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  • how to calculate intersection time and place of multiple moving arcs

    - by user20733
    I have rocks orbiting moons, moons orbiting planets, planets orbiting suns, and suns orbiting black holes, and the current system could have many many layers of orbitage. the position of any object is a function of time and relative to the object it orbits. (so far so good). now I want to know for a given 2 objects(A,B), a start time and a speed, how can I work out the when and where to go. I can work out where A and B is given a time. so i just need. 1: direction to travel in from A to B(remember B is moving(not in a straight line)) 2: Time to get to b in a straight line. travel must be in a straight line with the shortest possible distance. as an extension to this question, how will i know if its better to wait, EG is it faster to stay on object A and wait for a hour when the objects may be closer, than to set off from A to B at the start. Cheers, it hurt my brain.

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  • XNA: Retrieve texture file name during runtime

    - by townsean
    I'm trying to retrieve the names of the texture files (or their locations) on a mesh. I realize that the texture file name information is not preserved when the model is loaded. I've been doing tons of searching and some experimenting but I've been met with no luck. I've gathered that I need to extended the content pipeline and store the file location in somewhere like ModelMeshPart.Tag. My problem is, even when I'm trying to make my own custom processor, I still can't figure out where the texture file name is. :( Any thoughts? Thanks! UPDATE: Okay, so I found something kind of promising. NodeContent.Identity.SourceFilename, only that returns the location of my .X model. When I go down the node tree he is always null. Then there's the ContentItem.Name property. It seems to have names of my mesh, but not my actual texture file names. :(

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  • Problem when texturing triangles using glVertexPointer()

    - by tigrou
    I'm having a problem for displaying a single quad, here is how i do : float tex_coord[] = { 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 0.0 }; //how many coords should i give ? int indexes[] = { 3, 2, 0, 0, 1, 3 } float vertexes[] = { -37, 0, 30, -38, 0, 29, -41, 0, 32, -42, 0, 31 } glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, 0, vertexes); glTexCoordPointer(2, GL_FLOAT, 0, tex_coord); glDrawElements(GL_TRIANGLES, 2, GL_UNSIGNED_INT, indices); glDisableClientState(GL_VERTEX_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); The result : (with 2 triangles) (with 4 triangles)

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  • How to determine collision direction between two rectangles?

    - by Jon
    I am trying to figure out how to determine the direction a collision occurs between two rectangles. One rectangle does not move. The other rectangle has a velocity in any direction. When a collision occurs, I want to be able to set the position of the moving rectangle to the point of impact. I seem to be stuck in determining from what direction the impact occurs. If I am moving strictly vertically or horizontally I manage great detection. But when moving in both directions at the same time, strange things happen. What is the best way to determine what direction a collision occurs between two rectangles?

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  • Calculating angle between 2 vectors

    - by Error 454
    I am working on some movement AI where there are no obstacles and movement is restricted to the XY plane. I am calculating 2 vectors: v - the direction of ship 1 w - the vector pointing from the position of ship 1 to ship 2 I am then calculating the angle between these two vectors using the standard formula: arccos( v . w / ( |v| |w| ) ) The problem I'm having is the nature of arccos only returning values between 0 and 180. This makes it impossible to determine whether I should turn left or right to face the other ship. Is there a better way to do this?

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  • Rotation, further I go from 0:0, the further the object positions around the origin while rotating

    - by Serguei Fedorov
    For some reason I am having the issue where the following code: global.spriteBatch.Draw(obj.sprite, obj.getPosition(), null, Color.White, obj.rotation, obj.center, 2f, SpriteEffects.None, 1); causes the object to rotate around the origin in such a way, as though there is an offset to the position relative to its location. The calculation for the center it correct and this happens even if I set the pivot to be the location of the object. The further I get from 0:0 the larger the radius or rotation. I am not sure what is going on here because given the following tutorial http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series2D/Rotation.php I have done the code setup correctly. Any ideas? Any help is greatly appreciated!!!

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  • How do I implement a "sliding out of / into" effect on a settings menu similar to that in Angry Birds?

