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  • Offset Forward vector of object based on Rotation

    - by Taylor
    I'm using the Bullet 3D physics engine in a iOS application running openGL ES 1.1 Currently I'm accepting info from the gyroscope to allow the user to "look around" a 3d world that follows a bouncing ball (note: it only takes in the yaw to look around 360 degrees). Im also accepting information from the accelerometer based on the tilt to push the ball. As of right now, to move forward, the user tilts the devise forward (using the accelerometer); to move to the right, the user tilts the devise to the right and so on. The forward vector is currently along it's local Z-axis. The problem is that I want to change the ball bounce based on where the user has changed the view. If I change the view, the ball bounces in the fixed direction. I want to change the forward facing direction so that when a user changes the view (say to the look at the right of the world, the user rotates the device), tilting the devise forward will result in a forward force in that direction. Basically, I want the forward vector to take the rotation into consideration. Sorry if I didn't explain the issue well enough, its kind of confusing to write down.

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  • Problems using easing equations in C# XNA

    - by codinghands
    I'm having some trouble using the easing equations suggested by Robert Penner for ActionScript (http://www.robertpenner.com/easing/, and a Flash demo here) in my C# XNA game. Firstly, what is the definition of the following variables passed in as arguments to each equation? float t, float b, float c, float d I'm currently calculating the new X position of a sprite in the Update() loop, however even for the linear tween equation I'm getting some odd results. I'm using the following values: float t = gameTime.TotalGameTime.TotalMilliseconds; float d = 8000f; float b = x.Position.X; float c = (ScreenManager.Game.GraphicsDevice.Viewport.Width >> 1) - (x.Position.X + x.frameSize.X / 2); And this equation for linear easing: float val = c*t/d + b;

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  • Need to make animation whereby the character shatters into a bunch of pieces

    - by theprojectabot
    I would like to take a 3d character model, cut out a bunch of shapes (or a bunch of triangles in the shape of the pieces I want) and then have the pieces separate from each other at the beginning of the animation and fall apart with gravity so it looks like the model is falling apart in shattered pieces. Is there a way to run a script on a mesh, cut out these pieces, instantiate all of them as separate models and then run gravity on them during the simulation?

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  • How do I render an animation where some frames appear twice?

    - by hustlerinc
    I am animating a sprite. The sprite has 7 different frames, but the animation is 10 frames long. This is because 3 of the original frames appear twice in the animation: 3 -> 4 -> 5 -> 6 -> 4 -> 3 -> 2 -> 1 -> 0 -> 2 Frames 2, 3 and 4 appear twice. This avoids having to store duplicate frames in the spritesheet. How can I render the animation in this sequence with repeated frames?

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  • Coordinate spaces and transformation matrices

    - by Belgin
    I'm trying to get an object from object space, into projected space using these intermediate matrices: The first matrix (I) is the one that transforms from object space into inertial space, but since my object is not rotated or translated in any way inside the object space, this matrix is the 4x4 identity matrix. The second matrix (W) is the one that transforms from inertial space into world space, which is just a scale transform matrix of factor a = 14.1 on all coordinates, since the inertial space origin coincides with the world space origin. /a 0 0 0\ W = |0 a 0 0| |0 0 a 0| \0 0 0 1/ The third matrix (C) is the one that transforms from world space, into camera space. This matrix is a translation matrix with a translation of (0, 0, 10), because I want the camera to be located behind the object, so the object must be positioned 10 units into the z axis. /1 0 0 0\ C = |0 1 0 0| |0 0 1 10| \0 0 0 1/ And finally, the fourth matrix is the projection matrix (P). Bearing in mind that the eye is at the origin of the world space and the projection plane is defined by z = 1, the projection matrix is: /1 0 0 0\ P = |0 1 0 0| |0 0 1 0| \0 0 1/d 0/ where d is the distance from the eye to the projection plane, so d = 1. I'm multiplying them like this: (((P x C) x W) x I) x V, where V is the vertex' coordinates in column vector form: /x\ V = |y| |z| \1/ After I get the result, I divide x and y coordinates by w to get the actual screen coordinates. Apparenly, I'm doing something wrong or missing something completely here, because it's not rendering properly. Here's a picture of what is supposed to be the bottom side of the Stanford Dragon: Also, I should add that this is a software renderer so no DirectX or OpenGL stuff here.

