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  • Sprite animation problem

    - by hustlerinc
    I have this sprite I have to animate. The sprite is 7 images total but animation is 10 frames (2 positions are repeated). The order I want to go through the frames is like this: 3 - 4 - 5 - 6 - 4 - 3 - 2 - 1 - 0 - 2. My problem is how can I skip 1 frame once I reach the end of each direction? The reason I want to skip is to save me from creating duplicate positions in the spritesheet. I'm doing this in Javascript.

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  • Dynamic Components

    - by Alex
    I am attempting to design a component-based architecture that allows Components to be dynamically enabled and disabled, much like the system employed by Unity3D. For example, all Components are implicitly enabled by default; however, if one desires to halt execution of code for a particular Component, one can disable it. Naively, I want to have a boolean flag in Component (which is an abstract class), and somehow serialize all method calls into strings, so that some sort of ComponentManager can check if a given Component is enabled/disabled before processing a method call on it. However, this is a pretty bad solution. I feel like I should employ some variation of the state paradigm, but I have yet to make progress. Any help would be greatly appreciated,

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  • Without using a pre-built physics engine, how can I implement 3-D collision detection from scratch?

    - by Andy Harglesis
    I want to tackle some basic 3-D collision detection and was wondering how engines handle this and give you a pretty interface and make it so easy ... I want to do it all myself, however. 2-D collision detection is extremely simple and can be done multiple ways that even beginner programmers could think up: 1.When the pixels touch; 2.when a rectangle range is exceeded; 3.when a pixel object is detected near another one in a pixel-based rendering engine. But 3-D is different with one dimension, but complex in many more so ... what are the general, basic understanding/examples on how 3-D collision detection can be implemented? Think two shaded, OpenGL cubes that are moved next to each other with a simple OpenGL rendering context and keyboard events.

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  • how can I change object look point?

    - by jques
    I have tried to load image but system does not give permission. Please look image http://www.rps.net/gunslinger/scrnshot/gunslinger33.jpg I have two arm with two gun, I want to rotate these arm with mouse. For example, if I move mouse position to the left, arms with guns should be move also. Since this is hoby project, I am a bit confort to ask below question ; What should I do to achieve my wish ? some explanation: perspective view gun in viewing direction left click = trigger left gun perspective Feel free to change the title Thanks

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  • UDK - How to make sure a PhysicalMaterial mask actually works?

    - by tomacmuni
    Hello, I have been reading the documentation for UDK about physical materials and masks. I have my 1bit BMP mask, and the two physical material assets I want to shoot off in the black and white channels. I have applied my material to both a rigid body and to a skeletal mesh and neither apparently uses the mask. If I assign a regular physical material (one that doesn't use a mask) then it will work fine, but this defeats the point because it gives only one hit reaction. In the documentation it states that it is possible to extend a class on which we want to use a physical material based on the KActor class's usage. How to do that? Here is the quote: "The following properties [ie, ImpactEffect - Particle system to spawn at the point of impact + ImpactSound - Sound to play when an impact occurs] allow you to attach sounds and effects to physical collisions. These only work on classes which support them, which at the moment is only KActor. By looking at the implementation in KActor though, you can add this functionality to other classes (or you can subclass KActor)." Essentially, how to make sure a PhysicalMaterial mask actually works? What code could be added to a skeletal mesh class perhaps, to get it going? Any help appreciated.

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  • When attaching AI to a vehicle should I define all steps or try Line of Sight?