    - by VictorB
    I'm trying to implement a settings menu component similar to that in Angry Birds - a button control that makes an options menu slide out of it and back into it when clicked on. I use scene2d.ui to build the UI components: a Button in a Table to implement the button control, a Table to implement the options menu, and a Stack to lay these out one on top of the other and at this moment I have the following behavior: When the user hits the button control for the first time, then the alpha of the table component is set to 1; When the user hits the button control the second time, then the alpha of the table component is set to 0; And so on. Any ideas how I can get the sliding out of and into effect on user clicks with libgdx? Similar to what Angry Birds provides. Maybe using the TweenEngine, actions, interpolations, combinations of these? Thanks in advance.

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  • Why is my primitive xna square not drawn/shown?

    - by Mech0z
    I have made this class to draw a rectangle, but I cant get it to be drawn, I have no issues displaying a 3d model created in 3dmax, but shown these primitives seems much harder I use this to create it board = new Board(Vector3.Zero, 1000, 1000, Color.Yellow); And here is the implementation using System; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Ink; using System.Windows.Input; using System.Windows.Shapes; using Quadro.Models; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; namespace Quadro { public class Board : IGraphicObject { //Private Fields private Vector3 modelPosition; private BasicEffect effect; private VertexPositionColor[] vertices; private Matrix rotationMatrix; private GraphicsDevice graphicsDevice; private Matrix cameraProjection; //Constructor public Board(Vector3 position, float length, float width, Color color) { var _color = color; vertices = new VertexPositionColor[6]; vertices[0].Position = new Vector3(position.X, position.Y, position.Z); vertices[1].Position = new Vector3(position.X, position.Y + width, position.Z); vertices[2].Position = new Vector3(position.X + length, position.Y, position.Z); vertices[3].Position = new Vector3(position.X + length, position.Y, position.Z); vertices[4].Position = new Vector3(position.X, position.Y + width, position.Z); vertices[5].Position = new Vector3(position.X + length, position.Y + width, position.Z); for(int i = 0; i < vertices.Length; i++) { vertices[i].Color = color; } initFields(); } private void initFields() { graphicsDevice = SharedGraphicsDeviceManager.Current.GraphicsDevice; effect = new BasicEffect(graphicsDevice); modelPosition = Vector3.Zero; float screenWidth = (float)graphicsDevice.Viewport.Width; float screenHeight = (float)graphicsDevice.Viewport.Height; float aspectRatio = screenWidth / screenHeight; this.cameraProjection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); this.rotationMatrix = Matrix.Identity; } //Public Methods public void Update(GameTimerEventArgs e) { } public void Draw(Vector3 cameraPosition, GameTimerEventArgs e) { Matrix cameraView = Matrix.CreateLookAt(cameraPosition, Vector3.Zero, Vector3.Up); foreach (EffectPass pass in effect.CurrentTechnique.Passes) { pass.Apply(); effect.World = rotationMatrix * Matrix.CreateTranslation(modelPosition); effect.View = cameraView; effect.Projection = cameraProjection; graphicsDevice.DrawUserPrimitives(PrimitiveType.TriangleList, vertices, 0, 2, VertexPositionColor.VertexDeclaration); } } public void Rotate(Matrix rotationMatrix) { this.rotationMatrix = rotationMatrix; } public void Move(Vector3 moveVector) { this.modelPosition += moveVector; } } }

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  • b2Body moves without stopping