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  • Line Intersection from parametric equation

    - by Sidar
    I'm sure this question has been asked before. However, I'm trying to connect the dots by translating an equation on paper into an actual function. I thought It would be interesting to ask here instead on the Math sites (since it's going to be used for games anyway ). Let's say we have our vector equation : x = s + Lr; where x is the resulting vector, s our starting point/vector. L our parameter and r our direction vector. The ( not sure it's called like this, please correct me ) normal equation is : x.n = c; If we substitute our vector equation we get: (s+Lr).n = c. We now need to isolate L which results in L = (c - s.n) / (r.n); L needs to be 0 < L < 1. Meaning it needs to be between 0 and 1. My question: I want to know what L is so if I were to substitute L for both vector equation (or two lines) they should give me the same intersection coordinates. That is if they intersect. But I can't wrap my head around on how to use this for two lines and find the parameter that fits the intersection point. Could someone with a simple example show how I could translate this to a function/method?

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  • Numbers not adding up? (What am I not understanding here?) [closed]

    - by Milo
    I have the following output: Short version: The last numbers on the S= lines increase by H and SHOULD theoretically be linearly decreasing, ex: -285,-290,-295...but the fourth one jumps to -252. Yet, every other number is linearly increasing. Why is that and how could I fix that? To explain the numbers, it comes from slider value changed. I have a slider whose value is used to generate the float on the next line. Everything should be growing linearly here. This value is used to determine the size of a flow layout and it is also used in conjunction with a scrollbar. But basically I have a background for the flow layout and that number is the start location for rendering it. The numbers should linearly change to create a smooth transition but when that one jumps, it looks weird on screen and I dont understand why the numbers are jumping every X slider value changes. Mathematically what could be causing this? Here is the code for rendering the background and the function that is called when value changes: void LobbyTableManager::renderBG( GraphicsContext* g, agui::Rectangle& absRect, agui::Rectangle& childRect ) { float scale = 0.35f; int w = m_bgSprite->getWidth() * getTableScale() * scale; int h = m_bgSprite->getHeight() * getTableScale() * scale; int numX = ceil(absRect.getWidth() / (float)w) + 2; int numY = ceil(absRect.getHeight() / (float)h) + 2; int startY = childRect.getY(); int numAttempts = 0; while(startY + h < absRect.getY() && numAttempts < 1000) { startY += h; if(moo) { std::cout << startY << ","; } numAttempts++; } g->holdDrawing(); for(int i = 0; i < numX; ++i) { for(int j = 0; j < numY; ++j) { g->drawScaledSprite(m_bgSprite,0,0,m_bgSprite->getWidth(),m_bgSprite->getHeight(), absRect.getX() + (i * w) + (offsetX),absRect.getY() + (j * h) + startY,w,h,0); } } g->unholdDrawing(); g->setClippingRect(cx,cy,cw,ch); } void LobbyTableManager::setTableScale( float scale ) { scale += 0.3f; scale *= 2.0f; float scrollRel = m_vScroll->getRelativeValue(); setScale(scale); rescaleTables(); resizeFlow(); updateScrollBars(); float newVal = scrollRel * m_vScroll->getMaxValue(); m_vScroll->setValue(newVal); } void LobbyTableManager::valueChanged( agui::VScrollBar* source,int val ) { m_flow->setLocation(0,-val); } Any insight on mathematically why the anomaly might happen every Nth time would be helpful. I just dont understand why if every number linearly increates it jumps from -295 to -252! Thanks

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  • How do I draw a scrolling background?

    - by droidmachine
    How can I draw background tile in my 2D side-scrolling game? Is that loop logical for OpenGL es? My tile 2400x480. Also I want to use parallax scrolling for my game. batcher.beginBatch(Assets.background); for(int i=0; i<100; i++) batcher.drawSprite(0+2400*i, 240, 2400, 480, Assets.backgroundRegion); batcher.endBatch(); UPDATE And thats my onDrawFrame.I'm sending deltaTime for fps control. public void onDrawFrame(GL10 gl) { GLGameState state = null; synchronized(stateChanged) { state = this.state; } if(state == GLGameState.Running) { float deltaTime = (System.nanoTime()-startTime) / 1000000000.0f; startTime = System.nanoTime(); screen.update(deltaTime); screen.present(deltaTime); } if(state == GLGameState.Paused) { screen.pause(); synchronized(stateChanged) { this.state = GLGameState.Idle; stateChanged.notifyAll(); } } if(state == GLGameState.Finished) { screen.pause(); screen.dispose(); synchronized(stateChanged) { this.state = GLGameState.Idle; stateChanged.notifyAll(); } } }