    - by ThorDivDev
    This problem is related to an intersection simulation I am building for university. I will try to make it as general as possible. I am trying to assign AI to a vehicle using the JMonkeyEngine platform. AIGama_JmonkeyEngine explains that if you wish to create a car that follows a path you can define the path in steps. If there was no physics attached whatsoever then all you need to do is define the x,y,z values of where you want the object to appear in all subsequent steps. I am attaching the vehicleControl that implements jBullet. In this case the author mentions that I would need to define the steering and accelerating behaviors at each step. I was trying to use ghost controls that represented waypoints and when on colliding the car would decide what to do next like stopping at a red light. This didn't work so well. Car doesn't face right. public void update(float tpf) { Vector3f currentPos = aiVehicle.getPhysicsLocation(); Vector3f baseforwardVector = currentPos.clone(); Vector3f forwardVector; Vector3f subsVector; if (currentState == ObjectState.Running) { aiVehicle.accelerate(-800); } else if (currentState == ObjectState.Seeking) { baseforwardVector = baseforwardVector.normalize(); forwardVector = aiVehicle.getForwardVector(baseforwardVector); subsVector = pointToSeek.subtract(currentPos.clone()); System.out.printf("baseforwardVector: %f, %f, %f\n", baseforwardVector.x, baseforwardVector.y, baseforwardVector.z); System.out.printf("subsVector: %f, %f, %f\n", subsVector.x, subsVector.y, subsVector.z); System.out.printf("ForwardVector: %f, %f, %f\n", forwardVector.x, forwardVector.y, forwardVector.z); if (pointToSeek != null && pointToSeek.x + 3 >= currentPos.x && pointToSeek.x - 3 <= currentPos.x) { aiVehicle.steer(0.0f); aiVehicle.accelerate(-40); } else if (pointToSeek != null && pointToSeek.x > currentPos.x) { aiVehicle.steer(-0.5f); aiVehicle.accelerate(-40); } else if (pointToSeek != null && pointToSeek.x < currentPos.x) { aiVehicle.steer(0.5f); aiVehicle.accelerate(-40); } } else if (currentState == ObjectState.Stopped) { aiVehicle.accelerate(0); aiVehicle.brake(40); } }

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  • How can I achieve this lighting with OpenGL?

    - by Smallbro
    I'm currently trying to implement a type of "smooth" lighting. How can I achieve lighting which looks like this: http://dl.dropbox.com/u/1668516/concept/warp3.png Using OpenGl. I've attempted to use blending modes and have come very close to making it work but it came out like this: https://pbs.twimg.com/media/A1071viCEAAlFmJ.png and I also wasn't able to change the alpha of the black background which I want to be able to do. Could I get a few pointers in the right direction?

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  • Keeping the meshes "thickness" the same when scaling an object

    - by user1806687
    I've been bashing my head for the past couple of weeks trying to find a way to help me accomplish, on first look very easy task. So, I got this one object currently made out of 5 cuboids (2 sides, 1 top, 1 bottom, 1 back), this is just for an example, later on there will be whole range of different set ups. Now, the thing is when the user chooses to scale the whole object this is what should happen: X scale: top and bottom cuboids should get scaled by a scale factor, sides should get moved so they are positioned just like they were before(in this case at both ends of top and bottom cuboids), back should get scaled so it fits like before(if I simply scale it by a scale factor it will leave gaps on each side). Y scale: sides should get scaled by a scale factor, top and bottom cuboid should get moved, and back should also get scaled. Z scale: sides, top and bottom cuboids should get scaled, back should get moved. Hope you can help, EDIT: So, I've decided to explain the situation once more, this time more detailed(hopefully). I've also made some pictures of how the scaling should look like, where is the problem and the wrong way of scaling. I this example I will be using a thick walled box, with one face missing, where each wall is made by a cuboid(but later on there will be diffrent shapes of objects, where a one of the face might be roundish, or triangle or even under some angle), scaling will be 2x on X axis. 1.This is how the default object without any scaling applied looks like: http://img856.imageshack.us/img856/4293/defaulttz.png 2.If I scale the whole object(all of the meshes) by some scale factor, the problem becomes that the "thickness" of the object walls also change(which I do not want): http://img822.imageshack.us/img822/9073/wrongwaytoscale.png 3.This is how the correct scaling should look like. Appropriate faces gets caled in this case where the scale is on X axis(top, bottom, back): http://imageshack.us/photo/my-images/163/rightwayxscale1.png/ 4.But the scale factor might not be the same for all object all of the times. In this case the back has to get scaled a bit more or it leaves gaps: http://imageshack.us/photo/my-images/9/problemwhenscaling.png/ 5.If everything goes well this is how the final object should look like: http://imageshack.us/photo/my-images/856/rightwayxscale2.png/ So, as you have might noticed there are quite a bit of things to look out when scaling. I am asking you, if any of you have any idea on how to accomplish this scaling. I have tried whole bunch of things, from scaling all of the object by the same scale factor, to subtracting and adding sizes to get the right size. But nothing I tried worked, if one mesh got scaled correctly then others didnt. Donwload the example object. English is not my first language, so I am really sorry if its hard to understand what I am saying.