    - by SentineL
    I got a quite strange bug. It is difficult to explain it in two words, but i'll try to do this in short. My b2Body has restitution, friction, density, mass and collision group. I controlling my b2Body via setting linear velocity to it (called on every iteration): (void)moveToDirection:(CGPoint)direction onlyHorizontal:(BOOL)horizontal { b2Vec2 velocity = [controlledObject getBody]-GetLinearVelocity(); double horizontalSpeed = velocity.x + controlledObject.acceleration * direction.x; velocity.x = (float32) (abs((int) horizontalSpeed) < controlledObject.runSpeed ? horizontalSpeed : controlledObject.maxSpeed * direction.x); if (!horizontal) { velocity.y = velocity.y + controlledObject.runSpeed * direction.y; } [controlledObject getBody]->SetLinearVelocity(velocity); } My floor is static b2Body, it has as restitution, friction, density, mass and same collision group in some reason, I'm setting b2Body's friction of my Hero to zero when it is moving, and returning it to 1 when he stops. When I'm pushing run button, hero runs. when i'm releasing it, he stops. All of this works perfect. On jumping, I'm setting linear velocity to my Hero: (void)jump { b2Vec2 velocity = [controlledObject getBody]->GetLinearVelocity(); velocity.y = velocity.y + [[AppDel cfg] getHeroJumpVlelocity]; [controlledObject getBody]->SetLinearVelocity(velocity); } If I'll run, jump, and release run button, while he is in air, all will work fine. And here is my problem: If I'll run, jump, and continue running on landing (or when he goes from one static body to another: there is small fall, probably), Hero will start move, like he has no friction, but he has! I checked this via beakpoints: he has friction, but I can move left of right, and he will never stop, until i'll jump (or go from one static body to another), with unpressed running button. I allready tried: Set friction to body on every iteration double-check am I setting friction to right fixture. set Linear Damping to Hero: his move slows down on gugged moveing. A little more code: I have a sensor and body fixtures in my hero: (void) addBodyFixture { b2CircleShape dynamicBox; dynamicBox.m_radius = [[AppDel cfg] getHeroRadius]; b2FixtureDef bodyFixtureDef; bodyFixtureDef.shape = &dynamicBox; bodyFixtureDef.density = 1.0f; bodyFixtureDef.friction = [[AppDel cfg] getHeroFriction]; bodyFixtureDef.restitution = [[AppDel cfg] getHeroRestitution]; bodyFixtureDef.filter.categoryBits = 0x0001; bodyFixtureDef.filter.maskBits = 0x0001; bodyFixtureDef.filter.groupIndex = 0; bodyFixtureDef.userData = [NSNumber numberWithInt:FIXTURE_BODY]; [physicalBody addFixture:bodyFixtureDef]; } (void) addSensorFixture { b2CircleShape sensorBox; sensorBox.m_radius = [[AppDel cfg] getHeroRadius] * 0.95; sensorBox.m_p.Set(0, -[[AppDel cfg] getHeroRadius] / 10); b2FixtureDef sensor; sensor.shape = &sensorBox; sensor.filter.categoryBits = 0x0001; sensor.filter.maskBits = 0x0001; sensor.filter.groupIndex = 0; sensor.isSensor = YES; sensor.userData = [NSNumber numberWithInt:FIXTURE_SENSOR]; [physicalBody addFixture:sensor]; } Here I'm tracking is hero in air: void FixtureContactListener::BeginContact(b2Contact* contact) { // We need to copy out the data because the b2Contact passed in // is reused. Squirrel *squirrel = (Squirrel *)contact->GetFixtureB()->GetBody()->GetUserData(); if (squirrel) { [squirrel addContact]; } } void FixtureContactListener::EndContact(b2Contact* contact) { Squirrel *squirrel = (Squirrel *)contact->GetFixtureB()->GetBody()->GetUserData(); if (squirrel) { [squirrel removeContact]; } } here is Hero's logic on contacts: - (void) addContact { if (contactCount == 0) [self landing]; contactCount++; } - (void) removeContact { contactCount--; if (contactCount == 0) [self flying]; if (contactCount <0) contactCount = 0; } - (void)landing { inAir = NO; acceleration = [[AppDel cfg] getHeroRunAcceleration]; [sprite stopAllActions]; (running ? [sprite runAction:[self runAction]] : [sprite runAction:[self standAction]]); } - (void)flying { inAir = YES; acceleration = [[AppDel cfg] getHeroAirAcceleration]; [sprite stopAllActions]; [self flyAction]; } here is Hero's moving logic: - (void)stop { running = NO; if (!inAir) { [sprite stopAllActions]; [sprite runAction:[self standAction]]; } } - (void)left { [physicalBody setFriction:0]; if (!running && !inAir) { [sprite stopAllActions]; [sprite runAction:[self runAction]]; } running = YES; moveingDirection = NO; [bodyControls moveToDirection:CGPointMake(-1, 0) onlyHorizontal:YES]; } - (void)right { [physicalBody setFriction:0]; if (!running && !inAir) { [sprite stopAllActions]; [sprite runAction:[self runAction]]; } running = YES; moveingDirection = YES; [bodyControls moveToDirection:CGPointMake(1, 0) onlyHorizontal:YES]; } - (void)jump { if (!inAir) { [bodyControls jump]; } } and here is my update method (called on every iteration): - (void)update:(NSMutableDictionary *)buttons { if (!isDead) { [self updateWithButtonName:BUTTON_LEFT inButtons:buttons whenPressed:@selector(left) whenUnpressed:@selector(stop)]; [self updateWithButtonName:BUTTON_RIGHT inButtons:buttons whenPressed:@selector(right) whenUnpressed:@selector(stop)]; [self updateWithButtonName:BUTTON_UP inButtons:buttons whenPressed:@selector(jump) whenUnpressed:@selector(nothing)]; [self updateWithButtonName:BUTTON_DOWN inButtons:buttons whenPressed:@selector(nothing) whenUnpressed:@selector(nothing)]; [sprite setFlipX:(moveingDirection)]; } [self checkPosition]; if (!running) [physicalBody setFriction:[[AppDel cfg] getHeroFriction]]; else [physicalBody setFriction:0]; } - (void)updateWithButtonName:(NSString *)buttonName inButtons:(NSDictionary *)buttons whenPressed:(SEL)pressedSelector whenUnpressed:(SEL)unpressedSelector { NSNumber *buttonNumber = [buttons objectForKey:buttonName]; if (buttonNumber == nil) return; if ([buttonNumber boolValue]) [self performSelector:pressedSelector]; else [self performSelector:unpressedSelector]; } - (void)checkPosition { b2Body *body = [self getBody]; b2Vec2 position = body->GetPosition(); CGPoint inWorldPosition = [[AppDel cfg] worldMeterPointFromScreenPixel:CGPointMake(position.x * PTM_RATIO, position.y * PTM_RATIO)]; if (inWorldPosition.x < 0 || inWorldPosition.x > WORLD_WIDGH / PTM_RATIO || inWorldPosition.y <= 0) { [self kill]; } }

