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  • C# struct with an array

    - by Whitey
    I am making a game using C# with the XNA framework. The player is a 2D soldier on screen and the user is able to fire bullets. The bullets are stored in an array. I have looked into using Lists and arrays for this and I came to the conclusion that an array is a lot better for me, as there will be a lot of bullets firing and being destroyed at once, something that I read Lists don't handle so well. After reading through some posts on the XNA forums, this came to my attention: http://forums.xna.com/forums/p/16037/84353.aspx I have created a struct like so: // Bullets struct Bullet { Vector2 Position; Vector2 Velocity; float Rotation; Rectangle BoundingRect; bool Active; } And I made the array like this: Bullet[] bulletCollection = new Bullet[100]; But when I try to do some code like this: // Fire bullet if (mouseState.LeftButton == ButtonState.Pressed) { for (int i = 0; i < bulletCollection.Length; i++) { if (!bulletCollection[i].Active) { // something } } I get the following error: 'Zombie_Apocalypse.Game1.Bullet.Active' is inaccessible due to its protection level Can anyone lend a hand? I have no idea why this error is popping up, or even if I'm declaring the array properly or anything... as the post on the XNA forums doesn't go into detail about that. Thank you for any help you can provide. :)

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  • Class Self-Reference

    - by Free Bullets
    I have the following code. The angle function needs some information from the class it was called from. What's the best way to do this? class MyScannedRobotEvent extends robocode.ScannedRobotEvent { public int angle(robocode.Robot myRobot) { return (int) Math.toRadians((myRobot.getHeading() + getBearing()) % 360); } } public class MyRobot extends robocode.Robot { int a = angle(**WHATDOIPUTHERE?**) }

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  • Java IndexOutOfBoundsException

    - by Meko
    Hi all ... I made an little shoot em up game..It works normal but I want also implement if fires intersects they will disappear. I have two list for Player bullets and for computer bullets ...But if I have more bullets from computer or reverse .Here my loop for (int i = 0; i < cb.size(); i++) { for (int j = 0; j < b.size(); j++) { if (b.get(j).rect.intersects(cb.get(i).rect)) { cb.remove(i); b.remove(j); continue; } if (cb.get(i).rect.intersects(b.get(j).rect)) { b.remove(j); cb.remove(i); continue; } } }

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  • Slide Creation Checklist

    - by Daniel Moth
    PowerPoint is a great tool for conference (large audience) presentations, which is the context for the advice below. The #1 thing to keep in mind when you create slides (at least for conference sessions), is that they are there to help you remember what you were going to say (the flow and key messages) and for the audience to get a visual reminder of the key points. Slides are not there for the audience to read what you are going to say anyway. If they were, what is the point of you being there? Slides are not holders for complete sentences (unless you are quoting) – use Microsoft Word for that purpose either as a physical handout or as a URL link that you share with the audience. When you dry run your presentation, if you find yourself reading the bullets on your slide, you have missed the point. You have a message to deliver that can be done regardless of your slides – remember that. The focus of your audience should be on you, not the screen. Based on that premise, I have created a checklist that I go over before I start a new deck and also once I think my slides are ready. Turn AutoFit OFF. I cannot stress this enough. For each slide, explicitly pick a slide layout. In my presentations, I only use one Title Slide, Section Header per demo slide, and for the rest of my slides one of the three: Title and Content, Title Only, Blank. Most people that are newbies to PowerPoint, get whatever default layout the New Slide creates for them and then start deleting and adding placeholders to that. You can do better than that (and you'll be glad you did if you also follow item #11 below). Every slide must have an image. Remove all punctuation (e.g. periods, commas) other than exclamation points and question marks (! ?). Don't use color or other formatting (e.g. italics, bold) for text on the slide. Check your animations. Avoid animations that hide elements that were on the slide (instead use a new slide and transition). Ensure that animations that bring new elements in, bring them into white space instead of over other existing elements. A good test is to print the slide and see that it still makes sense even without the animation. Print the deck in black and white choosing the "6 slides per page" option. Can I still read each slide without losing any information? If the answer is "no", go back and fix the slides so the answer becomes "yes". Don't have more than 3 bullet levels/indents. In other words: you type some text on the slide, hit 'Enter', hit 'Tab', type some more text and repeat at most one final time that sequence. Ideally your outer bullets have only level of sub-bullets (i.e. one level of indentation beneath them). Don't have more than 3-5 outer bullets per slide. Space them evenly horizontally, e.g. with blank lines in between. Don't wrap. For each bullet on all slides check: does the text for that bullet wrap to a second line? If it does, change the wording so it doesn't. Or create a terser bullet and make the original long text a sub-bullet of that one (thus decreasing the font size, but still being consistent) and have no wrapping. Use the same consistent fonts (i.e. Font Face, Font Size etc) throughout the deck for each level of bullet. In other words, don't deviate form the PowerPoint template you chose (or that was chosen for you). Go on each slide and hit 'Reset'. 'Reset' is a button on the 'Home' tab of the ribbon or you can find the 'Reset Slide' menu when you right click on a slide on the left 'Slides' list. If your slides can survive doing that without you "fixing" things after the Reset action, you are golden! For each slide ask yourself: if I had to replace this slide with a single sentence that conveys the key message, what would that sentence be? This exercise leads you to merge slides (where the key message is split) or split a slide into many, if there were too many key messages on the slide in the first place. It can also lead you to redesign a slide so the text on it really is just explanation or evidence for the key message you are trying to convey. Get the length right. Is the length of this deck suitable for the time you have been given to present? If not, cut content! It is far better to deliver less in a relaxed, polished engaging, memorable way than to deliver in great haste more content. As a rule of thumb, multiply 2 minutes by the number of slides you have, add the time you need for each demo and check if that add to more than the time you have allotted. If it does, start cutting content – we've all been there and it has to be done. As always, rules and guidelines are there to be bent and even broken some times. Start with the above and on a slide-by-slide basis decide which rules you want to bend. That is smarter than throwing all the rules out from the start, right? Comments about this post welcome at the original blog.