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  • Hit Detection When rotating the camera

    - by SD1990
    This bug/feature has been plaguing me for a while and i want to know the best way to fix it. I'm testing simple hit detection with a wall, like: if (Forward button) if(Inv.w.z < -49 || Inv.w.z > 49) pos.z = 0.0f; else if(Inv.w.x < -49 || Inv.w.x > 49) pos.z = 0.0f; else pos.z = +1.0f; where Inv.w. is the camera positions. Now obviously when i now hit that certain point i can no longer move away from the wall or anywhere in fact. How can i change this code to allow for the camera to be turned away from the wall so therefore i should be allowed to move? for example, the player hits the wall and i cant move until i turn around or to the side? I know its something to do with velocity but im pretty new to this so please bare with me if this is easy.

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  • How to disguise a serverside mob as another?

    - by Shaun Wild
    I've been working a Minecraft sever mod and i want to be able to add a new entity to the server, but then make the server send the packets to the client, imitating another mob, for example.. Lets say say i have EntityPlayerNPC.class, what i want to do is have all of the packets that get sent to the client look like they are from that of another player which is on the player, therefore allowing me to add custom NPC's... Thinking about the theory i'm sure this can be done. I've tried looking around for where the packets are being sent from and whatnot, can anyone think up a solution? edit: i tried adding a new constructor to the Packet20NamedEntitySpawn class like so: public Packet20NamedEntitySpawn(String username, EntityLiving e){ this.entityId = 0; this.name = username; this.xPosition = MathHelper.floor_double(e.posX * 32.0D); this.yPosition = MathHelper.floor_double(e.posY * 32.0D); this.zPosition = MathHelper.floor_double(e.posZ * 32.0D); this.rotation = (byte)((int)(e.rotationYaw * 256.0F / 360.0F)); this.pitch = (byte)((int)(e.rotationPitch * 256.0F / 360.0F)); this.metadata = e.getDataWatcher(); } unfortunatley, that didn't work :(

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  • How to snap a 2D Quad to the mouse cursor using OpenGL 3.0?

    - by NoobScratcher
    I've been having issues trying to snap a 2D Quad to the mouse cursor position I'm able : 1.) To get values into posX, posY, posZ 2.) Translate with the values from those 3 variables But the quad positioning I'm not able to do correctly in such a way that the 2D Quad is near the mouse cursor using those values from those 3 variables eg."posX, posY, posZ" I need the mouse cursor in the center of the 2D Quad. I'm hoping someone can help me achieve this. I've tried searching around with no avail. Heres the function that is ment to do the snapping but instead creates weird flicker or shows nothing at all only the 3d models show up : void display() { glClearColor(0.0,0.0,0.0,1.0); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); for(std::vector<GLuint>::iterator I = cube.begin(); I != cube.end(); ++I) { glCallList(*I); } if(DrawArea == true) { glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ); cerr << winZ << endl; glGetDoublev(GL_MODELVIEW_MATRIX, modelview); glGetDoublev(GL_PROJECTION_MATRIX, projection); glGetIntegerv(GL_VIEWPORT, viewport); gluUnProject(winX, winY, winZ , modelview, projection, viewport, &posX, &posY, & posZ); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, DrawAreaSurface->w, DrawAreaSurface->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, DrawAreaSurface->pixels); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glTranslatef(posX , posY, posZ); glBegin(GL_QUADS); glTexCoord2f (0.0, 0.0); glVertex3f(0.5, 0.5, 0); glTexCoord2f (1.0, 0.0); glVertex3f(0, 0.5, 0); glTexCoord2f (1.0, 1.0); glVertex3f(0, 0, 0); glTexCoord2f (0.0, 1.0); glVertex3f(0.5, 0, 0); glEnd(); } SwapBuffers(hDC); } I'm using : OpenGL 3.0 WIN32 API C++ GLSL if you really want the full source here it is - http://pastebin.com/1Ncm9HNf , Its pretty messy.

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  • Why does this exported cube have too many vertices?