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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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  • Mouse pointer position to screen space

    - by Ylisar
    If I have a mouse pointer position in pixels of canvas, I can easily convert it to the -1..1 range for both X & Y by lerping by dividing with canvas dimensions. However, the problem is what I should put in Z & W if I want my screen space position to be on the near plane? The step afterwards would be for me to multiply by the inverse of view-projection to take me to world space, where I easily can construct a ray from the cameras world space position.

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  • What data-structure/algorithm will allow me to send a list of key/value dictionaries using the least amount of bits?

    - by user12365
    I have server objects that have corresponding client objects. The data to be kept in sync is inside the server object's key/value dictionary. To keep the client objects in sync with the sever objects, I want the server to send the key/value dictionary every frame for each object. What data-structure/algorithm will allow me to send a list of key/value dictionaries using the least amount of bits? Bonus constraint 1: For each type of object, the values of some keys change more often than others. Bonus constraint 2: Memory usage on the server side is relatively expensive.

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  • How to achieve 'forward' movement (into the screen) using Cocos2D?

    - by lemikegao
    I'm interested in creating a 2.5D first-person shooter (like Doom) and I currently don't understand how to implement the player moving forward. The player will also be able to browse around the world (left, right, up, down) via gyroscope control. I plan to only use 2D sprites and no 3D models. My first attempt was to increase the scale of layers to make it appear as if the player was moving toward the objects but I'm not sure how to make it seem as if the player is passing around the objects (instead of running into them). If there are extensions that I should take a look at (like Cocos3D), please let me know. Thanks for the help! Note: I've only created 2D games so was hoping to get guided into the right direction

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  • XNA - 3D AABB collision detection and response