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  • My grid based collision detection is slow

    - by Fibericon
    Something about my implementation of a basic 2x4 grid for collision detection is slow - so slow in fact, that it's actually faster to simply check every bullet from every enemy to see if the BoundingSphere intersects with that of my ship. It becomes noticeably slow when I have approximately 1000 bullets on the screen (36 enemies shooting 3 bullets every .5 seconds). By commenting it out bit by bit, I've determined that the code used to add them to the grid is what's slowest. Here's how I add them to the grid: for (int i = 0; i < enemy[x].gun.NumBullets; i++) { if (enemy[x].gun.bulletList[i].isActive) { enemy[x].gun.bulletList[i].Update(timeDelta); int bulletPosition = 0; if (enemy[x].gun.bulletList[i].position.Y < 0) { bulletPosition = (int)Math.Floor((enemy[x].gun.bulletList[i].position.X + 900) / 450); } else { bulletPosition = (int)Math.Floor((enemy[x].gun.bulletList[i].position.X + 900) / 450) + 4; } GridItem bulletItem = new GridItem(); bulletItem.index = i; bulletItem.type = 5; bulletItem.parentIndex = x; if (bulletPosition > -1 && bulletPosition < 8) { if (!grid[bulletPosition].Contains(bulletItem)) { for (int j = 0; j < grid.Length; j++) { grid[j].Remove(bulletItem); } grid[bulletPosition].Add(bulletItem); } } } } And here's how I check if it collides with the ship: if (ship.isActive && !ship.invincible) { BoundingSphere shipSphere = new BoundingSphere( ship.Position, ship.Model.Meshes[0].BoundingSphere.Radius * 9.0f); for (int i = 0; i < grid.Length; i++) { if (grid[i].Contains(shipItem)) { for (int j = 0; j < grid[i].Count; j++) { //Other collision types omitted else if (grid[i][j].type == 5) { if (enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].isActive) { BoundingSphere bulletSphere = new BoundingSphere(enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].position, enemy[grid[i][j].parentIndex].gun.bulletModel.Meshes[0].BoundingSphere.Radius); if (shipSphere.Intersects(bulletSphere)) { ship.health -= enemy[grid[i][j].parentIndex].gun.damage; enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].isActive = false; grid[i].RemoveAt(j); break; //no need to check other bullets } } else { grid[i].RemoveAt(j); } } What am I doing wrong here? I thought a grid implementation would be faster than checking each one.

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  • 3D/perspective Top down shooter bullet issues

    - by Tseng
    I'm developing a top-down shooter with multiple levels (ground for ground units, middle level for buildings, top level for air unity). The problem is the collision. Though I can make the collider box of a bullet be long enough to reach the ground (and collide with it), the real issue is optical. When the bullet is fired from a aircraft and collides with some object on the ground (building, ground unit) it will be optically offset due to the perspective camera, because it looks like the shot "by-passed" the target as seen below Is there any way to make the bullets collide perspectively correct? I'm using Unity3d Engine and it offers only simple colliders (box, sphere, cylinder, mesh and wheel), though I don't think a cone-formed collider would solve this issue. I'd need a (cheap) way to check if it's overlapping a destructible object? I thought of casting a ray from the camera through the bullet and if it hits something destructible, trigger an action, but that's quite punctual and maybe to performance heavy on certain number of bullets

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  • How to fire a bullet in a specific direction?

    - by Mike
    I am developing an Android game. I have problem with bullet firing. It's a space ship that has to fire bullets but right now it's firing in a random direction. I have to fire a bullet to the enemy from the only one point on the nose of the ship. Right now the bullets fire sometimes from the tailpart or other. So that's a problem. How do I give a bullet direction and how to fire it from only the head of my space ship?

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  • Determining the angle to fire a shot when target and shooter moves, and bullet moves with shooter velocity added in

