Game Development

Dave

23:00

he uses magic duh

from the tears of dwarfs

hasherr

How difficult is 3D w/ OpenGL?

Icy Defiance

I haven't actually researched how to do multiple point lights yet. I've just been thinking it over myself based on what I know.

Lasse

I'm using deferred and I draw each light on a separate light texture (just one, that is) and apply that on the rendered scene

Icy Defiance

@hasherr getting a triangle on the screen? not bad at all. making a full out game? much worse.

Dave

@hasherr what library ?

Lasse

23:01

let me take a debugging drawing screenshot

hasherr

OpenTK, let's say.

Dave

id say finish your 2D project first xD

Icy Defiance

OpenTK is basically OpenGL plus a math library and a few conveniences.

hasherr

Just wondering.

@IcyDefiance For C# as well, right?

Icy Defiance

well it also has OpenCL and OpenAL, but I haven't touched them yet

right

AttackingHobo

23:02

@hasherr fully wrap your head around more game development ideas and work on making some awesome 2d games before starting on 3d

Lasse

Icy Defiance

mhm

Lasse

the rightmost is the specular light component I believe

Icy Defiance

3D stuff is extremely heavy in vector and matrix maths, especially if you're not using a real high level library.

you have much to learn, padawan

@Lasse ooh okay, I get the general idea. no idea how to go about it, but that I can research on my own.

hasherr

lol

Icy Defiance

23:04

thanks

hasherr

My math teacher at school told me she could tutor me on some more extensive subjects.

If I needed it.

Icy Defiance

nice

as a tutor, I highly recommend taking her up on that. as a normal person, though, meeeeh just be lazy.

Lasse

@IcyDefiance that uses multiple render targets in a render buffer, and geometry gets rendered on it, and then there is the light pass that writes the diffuse and specular components in separate render targets as well, and then the final pass combines them

the light pass uses the generated normal texture and generated depth texture (which is packed in rgb, I did not get the 32bit float approach to work)

the fourth one is just for debugging purposes at the moment, I am planning to put illuminating textures in that one

Icy Defiance

hmm...I get everything you're saying, but something isn't clicking

first one is the texture, right?

second is normals?

Lasse

yes it's just the texture nothing else

yeps

Icy Defiance

23:08

the third...no idea

Lasse

it's the depth map put thru a float -> rgb converter

vec4 pack_depth(const in float depth)
{
    const vec4 bit_shift = vec4(256.0*256.0*256.0, 256.0*256.0, 256.0, 1.0);
    const vec4 bit_mask  = vec4(0.0, 1.0/256.0, 1.0/256.0, 1.0/256.0);
    vec4 res = fract(depth * bit_shift);
    res -= res.xxyz * bit_mask;
    return res;
}

then it's converted back like this:

float unpack_depth(const in vec4 rgba_depth)
{
    const vec4 bit_shift = vec4(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0), 1.0/256.0, 1.0);
    float depth = dot(rgba_depth, bit_shift);
    return depth;
}

I use this because I did not get the 32bit float buffer to work, so I just had to go with rgba buffer

Icy Defiance

okay that one I'll have to work out when I try implementing it. eventually.

hasherr

Does OpenTK have a Vector2 class?

Icy Defiance

@hasherr yep

Lasse

yes it has

hasherr

23:10

Vector3?

Lasse

yep

hasherr

Vector4?

Lasse

it even has vector4

Icy Defiance

yep

hasherr

Vector5?

Icy Defiance

23:10

nope

Lasse

what do you think?

Icy Defiance

I don't think...

hasherr

Dissapointing...

I expected much more.

Lasse

don't you think 4d-space is enough?

hasherr

0/10, failed framework.

@Lasse I don't understand how 4D space can be used in games.

Lasse

23:11

:D

that was a joke

Icy Defiance

actually 4D is a necessity

Lasse

the fourth component of the vec4 is mostly used to determine if the vector is a point in space (w = 1) or a direction (w = 0)

hasherr

Oh, really...

That makes sense actually.

Icy Defiance

and transformations usually rely on the 4th dimension

Lasse

and then it is used to contain the perspective stuff

hasherr

23:12

So would Vector (1, 2, 3, -1) technically be antimatter?

Shotgun Ninja

I've seen 4d games that rely on shifting geometry from one form to another.

hasherr

Dumb question, of course.