    - by fastinvsqrt
    I've been fiddling around with 3D AABB collision in my voxel engine for the last couple of days, and every method I've come up with thus far has been almost correct, but each one never quite worked exactly the way I hoped it would. Currently what I do is get two bounding boxes for my entity, one modified by the X translation component and the other by the Z component, and check if each collides with any of the surrounding chunks (chunks have their own octrees that are populated only with blocks that support collision). If there is a collision, then I cast out rays into that chunk to get the shortest collision distance, and set the translation component to that distance if the component is greater than the distance. The problem is that sometimes collisions aren't even registered. Here's a video on YouTube that I created showing what I mean. I suspect the problem may be with the rays that I cast to get the collision distance not being where I think they are, but I'm not entirely sure what would be wrong with them if they are indeed the problem. Here is my code for collision detection and response in the X direction (the Z direction is basically the same): // create the XZ offset vector Vector3 offsXZ = new Vector3( ( _translation.X > 0.0f ) ? SizeX / 2.0f : ( _translation.X < 0.0f ) ? -SizeX / 2.0f : 0.0f, 0.0f, ( _translation.Z > 0.0f ) ? SizeZ / 2.0f : ( _translation.Z < 0.0f ) ? -SizeZ / 2.0f : 0.0f ); // X physics BoundingBox boxx = GetBounds( _translation.X, 0.0f, 0.0f ); if ( _translation.X > 0.0f ) { foreach ( Chunk chunk in surrounding ) { if ( chunk.Collides( boxx ) ) { float dist = GetShortestCollisionDistance( chunk, Vector3.Right, offsXZ ) - 0.0001f; if ( dist < _translation.X ) { _translation.X = dist; } } } } else if ( _translation.X < 0.0f ) { foreach ( Chunk chunk in surrounding ) { if ( chunk.Collides( boxx ) ) { float dist = GetShortestCollisionDistance( chunk, Vector3.Left, offsXZ ) - 0.0001f; if ( dist < -_translation.X ) { _translation.X = -dist; } } } } And here is my implementation for GetShortestCollisionDistance: private float GetShortestCollisionDistance( Chunk chunk, Vector3 rayDir, Vector3 offs ) { int startY = (int)( -SizeY / 2.0f ); int endY = (int)( SizeY / 2.0f ); int incY = (int)Cube.Size; float dist = Chunk.Size; for ( int y = startY; y <= endY; y += incY ) { // Position is the center of the entity's bounding box Ray ray = new Ray( new Vector3( Position.X + offs.X, Position.Y + offs.Y + y, Position.Z + offs.Z ), rayDir ); // Chunk.GetIntersections(Ray) returns Dictionary<Block, float?> foreach ( var pair in chunk.GetIntersections( ray ) ) { if ( pair.Value.HasValue && pair.Value.Value < dist ) { dist = pair.Value.Value; } } } return dist; } I realize some of this code can be consolidated to help with speed, but my main concern right now is to get this bit of physics programming to actually work.

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  • How much time it will take to learn 3ds Max

    - by Mirror51
    I am not a 3d developer but i want to lean 3ds max just for simple house building with 2-3 rooms. Actually i don't want to develop from scratch . What i really want to do is get the existing models of homes , rooms , hotels from the internet and add my name there or my photo there , just for fun . SO i want to know that how much time do u think it will take me to that sort of stuff. Its not my career but just hobby . If its going to take longer time , then i don't want to waste but i can get going in one week or so that will go good but i want to ask from experience developers thanks

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  • Jumping over non-stationary objects without problems ... 2-D platformer ... how could this be solved? [on hold]

    - by help bonafide pigeons
    You know this problem ... take Super Mario Bros. for example. When Mario/Luigi/etc. comes in proximity with a nearing pipe image an invisible boundary setter must prevent him from continuing forward movement. However, when you jump and move both x and y you are coordinately moving in two dimensions at an exact time. When nearing the pipe in mid-air as you are falling, i.e. implementation of gravity in the computer program "pulling" the image back down, and you do not want them to get "stuck" in both falling and moving. That problem is solved, but how about this one: The player controlling the ball object is attempting to jump and move rightwards over the non-stationary block that moves up and down. How could we measure its top and lower x+y components to determine the safest way for the ball to accurately either fall back down, or catch the ledge, or get pushed down under it, etc.?

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  • Why isn't one of the constant buffers being loaded inside the shader?

    - by Paul Ske
    I however got the model to load under tessellation; only problem is that one of the constant buffers aren't actually updating the shader's tessellation factor inside the hullshader. I created a messagebox at the rendering point so I know for sure the tessellation factor is assigned to the dynamic constant buffer. Inside the shader code where it says .Edges[1] = tessellationAmount; the tessellationAmount is suppose to be sent from the dynamic buffer to the shader. Otherwise it's just a plain box. In better explanation; there's a matrixBuffer, cameraBuffer, TessellationBuffer for constant. There's a multiBuffer array that assigns the matrix, camera, tesselation. So, when I set the Hull Shader, PixelShader, VertexShader, DomainShader it gets assigned by the multibuffer. E.G. devcon-HSSetConstantBuffers(0,3,multibuffer); The only way around the whole ideal would be to go in the shader and change how much the edges tessellate and inside the edges as well with the same number. My question is why wouldn't the tessellationBuffer not work in the shader?

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  • 3D open source physics engine suitable for mobile platforms (Android and iOS)

    - by lukeluke
    I have made some research and found that bullet, ode, newton and some others are open source physics engines that should be portable enough (but I have never tried to comile/use anyone of them on phones). I am writing my games for mobile platforms in C++, so the engine should be C or C++. I need a fast engine, since mobile platforms have limited resources. I need a free engine. A good design would be nice to have too. What engine is best suited for my task? What I really would like to hear from you is your direct experience. Documentation and support (for example, forum or an IRC channel) is a really important aspect to take into consideration.

