it was kind of a disaster )

[t i l e x]

Now that is annoying.. I know how to do it but I never learned the maths required for this ( this year again... lol ) if it's what I think.

[RaH]

Colin I think what is meant is the user enters the initial [x,y] coordinate, then the radius of a circle. Your program must then calculate off the [x,y] coordinate to create a square or cube to encompass the circle.

Correct me if I'm wrong on this one.

[thompsok]

I've got an idea, why don't we all figure out the math on how to calculate the coordinates of a circle if you are given a starting point and the radius of the circle. Then we all figure out how to calculate the largest square that can fit in that circle.

Then we all stop right there satisfied that we could produce the program if some consensus were ever achieved on what the function is going to take for arguments and what the output is going to be. Here is what I would like to see from the OP.

Code: Select all

// function template
void FigureStuffOut(int Radius, int NumberOfPoints)
{
     // figure out what goes here...
     for (int i =1; i <= NumberOfPoints; i++)
          cout << // a set of coordinates;
   
     cout << "the size of the largest square is" << SquareSize << " x " << SquareSize << endl;
}


a little pseudocode with some sample output that doesn't give away the answer. I love the sample output by the way

ignore the programme that displays the points it was designed for another purpose. ignore the red cross as well

So just ignore everything on the screen? I think making a program that produces blank output might be too easy even for a beginner project.

I'm sorry if this sounds pissy, but seriously if you're going to write a beginner task or a programming challenge then you have to write the instructions almost as clearly as if you were writing the program. If you leave things vague, then you end up with a lot of people asking questions...and if they are getting different answers then eventually someone who doesn't have any patience (me) is going to send a flame.

Sorry to flame, but I had to get that off my chest. And if I'm the only person who doesn't understand what the output should be and what should be send into the function, then I'm sorry for being stupid.

[tougo]

enters the initial [x,y] coordinate

the initial coordinates can be just [0,0]

the radius and the number of points are enough to create a circle

I never learned the maths required for this

HINT: if you know the what radians are (iam sure you know) and the pythagorean theorem ...you are half a way in solving it
It can be solved with basic trigonometry...

EDIT (because i don't want to make a new post)

The results can very well be just ascii files or just output on the screen, it doesn't really matter.

I knew in doing something like these screenshot was not easy that why i said that the program could just output a set of coordinates.

having as an output just the 4 coordinates or the length of the edge of the square is too easy (if you sit down and think) even for a 12 year old kid

sorry if I didn't explain things properly. but I think I did

[RecursiveS]

I've just noticed the last two were moved to contests.

Unless anyone objects I'll move this one as well

[tougo]

ignore the programme that displays the points it was designed for another purpose. ignore the red cross as well

Well this program was written by me and it display files with [xy] or [xyz] coordinates as points using directX. when i said ignore it i meant the menu..because as you noticed there are options like RenderMode (actually is just a triangulation) and tools etc.. I just wanted to show you how the circle and the square look like in points (someone asked for a shot)

sample of file of the circle (with rounded values) radius set to 10

Code: Select all

0 20 0
3 20 0
6 19 0
9 18 0
12 16 0
14 14 0
16 12 0
18 9 0
19 6 0
20 3 0
20 0 0
20 -3 0