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  • Cocos-2D asteroids style movement (iOS)

    - by bwheeler96
    So I have a CCSprite subclass, well call this Spaceship. Spaceship needs to move on a loop, until I say othersise by calling a method. The method should look something like - (void)moveForeverAtVelocity { // method logic } The class Spaceship has two relevant iVars, resetPosition and targetPosition, the target is where we are headed, the reset is where we set to when we've hit our target. If they are both off-screen this creates a permanent looping effect. So for the logic, I have tried several things, such as CCMoveTo *move = [CCMoveTo actionWithDuration:2 position:ccp(100, 100)]; CCCallBlockN *repeat = [CCCallBlockN actionWithBlock: ^(CCNode *node) { [self moveForeverAtVelocity]; }]; [self runAction:[CCSequence actions: move, repeat, nil]]; self.position = self.resetPosition; recursively calling the moveForeverAtVelocity method. This is psuedo-code, so its not perfect. I have hard-coded some of the values for the sake of simplicity. Enough garble: The problem I am having, how can I make a method that loops forever, but can be called and reset at will. I'm running into issues with creating multiple instances of this method. If you can offer any assistance with creating this effect, that would be appreciated.

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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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  • Reflection velocity

    - by MindSeeker
    I'm trying to get a moving circular object to bounce (elastically) off of an immovable circular object. Am I doing this right? (The results look right, but I hate to trust that alone, and I can't find a tutorial that tackles this problem and includes the nitty gritty math/code to verify what I'm doing). If it is right, is there a better/faster/more elegant way to do this? Note that the object (this) is the moving circle, and the EntPointer object is the immovable circle. //take vector separating the two centers <x, y>, and then get unit vector of the result: MathVector2d unitnormal = MathVector2d(this -> Retxpos() - EntPointer -> Retxpos(), this -> Retypos() - EntPointer -> Retypos()).UnitVector(); //take tangent <-y, x> of the unitnormal: MathVector2d unittangent = MathVector2d(-unitnormal.ycomp, unitnormal.xcomp); MathVector2d V1 = MathVector2d(this -> Retxvel(), this -> Retyvel()); //Calculate the normal and tangent vector lengths of the velocity: (the normal changes, the tangent stays the same) double LengthNormal = DotProduct(unitnormal, V1); double LengthTangent = DotProduct(unittangent, V1); MathVector2d VelVecNewNormal = unitnormal.ScalarMultiplication(-LengthNormal); //the negative of what it was before MathVector2d VelVecNewTangent = unittangent.ScalarMultiplication(LengthTangent); //this stays the same MathVector2d NewVel = VectorAddition(VelVecNewNormal, VelVecNewTangent); //combine them xvel = NewVel.xcomp; //and then apply them yvel = NewVel.ycomp; Note also that this question is just about velocity, the position code is handled elsewhere (in other words, assume that this code is implemented at the exact moment that the circles begin to overlap). Thanks in advance for your help and time!

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  • Question about creating a sprite based 2-D Side Scroller with scaling/zooming

    - by Arthur
    I'm just wondering if anyone can offer any advice on how best to go about creating a 2-D game with zooming/scaling features akin to the early Samurai Showdown games. In this case it would be a side scroller a la Metal Slug, the zooming would come in as more enemy sprites entered the screen, or when facing a large sized boss. A feature that would be both cosmetic as well as functional to the game. I've done some reading and noticed a few suggestions that included drawing different sized sprites, a standard size and zoomed out size. Any thoughts? Thanks for your time.

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  • android multitouch problem