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  • I want to learn to program in SDL C++where do i start? I want to learn only what i need to to start making 2d games [on hold]

    - by user2644399
    Lazyfoo of Lazyfoo.net of the SDL 2d tutorial wrote that in order for me to start game programming in SDL, I need to know these concepts well; Operators, Controls, Loops, Functions, Structures, Arrays, References, Pointers, Classes, Objects how to use a template and Bitwise and/or. I want to know the fastest way to learn as much as I need of basic c++ that would allow me to make 2d games. Thanks in advance.

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  • Using elapsed time for SlowMo in XNA

    - by Dave Voyles
    I'm trying to create a slow-mo effect in my pong game so that when a player is a button the paddles and ball will suddenly move at a far slower speed. I believe my understanding of the concepts of adjusting the timing in XNA are done, but I'm not sure of how to incorporate it into my design exactly. The updates for my bats (paddles) are done in my Bat.cs class: /// Controls the bat moving up the screen /// </summary> public void MoveUp() { SetPosition(Position + new Vector2(0, -moveSpeed)); } /// <summary> /// Controls the bat moving down the screen /// </summary> public void MoveDown() { SetPosition(Position + new Vector2(0, moveSpeed)); } /// <summary> /// Updates the position of the AI bat, in order to track the ball /// </summary> /// <param name="ball"></param> public virtual void UpdatePosition(Ball ball) { size.X = (int)Position.X; size.Y = (int)Position.Y; } While the rest of my game updates are done in my GameplayScreen.cs class (I'm using the XNA game state management sample) Class GameplayScreen { ........... bool slow; .......... public override void Update(GameTime gameTime, bool otherScreenHasFocus, bool coveredByOtherScreen) base.Update(gameTime, otherScreenHasFocus, false); if (IsActive) { // SlowMo Stuff Elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds; if (Slowmo) Elapsed *= .8f; MoveTimer += Elapsed; double elapsedTime = gameTime.ElapsedGameTime.TotalMilliseconds; if (Keyboard.GetState().IsKeyDown(Keys.Up)) slow = true; else if (Keyboard.GetState().IsKeyDown(Keys.Down)) slow = false; if (slow == true) elapsedTime *= .1f; // Updating bat position leftBat.UpdatePosition(ball); rightBat.UpdatePosition(ball); // Updating the ball position ball.UpdatePosition(); and finally my fixed time step is declared in the constructor of my Game1.cs Class: /// <summary> /// The main game constructor. /// </summary> public Game1() { IsFixedTimeStep = slow = false; } So my question is: Where do I place the MoveTimer or elapsedTime, so that my bat will slow down accordingly?

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  • Issues implementing arcball viewer

    - by Pris
    My scene has a simple cube, and a camera built with the lookAt function (I'm using OpenGL). The scene renders fine, and I'm sure I have my model/view/projection matrices set up correctly. Now I'm trying to implement arcball rotation for my camera, but I'm having some trouble. I've got it down to calculating the angle/axis rotation for a virtual sphere in normalized screen coordinates. That means when I move my mouse left to right, I get an angle around the Y axis... and moving my mouse up/down will get me an angle about X. I'm not sure where to go from here -- what do I need to do with my axis so I can apply the angle to simulate camera rotation about its viewpoint? If I try directly applying the axis/angle rotation the camera/view transform I get what you'd expect. The view is rotated about the world axes which the mouse moving over the virtual sphere on the screen corresponds to. So if I move the mouse up/down the view rotates about the world's X axis (what I get reminds me of a first-person view)... but this isn't what I want. I think I need the axis I get to be transformed so it passes through the camera viewpoint and is oriented correct in reference to the camera... but I don't know if that's right or how to do that.

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  • How do you prevent inflation in a virtual economy?

    - by Tetrad
    With your typical MMORPG, players can usually farm the world for raw materials essentially forever. Monsters/mineral veins/etc are usually on some respawn timer so, other than time, there really isn't a good way to limit the amount of new currency entering the system. So that really only leaves money sinks to try to take money out of the system. What are some strategies to prevent inflation of the in-game currency?