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  • How do 2D physics engines solve the problem of resolving collisions along tiled walls/floors in non-grid-based worlds?

    - by ssb
    I've been working on implementing my SAT algorithm which has been coming along well, but I've found that I'm at a wall when it comes to its actual use. There are plenty of questions regarding this issue on this site, but most of them either have no clear, good answer or have a solution based on checking grid positions. To restate the problem that I and many others are having, if you have a tiled surface, like a wall or a floor, consisting of several smaller component rectangles, and you traverse along them with another rectangle with force being applied into that structure, there are cases where the object gets caught on a false collision on an edge that faces the inside of the shape. I have spent a lot of time thinking about how I could possibly solve this without having to resort to a grid-based system, and I realized that physics engines do this properly. What I want to know is how they do this. What do physics engines do beyond basic SAT that allows this kind of proper collision resolution in complex environments? I've been looking through the source code to Box2D trying to find out how they do it but it's not quite as easy as looking at a Collision() method. I think I'm not good enough at physics to know what they're doing mathematically and not good enough at programming to know what they're doing programmatically. This is what I aim to fix.

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  • Glm Vector Transformations [duplicate]

    - by Reanimation
    This question already has an answer here: Car-like Physics - Basic Maths to Simulate Steering 2 answers I have a cube rendered on the screen which represents a car (or similar). Using Projection/Model matrices and Glm I am able to move it back and fourth along the axes and rotate it left or right. I'm having trouble with the vector mathematics to make the cube move forwards no matter which direction it's current orientation is. (ie. if I would like, if it's rotated right 30degrees, when it's move forwards, it travels along the 30degree angle on a new axes). I hope I've explained that correctly. This is what I've managed to do so far in terms of using glm to move the cube: glm::vec3 vel; //velocity vector void renderMovingCube(){ glUseProgram(movingCubeShader.handle()); GLuint matrixLoc4MovingCube = glGetUniformLocation(movingCubeShader.handle(), "ProjectionMatrix"); glUniformMatrix4fv(matrixLoc4MovingCube, 1, GL_FALSE, &ProjectionMatrix[0][0]); glm::mat4 viewMatrixMovingCube; viewMatrixMovingCube = glm::lookAt(camOrigin, camLookingAt, camNormalXYZ); vel.x = cos(rotX); vel.y=sin(rotX); vel*=moveCube; //move cube ModelViewMatrix = glm::translate(viewMatrixMovingCube,globalPos*vel); //bring ground and cube to bottom of screen ModelViewMatrix = glm::translate(ModelViewMatrix, glm::vec3(0,-48,0)); ModelViewMatrix = glm::rotate(ModelViewMatrix, rotX, glm::vec3(0,1,0)); //manually turn glUniformMatrix4fv(glGetUniformLocation(movingCubeShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); //pass matrix to shader movingCube.render(); //draw glUseProgram(0); } keyboard input: void keyboard() { char BACKWARD = keys['S']; char FORWARD = keys['W']; char ROT_LEFT = keys['A']; char ROT_RIGHT = keys['D']; if (FORWARD) //W - move forwards { globalPos += vel; //globalPos.z -= moveCube; BACKWARD = false; } if (BACKWARD)//S - move backwards { globalPos.z += moveCube; FORWARD = false; } if (ROT_LEFT)//A - turn left { rotX +=0.01f; ROT_LEFT = false; } if (ROT_RIGHT)//D - turn right { rotX -=0.01f; ROT_RIGHT = false; } Where am I going wrong with my vectors? I would like change the direction of the cube (which it does) but then move forwards in that direction.

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  • 3D array in a 2D array

    - by Smallbro
    Currently I've been using a 3D array for my tiles in a 2D world but the 3D side comes in when moving down into caves and whatnot. Now this is not memory efficient and I switched over to a 2D array and can now have much larger maps. The only issue I'm having now is that it seems that my tiles cannot occupy the same space as a tile on the same z level. My current structure means that each block has its own z variable. This is what it used to look like: map.blockData[x][y][z] = new Block(); however now it works like this map.blockData[x][y] = new Block(z); I'm not sure why but if I decide to use the same space on say the floor below it wont allow me to. Does anyone have any ideas on how I can add a z-axis to my 2D array? I'm using java but I reckon the concept carries across different languages.