    - by Max
    Im aware that there a a couple of posts on this matter, but Ive tried all of them and none of them gets rid of my problem. Im starting to get close to the end of my game so I bought a cabel to try it on a real phone, and as I expected my multitouch dosnt work. I use 2 joysticks, one to move my character and one to change his direction so he can shoot while walking backwards etc. my local variable: public void update(MotionEvent event) { if (event == null && lastEvent == null) { return; } else if (event == null && lastEvent != null) { event = lastEvent; } else { lastEvent = event; } int index = event.getActionIndex(); int pointerId = event.getPointerId(index); statement for left Joystick: if (pointerId == 0 && event.getAction() == MotionEvent.ACTION_DOWN && (int) event.getX() > steeringxMesh - 50 && (int) event.getX() < steeringxMesh + 50 && (int) event.getY() > yMesh - 50 && (int) event.getY() < yMesh + 50) { dragging = true; } else if (event.getAction() == MotionEvent.ACTION_UP) { dragging = false; } if (dragging) { //code for moving my character statement for my right joystick: if (pointerId == 1 && event.getAction() == MotionEvent.ACTION_DOWN && (int) event.getX() > shootingxMesh - 50 && (int) event.getX() < shootingxMesh + 50 && (int) event.getY() > yMesh - 50 && (int) event.getY() < yMesh + 50) { shooting = true; } else if (event.getAction() == MotionEvent.ACTION_UP) { shooting = false; } if (shooting) { // code for aiming } This class is my main-Views onTouchListener and is called in a update-method that gets called in my game-loop, so its called every frame. Im really at a loss here, I've done a couple of tutorials and Ive tried all relevant solutions to similar posts. Can post entire Class if necessary but I think this is all the relevant code. Just hope someone can make some sence out of this.

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  • Top Down bounds of vision

    - by Rorrik
    Obviously in a first person view point the player sees only what's in front of them (with the exception of radars and rearview mirrors, etc). My game has a top down perspective, but I still want to limit what the character sees based on their facing. I've already worked out having objects obstruct vision, but there are two other factors that I worry would be disorienting and want to do right. I want the player to have reduced peripheral vision and very little view behind them. The assumption is he can turn his head and so see fairly well out to the sides, but hardly at all behind without turning the whole body. How do I make it clear you are not seeing behind you? I want the map to turn so the player is always facing up. Part of the game is to experience kind of a maze and the player should be able to lose track of North. How can I turn the map rather than the player avatar without causing confusion?

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  • How can I remove the "Dash Home" icon from the Unity launcher?

    - by user27451
    My notebook has a widescreen display so vertical space is an absolute premium for me. When I installed Ubuntu 11.10 I was disappointed to see that a new icon confusingly named "Dash Home" had been added to the very top of the Unity launcher. I can't move it to the bottom (by dragging it) and it doesn't have a context menu with which to remove it (by unchecking "Keep In Launcher"). It's horrible. How can I remove it from the Unity launcher and reclaim the space that was taken from me? (I realize that if it's removed I'll have to open the dashboard with the super key - I'm fine with that)

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  • World to Pixel Transformation

    - by D00d
    My objects have a location in world coordinates (basically 1.0f is a meter). If I simply draw my objects using their world coordinates, each meter will correspond to a pixel. Obviously that's not what I want. Now, I don't want to have to apply a transformation to each and every object's position when I draw them. As I happen to be using XNA, and spritebatch allows a Matrix to be passed in as an argument in it's begin method, I was wondering if there is a way to pass the World to Pixel transformation in there. Any suggestions? So far Matrix.CreateScale(new Vector3(zoom, zoom, 1)) puts the objects in their proper spot, but it also scales up the sprites. Is there a way to transform the position without enlarging the sprite? Thanks

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  • How to do proper Alpha in XNA?

    - by Soshimo
    Okay, I've read several articles, tutorials, and questions regarding this. Most point to the same technique which doesn't solve my problem. I need the ability to create semi-transparent sprites (texture2D's really) and have them overlay another sprite. I can achieve that somewhat with the code samples I've found but I'm not satisfied with the results and I know there is a way to do this. In mobile programming (BREW) we did it old school and actually checked each pixel for transparency before rendering. In this case it seems to render the sprite below it blended with the alpha above it. This may be an artifact of how I'm rendering the texture but, as I said before, all examples point to this one technique. Before I go any further I'll go ahead and paste my example code. public void Draw(SpriteBatch batch, Camera camera, float alpha) { int tileMapWidth = Width; int tileMapHeight = Height; batch.Begin(SpriteSortMode.Texture, BlendState.AlphaBlend, SamplerState.PointWrap, DepthStencilState.Default, RasterizerState.CullNone, null, camera.TransformMatrix); for (int x = 0; x < tileMapWidth; x++) { for (int y = 0; y < tileMapHeight; y++) { int tileIndex = _map[y, x]; if (tileIndex != -1) { Texture2D texture = _tileTextures[tileIndex]; batch.Draw( texture, new Rectangle( (x * Engine.TileWidth), (y * Engine.TileHeight), Engine.TileWidth, Engine.TileHeight), new Color(new Vector4(1f, 1f, 1f, alpha ))); } } } batch.End(); } As you can see, in this code I'm using the overloaded SpriteBatch.Begin method which takes, among other things, a blend state. I'm almost positive that's my problem. I don't want to BLEND the sprites, I want them to be transparent when alpha is 0. In this example I can set alpha to 0 but it still renders both tiles, with the lower z ordered sprite showing through, discolored because of the blending. This is not a desired effect, I want the higher z-ordered sprite to fade out and not effect the color beneath it in such a manner. I might be way off here as I'm fairly new to XNA development so feel free to steer me in the correct direction in the event I'm going down the wrong rabbit hole. TIA