    - by Joewsh
    I'm trying to export md5mesh models. Just as a test I decided to export a simple cube (i.e. with 8 vertices). When I opened the .md5mesh file it lists the following: numverts 24 numtris 12 numweights 24 Obviously the number of triangles makes sense: 6 faces * 2 to triangulate = 12. The model only has one bone so again it even makes sense that there is one weight for each vertex. The question is though, why is the file listing 24 vertices? Is the problem the exporter or is this normal for md5mesh's? Is it something that you have to rectify when you come to parsing the file in engine? I don't want to be parsing or drawing duplicated vertices without reason. I'm guessing it's something to do with shading and normals. Is it a case of listing each vert 3 times, one for each facing normal?

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  • Playing a death anim on an enemy that I want to remove

    - by Max
    I've been trying to find a tutorial on how to best make animations in Android. I already have some animations for my enemies and my character that are controlled by rectangles and changing rectangleframe between updates using a picture like this: When I'm shooting my enemies they lose HP, and when their HP == 0 they get removed. As long as I'm using an arrayList (which I do for all enemies and bullets) I'm fine, since I can just use list.remove(i). But when I'm on a boss-level and the Boss's HP == 0, I want to remove him and play an animation of an explosion of stars before the "End-screen". Is there a preferred way to do temporary animations like this? If you can give me an example or redirect me to a tutorial, I'd be really grateful!

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  • OpenGLES 2.0 gluunProject

    - by secheung
    I've spent more time than i should trying to get my ray picking program working. I'm pretty convinced my math is solid with respect to line plane intersection, but I believe the problem lies with the changing of the mouse screen touch into 3D world space. Heres my code public void passTouchEvents(MotionEvent e){ int[] viewport = {0,0,viewportWidth,viewportHeight}; float x = e.getX(), y = viewportHeight - e.getY(); float[] pos1 = new float[4]; float[] pos2 = new float[4]; GLU.gluUnProject( x, y, 0.0f, mViewMatrix, 0, mProjectionMatrix, 0, viewport, 0, pos1, 0); GLU.gluUnProject( x, y, 1.0f, mViewMatrix, 0, mProjectionMatrix, 0, viewport, 0, pos2, 0); } Just as a reference I've tried transforming the coordinates 0,0,0 and got an offset. It would be appreciated if you would answer using opengl es 2.0 code. Thanks

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  • Handling hitboxes

    - by TheBroodian
    So I have an issue that I'm laughing at myself about, because it really seems like it should be something that I should be able to figure out pretty quickly. I am designing a 2D action platformer; I have a playable character, and a dummy 'punching bag' character for testing purposes that I've created. I've just gotten enough of both of them done that I can start prototyping and testing them in runtime. Then I realized- neither of them have references of each other (intentionally so), so how do I check for hitboxes stored within my playable character from my dummy character? Long story short, how do I make my dummy know when he's been punched by my hero?

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  • Inventory Item Exist checker

    - by Annalyne
    I have a question regarding declaring my inventory. I made it a string named inventory, with a constant number as its max value. The thing is, I want the user to use an item if he / she gains an item. The problem is, I do not know what syntax should I use to determine if the user has an item and use that item. Here's my code I just started: so declaring the inventory: const int MAX_ITEMS = 15; string game_inventory [MAX_ITEMS]; int itemnum = 0; I have some items like potion, antidote, gems and others. I use the: game_inventory[itemnum++] = "Potion" to place items in my inventory. If I want to use the potion, IF I HAVE one, how can i make a function to check whether I have a potion or anything and use it?

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  • How can I determine the first visible tile in an isometric perspective?

    - by alekop
    I am trying to render the visible portion of a diamond-shaped isometric map. The "world" coordinate system is a 2D Cartesian system, with the coordinates increasing diagonally (in terms of the view coordinate system) along the axes. The "view" coordinates are simply mouse offsets relative to the upper left corner of the view. My rendering algorithm works by drawing diagonal spans, starting from the upper right corner of the view and moving diagonally to the right and down, advancing to the next row when it reaches the right view edge. When the rendering loop reaches the lower left corner, it stops. There are functions to convert a point from view coordinates to world coordinates and then to map coordinates. Everything works when rendering from tile 0,0, but as the view scrolls around the rendering needs to start from a different tile. I can't figure out how to determine which tile is closest to the upper right corner. At the moment I am simply converting the coordinates of the upper right corner to map coordinates. This works as long as the view origin (upper right corner) is inside the world, but when approaching the edges of the map the starting tile coordinate obviously become invalid. I guess this boils down to asking "how can I find the intersection between the world X axis and the view X axis?"