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  • Symfony2 Forms: is it possible to bind a form in an "unconventional way"?

    - by DonCallisto
    Imagine this scenario: in our company there is an employee that "play" around graphic,css,html and so on. Our new project will born under symfony2 so we're trying some silly - but "real" - stuff (like authentication from db, submit data from a form and persist it to db and so on..) The problem As far i know, learnt from symfony2 "book" that i found on the site (you can find it here), there is an "automated" way for creating and rendering forms: 1) Build the form up into a controller in this way $form = $this->createFormBuilder($task) ->add('task','text'), ->add('dueDate','date'), ->getForm(); return $this->render('pathToBundle:Controller:templateTwig', array('form'=>$form->createview()); 2) Into templateTwig render the template {{ form_widget(form) }} // or single rows method 3) Into a controller (the same that have a route where you can submit data), take back submitted information if($rquest->getMethod()=='POST'){ $form->bindRequest($request); /* and so on */ } Return to scenario Our graphic employee don't want to access controllers, write php and other stuff like those. So he'll write a twig template with a "unconventional" (from symfony2 point of view, but conventional from HTML point of view) method: /* into twig template */ <form action="{{ path('SestanteUserBundle_homepage') }}" method="post" name="userForm"> <div> USERNAME: <input type="text" name="user_name" value="{{ user.username}}"/> </div> <div> EMAIL: <input type="text" name="user_mail" value="{{ user.email }}"/> </div> <input type="hidden" name="user_id" value="{{ id }}" /> <input type="submit" value="modifica i dati"> </form> Now, if into the controller that handle the submission of data we do something like that public function indexAction(Request $request) { if($request->getMethod() == 'POST'){ // sono arrivato per via di un submit, quindi devo modificare i dati prima di farli vedere a video $defaultData = array('message'=>'ho visto questa cosa in esempio, ma non capisco se posso farne a meno'); $form = $this->createFormBuilder($defaultData) ->add('user_name','text') ->add('user_mail','email') ->add('user_id','integer') ->getForm(); $form->bindRequest($request); //bindo la form ad una request $data = $form->getData(); //mi aspetto un'array chiave=>valore /* .... */ We expected that $data will contain an array with key,value from the submitted form. We found that it isn't true. After googling for a while and try with other "bad" ideas, we're frozen into that. So, if you have a "graphic office" that can't handle directly php code, how can we interface from form(s) to controller(s) ? UPDATE It seems that Symfony2 use a different convention for form's field name and lookup once you've submitted that. In particular, if my form's name is addUser and a field is named userName, the field's name will be AddUser[username] so maybe it have a "dynamic" lookup method that will extract form's name, field's name, concat them and lookup for values. Is it possible?

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  • How to move a rectangle properly?