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  • Rendering multiple squares fast?

    - by Sam
    so I'm doing my first steps with openGL development on android and I'm kinda stuck at some serious performance issues... What I'm trying to do is render a whole grid of single colored squares on to the screen and I'm getting framerates of ~7FPS. The squares are 9px in size right now with one pixel border in between, so I get a few thousand of them. I have a class "Square" and the Renderer iterates over all Squares every frame and calls the draw() method of each (just the iteration is fast enough, with no openGL code the whole thing runs smootlhy at 60FPS). Right now the draw() method looks like this: // Prepare the square coordinate data GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer); // Set color for drawing the square GLES20.glUniform4fv(mColorHandle, 1, color, 0); // Draw the square GLES20.glDrawElements(GLES20.GL_TRIANGLES, drawOrder.length, GLES20.GL_UNSIGNED_SHORT, drawListBuffer); So its actually only 3 openGL calls. Everything else (loading shaders, filling buffers, getting appropriate handles, etc.) is done in the Constructor and things like the Program and the handles are also static attributes. What am I missing here, why is it rendering so slow? I've also tried loading the buffer data into VBOs, but this is actually slower... Maybe I did something wrong though. Any help greatly appreciated! :)

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  • How do I implement powerups for my Breakout clone?

    - by Eva
    I'm making a simple Breakout clone in Python that will have very many powerups/powerdowns (so far I came up with 26). Some will affect the paddle (paddle missile, two paddles, short paddle, etc.), some will affect the ball (slow ball, destructo-ball, invisible ball, etc.), some will affect the bricks (brick scramble, move up, bricks indestructible, etc.), and some will affect other game aspects (extra life, more points, less points, etc.). I'm pretty sure I have the code to draw the falling powerups and test for collisions with the paddle down, but I'm confused about how to code the effects of the powerups. Since there are very many powerups, it seemed inefficient to add specific methods to each component as done in this tutorial. However, I can't think of an other ways to implement the powerups. I found a page that hints at some way to design powerup behavior using classes, but I'm at a loss for how to do that. (A short example would help.) Please give me a short code example of another way to implement the effects of the powerups.

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  • Higher Performance With Spritesheets Than With Rotating Using C# and XNA 4.0?

    - by Manuel Maier
    I would like to know what the performance difference is between using multiple sprites in one file (sprite sheets) to draw a game-character being able to face in 4 directions and using one sprite per file but rotating that character to my needs. I am aware that the sprite sheet method restricts the character to only be able to look into predefined directions, whereas the rotation method would give the character the freedom of "looking everywhere". Here's an example of what I am doing: Single Sprite Method Assuming I have a 64x64 texture that points north. So I do the following if I wanted it to point east: spriteBatch.Draw( _sampleTexture, new Rectangle(200, 100, 64, 64), null, Color.White, (float)(Math.PI / 2), Vector2.Zero, SpriteEffects.None, 0); Multiple Sprite Method Now I got a sprite sheet (128x128) where the top-left 64x64 section contains a sprite pointing north, top-right 64x64 section points east, and so forth. And to make it point east, i do the following: spriteBatch.Draw( _sampleSpritesheet, new Rectangle(400, 100, 64, 64), new Rectangle(64, 0, 64, 64), Color.White); So which of these methods is using less CPU-time and what are the pro's and con's? Is .NET/XNA optimizing this in any way (e.g. it notices that the same call was done last frame and then just uses an already rendered/rotated image thats still in memory)?

