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Member Since 23 Feb 2001
Offline Last Active Yesterday, 04:11 PM

#5240178 Efficient 2D collision detection with many dynamic OBB

Posted by slayemin on 13 July 2015 - 09:02 PM

It looks like your shapes are all four sided polygons, so there's another technique you can use... Convert each 4 sided polygon into 2 triangles. You can then treat your bullets as points and look to see if any triangle has a point within it.


Here is my code to test for a point within a triangle:

/// <summary>
/// Determine whether a point P is inside the triangle ABC. Note, this function
/// assumes that P is coplanar with the triangle.
/// </summary>
/// <returns>True if the point is inside, false if it is not.</returns>
public static bool PointInTriangle(ref Vector3 A, ref Vector3 B, ref Vector3 C, ref Vector3 P)
	// Prepare our barycentric variables
	Vector3 u = B - A;
	Vector3 v = C - A;
	Vector3 w = P - A;
	Vector3 vCrossW = Vector3.Cross(v, w);
	Vector3 vCrossU = Vector3.Cross(v, u);

	// Test sign of r
	if (Vector3.Dot(vCrossW, vCrossU) < 0)
		return false;

	Vector3 uCrossW = Vector3.Cross(u, w);
	Vector3 uCrossV = Vector3.Cross(u, v);

	// Test sign of t
	if (Vector3.Dot(uCrossW, uCrossV) < 0)
		return false;

	// At this piont, we know that r and t and both > 0
	float denom = uCrossV.Length();
	float r = vCrossW.Length() / denom;
	float t = uCrossW.Length() / denom;

	return (r <= 1 && t <= 1 && r + t <= 1);

You'll have to look at your maximum worst case scenario as well: How many bullets can be on the screen at the same time? How many triangles will you have to test for intersections? If you're going for a O(N*N) solution, you'll start noticing some performance issues with lots of bullets. Measure the total collision routine run time (in microseconds) and see how much of a performance impact you get as you increase bullet counts. If you don't notice any issues, don't optimize :)

If you do notice issues, you can either reduce the number of intersection triangles, reduce the number of bullets, or choose an algorithm which runs better than O(N*N) [Quad Trees, BSP, etc].

#5239821 DigiPen: Computer Science and Game Design vs. Computer Science

Posted by slayemin on 11 July 2015 - 04:58 PM

I try to steer people away from DigiPen. Why?


1) The degree is centered around game development and that's too niche. The average game developer spends about 10 years in the game development industry. If you have a 30 year career, you'll eventually change jobs and get out of the industry. You'll want to have a broader degree and experience base you can fall back on when and if you want to get out of the industry.


2) Game development is fun, but so is non-game development. It's all interesting as fuck, so why deprive yourself of those other amazing, enriching development experiences out there?! I've built enterprise applications which managed billions of dollars in goods and reconstruction projects. It was very awesome and fulfilling and I loved it. I've built distributed computing systems. I've done science with computers. It's amazing.


3) It's more expensive.

4) The market place value is actually lower for a game programming degree than a general CS degree (see #1).

5) Just because you get a degree in game programming doesn't guarantee a job in game programming. If you get a game programming degree, you're already limiting your opportunities for employment.

So: Get a CS degree. Go to community college for the first two years, get those core requirements out of the way, then transfer to a four year university and get that CS degree. Your wallet and career will thank you.

#5239817 What kind of games can I create with my 3 member team that someone may actual...

Posted by slayemin on 11 July 2015 - 04:44 PM

Alright, here are the core things you really need to worry about:

1) How talented and experienced is your team? At a minimum, you should have at least one artist and one programmer and they should have quite a bit of experience.

2) Morale: How much are you paying your team members? If nothing, then you're going to have to find some extremely compelling reasons for people to stay on the project after months pass and the going gets tough. Don't promise equity or sales proceeds; 50% of $0 is zero, so when your team members think that the prospects for their efforts are zero, then you've got a huge problem coming down the project pipeline -- team members are going to abandon ship.


3) Scope: You've got a three man team, a finite amount of time, and a finite amount of resources. Be very realistic about what your team can achieve based on these resources and the teams talent. It's infinitely better to build a small, simple polished game which ships than a large, complicated and unpolished game which is impossible to complete.