Icy Defiance

@hasherr considering how it would blow up whatever it came into contact with...yeah, pretty much

Shotgun Ninja

Antichamber was originally designed for a game jam where the concept was 4D.

hasherr

I always wanted to play Antichamber

Shotgun Ninja

23:13

It's a fun game. I met the guy who made it, Alexander Bruce, at E3.

Back then it was called Hazard: A Journey of Life.

Bit of a mouthful.

hasherr

Interesting guy?

Lasse

if you get a point from screen coordinates converted back to view coordinates you have to reverse the perspective by doing 4dvec = 4dvec / 4dvec.w

Shotgun Ninja

Really cool. Former art student, decided making a game his own way would be better.

hasherr

Cool.

Shotgun Ninja

Taught himself the mathematics behind it, and how to program and build a game with Unreal Engine.

hasherr

23:14

I can't really even comprehend 4D, but then again, I really don't know much about 3D either. I'm still reading that book Vaughan gave me though.

Icy Defiance

@hasherr well in the context of games, the 4th dimension isn't really time

Timtech

@IcyDefiance It's not?

Lasse

well time is just not in the vector

Icy Defiance

you can think of it as just a requirement to make transformations work properly

Lasse

it is otherwise present

Timtech

23:16

Oh ok.

hasherr

For instance, I can't understand this gif.

Lasse

the w component represents just another direction, which you don't actually have to understand as a direction

hasherr

nvm, I'll just upload it.

Timtech

Please give me your feedbac, Windows computers only:
http://timtechsoftware.com/wp-content/uploads/2012/09/Arrethtrae0200.zip

Icy Defiance

for example, a translation matrix looks like so:
1 0 0 x
0 1 0 y
0 0 1 z
0 0 0 1

and it only works when the 4th dimension of the vector you're multiplying with is 1

hasherr

23:17

Lasse

a tesseract

Timtech

Cool

hasherr

Can you guys understand that?

Timtech

Yes

It's 4D

Lasse

sort of yes, I don't see how that is representing the 4d object, since the object can move in many more directions in the 4th dimension

hasherr

23:18

something about that is so off.

Icy Defiance

I can kind of understand it, because one of my profs gave an incredible explanation. I can try repeating it if you want.

it's not actually 4D - just a representation of the mathematical concept of 4D

heck it's not even a representation of a 4D object. that's impossible.

Timtech

It's not even 3D

Lasse

yeah it's 2D

Icy Defiance

well, technically, yeah, but it does represent a 3D object

Timtech

It's impossible to represent something one dimensional as a picture, correct?

Lasse

23:19

it's projected on 2D surface and it looks like 3D because of that

Icy Defiance

@Timtech a line would work

kind of

Timtech

Nope :)

Lasse

and then 4d objects need to be projected on 3d surface, which then again need to be projected on 2d surface, and that is the end result sort of

Timtech

But that's what it's supposed to represent

YEAAAA

Icy Defiance

anyway, as far as 4D goes, think of it this way:

0D is a point, right?

Timtech

23:20

Like points are 0D

Yea

Icy Defiance

to get to 1D, you extend that point into a line

Timtech

Yep

Icy Defiance

to get 2D you extend the line to the side, and get a square

Timtech

:D

Icy Defiance

to get 3D you extend the square to the side and get a cube

Timtech

23:21

xD

Icy Defiance

to get 4D you literally extend the cube to the side and get a tesseract

that's what the gif is supposed to represent

Timtech

:/

I'm unfamiliar with tesseracts?

hasherr

Woah.

Timtech

:P

What?

Icy Defiance

no, you can't imagine it. you can't draw it either. the tesseract just represents the concept.

AttackingHobo

23:21

The tesserect above is a 2d projection of a 3d object which is a shadow of a 4d object rotating

Lasse

►

Timtech

Yep

hasherr

I saw a a video about the 10th dimension. The best way the guy could describe it was that it was a line going through a universe, and all universes extend on that one line.

Lasse

yeah that's the last video of that video series I believe

Icy Defiance

@hasherr no I believe that was the 7th dimension

Lasse

23:23

might be that too yeah

AttackingHobo

@Lasse that video is filled with so much pseudoscience

Shotgun Ninja

7th dimension = possibility clouds.

AttackingHobo

physics.stackexchange.com/questions/391/… antimatter is not going backwards in time

Lasse

@AttackingHobo he's just talking to general people

AttackingHobo

@Lasse much of it is wrong though. Some interesting and good ideas

Icy Defiance

23:24

7th dimension was all variations of a single property of the universes, like different gravitational constants. 8th dimensions was different properties being varied. 9th was all universes condensed into a single point. then he didn't really explain the 10th.

at least that's what I remember

AttackingHobo

And while its impossible to deal with 4 spacial dimentions in a 3d universe, its possible to work with systems that have n Dimensions

Icy Defiance

right. and really the word "dimension" is a far more versatile word than people know.

for example, X and Y coords are 2 dimensions, right?