    - by Azaral
    I saw this question: Predicting enemy position in order to have an object lead its target and followed the link in the answer to stack overflow. In the stack overflow page I used the 2nd answer, the one that is a large mathematical derivation. My situation is a little different though. My first question though is will the answer provided in the stack overflow page even work to begin with, assuming the original circumstances of moving target and stationary shooter. My situation is a little different than that situation. My target moves, the shooter moves, and the bullets from the shooter start off with the velocities in x and y added to the bullets' x and y velocities. If you are sliding to the right, the bullets will remain in front of you as you move so as long as your velocity remains constant. What I'm trying to do is to get the enemy to be able to determine where they need to shoot in order to hit the player. Unless the player and enemy is stationary, the velocity from the ship adding to the velocity of the bullets will cause a miss. I'd rather like to prevent that. I used the formula in the stack overflow answer and did what I thought were the appropriate adjustments. I've been banging at this for the last four hours and I just can't make it click. It is probably something really simple and boneheaded that I am missing (that seems to be a lot of my problems lately). Here is the solution presented from the stack overflow answer: It boils down to solving a quadratic equation of the form: a * sqr(x) + b * x + c == 0 Note that by sqr I mean square, as opposed to square root. Use the following values: a := sqr(target.velocityX) + sqr(target.velocityY) - sqr(projectile_speed) b := 2 * (target.velocityX * (target.startX - cannon.X) + target.velocityY * (target.startY - cannon.Y)) c := sqr(target.startX - cannon.X) + sqr(target.startY - cannon.Y) Now we can look at the discriminant to determine if we have a possible solution. disc := sqr(b) - 4 * a * c If the discriminant is less than 0, forget about hitting your target -- your projectile can never get there in time. Otherwise, look at two candidate solutions: t1 := (-b + sqrt(disc)) / (2 * a) t2 := (-b - sqrt(disc)) / (2 * a) Note that if disc == 0 then t1 and t2 are equal. If there are no other considerations such as intervening obstacles, simply choose the smaller positive value. (Negative t values would require firing backward in time to use!) Substitute the chosen t value back into the target's position equations to get the coordinates of the leading point you should be aiming at: aim.X := t * target.velocityX + target.startX aim.Y := t * target.velocityY + target.startY Here is my code, after being corrected by Sam Hocevar (thank you again for your help!). It still doesn't work. For some reason it never enters the section of code inside the if(disc = 0) (obviously because it is always less than zero but...). However, if I plug the numbers from my game log on the enemy and player positions and velocities it outputs a valid firing solution. I have looked at the code side by side a couple of times now and I can't find any differences. There has got to be something simple I'm missing here. If someone else could look at this code and determine what is going on here I'd appreciate it. I know it's not going through that section because if it were, shouldShoot would become true and the enemy would be blasting away at the player. This section calls the function in question, CalculateShootHeading() if(shouldMove) { UseEngines(); } x += xVelocity; y += yVelocity; CalculateShootHeading(); if(shouldShoot) { ShootWeapons(); } UpdateWeapons(); This is CalculateShootHeading(). This is inside the enemy class so x and y are the enemy's x and y and the same with velocity. One output from my game log gives Player X = 2108, Player Y = -180.956, Player X velocity = 10.9949, Player Y Velocity = -6.26017, Enemy X = 1988.31, Enemy Y = -339.051, Enemy X velocity = 1.81666, Enemy Y velocity = -9.67762, 0 enemy projectiles. The output from the console tester is Bullet position = 2210.49, -239.313 and Player Position = 2210.49, -239.313. This doesn't make any sense. The only thing that could be different is the code or the input into my function in the game and I've checked that and I don't think that it is wrong as it's updated before this and never changed. float const bulletSpeed = 30.f; float const dx = playerX - x; float const dy = playerY - y; float const vx = playerXVelocity - xVelocity; float const vy = playerYVelocity - yVelocity; float const a = vx * vx + vy * vy - bulletSpeed * bulletSpeed; float const b = 2.f * (vx * dx + vy * dy); float const c = dx * dx + dy * dy; float const disc = b * b - 4.f * a * c; shouldShoot = false; if (disc >= 0.f) { float t0 = (-b - std::sqrt(disc)) / (2.f * a); float t1 = (-b + std::sqrt(disc)) / (2.f * a); if (t0 < 0.f || (t1 < t0 && t1 >= 0.f)) { t0 = t1; } if (t0 >= 0.f) { float shootx = vx + dx / t0; float shooty = vy + dy / t0; heading = std::atan2(shooty, shootx) * RAD2DEGREE; } shouldShoot = true; }

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  • XNA - positioning after rotation

    - by DijkeMark
    I have a turret with a 2 gunbarrels. The turret rotates towards my mouse. So far no problem. When it creates a few bullets and positions them at the end of the gun barrels. Here is the problem. It only works the moment the gun is point upwards. The moment it rotates the end of the gun barrels have moved ofcourse, thus the bullets don't spawn at the end of the gun battels, but at the place the where the gun barrels are when the turret is pointing upwards. How can I check where the end of the gun barrels are the moment it rotates? Thanks in Advance, Mark Dijkema PS. If you need code please let me know, I didn't post any yet, because I didn't what code you would need.

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  • Java collision detection and player movement: tips

