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apatriarca

Member Since 03 Jul 2006
Offline Last Active Yesterday, 04:28 PM
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#4884280 My FPS MORPG

Posted by apatriarca on 15 November 2011 - 02:09 PM

Implementing a complete or even incomplete modeler takes a lot of time. I suggest using Blender or other free tools instead.


#4880837 2D Running Character using Vector Graphics

Posted by apatriarca on 05 November 2011 - 12:47 PM

I'm not an expert, but there should be a rotation of the torso and abdomen which should also be visible in 2D. I think that the animation looks weird without it.


#4879022 Ideas for games in Italy

Posted by apatriarca on 31 October 2011 - 03:54 PM

Ciao m3rlino. Where do you live in Italy? There are some game studios in Italy (for example there are Ubisoft and Milestone in Milan), but if you really want to have more job opportunities in the game industry you probably have to move to another country.


#4861733 my concept - the importance of using floating point

Posted by apatriarca on 14 September 2011 - 03:05 PM

After reading Cornstalks reply I have decided to test it and it comes out quite unsurprisingly that the last version of add is two order of magnitude slower than the naive method on my computer (release mode and all optimizations and SSE turned on).


#4842516 Modern RTS style Terrains (Starcraft II, DoW2, Renegade Ops)

Posted by apatriarca on 30 July 2011 - 07:41 AM

I think it's basically what you are doing already plus lighting, models for grass/rocks/trees... , more detailed textures (maybe with some procedural details added).


#4839923 Determine which side of a line a point is

Posted by apatriarca on 25 July 2011 - 04:00 AM

It is the dot product between the vector perpendicular to the direction and the difference between the points. If (x, y) is a vector, (-y, x) is perpendicular to it (it's the vector rotated by 90°). It works because the projection of one vector v along the direction of another vector d is defined to be (dot(d, v)/dot(d, d))d, but since we are only interested if the projection of the difference vector has the same direction of the perpendicular vector we have chosen, it is enough to determine the sign of the dot product between these two vectors.




#4839777 Vector 2D normals

Posted by apatriarca on 24 July 2011 - 05:27 PM

As long as you are consistent you should be ok with either conventions. I think it's more common to use (-y,x) since it represents a “positive” rotation of 90° and { (x,y), (-y,x) } is a positively oriented basis (it has the same orientation of the current basis). It also corresponds to the multiplication by the imaginary unit when using complex numbers.


#4838537 Guessing and finding point coordinates (with screenshot)

Posted by apatriarca on 21 July 2011 - 11:31 AM

You can use   barycentric coordinates like in the following pseudocode:

a = rand(0,1)
b = rand(0,1 - a)
c = 1 - a - b
P = a*P1 + b*P2 + c*P3


EDIT: Corrected a typo




#4828811 Red-Black Trees-> How to determine node colors at all times?

Posted by apatriarca on 28 June 2011 - 01:45 PM

I don't know what book are you following, but Sedgewick have recently given some talks about left-leaning red-black trees (here for example) which I think may be interesting if you are interested in learning about these trees. The left leaning part of his variant is an additional constraints in the colors of the tree which simplifies the code.


#4825093 Dynamic VBO vs VAO

Posted by apatriarca on 19 June 2011 - 09:22 AM

First of all, VAO is probably not what you are thinking about (look here). It's VA (vertex arrays) without the O.

What do you mean by changing the size of the buffer every frame? What you should do is using a fixed size VBO (the maximum size you want to support) and then only use a part of it (sending the data with glBufferSubData). How do you create the VBO? Are you using the correct GL_STREAM_DRAW usage flag?




#4792789 Need some opinions on my tutorial.

Posted by apatriarca on 31 March 2011 - 04:51 PM

I think it needs a little more structure. You should probably separate your tutorial in different sections like Tools, Library dependencies.. and maybe make use of lists to better separate the various steps to do things like building the libraries or installing some tools. Moreover, you should probably includes some images to make the tutorial easier to follow.




#4788313 How much maths needed to understand papers

Posted by apatriarca on 20 March 2011 - 01:02 PM

You will probably also need multi-variate calculus since in graphics and physics you often have to integrate on 2 or 3 dimensional domains (for example on surfaces).


#4781368 Parallel Qsort

Posted by apatriarca on 03 March 2011 - 06:55 AM

I suggest looking at this blog post about sorting algorithms. It discuss the implementation of sorting algorithms on the PS3. It doesn't discuss parallel quicksort, but I think the suggested parallel sorting algorithm (Parallel AA-Sort) described at the end of that post is superior.

EDIT: Some ideas of this algorithm are particularly important on clusters. You probably want to break the data in chunk and then send each part to a computer in the network to sort. Once a part is sorted, you can then merge the various parts trying to minimize network traffic.




#4773722 What concepts i need to know in C++?

Posted by apatriarca on 13 February 2011 - 12:25 PM

I think the easier way to learn about more advanced and specific topics is to use them. Once you relearn the basics of C++, it's probably better to jump directly in making simple games. You will learn by yourself what you will need to create your game.


#4757184 Factoring Multivariable Polynomials

Posted by apatriarca on 11 January 2011 - 04:15 AM

Technically, an expression like


cos4(x) + 2cos2(x)sin2(x) + sin4(x)


is not a polynomial, but a transcendental function. In this particular case, you can simply consider sin2(x) and cos2(x) as indeterminate and then use a polynomial factorization algorithm to simplify it, but it is not always possible or useful to use such an algorithm. Sometimes, it is better to use some trigonometric identity for example. Moreover, the algorithm in that book is designed for polynomials with rational coefficients (actually integer) and you may have expressions with transcendental numbers like pi or with square roots. You have to consider them as "indeterminate" if you want to use that algorithm, but the results may not be particularly good. A factorization algorithm which works on reals or complex numbers may however introduce bad looking factorizations and also contains some approximations of the real roots.

I'm not an expert of this field, but I know there are some ACM journal on mathematical softwares. You may search for papers on expression simplification and polynomial factorization at the ACM portal (http://portal.acm.org/) to find additional material on the subject. To read the paper there you have to pay, but the preprints of several papers are freely available on internet. Note however that some papers may require advanced knowledge of algebra (in particular of field or ring theory).




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