4) Team Dynamics and leadership: People are people. They're not always going to get along perfectly and agree 100% on everything. That's good and usually healthy to have a diversity of opinions and insights on a team, but whoever is leading the team has to make sure that the interactions are constructive and not destructive and toxic. You'll want to build a sense of camaraderie among your team mates -- bring beer into the office, hold pizza parties, give recognition where its due, etc.

5) Market Research: You *must* look at what people are buying and where. This is very much like fishing: Where are the fish biting? What are they biting on? What kinds of fish are they? Don't go fishing where there are no fish, don't put lures out there which they have no interest in, and don't attract the kind of fish you don't want to catch. Do you want to build a web game? Do you want to build a mobile game? a PC game? These are all your fishing spots. Different fish lurk in different fishing spots, so be sure to use the right tackle to catch the right fish. The general customer expectation for mobile and web games is "free to play", and you want to make money, so "freemium" is the only viable business model. I suspect that the market is getting tired of these business models and it's getting kind of saturated, so maybe it's worth considering a different fishing spot or a different lure type.


Anyways, enough talk. It's 100% possible to create and ship a game today. It's the age of the indie developer right now. I'm on a 2 person team working on a commercial release for the PC platform. Be realistic about what you have to work with, make a sane business plan to achieve your objectives, and figure out what your strengths, weaknesses, opportunities and threats are (SWOT) and plan accordingly. This is all very much like a chess game -- you only make moves when you have a well thought out plan and each move should play a part in achieving that plan. Don't move with a plan. Strengthen your position to increase your chances of victory. Good luck, and have fun!

#5224031 Is it possible to finish a game on nights and weekends, while working a full-...

Posted by slayemin on 17 April 2015 - 12:35 PM


I just made a game over the weekend.

What about the big project now? I probably need to catch up on your journal...


I'm still working on it :) The weekend game was just a tech demo / MVP to get some quick lessons learned and a feasibility assessment for implementing a virtual reality game with hand gestures -- ie, fail faster. I'll use these notes as design considerations for the main game we're working on. 

#5223802 Is it possible to finish a game on nights and weekends, while working a full-...

Posted by slayemin on 16 April 2015 - 04:22 PM

Yes, it's possible. In fact, I just made a game over the weekend.


How do you do it? You have to be very careful about what you work on and how you do it.


1. Scope is your ENEMY! If you have a weekend to put out a game, your game needs to be super simple. Almost a tech demo / prototype.

2. You're going to have to spend money. I spent $110 to make my weekend game by purchasing assets from a market. It took the creators weeks to make these assets, so if you want to create them yourself... you're not going to finish in a weekend.

3. Build the CORE game play first, then add on to it. Don't invent the core game play in your head and add on to it in your head. Add, test, iterate.

4. You should use Unity or Unreal Engine. It's going to take you several months to get proficient enough to bust out a game in a weekend. DO NOT build your own game engine.


I'm going to spend a day or two more to polish my game, then release it into the wild and see how people like it.

#5222787 Looking for a online college to get my Computer Science degree

Posted by slayemin on 12 April 2015 - 01:07 PM

Call me old school, but I say, don't do online "schooling" if you can avoid it. Why?


-In person lectures are awesome.

-University isn't just about the classroom, it's VERY much about meeting similar people and making new friends. Later, those can turn into job opportunities. This is what makes some MBA schools much better than others, even though they all teach roughly the same material.

-If you have a question during a lecture, you can raise your hand and ask it right away and get immediate clarification and follow along the rest of the lecture without confusion / uncertainty.

-It's great to get out of the house / apartment / basement


I did all of my schooling in person. Not a single online class was taken.


My brother did 100% of his university education online at a school which was 300 miles away. Not a single in-person class was taken.


His university experience was pretty much sitting in a basement for 3-4 years, reading books, taking online multiple choice tests, and going through the bullshit which online teachers put him through ("you have to write a three paragraph response to the reading, then respond to your class mates response! Participation is mandatory.") to give a semblance of "instruction". It was pretty much a guided reading book club for four years.