    - by Loris
    I have read a short guide for game develompent (java, without external libraries). I'm facing with collision detection and player (and bullets) movements. Now i put the code. Most of it is taken from the guide (should i link this guide?). I'm just trying to expand and complete it. This is the class that take care of updates movements and firing mechanism (and collision detection): public class ArenaController { private Arena arena; /** selected cell for movement */ private float targetX, targetY; /** true if droid is moving */ private boolean moving = false; /** true if droid is shooting to enemy */ private boolean shooting = false; private DroidController droidController; public ArenaController(Arena arena) { this.arena = arena; this.droidController = new DroidController(arena); } public void update(float delta) { Droid droid = arena.getDroid(); //droid movements if (moving) { droidController.moveDroid(delta, targetX, targetY); //check if arrived if (droid.getX() == targetX && droid.getY() == targetY) moving = false; } //firing mechanism if(shooting) { //stop shot if there aren't bullets if(arena.getBullets().isEmpty()) { shooting = false; } for(int i = 0; i < arena.getBullets().size(); i++) { //current bullet Bullet bullet = arena.getBullets().get(i); System.out.println(bullet.getBounds()); //angle calculation double angle = Math.atan2(bullet.getEnemyY() - bullet.getY(), bullet.getEnemyX() - bullet.getX()); //increments x and y bullet.setX((float) (bullet.getX() + (Math.cos(angle) * bullet.getSpeed() * delta))); bullet.setY((float) (bullet.getY() + (Math.sin(angle) * bullet.getSpeed() * delta))); //collision with obstacles for(int j = 0; j < arena.getObstacles().size(); j++) { Obstacle obs = arena.getObstacles().get(j); if(bullet.getBounds().intersects(obs.getBounds())) { System.out.println("Collision detect!"); arena.removeBullet(bullet); } } //collisions with enemies for(int j = 0; j < arena.getEnemies().size(); j++) { Enemy ene = arena.getEnemies().get(j); if(bullet.getBounds().intersects(ene.getBounds())) { System.out.println("Collision detect!"); arena.removeBullet(bullet); } } } } } public boolean onClick(int x, int y) { //click on empty cell if(arena.getGrid()[(int)(y / Arena.TILE)][(int)(x / Arena.TILE)] == null) { //coordinates targetX = x / Arena.TILE; targetY = y / Arena.TILE; //enables movement moving = true; return true; } //click on enemy: fire if(arena.getGrid()[(int)(y / Arena.TILE)][(int)(x / Arena.TILE)] instanceof Enemy) { //coordinates float enemyX = x / Arena.TILE; float enemyY = y / Arena.TILE; //new bullet Bullet bullet = new Bullet(); //start coordinates bullet.setX(arena.getDroid().getX()); bullet.setY(arena.getDroid().getY()); //end coordinates (enemie) bullet.setEnemyX(enemyX); bullet.setEnemyY(enemyY); //adds bullet to arena arena.addBullet(bullet); //enables shooting shooting = true; return true; } return false; } As you can see for collision detection i'm trying to use Rectangle object. Droid example: import java.awt.geom.Rectangle2D; public class Droid { private float x; private float y; private float speed = 20f; private float rotation = 0f; private float damage = 2f; public static final int DIAMETER = 32; private Rectangle2D rectangle; public Droid() { rectangle = new Rectangle2D.Float(x, y, DIAMETER, DIAMETER); } public float getX() { return x; } public void setX(float x) { this.x = x; //rectangle update rectangle.setRect(x, y, DIAMETER, DIAMETER); } public float getY() { return y; } public void setY(float y) { this.y = y; //rectangle update rectangle.setRect(x, y, DIAMETER, DIAMETER); } public float getSpeed() { return speed; } public void setSpeed(float speed) { this.speed = speed; } public float getRotation() { return rotation; } public void setRotation(float rotation) { this.rotation = rotation; } public float getDamage() { return damage; } public void setDamage(float damage) { this.damage = damage; } public Rectangle2D getRectangle() { return rectangle; } } For now, if i start the application and i try to shot to an enemy, is immediately detected a collision and the bullet is removed! Can you help me with this? If the bullet hit an enemy or an obstacle in his way, it must disappear. Ps: i know that the movements of the bullets should be managed in another class. This code is temporary. update I realized what happens, but not why. With those for loops (which checks collisions) the movements of the bullets are instantaneous instead of gradual. In addition to this, if i add the collision detection to the Droid, the method intersects returns true ALWAYS while the droid is moving! public void moveDroid(float delta, float x, float y) { Droid droid = arena.getDroid(); int bearing = 1; if (droid.getX() > x) { bearing = -1; } if (droid.getX() != x) { droid.setX(droid.getX() + bearing * droid.getSpeed() * delta); //obstacles collision detection for(Obstacle obs : arena.getObstacles()) { if(obs.getRectangle().intersects(droid.getRectangle())) { System.out.println("Collision detected"); //ALWAYS HERE } } //controlla se è arrivato if ((droid.getX() < x && bearing == -1) || (droid.getX() > x && bearing == 1)) droid.setX(x); } bearing = 1; if (droid.getY() > y) { bearing = -1; } if (droid.getY() != y) { droid.setY(droid.getY() + bearing * droid.getSpeed() * delta); if ((droid.getY() < y && bearing == -1) || (droid.getY() > y && bearing == 1)) droid.setY(y); } }

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  • Toggling list image and expand all jquery accordion w/ unordered lists

    - by Evan
    I have a functioning jquery accordion using pure unordered lists. I'm trying to incorporate 2 pieces of functionality. Here is my functioning accordion code and a demo of it working. http://jsbin.com/itibi4/ Toggling Arrows. i'm tring to get the parent bullets to be a toggling arrow and point down when clicked while the child bullets stay as bullets instead of an arrow. Would I be able to get some help with this? .inactive { background-image:url("http://img547.imageshack.us/img547/4103/arrowp.gif"); background-position:4px -31px; background-repeat:no-repeat; cursor:pointer; padding-left:20px; padding-top:10px; } .active { background-image: url("http://img547.imageshack.us/img547/4103/arrowp.gif"); background-position: 4px 12px; background-repeat:no-repeat; font-weight:bold; } Expand All / Collapse All also, i'm trying to incorporate an expand all / collapse all functionality. this is code to the same demo the code is from a previous project, which i've added below the unordered list menu, but i'm having difficulty incorporating it into this project. Would I be able to get some help with this? $('.swap').click(function() { if($(this).text() == 'Click to Collapse All FAQs') { $('ul.menu').slideUp('normal'); $('ul.menu li a').removeClass('active'); $(this).text($(this).text() == 'Click to Expand All FAQs' ? 'Click to Collapse All FAQs' : 'Click to Expand All FAQs'); } else { $('ul.menu').slideDown('normal'); $('ul.menu li a').addClass('active'); $(this).text($(this).text() == 'Click to Expand All FAQs' ? 'Click to Collapse All FAQs' : 'Click to Expand All FAQs'); } } Thank you so much for your help! Evan

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  • Weird symbols on Mac

    - by Rich Bradshaw
    Since I've had my mac, I keep seeing this weird symbol. Till today, it had been only in the place of bullet points in OpenOffice.org. The first pictures shows this in a .doc file created on a Windows system. I thought nothing of it - just an annoyance. It appears no matter what the font. Real bullets appear if I delete the text and insert a bulletted list using the toolbar. Then, today I noticed in in iTunes - which seemed strange. Image 3 is a zoom of the character. It says on it: Private Use E000 F8FF. What is it (unicode related?), and how do I get the bullets working properly? Edit: The plot thickens... If I boot in Safe Mode, the symbols look like little snap boards like you'd have at the beginning of filming a scene in a film...