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  • XNA 2D vehicle wall collisions

    - by mike
    I am attempting to implement collisions for my truck game, where the truck can drive around the world and hit walls surrounding the level and various randomly placed walls within the level. I am able to get direct collisions working correctly. However, it is getting very complicated and tricky very quickly. I am trying to accommodate various other collisions such as when a truck is against the wall then turns an adjacent direction or when they reverse into a wall. Both of these result in a slight collision as the image of the truck flips around to the direction the player wants to move. All of this has resulted in a whole lot of if statements to check how I should be fixing the collision. This in turn makes the player jump to random locations and "teleport" around corners, etc. The rest of my game is fine, I am not completely new to game development or C# for that matter. It's just the logic of collisions. Any ideas on how I can approach this? Image of the collisions I am trying to resolve: http://tinypic.com/r/2qtflvq/6

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  • Problem with scrolling background in one OpenGL loop

    - by GvS
    I have 960x3000 map image in png and I'm scrolling it in a loop like this (it's called in 60 FPS loop): glPushMatrix(); glBindTexture( GL_TEXTURE_2D, mapTex[iBgImg]); glBegin(GL_QUADS); double mtstart = 0.0f - fBgVPos/(double)BgSize; double mtend = mtstart + mtsize; glTexCoord2d(0.0, mtstart); glVertex2f(fBgX, TOP_MARGIN); glTexCoord2d(1.0, mtstart); glVertex2f(fBgX + MAP_WIDTH, TOP_MARGIN); glTexCoord2d(1.0, mtend); glVertex2f(fBgX + MAP_WIDTH, BOTTOM_MARGIN); glTexCoord2d(0.0, mtend); glVertex2f(fBgX, BOTTOM_MARGIN); glEnd(); glPopMatrix(); unfortunately it isn't smooth when the game is in windowed mode. However, it is smooth in full screen mode. I'm using GLFW for windows. Maybe there is something wrong with my method? Is there anything better? Or could this be hardware problem? Edit: Window is created using glfwOpenWindowHint(GLFW_WINDOW_NO_RESIZE, GL_TRUE); glfwOpenWindowHint(GLFW_REFRESH_RATE, 60); and main loop is using glfwSwapInterval(1) to ensure 60 FPS;

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  • Trouble with collision detection in XNA?

    - by Lewis Wilcock
    I'm trying to loop through an list of enemies (enemyList) and then any that have intersected the rectangle belonging to the box object (Which doesn't move), declare there IsAlive bool as false. Then another part of the code removes any enemies that have the IsAlive bool as false. The problem im having is getting access to the variable that holds the Rectangle (named boundingBox) of the enemy. When this is in a foreach loop it works fine, as the enemy class is declared within the foreach. However, there are issues in using the foreach as it removes more than one of the enemies at once (Usually at positions 0 and 2, 1 and 3, etc...). I was wondering the best way to declare the enemy class, without it actually creating new instances of the class? Heres the code I currently have: if (keyboardState.IsKeyDown(Keys.Q) && oldKeyState.IsKeyUp(Keys.Q)) { enemyList.Add(new enemy(textureList.ElementAt(randText), new Vector2(250, 250), graphics)); } //foreach (enemy enemy in enemyList) //{ for (int i = 0; i < enemyList.Count; i++) { if (***enemy.boundingBox***.Intersects(theDefence.boxRectangle)) { enemyList[i].IsDead = true; i++; } } //} for(int j = enemyList.Count - 1; j >= 0; j--) { if(enemyList[j].IsDead) enemyList.RemoveAt(j); } (The enemy.boundingBox is the variables I can't get access too). This is a complete copy of the code (Zipped) If it helps: https://www.dropbox.com/s/ih52k4e21g98j3k/Collision%20tests.rar I managed to find the issue. Changed enemy.boundingBox to enemyList[i].boundingBox. Collision works now! Thanks for any help!

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  • Physics Engine [Collision Response, 2-dimensional] experts, help!! My stack is unstable!