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  • How do you deal with transitions in animating walking?

    - by Aerovistae
    I'm pretty new to this whole animating models thing. Just learning the ropes. I got a nice walking animation going, which I can loop while a character is walking, but what about when they stop walking? I mean, they could be at any point in the animation at the time the player stops walking. How do I get them to smoothly return to a standing still position without having them snap into that position? The same goes for starting walking from a standing still position. Do you need a separate animation? How is this dealt with?

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  • How do I make camera move at same speed when rotating and moving forward

    - by dez
    I made a camera in DX9. To move forward I press the Up arrow. To rotate on the Y axis I use the mouse. When I perform these movements on their own the camera moves at the speed I want. However, if I hold down Up and move the mouse at the same time then the camera moves a lot faster than it should. I want it to move at the same speed as it does when only the Up arrow is pressed. I think I need to normalize something somewhere but not sure what and not sure where. Have tried various combinations without success so if anyone can point me in the right direction that would be great. Thanks. I've post code below. #define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0) LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam ) { if( KEY_DOWN(VK_UP)) MovePlayer(D3DXVECTOR3(0, 0, -1.0f)); if( KEY_DOWN(VK_DOWN)) MovePlayer(D3DXVECTOR3(0, 0, 1.0f)); switch( msg ) { case WM_MOUSEMOVE: ProcessMouseInput(); } } void MovePlayer( D3DXVECTOR3 in_vec ) { D3DXMATRIX CameraRot; D3DXMatrixRotationY(&CameraRot,D3DXToRadian(AngleY)); D3DXVECTOR3 CameraRotTarget; D3DXVec3TransformNormal(&CameraRotTarget,&in_vec,&CameraRot); CameraPos += (m_timeElapsed * CameraRotTarget); } void ProcessMouseInput() { GetCursorPos( &CurrentMouseState ); if ((CurrentMouseState.x != GameMouseState.x) || (CurrentMouseState.y != GameMouseState.y)) { int dx = CurrentMouseState.x - GameMouseState.x; int dy = CurrentMouseState.y - GameMouseState.y; AngleY+=m_timeElapsed*dx*7.0f; } GameMouseState = CurrentMouseState; // Set back to window center in Render function } VOID UpdateCamera() { D3DXVECTOR3 CameraOrigTarget(0, 0, -1); D3DXVECTOR3 CameraOrigUp(0, 1, 0); D3DXMATRIX CameraRot; D3DXMATRIX CameraRotX; D3DXMatrixRotationX(&CameraRotX,D3DXToRadian(AngleX)); D3DXMATRIX CameraRotY; D3DXMatrixRotationY(&CameraRotY,D3DXToRadian(AngleY)); CameraRot = CameraRotX * CameraRotY; D3DXVECTOR3 CameraRotTarget; D3DXVec3TransformNormal(&CameraRotTarget,&CameraOrigTarget,&CameraRot); D3DXVECTOR3 CameraTarget; CameraTarget = CameraPos + CameraRotTarget; D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f ); D3DXMatrixLookAtLH( &matView, &CameraPos, &CameraTarget, &vUpVec ); g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView ); D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI / 4, 1.0f, 1.0f, 100.0f ); g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj ); }

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  • How to setup my texture cordinates correctly in GLSL 150 and OpenGL 3.3?

    - by RubyKing
    I'm trying to do texture mapping in GLSL 150 and OpenGL 3.3 Here are my shaders I've tried my best to get this correct as possible hopefully this is :) I'm guessing you want to know what the problem is well my texture shows but not in its fullest form just one section of it not the full texture on the quad. All I can think of is its the texture cordinates in the main.cpp which is at the bottom of this post. FRAGMENT SHADER #version 150 in vec2 Texcoord_VSPS; out vec4 color; // Values that stay constant for the whole mesh. uniform sampler2D myTextureSampler; //Main Entry Point void main() { // Output color = color of the texture at the specified UV color = texture2D( myTextureSampler, Texcoord_VSPS ); } VERTEX SHADER #version 150 //Position Container in vec3 position; //Container for TexCoords attribute vec2 Texcoord0; out vec2 Texcoord_VSPS; //out vec2 ex_texcoord; //TO USE A DIFFERENT COORDINATE SYSTEM JUST MULTIPLY THE MATRIX YOU WANT //Main Entry Point void main() { //Translations and w Cordinates stuff gl_Position = vec4(position.xyz, 1.0); Texcoord_VSPS = Texcoord0; } LINK TO MAIN.CPP http://pastebin.com/t7Vg9L0k

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  • Dropping multiple objects using an array in Actionscript?