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  • Bullet pattern isn't behaving as expected

    - by Fibericon
    I have a boss that's supposed to continuously shoot five streams of bullets, each at a different angle. It starts off just fine, but doesn't seem to want to use its entire array of bullets. No matter how large I set the length of bulletList, the boss simply stops shooting after a couple of seconds, then pick up again shortly. Here's what I'm using to generate the pattern: Vector3 direction = new Vector3(0.5f, -1, 0); for (int r = 0; r < boss.gun.bulletList.Length; r++) { if (!boss.gun.bulletList[r].isActive) { boss.gun.bulletList[r].direction = direction; boss.gun.bulletList[r].speed = boss.gun.BulletSpeedAdjustment; boss.gun.bulletList[r].position = boss.position; boss.gun.bulletList[r].isActive = true; break; } } direction = new Vector3(-0.5f, -1, 0); //Repeat with four similar for loops, to place a bullet in each direction It doesn't seem to matter if the bulletList length is 1000 or 100000. What could be the issue here?

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  • Cocos2d v2.0 and OpenGL 2.0/1.0: where to start

    - by mm24
    I started developing my very first game 3 months ago using Cocos2d 2.0 for iPhone. I am now in the stage where I'd like to add some cool effects to the bullets and some special weapons (see my waveforms question here). I got a good answer in the cocos2d-iphone forum (see this one). Unfortunately I am a bit paralized now. I don't know if I will be overdoing by learning OpengGL 2.0 or if I should just stick ot the old 1.0. There is a good intro on various tutorial's written in Steffen Itterheims blog (see this post). I would like to add to my game: a blur effect to the bullets (here is a tutorial for OpenGL 1.0) a waveform (see above) some realistic water ripples (here is a nice sample code) So now, given that I don't want to overdo things but at the same time I want to achieve those effects, from where should I start? Should I discard the OpenGL 1.0 tutorials? OR should I use only OpenGL 1.0 code? How can I avoid confusion? I mean, it seems that the compiler recognizes both, but that there are some conflictual calls in some circumnstances, I am fairly sure this has some explanation, is there some reference to this somewhere?

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  • Trouble with speed and vectors

    - by Eegabooga
    I'm working on adding bullets to my game. Right now I can shoot bullets in the direction that I would like from a ship by getting the ship's angle: int speed = 5; int dx = -(cos(degreesToRadians(ship.angle)) * speed); // rate of change in the x direction int dy = -(sin(degreesToRadians(ship.angle)) * speed); // rate of change in the y direction bulletPosition.addX(dx); // addX(dx) is simply bulletPosition.x += dx bulletPosition.addY(dy); The ship is pretty much the exact same thing, except I use the += operator: int dx += -(cos(degreesToRadians(angle)) * 0.15) int dy += -(sin(degreesToRadians(angle)) * 0.15); shipPosition.addX(dx); shipPosition.addY(dy); I would like to be able to add the ship's velocity to the bullet's velocity, but I'm a little confused as to how should get the speed from the ship's vector. I thought that adding the ship's dx to the bullet's dx like int dx = -(cos(degreesToRadians(ship.angle)) * speed * dx) would work because I'm adding the rate of change of the ship to the rate of change of the bullet, but that doesn't work. So here's the final question: How can I get the speed of my ship and apply it to my bullet's speed? Thanks in advance for all help :)

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  • Moving sprite from one vector to the other

    - by user2002495
    I'm developing a game where enemy can shoot bullets towards the player. I'm using 2 vector that is normalized later to determine where the bullets will go. Here is the code where enemy shoots: private void UpdateCommonBullet(GameTime gt) { foreach (CommonEnemyBullet ceb in bulletList) { ceb.pos += ceb.direction * 1.5f * (float)gt.ElapsedGameTime.TotalSeconds; if (ceb.pos.Y >= 600) ceb.hasFired = false; } for (int i = 0; i < bulletList.Count; i++) { if (!bulletList[i].hasFired) { bulletList.RemoveAt(i); i--; } } } And here is where i get the direction (in the constructor of the bullet): direction = Global.currentPos - this.pos; direction.Normalize(); Global.currentPos is a Vector2 where currently player is located, and is updated eveytime the player moves. This all works fine except that the bullet won't go to player's location. Instead, it tends goes to the "far right" of the player's position. I think it might be the problem where the bullet (this.pos in the direction) is created (at the position of the enemy). But I found no solution of it, please help me.

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  • Changing the colour of \textbullet in LaTeX Beamer

    - by Seamus
    I don't want to use Beamer's standard blue colour theme. I want to use beaver, which is deep reds. Everything looks nice, except that if I use itemize the bullet points are still blue. Is there a nice way to have the bullets vary with what colour theme I was using? (If I were to opt for a yellowish colour theme, I'd expect the bullets to go yellow too.) If there isn't, what is the brute force way to change the bullet points red? Or at the very least, make them go back to black again.

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  • Collision detection between layers in Cocos2d?

    - by ipodfreak0313
    I am making a game in Cocos2d. I have enemies that shoot, and have the character shoot. I created a separate layer for the enemies (and their bullets) and a separate layer for the character (and its bullets). The problem is, I don't know how to detect collisions between the two layers. Note, I have the Scene in HelloWorldLayer, and each of the above layers is a child of the scene. Any help is appreciated. Thanks!