    - by Register Sole
    Previously, I struggle with the sequential impulse-based method I developed. Thanks to jedediah referring me to this paper, I managed to rebuild the codes and implement the simultaneous impulse based method with Projected-Gauss-Seidel (PGS) iterative solver as described by Erin Catto (mentioned in the reference of the paper as [Catt05]). So here's how it currently is: The simulation handles 2-dimensional rotating convex polygons. Detection is using separating-axis test, with a SKIN, meaning closest points between two polygons is detected and determined if their distance is less than SKIN. To resolve collision, simultaneous impulse-based method is used. It is solved using iterative solver (PGS-solver) as in Erin Catto's paper. Error-correction is implemented using Baumgarte's stabilization (you can refer to either paper for this) using J V = beta/dt*overlap, J is the Jacobian for the constraints, V the matrix containing the velocities of the bodies, beta an error-correction parameter that is better be < 1, dt the time-step taken by the engine, and overlap, the overlap between the bodies (true overlap, so SKIN is ignored). However, it is still less stable than I expected :s I tried to stack hexagons (or squares, doesn't really matter), and even with only 4 to 5 of them, they hardly stand still! Also note that I am not looking for a sleeping scheme. But I would settle if you have any explicit scheme to handle resting contacts. That said, I would be more than happy if you have a way of treating it generally (as continuous collision, instead of explicitly as a special state). Ideas I have: I would try adding a damping term (proportional to velocity) to the Baumgarte. Is this a good idea in general? If not I would not want to waste my time trying to tune the parameter hoping it magically works. Ideas I have tried: Using simultaneous position based error correction as described in the paper in section 5.3.2, turned out to be worse than the current scheme. If you want to know the parameters I used: Hexagons, side 50 (pixels) gravity 2400 (pixels/sec^2) time-step 1/60 (sec) beta 0.1 restitution 0 to 0.2 coeff. of friction 0.2 PGS iteration 10 initial separation 10 (pixels) mass 1 (unit is irrelevant for now, i modified velocity directly<-impulse method) inertia 1/1000 Thanks in advance! I really appreciate any help from you guys!! :)

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  • Android game scrolling background

    - by Stevanicus
    Hi There, I'm just trying to figure out the best approach for running a scolling background on an android device. The method I have so far.... its pretty laggy. I use threads, which I believe is not the best bet for android platforms @Override public void run() { // Game Loop while(runningThread){ //Scroll background down bgY += 1; try { this.postInvalidate(); t.sleep(10); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } where postinvalidate in the onDraw function simply pushings the background image down canvas.drawBitmap(backgroundImage, bgX, bgY, null); Thanks in advance

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  • 2-D Lighting Theory

    - by Richard
    I am writing a rogue-like 'zombie' management game. The game map will be similar to Prison Architect. A top-down 50 X 50 grid. I want to implemented a day night cycle and during the night I would like the player to be able to position lights. I would like to be able to lighten and dark to whole map to display the day and night cycle. Then lights would be a circle of light blocked by game entities such as walls, players, trees etc. How would I achieve and what is the standard way of achieving this?

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  • XNA 2D Rotated Rectangle Collision Response

    - by Kyle Uithoven
    I am using Rotated Rectangles which collide using the Separating Axis Theorem and they work perfectly fine for collision detection using Intersects and Contains. However, I am starting to use faster objects in my game now and there is the issue of the two object overlapping during collision due to their higher velocities. I would like to do a collision response where I find out how much they are overlapping in the X and Y and put position them outside of each other. I would like to use something like this: http://go.colorize.net/xna/2d_collision_response_xna/index.html. But I am having some issues trying to adapt this to handle the rotation of the bounds. Is this possible? Are there any resources out there that I can look at?

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  • How do I calculate the motion of 2 massive bodies in space?

    - by 1224
    I'm writing code simulating the 2-dimensional motion of two massive bodies with gravitational fields. The bodies' masses are known and I have a gravitational force equation. I know from that force I can get a differential equation for coordinates. I know that I once I solve this equation I will get the coordinates. I will need to make up some initial position and some initial velocity. I'd like to end up with a numeric solver for the ordinal differential equation for coordinates to get the formulas that I can write in code. Could someone break down how from laws and initial conditions we get to the formulas that calculate x and y at time t?