If you go WAY back and look at how skilled tradesmen were educated, they went through an apprenticeship program. An apprentice blacksmith would learn under a master blacksmith. The master blacksmith would have one on one training with his apprentice, and be able to guide him, spot his mistakes, and correct them quickly. You don't get better training than that. Today, the best equivalent you can get is a mentor. Going to a university in person can provide you with the opportunity to get that oh so valuable one on one mentorship, but it's not guaranteed by simply attending. Teachers / professors are supposed to be these mentors for their students, but much more often than not, they are there to just go through the motions, lecture for a few days a week, and call it a day. They're victims of the university classroom format. But, if you get to know a particular professor, do their office hours, and really try to take advantage of their expertise, they will be excellent mentors. In an online "classroom" setting, this is all but impossible. My thought is that just because something is online and "high tech" doesn't necessarily make it good or better. Usually, you have to (unknowingly) make some pretty big sacrifices for that convenience.


So yeah, don't do online classes if you can avoid it.

#5220591 Starting A Company From Scratch - With no Money, Friends, or Education...

Posted by slayemin on 31 March 2015 - 07:27 PM

Yeah, I agree with everyone else here. You are by no means ready to start making games. There are thousands of people who want to make games but very few who will get the skills necessary to actually make them. It takes LOTS of hard work and dedication to get good at making games. Do you have that? Or is this a passing interest?


If you do have a strong interest in building games, you're going to have to educate yourself to improve your existing skill set. In 2015, there really is no excuse for not being educated anymore. You have access to the internet. You can go watch youtube videos at Khan Academy to teach yourself the basics in mathematics which you've missed out on. Then, you can download and install a free compiler (Visual Studio 2013 Community Edition) and start building an XNA game. There are tutorials for that too. There are thousands of tutorials for beginners. Whatever happens, you HAVE to be someone who contributes meaningful work and adds progress to the game project. If you can't do that, then get there. If you can't ever get there, then forget about it.


You're only 23. You aren't doomed. You have lots of time, but you're going to have to work your ass off like you've never worked before. Making games is a slog and it is nothing like playing games. It's all about building software which happens to be entertaining.

#5219715 Indie Job Titles

Posted by slayemin on 27 March 2015 - 03:40 PM

Titles don't really matter to an indie, do they?


If you have to put yourself in the credits, just say "Developed by: yourname"


If you have to talk about your role in a company, just call yourself a "founder".

#5217239 Review of class rendering code using marmalade c++

Posted by slayemin on 17 March 2015 - 07:19 PM

I agree with Frob.


The code you have posted above is at least missing a curly bracket after the if statement. And you're also mixing rendering with your game model, which is a big architectural mistake. You should never change your model state within your rendering code.


If you're struggling with bounding rects, you need to back up a bunch and just get a simple bounding rect working in isolation. Forget about your game and pong, that's too much complexity for you right now. Before you even write your first line of code, you need to have a conceptual understanding of what you're trying to do. Draw a picture if it helps (I do this all the time with a hand held white board). If you can't get a conceptual understanding of what you're trying to do, then it's futile to write code. 


So, let's start super simple:


What is a boundary?


It's a line, right?


Let us define a simple flat line like Y = 0


What points are above it? Which ones are below it? How can you tell? Can we write code which can return a boolean value for this? If not, then you've got some basics in code and mathematics which need to be reviewed. Let's assume that you can.


Well, let's complicate the problem a bit now. Let's draw two horizontal lines.


Line 1: Y = 0

Line 2: Y = 2


Can we figure out which points lie between lines 1 and 2? It should be pretty straight forward. 


Now, let's complicate the problem slightly more. Can we draw two vertical lines as well?


Line 3: X = 0

Line 4: X = 2


Can we figure out if a point lies between those two lines? Can we figure out if a point lies between all four lines?


If you can, now you've got a bounding box!


Typically with most bounding box implementations, you specify a rectangle by setting the top left coordinate, then specifying a width and height. Then the bounding rectangle may have a method which returns a boolean value on whether or not the rectangle contains a point. The math for this is super simple.


Now, if you want to get crazy, you can also rotate this bounding box. The question is, what do you rotate around? Do you use the top left corner or the center? How do you know if a point is within a rotated bounding box?


Simple: You figure out the rotation of the bounding box, the pivot point of that box, and then you unrotate the bounding box around the pivot point, and you also unrotate the position you're testing against.


Can you do all of this? Where do you get stuck? 


If it helps, forget about rendering anything to the screen and stick to pure mathematical representation until you get it right. Use a C++ console application to test your bounding box code. If you still struggle with this, you're going to have to do some self-teaching. The answers are already out there, you have to find them.