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  • Why does creating dynamic bodies in JBox2D freeze my app?

    - by Amplify91
    My game hangs/freezes when I create dynamic bullet objects with Box2D and I don't know why. I am making a game where the main character can shoot bullets by the user tapping on the screen. Each touch event spawns a new FireProjectileEvent that is handled properly by an event queue. So I know my problem is not trying to create a new body while the box2d world is locked. My bullets are then created and managed by an object pool class like this: public Projectile getProjectile(){ for(int i=0;i<mProjectiles.size();i++){ if(!mProjectiles.get(i).isActive){ return mProjectiles.get(i); } } return mSpriteFactory.createProjectile(); } mSpriteFactory.createProjectile() leads to the physics component of the Projectile class creating its box2d body. I have narrowed the issue down to this method and it looks like this: public void create(World world, float x, float y, Vec2 vertices[], boolean dynamic){ BodyDef bodyDef = new BodyDef(); if(dynamic){ bodyDef.type = BodyType.DYNAMIC; }else{ bodyDef.type = BodyType.STATIC; } bodyDef.position.set(x, y); mBody = world.createBody(bodyDef); PolygonShape dynamicBox = new PolygonShape(); dynamicBox.set(vertices, vertices.length); FixtureDef fixtureDef = new FixtureDef(); fixtureDef.shape = dynamicBox; fixtureDef.density = 1.0f; fixtureDef.friction = 0.0f; mBody.createFixture(fixtureDef); mBody.setFixedRotation(true); } If the dynamic parameter is set to true my game freezes before crashing, but if it is false, it will create a projectile exactly how I want it just doesn't function properly (because a projectile is not a static object). Why does my program fail when I try to create a dynamic object at runtime but not when I create a static one? I have other dynamic objects (like my main character) that work fine. Any help would be greatly appreciated. This is a screenshot of a method profile I did: Especially notable is number 8. I'm just still unsure what I'm doing wrong. Other notes: I am using JBox2D 2.1.2.2. (Upgraded from 2.1.2.1 to try to fix this problem) When the application freezes, if I hit the back button, it appears to move my game backwards by one update tick. Very strange.

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  • How do I deal with the problems of a fast side-scroller?

    - by Ska
    I'm making a side scrolling airplane game and when I begin going very fast I begin to experience some problems as a player: Elements are not distinguishable, like power-ups from bullets, etc I start to feel dizzy and uncomfortable There isn't enough time to see what's coming How can I sort this out? Do I use less details in all the grahpics? Tiny Wings has the same horizontal movement speed as in my game but it doesn't suffer from these problems. Are there any other really fast side-scrollers I could take as a reference?

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  • How to synchronize the ball in a network pong game?

    - by Thaars
    I’m developing a multiplayer network pong game, my first game ever. The current state is, I’ve running the physic engine with the same configurations on the server and the clients. The own paddle movement is predicted and get just confirmed by the authoritative server. Is a difference detected between them, I correct the position at the client by interpolation. The opponent paddle is also interpolated 200ms to 100ms in the past, because the server is broadcasting snapshots every 100ms to each client. So far it works very well, but now I have to simulate the ball and have a problem to understanding the procedure. I’ve read Valve’s (and many other) articles about fast-paced multiplayer several times and understood their approach. Maybe I can compare my ball with their bullets, but their advantage is, the bullets are not visible. When I have to display the ball, and see my paddle in the present, the opponent in the past and the server is somewhere between it, how can I synchronize the ball over all instances and ensure, that it got ever hit by the paddle even if the paddle is fast moving? Currently my ball’s position is simply set by a server update, so it can happen, that the ball bounces back, even if the paddle is some pixel away (because of a delayed server position). Until now I’ve got no synced clock over all instances. I’m sending a client step index with each update to the server. If the server did his job, he sends the snapshot with the last step index of each client back to the clients. Now I’m looking for the stored position at the returned step index and compare them. Do I need a common clock to sync the ball? EDIT: I've tried to sync a common clock for the server and all clients with a timestamp. But I think it's better to use an own stepping instead of a timestamp (so I don't need to calculate with the ping and so on - and the timestamp will never be exact). The physics are running 60 times per second and now I use this for keeping them synchronized. Is that a good way? When the ball gets calculated by each client, the angle after bouncing can differ because of the different position of the paddles (the opponent is 200ms in the past). When the server is sending his ball position, velocity and angle (because he knows the position of each paddle and is authoritative), the ball could be in a very different position because of the different angles after bouncing (because the clients receive the server data after 100ms). How is it possible to interpolate such a huge difference? I posted this question some days ago at stackoverflow, but got no answer yet. Maybe this is the better place for this question.

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  • Virtual SMTP not sending mails

    - by DoStuffZ
    Hi I have been googling for the better part of the last two hours without finding any conclusion. My mails are not being sent from the production webserver. If I stop/start the Virtual SMTP I get this in the event log: No usable TLS server certificate for SMTP virtual server instance '1' could be found. TLS will be disabled for this virtual-server. We recently updated the webapplication running and I assume something went amiss during that. Googling the message straight up gave me a list that just as well could have been in greek. I found a security certificate on the server, installing that gave no change. I basicly played russian roulette with the certificate file (.cer), though I was somewhat certain it would not have a negative effect. (Russian roulette with a 6 chamber gun and 2 bullets.) I found a .pfx in our local documentation folder, though I'm far from certain that to have a positive effect. (6 chambers and 5 bullets). I found a site describing how the Virtual SMTP - Properties - Access - should have a button saying Certificates. I have a text saying "Did not find any TLS certificates" and a grayed out tick box saying "Require TLS certificate". I found the TLS being SSL ver3.1+ (3.1-3.3). So question goes - How do I enable the SMTP to once again send emails, like before.