    - by bodycountPP
    I recently started to learn OpenGL. Right now I finished the first chapter of the "OpenGL SuperBible". There were two examples. The first had the complete code and showed how to draw a simple triangle. The second example is supposed to show how to move a rectangle using SpecialKeys. The only code provided for this example was the SpecialKeys method. I still tried to implement it but I had two problems. In the previous example I declared and instaciated vVerts in the SetupRC() method. Now as it is also used in the SpecialKeys() method, I moved the declaration and instantiation to the top of the code. Is this proper c++ practice? I copied the part where vertex positions are recalculated from the book, but I had to pick the vertices for the rectangle on my own. So now every time I press a key for the first time the rectangle's upper left vertex is moved to (-0,5:-0.5). This ok because of GLfloat blockX = vVerts[0]; //Upper left X GLfloat blockY = vVerts[7]; // Upper left Y But I also think that this is the reason why my rectangle is shifted in the beginning. After the first time a key was pressed everything works just fine. Here is my complete code I hope you can help me on those two points. GLBatch squareBatch; GLShaderManager shaderManager; //Load up a triangle GLfloat vVerts[] = {-0.5f,0.5f,0.0f, 0.5f,0.5f,0.0f, 0.5f,-0.5f,0.0f, -0.5f,-0.5f,0.0f}; //Window has changed size, or has just been created. //We need to use the window dimensions to set the viewport and the projection matrix. void ChangeSize(int w, int h) { glViewport(0,0,w,h); } //Called to draw the scene. void RenderScene(void) { //Clear the window with the current clearing color glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT); GLfloat vRed[] = {1.0f,0.0f,0.0f,1.0f}; shaderManager.UseStockShader(GLT_SHADER_IDENTITY,vRed); squareBatch.Draw(); //perform the buffer swap to display the back buffer glutSwapBuffers(); } //This function does any needed initialization on the rendering context. //This is the first opportunity to do any OpenGL related Tasks. void SetupRC() { //Blue Background glClearColor(0.0f,0.0f,1.0f,1.0f); shaderManager.InitializeStockShaders(); squareBatch.Begin(GL_QUADS,4); squareBatch.CopyVertexData3f(vVerts); squareBatch.End(); } //Respond to arrow keys by moving the camera frame of reference void SpecialKeys(int key,int x,int y) { GLfloat stepSize = 0.025f; GLfloat blockSize = 0.5f; GLfloat blockX = vVerts[0]; //Upper left X GLfloat blockY = vVerts[7]; // Upper left Y if(key == GLUT_KEY_UP) { blockY += stepSize; } if(key == GLUT_KEY_DOWN){blockY -= stepSize;} if(key == GLUT_KEY_LEFT){blockX -= stepSize;} if(key == GLUT_KEY_RIGHT){blockX += stepSize;} //Recalculate vertex positions vVerts[0] = blockX; vVerts[1] = blockY - blockSize*2; vVerts[3] = blockX + blockSize * 2; vVerts[4] = blockY - blockSize *2; vVerts[6] = blockX+blockSize*2; vVerts[7] = blockY; vVerts[9] = blockX; vVerts[10] = blockY; squareBatch.CopyVertexData3f(vVerts); glutPostRedisplay(); } //Main entry point for GLUT based programs int main(int argc, char** argv) { //Sets the working directory. Not really needed gltSetWorkingDirectory(argv[0]); //Passes along the command-line parameters and initializes the GLUT library. glutInit(&argc,argv); //Tells the GLUT library what type of display mode to use, when creating the window. //Double buffered window, RGBA-Color mode,depth-buffer as part of our display, stencil buffer also available glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH|GLUT_STENCIL); //Window size glutInitWindowSize(800,600); glutCreateWindow("MoveRect"); glutReshapeFunc(ChangeSize); glutDisplayFunc(RenderScene); glutSpecialFunc(SpecialKeys); //initialize GLEW library GLenum err = glewInit(); //Check that nothing goes wrong with the driver initialization before we try and do any rendering. if(GLEW_OK != err) { fprintf(stderr,"Glew Error: %s\n",glewGetErrorString); return 1; } SetupRC(); glutMainLoop(); return 0; }

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  • Drawing Shape in DebugView (Farseer)

    - by keyvan kazemi
    As the title says, I need to draw a shape/polygon in Farseer using debugview. I have this piece of code which converts a Texture to polygon: //load texture that will represent the tray trayTexture = Content.Load<Texture2D>("tray"); //Create an array to hold the data from the texture uint[] data = new uint[trayTexture.Width * trayTexture.Height]; //Transfer the texture data to the array trayTexture.GetData(data); //Find the vertices that makes up the outline of the shape in the texture Vertices verts = PolygonTools.CreatePolygon(data, trayTexture.Width, false); //Since it is a concave polygon, we need to partition it into several smaller convex polygons _list = BayazitDecomposer.ConvexPartition(verts); Vector2 vertScale = new Vector2(ConvertUnits.ToSimUnits(1)); foreach (Vertices verti in _list) { verti.Scale(ref vertScale); } tray = BodyFactory.CreateCompoundPolygon(MyWorld, _list, 10); Now in DebugView I guess I have to use "DrawShape" method which requires: DrawShape(Fixture fixture, Transform xf, Color color) My question is how can I get the variables needed for this method, namely Fixture and Transform?

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  • Render 2D textures on a 3D object's face

    - by www.Sillitoy.com
    I am not familiar with 3D graphics, and I'd like to know the right way to render some 2D figures on different points of a wider face of a 3D object. My 3D object is just a cube representing a poker table. I have a 2D png for players' placeholders, and I'd like to render these figures on the 3D object where needed. An alternative solution would be to render the whole face with a big picture containing all the placeholders figures. However, it would be a waste of memory and thus less efficient. What do you suggest?

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