The essence of all programming is breaking a problem down into its smallest parts, solving those, then putting the parts back together to solve a bigger problem.

#5217143 Using octrees for spatial representation

Posted by slayemin on 17 March 2015 - 02:10 PM

I wrote an article on Octrees a while back. It should give you 90% of what you're looking for if you want to learn about octrees.


My recommendation is to avoid the overly complicated "updates in place" I wrote about and instead just wipe the whole tree each frame and rebuild it. It's still faster than O(N^2) search time and way more simple to find and fix problems ;) The important thing is to get it to work first, then optimize later if you still have performance issues which you've determined through measurements. In some cases, the added complexity you think will increase performance will actually decrease it :o


Anyways, let me know if you have any questions.

#5215102 Employee appraisal

Posted by slayemin on 07 March 2015 - 02:38 AM

Based purely off of what I've been reading, I probably wouldn't want to have you work for me either. If after a year you aren't 95% self-sufficient and independent, and working to refine your processes and output quality product, and instead you're asking the rest of the team for help, you're really not a good employee. If I'm paying each employee $60 per hour (just to keep the math simple) and after a year, you still routinely take 15 minutes to get help from someone else, I'm paying for your time and their time, so I'm losing $30 for those 15 minutes. At first, I could justify this as a cost which could be seen as a long term investment in the development of an employee and their skill set. I would expect to see lots of positive growth with a tendency towards self sufficiency and a progression of the technical difficulty of the questions being asked, and a greater independence. If that doesn't happen, and instead I see an employee using fellow coworkers as a crutch in order to avoid the necessary pain it takes to grow, I won't be happy.


I would have no problems IF you said, "Hey, I can't figure out how to do X. I've done all this research and progressed to this point, but Y is really hard to wrap my head around. Have you ever dealt with this before? Do you have an suggestions on where I should aim my efforts?" There are a few important things to realize in this approach. First, you have identified the problem. Second, you have given a really honest attempt at solving the problem yourself, and you have made some progress. Third, you can admit that a portion of it is confusing to you. Fourth, you're not asking someone to tell you what to do, you're asking for guidance.


In my humble opinion, your boss has been really generous to let you stay on the team for a year. Wow. Seriously. That's a lot of money you've costed him in wages. He must really be all about that employee development and giving you a good solid chance to prove yourself. It's a bit shitty that he's only bringing up this issue now rather than nine months ago. You can bet that there have been conversations about you and your performance behind your back with your team mates, and they haven't been favorable. If you want to stay on the job, you need to start pushing yourself towards becoming self-sufficient as a problem solver. When you accomplish great things and contribute to the teams success, don't keep it a secret. Tell people what you did. Talk to people. See how you can help them be better. 


If in fact you ARE a great employee and I'm completely misreading the situation here, and you're doing great work, then you have a big communication and perception problem with your boss and coworkers. This is an area we can all improve in, and it may also cost you your job if you don't make some rapid changes. Again, talk to people. Figure out what's expected of you. Communicate your progress, ask for assessments, try to get better, help your team mates, don't weigh them down with questions which can be googled in 5 minutes. Figure out what the big picture is, what the project vision is, where you fit in, and how you can push it forward and bring success to the team.

#5208267 Terrain sculpting

Posted by slayemin on 02 February 2015 - 02:59 PM

When I built my terrain system, I also used a texture heightmap to determine vertex heights. However, I considered the heightmap values to be an initial starting position for the terrain height values, not the definitive values. After the terrain was loaded, I was free to discard the heightmap textures. If I needed to modify the vertex positions, I would do that within the terrain's internal data values. If I need to save the terrain height, I could easily generate a new height map texture and export it to disk. You could consider this approach if you aren't doing it already.


Also: I think you should try to measure the performance of your code. It would help you a lot if you could isolate exactly where your performance slows down so that you aren't making guesses at your optimization needs. It can be something as simple as starting and stopping a stop watch to count ticks between a code block. Until you do this, we can only guess at what's causing slowdowns.

#5208265 2.5D Dynamic LOD Voxel Renderer

Posted by slayemin on 02 February 2015 - 02:45 PM

I've seen the euclidean thing, And as far as i can tell, It doesnt really support dynamic lighting.