Timtech

yes

Icy Defiance

but so are angle and radius.

Timtech

Yep

And Z is the 3rd dimension

AttackingHobo

23:26

And its easy to make a 4d array as well

Icy Defiance

angle and radius represent 2D coordinates that, because of how we define angle and radius, when mapped to X and Y take the shape of a circle.

Timtech

That's right

Icy Defiance

and this is what I meant earlier when I said that the 4th dimension in a 4D vector is not time.

it's W, which I believe stands for "whatever" <- joke right there

Timtech

it's duration :)

:P

Icy Defiance

not that either

AttackingHobo

23:28

No

Icy Defiance

W should only be 0 or 1. 0 represents a direction, while 1 is a position...I think. hope I didn't get that mixed up.

Timtech

What is 4d then :S

AttackingHobo

Nope, icy is talking about 4 spacial dimensions, which a tesserect is showing.

Icy Defiance

oh sorry I kind of jumped back a few subjects, before the tesseract

trying to relate it all back to games

AttackingHobo

Math is possible to do on 4d objects, just kind of hard to show whats happening

Timtech

23:30

ok

Lasse

@IcyDefiance btw (this just popped in my mind) if you want not to use deferred, then you need to find out which light hits which object and draw only them, one light at a time and combine the result

Icy Defiance

yeah that sounds way too slow

Lasse

that's how forward rendering works

AttackingHobo

Icy, Yup. Forward rendering gets very slow with lots of lights. Defered doesnt give a shit

Lasse

that includes a whole lot of culling

to make it bearable fps

Icy Defiance

23:34

okay I got an example typed up for why this whole 4D thing is important in 3D graphics

take this matrix:
1 0 0 5
0 1 0 0
0 0 1 0
0 0 0 1

this is a translation matrix, meant to move a vector 5 units along the X axis

now, depending on whether the 4th dimension of the vector is 0 or 1, you get entirely different results

1 0 0 5     0     5
0 1 0 0     0     0
0 0 1 0  *  0  =  0
0 0 0 1     1     1

1 0 0 5     0     0
0 1 0 0     0     0
0 0 1 0  *  0  =  0
0 0 0 1     0     0

if the 4th dimension is 0, it does...absolutely nothing

Dave

ive turned up in a nerd moment

Icy Defiance

if the 4th dimension is 1, it works perfectly

Lasse

@Dave yes

Jon

if you multiply by 0, what do you expect.

Timtech

@Dave Too true :)

Icy Defiance

23:36

well yeah, pretty much

user4704

w = 0 is often used to mean (x, y, z, w) is a vector whereas w = 1 is often used to mean it's a point.

Icy Defiance

not exactly clear without typing it out, though

user4704

But that is a useful aside.

Dave

you might get more detailed info as a question on the SE

user4704

There's a question for this already.

Dave

23:37

oh

Timtech

so if x moves 1 over then its {(0,0,0,0),(1,0,0,1)} right?

user4704

4x4 matrices are used mainly because it allows us to usefully combine translation and rotation into a single matrix.

user4704

(and scale, but nobody cares about scale)

Icy Defiance

@Timtech I'm not sure what you mean

Timtech

So the w is the time it moves

Lasse

23:38

and then there's quaternions

Timtech

and in the second set, the x is += 1

user4704

See: gamedev.stackexchange.com/questions/18470/…

Icy Defiance

@Timtech actually...if you set W to 2, then it moves twice as far, so yeah you're kind of right.

Timtech

Yeah

user4704

See also: en.wikipedia.org/wiki/Homogeneous_coordinates

Timtech

23:39

:D

I might be understanding this now

user4704

What we do 3D graphics transformations is not, per "4D."

user4704

Rather it is a homogenous coordinate system.

Dave

ah you guys do this for fun ! :| lol

2D gives me headache as it is

user4704

You can normalize a homogenous coordinate back by dividing out by w.

Timtech

I didn't know the origin is 0,0,1

Interesting

user4704

23:40

The origin is not 0,0,1.

