• Advertisement
Sign in to follow this  

Unity Critique on an explanation I gave someone

This topic is 4796 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Quote:
Original post by Alpha_ProgDes ok. now acceleration (this explanation may be a little more complicated, unclear). the basics of acceleration and velocity assume that +velocity means moving forward at a certain speed assume that -velocity means moving backward at a certain speed assume that +accel means moving in the direction of the axis (ie. going faster) assume that -accel means moving in the direction opposite of the axis (ie. going slower)** now all of these values do depend on what directions you're going and how you have your coordinates setup. for example:
on a computer screen, the axes are so:
  

(0,0) |
    - | - - - - - - - -> (+x)
      |                
      |
      |
      |
      | 
      |                
      |
     \/ (+y)
as you can see the origin (0,0) starts at the top of the screen. and y increases the further down the graph you go. now i won't put the normal graph you normally see in math class because you need to concentrate on this and realize this only applies to computer screens and graphics. now your character will NOT be at the origin. it most likely will be further down the screen. for now let's say (0,100). so when you jump you going in the opposite direction. therefore you get -velocity. to counteract -velocity you have to have an +accel. an equation of velocity is velocity + acceleration*time. let's tackle the acceleration*time. the target frame rate for your game is 30 frames per second which equates to 33ms a frame. now gravity accelerates at 9.8 m/s^2. which in the game world could easily be 9.8 pixels per frame squared. well unfortunately i'm not going to do all the conversions but get straight to the point: acceleration is 9.8 and time is .33 (remember velocity + acceleration*time). so we have 3.2 (velocity + 3.2) acceleration (ie. gravity) is going in the same direction as the y-axis, which is down. so the velocity will be negative because you're travelling opposite the axis. (assuming velocity = -10; -10 + 3.2) ok so now here's some (pseudo)code:
struct player {
  float y_vel;
  float y_pos;
  int height;
  int width;
} Player;

gravity = 9.8;  //this is a global variable;
Player pl;
pl.y_vel = -10;
pl.y_pos = 100;
pl.height = 32;
pl.width = 16;

if (key_up) {
   float player_bottom = y_pos + pl.height
   do {
      y_pos = y_pos + y_vel;
      y_vel = y_vel + gravity*time; //remember we said time is .33
   } while (player_bottom < floor_coordinate);

   if (player_bottom > floor_coordinate) {
     player_bottom = floor_coordinate;
} 
granted this is not highly optimized code, but it should get the point across. i'll stop here, since i'm sure anyone math-inclined is ready to flame for mathematical fallacies typed above [flaming] ** normally in physics the above do hold some truth, well the way i've written them anyway. here are some other things to think about when dealing with movement and speed. -- -accel and -velocity means an object is moving in the opposite direction and increasing speed -- -accel and +velocity means an object is moving in direction of positive axis and slowing down -- +accel and -velocity means an object is moving in the opposite direction and slowing down -- +accel and +velocity mean an object is moving in the direction of the positive axis and increasing speed i hope i didn't confuse you. good luck on your coding [smile] everyone else may correct, bash, or flame now
Just wanted to get some feedback on it that's all. Here's where the original post came from: http://www.gamedev.net/community/forums/topic.asp?whichpage=2&pagesize=25&topic_id=292754

Share this post


Link to post
Share on other sites
Advertisement
It all depends on how much the person reading it already knows. Without reading much of the details, I know some people may get confused when they see +velocity and think it's a scalar (do they understand what a vector is?). Also y does not always go down the screen. In OpenGL, at least, it increases upwards and is not tied to the the screen.

Share this post


Link to post
Share on other sites
It's pretty hard anyway to teach motion under gravity to a person that doesn't even know what velocity is. It's not something you can explain in a few paragraphs. He'll have to take at least some physics courses or at least read a physics book if he wants to learn about it.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
  • Advertisement
  • Popular Tags

  • Advertisement
  • Popular Now

  • Similar Content

    • By Manuel Berger
      Hello fellow devs!
      Once again I started working on an 2D adventure game and right now I'm doing the character-movement/animation. I'm not a big math guy and I was happy about my solution, but soon I realized that it's flawed.
      My player has 5 walking-animations, mirrored for the left side: up, upright, right, downright, down. With the atan2 function I get the angle between player and destination. To get an index from 0 to 4, I divide PI by 5 and see how many times it goes into the player-destination angle.