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  • How can I clear explosions in my function?

    - by hustlerinc
    Hi I have a function to place bombs, and a for loop that places explosions on the tiles where possible. My problem is that I can't remove the explosions after a while. I've tried everything I can come up with so now I turn here as a last resort. The function looks like this: function Bomb(){ var placebomb = false; if(placeBomb && player.bombs != 0){ map[player.Y][player.X].object = 2; var bombX = player.X; var bombY = player.Y; placeBomb = false; player.bombs--; setTimeout(explode, 3000); } function explode(){ var explodeNorth = true; var explodeEast = true; var explodeSouth = true; var explodeWest = true; map[bombY][bombX].explosion = 1; delete map[bombY][bombX].object; for(i=0;i<=player.bombRadius;i++){ if(explodeNorth && map[bombY-i][bombX]){ if(!map[bombY-i][bombX].wall){ if(!map[bombY-i][bombX].object){ map[bombY-i][bombX].explosion = 1; } else var explodeNorth = false; delete map[bombY-i][bombX].object; map[bombY-i][bombX].explosion = 1; } else var explodeNorth = false; } if(explodeEast && map[bombY][bombX+i]){ if(!map[bombY][bombX+i].wall){ if(!map[bombY][bombX+i].object){ map[bombY][bombX+i].explosion = 1; } else var explodeEast = false; delete map[bombY][bombX+i].object; map[bombY][bombX+i].explosion = 1; } else var explodeEast = false; } if(explodeSouth && map[bombY+i][bombX]){ if(!map[bombY+i][bombX].wall){ if(!map[bombY+i][bombX].object){ map[bombY+i][bombX].explosion = 1; } else var explodeSouth = false; delete map[bombY+i][bombX].object; map[bombY+i][bombX].explosion = 1; } else var explodeSouth = false; } if(explodeWest && map[bombY][bombX-i]){ if(!map[bombY][bombX-i].wall){ if(!map[bombY][bombX-i].object){ map[bombY][bombX-i].explosion = 1; } else var explodeWest = false; delete map[bombY][bombX-i].object; map[bombY][bombX-i].explosion = 1; } else var explodeWest = false; } } player.bombs++; } } If anyone can think of a good way to remove the explosion after a delay please help.

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  • Find Nearest Object

    - by ultifinitus
    I have a fairly sizable game engine created, and I'm adding some needed features, such as this, how do I find the nearest object from a list of points? In this case, I could simply use the Pythagorean theorem to find the distance, and check the results. I know I can't simply add x and y, because that's the distance to the object, if you only took right angle turns. However I'm wondering if there's something else I could do? I also have a collision system, where essentially I turn objects into smaller objects on a smaller grid, kind of like a minimap, and only if objects exist in the same gridspace do I check for collisions, I could do the same thing, only make the gridspace larger to check for closeness. (rather than checking every. single. object) however that would take additional setup in my base class and clutter up the already cluttered object. TL;DR Question: Is there something efficient and accurate that I can use to detect which object is closest, based on a list of points and sizes?

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  • Making efficeint voxel engines using "chunks"

    - by Wardy
    Concept I'm currently looking in to how voxel engines work with a view to possibly making one myself. I see a lot of stuff like this ... https://sites.google.com/site/letsmakeavoxelengine/home/chunks ... which talks about how to go about reducing the draw calls. What I can't seem to understand is how it actually saves draw call counts on the basis of the logic being something like this ... Without chunks foreach voxel in myvoxels DrawIfVisible() With Chunks foreach chunk in mychunks DrawIfVisible() which then does ... foreach voxel in myvoxels DrawIfVisible() So surely you saved nothing ?!?! You still make a draw call for each visible voxel do you not? A visible voxel needs a draw call in either scenario. The only real saving I can see is that the logic that evaluates a chunk will be able to determine if a large number of voxels are visible or not effectively saving a bit of "is this chunk visible" cpu time. But it's the draw calls that interest me ... The fewer of those, the faster the application. EDIT: In case it makes any difference I will probably be using XNA (DX not OpenGL) for my engine so don't consider my choice of example in the link above my choice of technology. But this question is such that I doubt it would matter.