Timtech

@Dave That's aka a coordinate plane with lines or points graphed on it

Yeah it is

Icy Defiance

yeah Josh, I think you know more about this than I do XD

Timtech

"Note that the triple (0, 0, 0) is omitted and does not represent any point. The origin is represented by (0, 0, 1)"

Homogeneous coordinates

In mathematics, homogeneous coordinates or projective coordinates, introduced by August Ferdinand Möbius in his 1827 work Der barycentrische Calcül, are a system of coordinates used in projective geometry, as Cartesian coordinates are used in Euclidean geometry. They have the advantage that the coordinates of points, including points at infinity, can be represented using finite coordinates. Formulas involving homogeneous coordinates are often simpler and more symmetric than their Cartesian counterparts. Homogeneous coordinates have a range of applications, including computer graphics and ...

Icy Defiance

I haven't actually heard the terms homogeneous or heterogeneous before.

user4704

It is represented by

Timtech

23:41

OOH

:)

user4704

@IcyDefiance I used "heterogeneous" up there when I meant "homogenous."

Timtech

Yeah I noticed

user4704

:D

Dave

@JoshPetrie i thought you meant that because i had to google heterogeneous

user4704

"Homogenous" means "all the same," "heterogeneous" is the opposite.

user4704

23:45

The coordinate system is homogenous because all points with a given W are the same because they can be projected back to regular space by dividing out W.

user4704

Homogenous coordinate systems, in addition to working conveniently with our desire to use 4x4 matrices so we can encode all transformations, make working in clip space much easier.

user4704

In such a space, the normally non-parallel planes of the view frustum are transformed such that they are parallel, and clipping against them becomes massively easier because most of the inequalities simplify out.

Timtech

This is past Trigonometry? :}

Icy Defiance

actually I find trig to be harder XD

Dave

why do people make apps only for iOS

is there something about Android that puts developers off :S

user4704

23:49

@Timtech Yes.

Timtech

Good :P

user4704

This is linear algebra.

Icy Defiance

well, there's a much larger range of android devices to support

Timtech

Is that past calculus?

user4704

@Dave It's ugly and diverse.

Icy Defiance

23:50

different screen sizes, different hardware...

user4704

@Timtech Usually.

user4704

It can be concurrent with about the calculus 3 level.

Dave

@IcyDefiance ah good point

Icy Defiance

also Apple has a better name among the less technologically literate

Timtech

Calculus 3 > AP Calculus?

hasherr

23:51

@IcyDefiance Are you sure? I could've sworn it was the 10th.

Lasse

@IcyDefiance that's just matter of including different resolution resources, or just use vector graphics

user4704

@Timtech AP calculus is a high school prep subject for, like, Calc 1.

Timtech

Ohhh

:S

user4704

I have never seen linear taught in high schools.

Timtech

You're talking college :)

Icy Defiance

23:52

@Lasse true. it just forces people to actually take these measures, instead of statically positioning everything.

AttackingHobo

There is also an ios bubble around big cities with lots of programmers.

Timtech

Gtg, prolly bbl. Cya

Lasse

@IcyDefiance that reminded me of good old 90's internet

Icy Defiance

we don't talk about 90's internet anymore.

N64's were awesome. Internet...not so much.

actually my Wii is softmodded just so I can play N64 games with a GC controller. it's great.

Dave

i miss the dial up modem sound

hasherr

23:55

'Wii'

lol

Icy Defiance

well that and all my games are on an external hard drive so I don't have to keep track of discs.

Lasse

►

Icy Defiance

@hasherr okay, not actually my Wii. it's my brother's. I'm just the only one to use it for more than Wii Sports and Wii Play.

I tried to get him to buy a PS3, but nooo, gotta follow the hype train

Lasse

@hasherr have you ever heard that sound?

that's the sound of our youth

Dave

wii was a hype?

Icy Defiance

23:57

motion controls, man

it's the future!

this was before MS and Sony tried to copy them and steal some of the hype

Dave

arcade games probably had them before nintendo

unless they were made by nintendo :P

Lasse

I've got a wii too

Dave

i know sony are aiming to rival the oculus rift

Icy Defiance

eh, kind of. I don't visit arcades often, but the ones I did see had pretty horrible sensitivity

Dave

which im excited for because Sony do make good TV screens

nor i but i used to go arcades in my youth xD

Lasse

23:58

But I got fed up with it, as it's a console and they get old and you can't upgrade them like PC

hasherr

@Lasse I remember the sound, at least parts of it.

Icy Defiance

@Lasse yeah that's about right

I still take it out once in a while when friends are over, to play super smash bros.

metroid prime trilogy was great too

that's about it

oh, and skyward sword was okay

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