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  • Need help with implementing collision detection using the Separating Axis Theorem

    - by Eddie Ringle
    So, after hours of Googling and reading, I've found that the basic process of detecting a collision using SAT is: for each edge of poly A project A and B onto the normal for this edge if intervals do not overlap, return false end for for each edge of poly B project A and B onto the normal for this edge if intervals do not overlap, return false end for However, as many ways as I try to implement this in code, I just cannot get it to detect the collision. My current code is as follows: for (unsigned int i = 0; i < asteroids.size(); i++) { if (asteroids.valid(i)) { asteroids[i]->Update(); // Player-Asteroid collision detection bool collision = true; SDL_Rect asteroidBox = asteroids[i]->boundingBox; // Bullet-Asteroid collision detection for (unsigned int j = 0; j < player.bullets.size(); j++) { if (player.bullets.valid(j)) { Bullet b = player.bullets[j]; collision = true; if (b.x + (b.w / 2.0f) < asteroidBox.x - (asteroidBox.w / 2.0f)) collision = false; if (b.x - (b.w / 2.0f) > asteroidBox.x + (asteroidBox.w / 2.0f)) collision = false; if (b.y - (b.h / 2.0f) > asteroidBox.y + (asteroidBox.h / 2.0f)) collision = false; if (b.y + (b.h / 2.0f) < asteroidBox.y - (asteroidBox.h / 2.0f)) collision = false; if (collision) { bool realCollision = false; float min1, max1, min2, max2; // Create a list of vertices for the bullet CrissCross::Data::LList<Vector2D *> bullVerts; bullVerts.insert(new Vector2D(b.x - b.w / 2.0f, b.y + b.h / 2.0f)); bullVerts.insert(new Vector2D(b.x - b.w / 2.0f, b.y - b.h / 2.0f)); bullVerts.insert(new Vector2D(b.x + b.w / 2.0f, b.y - b.h / 2.0f)); bullVerts.insert(new Vector2D(b.x + b.w / 2.0f, b.y + b.h / 2.0f)); // Create a list of vectors of the edges of the bullet and the asteroid CrissCross::Data::LList<Vector2D *> bullEdges; CrissCross::Data::LList<Vector2D *> asteroidEdges; for (int k = 0; k < 4; k++) { int n = (k == 3) ? 0 : k + 1; bullEdges.insert(new Vector2D(bullVerts[k]->x - bullVerts[n]->x, bullVerts[k]->y - bullVerts[n]->y)); asteroidEdges.insert(new Vector2D(asteroids[i]->vertices[k]->x - asteroids[i]->vertices[n]->x, asteroids[i]->vertices[k]->y - asteroids[i]->vertices[n]->y)); } for (unsigned int k = 0; k < asteroidEdges.size(); k++) { Vector2D *axis = asteroidEdges[k]->getPerpendicular(); min1 = max1 = axis->dotProduct(asteroids[i]->vertices[0]); for (unsigned int l = 1; l < asteroids[i]->vertices.size(); l++) { float test = axis->dotProduct(asteroids[i]->vertices[l]); min1 = (test < min1) ? test : min1; max1 = (test > max1) ? test : max1; } min2 = max2 = axis->dotProduct(bullVerts[0]); for (unsigned int l = 1; l < bullVerts.size(); l++) { float test = axis->dotProduct(bullVerts[l]); min2 = (test < min2) ? test : min2; max2 = (test > max2) ? test : max2; } delete axis; axis = NULL; if ( (min1 - max2) > 0 || (min2 - max1) > 0 ) { realCollision = false; break; } else { realCollision = true; } } if (realCollision == false) { for (unsigned int k = 0; k < bullEdges.size(); k++) { Vector2D *axis = bullEdges[k]->getPerpendicular(); min1 = max1 = axis->dotProduct(asteroids[i]->vertices[0]); for (unsigned int l = 1; l < asteroids[i]->vertices.size(); l++) { float test = axis->dotProduct(asteroids[i]->vertices[l]); min1 = (test < min1) ? test : min1; max1 = (test > max1) ? test : max1; } min2 = max2 = axis->dotProduct(bullVerts[0]); for (unsigned int l = 1; l < bullVerts.size(); l++) { float test = axis->dotProduct(bullVerts[l]); min2 = (test < min2) ? test : min2; max2 = (test > max2) ? test : max2; } delete axis; axis = NULL; if ( (min1 - max2) > 0 || (min2 - max1) > 0 ) { realCollision = false; break; } else { realCollision = true; } } } if (realCollision) { player.bullets.remove(j); int numAsteroids; float newDegree; srand ( j + asteroidBox.x ); if ( asteroids[i]->degree == 90.0f ) { if ( rand() % 2 == 1 ) { numAsteroids = 3; newDegree = 30.0f; } else { numAsteroids = 2; newDegree = 45.0f; } for ( int k = 0; k < numAsteroids; k++) asteroids.insert(new Asteroid(asteroidBox.x + (10 * k), asteroidBox.y + (10 * k), newDegree)); } delete asteroids[i]; asteroids.remove(i); } while (bullVerts.size()) { delete bullVerts[0]; bullVerts.remove(0); } while (bullEdges.size()) { delete bullEdges[0]; bullEdges.remove(0); } while (asteroidEdges.size()) { delete asteroidEdges[0]; asteroidEdges.remove(0); } } } } } } bullEdges is a list of vectors of the edges of a bullet, asteroidEdges is similar, and bullVerts and asteroids[i].vertices are, obviously, lists of vectors of each vertex for the respective bullet or asteroid. Honestly, I'm not looking for code corrections, just a fresh set of eyes.