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  • Arranging Gizmos in Unity 3D [on hold]

    - by Simran kaur
    I have this arrangement of Gizmos which was handed over to me. ! 1. How do I get it? I have read the documentation but I could get it as shown. I have basically track or lane that is coming towards the camera by moving towards negative z. I am moving lanes so that it appears as if cars are moving, The roads need to be rotated by 90 degrees otherwise they appear to move towards the upper end of the screen and that too parellely.Why exactly is that?

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  • OpenGL Vertex Attributes - Normalisation

    - by Daniel
    Alas, I have searched, and have found no definitive answer. When would you normalize the vertex data in OpenGL using the following command: glVertexAttribPointer(index, size, type, normalize, stride, pointer); I.e when would normalize == GL_TRUE; what situations, and why would you choose to let the GPU do the calculations instead of preprocessing it? All examples I have ever seen, have this set to GL_FALSE; and I cannot personally see a use for it. But Khronos aren't stupid, so it must be there for something useful (and probably common).

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  • Big level objects collision system for 2d game

    - by Aristarhys
    I read many variants today and get some knowledge in general, so here is a steps of mine thoughts in pictures (horrible paint.net ones). We need to develop grid system, so we check only thing near, perform simple check to cut out deep check, and at - last deep check like per-pixel collision check. Step 1 - Let p1, p2 are some sprites lets first just check with circle collision - because large distance between p1, p2 this fails and of course so we don't need test more deeply. But if we have not 2, but 20 objects, why we need to even circle test something so far outside of our view. Step 2 - Add basic column system, now we don't bother with p2 if it's in a column far from p1 column, so we even don't do circle test. But p3 is in the same col, so let do circle test, which of course will fail. Step 3 - Lets improve column system to the grid system with grid cell size just like p1, p2, p3 collision boxes, so we cut out things much top or below p1. And this is all great until comes BIG OBJs which is some kind of platforms. They are much bigger then grid cell. Circle test for will be successful, but deep check for whole big obj will fail And that the part I can't get. How do I store the grid position of big object? Like 4 grid coords for big object vertexes? And if one of them close to p1 do circle check for centre of big object then a deep one if succeed? Am I do it wrong? My possible solution:

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  • What kind of physics to choose for our arcade 3D MMO?

    - by Nick
    We're creating an action MMO using Three.js (WebGL) with an arcadish feel, and implementing physics for it has been a pain in the butt. Our game has a terrain where the character will walk on, and in the future 3D objects (a house, a tree, etc) that will have collisions. In terms of complexity, the physics engine should be like World of Warcraft. We don't need friction, bouncing behaviour or anything more complex like joints, etc. Just gravity. I have managed to implement terrain physics so far by casting a ray downwards, but it does not take into account possible 3D objects. Note that these 3D objects need to have convex collisions, so our artists create a 3D house and the player can walk inside but can't walk through the walls. How do I implement proper collision detection with 3D objects like in World of Warcraft? Do I need an advanced physics engine? I read about Physijs which looks cool, but I fear that it may be overkill to implement that for our game. Also, how does WoW do it? Do they have a separate raycasting system for the terrain? Or do they treat the terrain like any other convex mesh? A screenshot of our game so far:

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  • lwjgl custom icon

    - by melchor629
    I have a little problem with the icon in lwjgl, it doesn't work. I google about it, but i haven't found anything that works for me yet. This is my code for now: PNGDecoder imageDecoder = new PNGDecoder(new FileInputStream("res/images/Icon.png")); ByteBuffer imageData = BufferUtils.createByteBuffer(4 * imageDecoder.getWidth() * imageDecoder.getHeight()); imageDecoder.decode(imageData, imageDecoder.getWidth() * 4, PNGDecoder.Format.RGBA); imageData.flip(); System.err.println(Display.setIcon(new ByteBuffer[]{imageData}) == 0 ? "No se ha creado el icono" : "Se ha creado el icono"); The png file is a 128x128px with transparency. PNGDecoder is from the matthiasmann utility (de.matthiasmann.twl.utils). I'm using Mac OS, 10.8.4 with lwjgl 2.9.0. Thanks :)

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  • How to set orthgraphic matrix for a 2d camera with zooming?