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  • Can Layer Masks Achieve This Effect

    - by Julian
    If you look at the image below you will see the player surrounded by a dotted yellow box. The dotted yellow box is also part of the player and represented a portion of the player being masked from both rendering and affected by physics. My question is if layer masks in Unity can achieve the following effect. -In Area 1, the red box/animations of the player are visible and the rigidbody of this shape is affected by all Physics. -Any portion of the player that enters Area 2 makes the larger yellow box within the area become visible (and affected by physics) and vice versa for any portion of the smaller red box that enters. -This can persist when both entering and leaving either area from any direction. Thank you for any help!

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  • Cocos 2D - Hold down CCMenuItem

    - by Will Youmans
    I am using the following code to move a CCSprite left and right. -(id)init{ CCMenuItemImage * moveLeftButton = [CCMenuItemImage itemFromNormalImage:@"Move Left Button.png" selectedImage:@"Move Left Button.png" target:self selector:@selector(moveLeftVoid:)]; } -(void)moveLeftVoid{ id moveLeft = [CCMoveBy actionWithDuration:.3 position:ccp(-10, 0)]; [_mainSprite runAction:moveLeft]; } This does work, but only as a single tap. What I want for the CCSprite to move continously in that direction when the CCMenuItem is held down. Then when it's released the character stops moving. If you need to see more code, please just ask. :) Thanks

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  • Vectors with Circles Physics -java

    - by Joe Hearty
    This is a problem I've been having, When making a set number of filled circles at random locations on a JPanel and applying a gravity (a negative change in the y), each of the circles collide. I want them to have collision detection and push in the opposite direction using vectors but i don't know how to apply that to my scenario could someone help? public void drawballs(Graphics g){ g.setColor (Color.white); //displays circles for(int i = 0; i<xlocationofcircles.length-1; i++){ g.fillOval( (int) xlocationofcircles[i], (int) (ylocationofcircles[i]) ,16 ,16 ); ylocationofcircles[i]+=.2; //gravity if(ylocationofcircles[i] > 550) //stops gravity at bottom of screen ylocationofcircles[i]-=.2; //Check distance between circles(i think..) float distance =(xlocationofcircles[i+1]-xlocationofcircles[i]) + (ylocationofcircles[i+1]-xlocationofcircles[i]) ; if( Math.sqrt(distance) <16)

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  • How to reset a List c# and XNA [on hold]

    - by P3erfect
    I need to do a "retry" option when the player finishes the game.For doing this I thought to reset the lists of Monsters and other objects that moved at the first playing or which have been "killed".for example I have a list like that: //the enemy1 class is already done // in Game1 I declare it List<enemy1> enem1 = new List<enemy1>(); //Initialize method List<enemy1> enem1 = new List<enemy1>(); //LoadContent foreach (enemy1 enemy in enem1) { enemy.Load(Content); } enem1.Add(new enemy1(Content.Load<Texture2D>("enemy"), new Vector2(5900, 12600))); //Update foreach (enemy1 enemy in enem1) { enemy.Update(gameTime); } //after being shoted the enemies disappear and i remove them //if the monsters are shoted the bool "visible" goes from false to true for (int i = enem1.Count - 1; i >= 0; --i) { if (enem1[i].visible == true) enem1.RemoveAt(i); } //Draw foreach (enemy1 enemy in enem1) { if(enemy.visble==false) { enemy.Draw(spriteBatch, gameTime); } } //So my problem is to restart the game. I did this in Update method if(lost==false) { //update all the things... } if(lost==true)//this is if I die { //here I have to put the code that restore the list //I tried: foreach (enemy1 enemy in enem1) { enemy.visible=false; } player.life=3;//initializing the player,points,time player.position=initialPosition; points=0; time=0; }//the player works.. } } they should be drawn again but if I removed them they won't be drawn anymore.If I don't remove them ,instead, the enemies are in different places (because they follow me). Any suggestions to restore or reinitialize the list??

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  • Box2d contant speed before and after collision

    - by bobenko
    I want to make my body fly at constant speed, how to make it fly at constant speed before and after collision? I set restitution of my body to 1.0 but after some direct and powerful collisions my objects begins to slow, I want it to fly same speed as before. I heard this can be done by setting liner damping of the object, I think it can prevent only from fast flying objects not slow. Thanks in advance.

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