      In Pseudo-Code:
      angle = atan2(destination.x - player.x, destination.y - player.y) //swapped y and x to get mirrored angle around the y axis
      index = (int) (angle / (PI / 5));
      PlayAnimation(index); //0 = up, 1 = up_right, 2 = right, 3 = down_right, 4 = down

      Besides the fact that when angle is equal to PI it produces an index of 5, this works like a charm. Or at least I thought so at first. When I tested it, I realized that the up and down animation is playing more often than the others, which is pretty logical, since they have double the angle.

      What I'm trying to achieve is something like this, but with equal angles, so that up and down has the same range as all other directions.

      I can't get my head around it. Any suggestions? Is the whole approach doomed?

      Thank you in advance for any input!
       
    • By devbyskc
      Hi Everyone,
      Like most here, I'm a newbie but have been dabbling with game development for a few years. I am currently working full-time overseas and learning the craft in my spare time. It's been a long but highly rewarding adventure. Much of my time has been spent working through tutorials. In all of them, as well as my own attempts at development, I used the audio files supplied by the tutorial author, or obtained from one of the numerous sites online. I am working solo, and will be for a while, so I don't want to get too wrapped up with any one skill set. Regarding audio, the files I've found and used are good for what I was doing at the time. However I would now like to try my hand at customizing the audio more. My game engine of choice is Unity and it has an audio mixer built in that I have experimented with following their tutorials. I have obtained a great book called Game Audio Development with Unity 5.x that I am working through. Half way through the book it introduces using FMOD to supplement the Unity Audio Mixer. Later in the book, the author introduces Reaper (a very popular DAW) as an external program to compose and mix music to be integrated with Unity. I did some research on DAWs and quickly became overwhelmed. Much of what I found was geared toward professional sound engineers and sound designers. I am in no way trying or even thinking about getting to that level. All I want to be able to do is take a music file, and tweak it some to get the sound I want for my game. I've played with Audacity as well, but it didn't seem to fit the bill. So that is why I am looking at a better quality DAW. Since being solo, I am also under a budget contraint. So of all the DAW software out there, I am considering Reaper or Presonus Studio One due to their pricing. My question is, is investing the time to learn about using a DAW to tweak a sound file worth it? Are there any solo developers currently using a DAW as part of their overall workflow? If so, which one? I've also come across Fabric which is a Unity plug-in that enhances the built-in audio mixer. Would that be a better alternative?
      I know this is long, and maybe I haven't communicated well in trying to be brief. But any advice from the gurus/vets would be greatly appreciated. I've leaned so much and had a lot of fun in the process. BTW, I am also a senior citizen (I cut my programming teeth back using punch cards and Structured Basic when it first came out). If anyone needs more clarification of what I am trying to accomplish please let me know.  Thanks in advance for any assistance/advice.
    • By Yosef BenSadon
      Hi , I was considering this start up http://adshir.com/, for investment and i would like a little bit of feedback on what the developers community think about the technology.
      So far what they have is a demo that runs in real time on a Tablet at over 60FPS, it runs locally on the  integrated GPU of the i7 . They have a 20 000 triangles  dinosaur that looks impressive,  better than anything i saw on a mobile device, with reflections and shadows looking very close to what they would look in the real world. They achieved this thanks to a  new algorithm of a rendering technique called Path tracing/Ray tracing, that  is very demanding and so far it is done mostly for static images.
      From what i checked around there is no real option for real time ray tracing (60 FPS on consumer devices). There was imagination technologies that were supposed to release a chip that supports real time ray tracing, but i did not found they had a product in the market or even if the technology is finished as their last demo  i found was with a PC.  The other one is OTOY with their brigade engine that is still not released and if i understand well is more a cloud solution than in hardware solution .
      Would there  be a sizable  interest in the developers community in having such a product as a plug-in for existing game engines?  How important  is Ray tracing to the  future of high end real time graphics?
    • By bryandalo
      Good day,

      I just wanted to share our casual game that is available for android.

      Description: Fight your way from the ravenous plant monster for survival through flips. The rules are simple, drag and release your phone screen. Improve your skills and show it to your friends with the games quirky ranks. Select an array of characters using the orb you acquire throughout the game.

      Download: https://play.google.com/store/apps/details?id=com.HellmodeGames.FlipEscape&hl=en
       
      Trailer: 
       
    • By khawk
      Watch the latest from Unity.
       
  • Advertisement