    - by Eratosthenes
    I'm trying to get these fireBalls to drop more often, I'm not sure if I'm using Math.random correctly. Also, for some reason I'm getting a null reference because I think the fireBalls array waits for one to leave the stage before dropping another one? This is the relevant code: var sun:Sun=new Sun var fireBalls:Array=new Array() var left:Boolean; function onEnterFrame(event:Event){ if (left) { sun.x = sun.x - 15; }else{ sun.x = sun.x + 15; } if (fireBalls.length>0&&fireBalls[0].y>stage.stageHeight){ // Fireballs exit stage removeChild(fireBalls[0]); fireBalls.shift(); } for (var j:int=0; j<fireBalls.length; j++){ fireBalls[j].y=fireBalls[j].y+15; if (fireBalls[j].y>stage.stageHeight-fireBall.width/2){ } } if (Math.random()<.2){ // Fireballs shooting from Sun var fireBall:FireBall=new FireBall; fireBall.x=sun.x; addChild(fireBall); fireBalls.push(fireBall); } }

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  • How to make a stack stable? Need help for an explicit resting contact scheme (2-dimensional)

    - 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 would swing! 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 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!! :) EDIT In response to Cholesky's comment about warm starting the solver and Baumgarte: Oh right, I forgot to mention! I do save the contact history and the impulse determined in this time step to be used as initial guess in the next time step. As for the Baumgarte, here's what actually happens in the code. Collision is detected when the bodies' closest distance is less than SKIN, meaning they are actually still separated. If at this moment, I used the PGS solver without Baumgarte, restitution of 0 alone would be able to stop the bodies, separated by a distance of ~SKIN, in mid-air! So this isn't right, I want to have the bodies touching each other. So I turn on the Baumgarte, where its role is actually to pull the bodies together! Weird I know, a scheme intended to push the body apart becomes useful for the reverse. Also, I found that if I increase the number of iteration to 100, stacks become much more stable, though the program becomes so slow. UPDATE Since the stack swings left and right, could it be something is wrong with my friction model? Current friction constraint: relative_tangential_velocity = 0

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  • XNA Octree with batching

    - by Alex
    I'm integrating batching in my engine. However I'm using an octree which is auto generated around my scene. Now batching renders a hole group at ones while an octree sorts out which objects that should be rendered within the camera frustum, therefore dividing the group. Batching and octree doesn't go along very well, right? Problem: The way I see it I have two options, either create batch groups based on objects who are close to one another within the octree or I can rebuild the batching matrixbuffer for the instances visible each frame. Which approach should I go with or does there exist another solution?

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  • matrix to transform unit cube to space defined by 8 arbitrary points

    - by aadster
    I asked a question relating to similar to this already, but I think this is a clearer objective of what Im trying to achieve.. or whether its possible at all! Im trying to find a transformation (matrix ideally) which would transform the 8 points of a 3d unit cube to 8 arbitrary points in space. The 8 target points have no known structure. e.g: My gut feeling is that a matrix is unable to provide this xform since the cube faces vertices can be concave.. but are there any other methods of transformation? Thanks!

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  • Enemies don't shoot. What is wrong? [closed]