I dont neccessarily need the engine to run in real-time, but closer to something like a beefed up blender "cycles"

As well, a huge part of this is expected to be working on the hardware side, as well as the soft side.

Based on what I can gather from your stated requirements, you'd get the most bang for your buck by just writing HLSL shaders and taking advantage of instancing.

You don't *need* an external USB device and you don't want one either! Problems:
-How fast is the communication link between a USB 3.0 device and the CPU? Very slow (relatively speaking).
-If you use specialized hardware, you put that hardware requirement on your end users. That's going to add a big barrier for entry for people who want to play your game. This brings up a question you need to answer for yourself: is this a hobby project or do you want to release this commercially? If its a hobby project to "learn", then what's the value in learning something you won't be able to use in the industry? If its a hobby project to just have fun and play around, you can do whatever you want.

-A GPU IS a super computer which does things in parallel very well. All you have to do is send it the data you want it to do operations on, send the instructions, and let 'er rip. Rendering millions of voxels with dynamic lighting would be childs play for most modern GPU's. Who needs an external USB device?! Harness the power of that GPU, it's begging you to take advantage of all of its raw processing power.

#5207519 Programming

Posted by slayemin on 29 January 2015 - 02:29 PM

Perhaps I wasn't very clear, seeing L. Spiro 's comment, I'm not the programmer for this game, I simply planned the entire game and have basically everything written down for it, like research towards stuff that will be inside the game, information, what will be in the game, game mechanics that should be implemented, realistic things like pollution and such, how people calculate certain things in real life, resources, biomes, basically everything that a Writer for a game is suppose to do. I just felt, that learning how to program would be cool. I only suggested that I learn programing because I really don't have anyone at the moment to program. I could surely find someone if I really threw myself out there, but I really only have talked to people I've known for a long time because I trust them, I'd rather not rely on someone I don't trust. I just figured if I learned how to program I could help. That is all, that's for your guys responses.


I don't really plan on posting this game for money or for fame, me and my friends really just wanted a game for ourselves to play, seeing how there isn't really a game that grants us everything we desire, so we figured, why not have fun making something of our own to enjoy and for ourselves instead of playing pointless games on the internet that don't offer us everything we want.

Let's put it another way...

You have come up with an ambitious design to build a sky scraper. You've gotten a few people to help you decorate the interior and paint the exterior, but now you need construction workers and steel workers to actually assemble the sky scraper. You say, "Well, I can't find any right now but I think construction sounds cool. Maybe I'll start building this sky scraper myself! Oh by the way, I've never even built a dog house."

Then you say, "Me and my friends aren't really planning to rent the sky scraper out to tenants to make money, we're just doing this for fun." That doesn't negate the fact that its going to take a shit load of work to build the thing in the first place.

L.Spiro's advice is 100% solid. Start super small. Build the dog house before you attempt anything larger. The dog house sized projects may seem trivial, but they're essentially like the game programmers version of "hello world". It shows you have the necessary project management skills, workflow, and dedication to see a super small project through to the end. The risk of failure is minimal and shows you the areas you need to work on before taking on bigger projects. Once you've got a solid grasp of what it takes, you can move on from the dog house to human houses, then from human houses to small office buildings, and eventually to sky scrapers. Building huge projects are not solo projects, they require a team, and teams are all institutions which require a working team infrastructure which gets developed over time and with experience.


Yes, you should shelf your current project. It's not possible with your current resources. Shelving it doesn't mean you throw it away, you can always pick it up later when you DO have the necessary resources to make it happen.


There are also some project management issues which will come up but you may not know about them yet: Cost overruns and schedules being missed (which are hard to foresee). If you can only support a project and its expenses for two years but in practice it takes three years to complete, your project will fail. Even if you aren't paying your staff, the real "cost" I'm talking about is the cost of motivation and morale (money helps increase this, but isn't the only solution to incentivize people to stay motivated for the duration of a project).

#5207508 2.5D Dynamic LOD Voxel Renderer

Posted by slayemin on 29 January 2015 - 02:02 PM

Well, I suppose that if Euclidean can figure out how to do a ridiculous amount of rendering on the computer using trillions of voxels, you shouldn't have too much to worry about. Check out their latest video of their tech.


Conclusion: The performance you will have depends mostly on the algorithms you choose.