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  • libgdx draw issue and animation

    - by johnny-b
    it seems as though i cannot get the draw method to work??? it seems as though the bullet.draw(batcher) does not work and i cannot understand why as the bullet is a sprite. i have made a Sprite[] and added them as animation. could that be it? i tried batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY(), bullet.getOriginX() / 2, bullet.getOriginY() / 2, bullet.getWidth(), bullet.getHeight(), 1, 1, bullet.getRotation()); but that dont work, the only way it draws is this batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY()); below is the code. // this is in a Asset Class texture = new Texture(Gdx.files.internal("SpriteN1.png")); texture.setFilter(TextureFilter.Nearest, TextureFilter.Nearest); bullet1 = new Sprite(texture, 380, 350, 45, 20); bullet1.flip(false, true); bullet2 = new Sprite(texture, 425, 350, 45, 20); bullet2.flip(false, true); Sprite[] bullets = { bullet1, bullet2 }; bulletAnimation = new Animation(0.06f, bullets); bulletAnimation.setPlayMode(Animation.PlayMode.LOOP); // this is the GameRender class public class GameRender() { private Bullet bullet; private Ball ball; public GameRenderer(GameWorld world) { myWorld = world; cam = new OrthographicCamera(); cam.setToOrtho(true, 480, 320); batcher = new SpriteBatch(); // Attach batcher to camera batcher.setProjectionMatrix(cam.combined); shapeRenderer = new ShapeRenderer(); shapeRenderer.setProjectionMatrix(cam.combined); // Call helper methods to initialize instance variables initGameObjects(); initAssets(); } private void initGameObjects() { ball = GameWorld.getBall(); bullet = myWorld.getBullet(); scroller = myWorld.getScroller(); } private void initAssets() { ballAnimation = AssetLoader.ballAnimation; bulletAnimation = AssetLoader.bulletAnimation; } public void render(float runTime) { Gdx.gl.glClearColor(0, 0, 0, 1); Gdx.gl.glClear(GL30.GL_COLOR_BUFFER_BIT); batcher.begin(); // Disable transparency // This is good for performance when drawing images that do not require // transparency. batcher.disableBlending(); // The ball needs transparency, so we enable that again. batcher.enableBlending(); batcher.draw(AssetLoader.ballAnimation.getKeyFrame(runTime), ball.getX(), ball.getY(), ball.getWidth(), ball.getHeight()); batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY()); // End SpriteBatch batcher.end(); } } // this is the gameworld class public class GameWorld { public static Ball ball; private Bullet bullet; private ScrollHandler scroller; public GameWorld() { ball = new Ball(480, 273, 32, 32); bullet = new Bullet(10, 10); scroller = new ScrollHandler(0); } public void update(float delta) { ball.update(delta); bullet.update(delta); scroller.update(delta); } public static Ball getBall() { return ball; } public ScrollHandler getScroller() { return scroller; } public Bullet getBullet() { return bullet; } } is there anyway so make the sprite work?

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  • Auto-organized / smart inventory system?

    - by VeXe
    for the past week I've been working on an inventory system with Unity3D. At first I got help from the guys at Design3 but it wasn't too long till we split path, because I really didn't like the way they did their code, it didn't have any smell of OOP whatsoever. I took it further steps ahead - items take more than one slot, advanced placement system (items tries their best to find the best close fit), local mouse system (mouse gets trapped in active bag area), etc. Here's a demo of my work. What we would like to have in our game, is an auto-organizing feature - not auto-sort. We want this feature because our inventory's going to be in 'real-time' - not like in Resident Evil 1,2,3 etc where you would pause the game and do things in your inventory. Now imagine your self in a sticky situation surrounded by zombies, and you don't have bullets, you look around, you see that there are bullets nearby on the ground, so you go for them and try to pick them up, but they don't fit! you look at your inventory and find out that if you reorganize some of the items, it will fit! - now the player - in that situation doesn't have time to reorganize because he's surrounded with zombies and will die if he stops and organizes the inventory to make space (remember inventory in real-time, no pausing) - wouldn't it be nice for that to happen automatically? - Yes! (I believe this has been implemented in some games like Dungeon siege or something, so sure it's doable) take a look at this picture for example: Yes, so if you auto-sort the issue you will get your spaces but it's bad because: 1- Expensive: it doesn't need a whole sort operation to free those spaces, in the first picture, just slide the red item at the bottom to the very left, and you get the same spaces that you got from the auto-sort. 2- It's annoying to the player: "Who the F told you to re-order my stuff?" I'm not asking for "How to write the code" for this, I'm just asking for some guidance, where to look, what algorithms are involved? Is this something related to graphs and shortest path stuff? I hope not cuz I didn't manage to continue my college studies :/ But even if it is, just tell me and I will learn the stuff related. Notice there could be more than just one solution. So I guess the first thing I have to do is figure out if the situation is 'solvable' - if I know how to determine if a situation is solvable or not, then I can 'solve' it. I just need to know the conditions that makes it 'solvable'. And I believe there must be some algorithm/data structure for this. Here's a pic for more than one solution of trying to fit a 1x3 item: The arrows show just one of the solutions, but if you look you will find more than one. This is what I ultimately not auto-sorting but find a solution and applying it. Note that if I spend time on it I will come up with a way to solve it, but it wouldn't be the best way, it's like, holding a car wheel with your feet instead of your hands! XD Or just like trying to solve an issue that requires arrays, but you're not yet aware of their existence! So what is the right approach to this? Hope somebody helps, thanks a lot in advance :)

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