    - by MahanGM
    I'm using ID3DXSprite to draw my sprites and haven't set any kind of camera projection matrix. How to setup an orthographic projection matrix for camera in DirectX which it would be able to support zoom functionality? D3DXMATRIX orthographicMatrix; D3DXMATRIX identityMatrix; D3DXMatrixOrthoLH(&orthographicMatrix, nScreenWidth, nScreenHeight, 0.0f, 1.0f); D3DXMatrixIdentity(&identityMatrix); device->SetTransform(D3DTS_PROJECTION, &orthographicMatrix); device->SetTransform(D3DTS_WORLD, &identityMatrix); device->SetTransform(D3DTS_VIEW, &identityMatrix); This code is for initial setup. Then, for zooming I multiply zoom factor in nScreenWidth and nScreenHeight.

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  • How to create games with scrolling?

    - by Chandan Shetty SP
    In games like city story or we farm how do they implement scrolling? To do scrolling using UIScrollView the EAGLView size has to be bigger. In those games EAGLView size look like more than 1024*1024. But there is limitation in viewport size in iphone devices(in 3G iphone max is 1024). I played those games in 3G iphone they are working fine. Any idea how they implemented their scrolling mechanism?

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  • How should I sort images in an isometric game so that they appear in the correct order?

    - by Andrew
    This seems like a rather simple problem but I am having a lot of difficulty with it. What should I do to properly sort images in an isometric game? In a normal 2d top-down game one could use the screen y axis to sort the images. In this example the trees are properly sorted but the isometric walls are not. Example image: sorted by screen y Wall2 is one pixel below wall1 therefore it is drawn after wall1. If I sort by the isometric y axis the walls appear in the correct order but the trees do not. Example image: sorted by isometric y

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  • Procedural Planets, Heightmaps and Textures

    - by henryprescott
    I am currently working on an OpenGL procedural planet generator. I hope to use it for a space RPG, that will not allow players to go down to the surface of a planet so I have ignored anything ROAM related. At the moment I am drawing a cube with VBOs and mapping onto a sphere. I am familiar with most fractal heightmap generating techniques and have already implemented my own version of midpoint displacement (not that useful in this case I know). My question is, what is the best way to procedurally generate the heightmap. I have looked at libnoise which allows me to make tilable heightmaps/textures, but as far as I can see I would need to generate a net like this. Leaving the tiling obvious. Could anyone advise me on the best route to take? Any input would be much appreciated.

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  • What common interface would be appropriate for these game object classes?

    - by Jefffrey
    Question A component based system's goal is to solve the problems that derives from inheritance: for example the fact that some parts of the code (that are called components) are reused by very different classes that, hypothetically, would lie in a very different branch of the inheritance tree. That's a very nice concept, but I've found out that CBS is often hard to accomplish without using ugly hacks. Implementations of this system are often far from clean. But I don't want to discuss this any further. My question is: how can I solve the same problems a CBS try to solve with a very clean interface? (possibly with examples, there are a lot of abstract talks about the "perfect" design already). Context Here's an example I was going for before realizing I was just reinventing inheritance again: class Human { public: Position position; Movement movement; Sprite sprite; // other human specific components }; class Zombie { Position position; Movement movement; Sprite sprite; // other zombie specific components }; After writing that I realized I needed an interface, otherwise I would have needed N containers for N different types of objects (or to use boost::variant to gather them all together). So I've thought of polymorphism (move what systems do in a CBS design into class specific functions): class Entity { public: virtual void on_event(Event) {} // not pure virtual on purpose virtual void on_update(World) {} virtual void on_draw(Window) {} }; class Human : public Entity { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; class Zombie : public Entity { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; Which was nice, except for the fact that now the outside world would not even be able to know where a Human is positioned (it does not have access to its position member). That would be useful to track the player position for collision detection or if on_update the Zombie would want to track down its nearest human to move towards him. So I added const Position& get_position() const; to both the Zombie and Human classes. And then I realized that both functionality were shared, so it should have gone to the common base class: Entity. Do you notice anything? Yes, with that methodology I would have a god Entity class full of common functionality (which is the thing I was trying to avoid in the first place). Meaning of "hacks" in the implementation I'm referring to I'm talking about the implementations that defines Entities as simple IDs to which components are dynamically attached. Their implementation can vary from C-stylish: int last_id; Position* positions[MAX_ENTITIES]; Movement* movements[MAX_ENTITIES]; Where positions[i], movements[i], component[i], ... make up the entity. Or to more C++-style: int last_id; std::map<int, Position> positions; std::map<int, Movement> movements; From which systems can detect if an entity/id can have attached components.

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