    - by Bryan
    I want that every enemy shoots independently bullets. If an enemy’s bullet left the screen, the enemy can shoot a new bullet. Not earlier. But for the moment, the enemies don't shoot. Not a single bullet. I guess their is something wrong with my Enemy class, but I can't find a bug and I get no error message. What is wrong? public class Map { Texture2D myEnemy, myBullet ; Player Player; List<Enemy> enemieslist = new List<Enemy>(); List<Bullet> bulletslist = new List<Bullet>(); float fNextEnemy = 0.0f; float fEnemyFreq = 3.0f; int fMaxEnemy = 3 ; Vector2 Startposition = new Vector2(200, 200); GraphicsDeviceManager graphicsDevice; public Map(GraphicsDeviceManager device) { graphicsDevice = device; } public void Load(ContentManager content) { myEnemy = content.Load<Texture2D>("enemy"); myBullet = content.Load<Texture2D>("bullet"); Player = new Player(graphicsDevice); Player.Load(content); } public void Update(GameTime gameTime) { Player.Update(gameTime); float delta = (float)gameTime.ElapsedGameTime.TotalSeconds; for(int i = enemieslist.Count - 1; i >= 0; i--) { // Update Enemy Enemy enemy = enemieslist[i]; enemy.Update(gameTime, this.graphicsDevice, Player.playershape.Position, delta); // Try to remove an enemy if (enemy.Remove == true) { enemieslist.Remove(enemy); enemy.Remove = false; } } this.fNextEnemy += delta; //New enemy if (fMaxEnemy > 0) { if ((this.fNextEnemy >= fEnemyFreq) && (enemieslist.Count < 3)) { Vector2 enemyDirection = Vector2.Normalize(Player.playershape.Position - Startposition) * 100f; enemieslist.Add(new Enemy(Startposition, enemyDirection, Player.playershape.Position)); fMaxEnemy -= 1; fNextEnemy -= fEnemyFreq; } } } public void Draw(SpriteBatch batch) { Player.Draw(batch); foreach (Enemy enemies in enemieslist) { enemies.Draw(batch, myEnemy); } foreach (Bullet bullets in bulletslist) { bullets.Draw(batch, myBullet); } } } public class Enemy { List<Bullet> bulletslist = new List<Bullet>(); private float nextShot = 0; private float shotFrequency = 2.0f; Vector2 vPos; Vector2 vMove; Vector2 vPlayer; public bool Remove; public bool Shot; public Enemy(Vector2 Pos, Vector2 Move, Vector2 Player) { this.vPos = Pos; this.vMove = Move; this.vPlayer = Player; this.Remove = false; this.Shot = false; } public void Update(GameTime gameTime, GraphicsDeviceManager graphics, Vector2 PlayerPos, float delta) { nextShot += delta; for (int i = bulletslist.Count - 1; i >= 0; i--) { // Update Bullet Bullet bullets = bulletslist[i]; bullets.Update(gameTime, graphics, delta); // Try to remove a bullet... Collision, hit, or outside screen. if (bullets.Remove == true) { bulletslist.Remove(bullets); bullets.Remove = false; } } if (nextShot >= shotFrequency) { this.Shot = true; nextShot -= shotFrequency; } // Does the enemy shot? if ((Shot == true) && (bulletslist.Count < 1)) // New bullet { Vector2 bulletDirection = Vector2.Normalize(PlayerPos - this.vPos) * 200f; bulletslist.Add(new Bullet(this.vPos, bulletDirection, PlayerPos)); Shot = false; } if (!Remove) { this.vMove = Vector2.Normalize(PlayerPos - this.vPos) * 100f; this.vPos += this.vMove * delta; if (this.vPos.X > graphics.PreferredBackBufferWidth + 1) { this.Remove = true; } else if (this.vPos.X < -20) { this.Remove = true; } if (this.vPos.Y > graphics.PreferredBackBufferHeight + 1) { this.Remove = true; } else if (this.vPos.Y < -20) { this.Remove = true; } } } public void Draw(SpriteBatch batch, Texture2D myTexture) { if (!Remove) { batch.Draw(myTexture, this.vPos, Color.White); } } } public class Bullet { Vector2 vPos; Vector2 vMove; Vector2 vPlayer; public bool Remove; public Bullet(Vector2 Pos, Vector2 Move, Vector2 Player) { this.Remove = false; this.vPos = Pos; this.vMove = Move; this.vPlayer = Player; } public void Update(GameTime gameTime, GraphicsDeviceManager graphics, float delta) { if (!Remove) { this.vPos += this.vMove * delta; if (this.vPos.X > graphics.PreferredBackBufferWidth +1) { this.Remove = true; } else if (this.vPos.X < -20) { this.Remove = true; } if (this.vPos.Y > graphics.PreferredBackBufferHeight +1) { this.Remove = true; } else if (this.vPos.Y < -20) { this.Remove = true; } } } public void Draw(SpriteBatch spriteBatch, Texture2D myTexture) { if (!Remove) { spriteBatch.Draw(myTexture, this.vPos, Color.White); } } }

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