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  • HLSL How to flip geometry horizontally

    - by cubrman
    I want to flip my asymmetric 3d model horizontally in the vertex shader alongside an arbitrary plane parallel to the YZ plane. This should switch everything for the model from the left hand side to the right hand side (like flipping it in Photoshop). Doing it in pixel shader would be a huge computational cost (extra RT, more fullscreen samples...), so it must be done in the vertex shader. Once more: this is NOT reflection, i need to flip THE WHOLE MODEL. I thought I could simply do the following: Turn off culling. Run the following code in the vertex shader: input.Position = mul(input.Position, World); // World[3][0] holds x value of the model's pivot in the World. if (input.Position.x <= World[3][0]) input.Position.x += World[3][0] - input.Position.x; else input.Position.x -= input.Position.x - World[3][0]; ... The model is never drawn. Where am I wrong? I presume that messes up the index buffer. Can something be done about it? P.S. it's INSANELY HARD to format code here. Thanks to Panda I found my problem. SOLUTION: // Do thins before anything else in the vertex shader. Position.x *= -1; // To invert alongside the object's YZ plane.

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  • iOS persistant storage with update function

    - by jernej
    im developing a game which has different levels and i need to store all levels and its elements (position, image, sounds,..) into a file/database. The levels will be updated so i need a function that checks online for a update and downloads a database dump and additional files. I was planing to store all the persistent data into a SQLLite database, but not quite sure how to do the update part - to pack the database dump and the files together (in a .zip or with a xml). Can this be done any other way (as secure as possible)? thanks!

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  • Moving a Cube from a GUI texture on iOS [on hold]

    - by London2423
    I really hope someone can help me in this since I am working already two days but without any result. What I' am trying to achieve in this instance is to move a GameObject when a GUI Texture is touch on a Iphone. The GameObject to be moved is named Cube. The Cube has a Script named "Left" that supposedly when is "call it " from the GUITexture the Cube should move left. I hope is clear: I want to "activated" the script in the Game Object from the Guitexture. I try to use send message but without any joy as well so I am using GetComponent. This is the script "inside" the GUITexture using Unity and C# //script inside the gameobject cube so it can move left when call it from the GUItexture void Awake() { left = Cube.GetComponent<Left>().enable = true; } void Start() { Cube = GameObject.Find ("Cube"); } void Update () { //loop through all the touches on the screeen for(int i = 0 ; i < Input.touchCount; i++) { //execute this code for current touch (i) on the screen if(this.guiTexture.HitTest(Input.GetTouch(i).position)) { //if current hits our guiTecture, run this code if(Input.GetTouch (i).phase == TouchPhase.Began) //move the cube object Cube.GetComponent<Left> (); } if(Input.GetTouch (i).phase == TouchPhase.Ended) { return; } if(Input.GetTouch(i).phase == TouchPhase.Stationary); //if current finger is stationary run this code { Cube.GetComponent<Left> (); } } } } } This is the script inside the GameObject named "Cube" that is activated from the Gui Texture and when is activated from the GUITexture should allow the cube to move left public class Left : MonoBehaviour { // Use this for initialization void Start () { } // Update is called once per frame void OnMousedown () { transform.position += Vector3.left * Time.deltaTime; } } Before write here I search all documentation, tutorial videos, forums but I still don't understand where is my mistake. May please someone help me Thanks CL

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  • Looking for a small, light scene graph style abstraction lib for shader based OpenGL

    - by Pris
    I'm looking for a 'lean and mean' c/c++ scene graph library for OpenGL that doesn't use any deprecated functionality. It should be cross platform (strictly speaking I just dev on Linux so no love lost if it doesn't work on Windows), and it should be possible to deploy to mobile targets (ie OpenGLES2, and no crazy mandatory dependencies that wouldn't port well to modern mobile frameworks like iOS, Android, etc), with a license that's compatible with closed source software (LGPL or more liberal). Specific nice-to-haves would be: Cameras and Viewers (trackball, fly-by, etc) Object transform hierarchies (if B is a child of A, and you move A, B has the same transform applied to it) Simple animation Scene optimization (frustum culling, use VBOs, minimize state changes, etc) Text I've played around with OpenSceneGraph a lot and it's pretty amazing for fixed function pipeline stuff, but I've had a few of problems using it with the programmable pipeline and after going through their mailing list, it seems several people have had similar issues (going back years). Kitware's VES looks neat (http://www.vtk.org/Wiki/VES), but VES + VTK is pretty heavy. VTK is also typically for analyzing scientific data and I've read that it's not that appropriate for a general use case (not that great at rendering a lot of objects on scene,etc) I'm currently looking at VisualizationLibrary (http://www.visualizationlibrary.org/documentation/pag_gallery.html) which looks like it offers some of the functionality I'd like, but it doesn't explicitly support mobile targets. Other solutions like Ogre, Horde3D, Irrlicht, etc tend to be full on game engines and that's not really what I'm looking for. I'd like some suggestions for other libraries that I may have missed... please note I'm not willing to roll my own solution from scratch.

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  • How to design a separated tutorial mode?

    - by Sylpheed
    I'm working on a "social" game that's about 90% completion. One of the remaining features is the tutorial mode. Basically, the tutorial mode will restrict the user to access some parts of UI and limit the features (like store items). The tutorial will only progress if a certain event is triggered, specifically following the tutorial. The code is ready and we already have an "almost" working game. The problem is I haven't foreseen the tutorial mode while I was doing those 90%. My requirement is there shouldn't be any loading/transition from tutorial mode to normal mode. This means I have to pick up the progress from the tutorial (no re-rendering of assets and stuff). How should I design this in a way where I won't touch anything from my old code? I want it to be as easy as just plugging it in. I don't want to jam the tutorial in my old code since this will lead to many bugs.

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  • How is the terrain generated in Commandos and Commandos game clones/look-alikes?

    - by teodron
    The Commandos series of games and its similar western counterpart, Desperados, use a mix of 2D and 3D elements to achieve a very pleasing and immersive atmosphere. Apart from the concept that alone made the series a best-seller, the graphics eye-candy was also a much appreciated asset of that game. I was very curious on what was the technique used to model and adorn the realistic terrains in those titles? Below are some screenshots that could be relevant as a reference for whomever has a candidate answer: The tiny details and patternless distribution of ornamental textures make me think that these terrains were not generated using a standard heightmap-blendmap method.

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  • AI to move custom-shaped spaceships (shape affecting movement behaviour)

    - by kaoD
    I'm designing a networked turn based 3D-6DOF space fleet combat strategy game which relies heavily on ship customization. Let me explain the game a bit, since you need to know a bit about it to set the question. What I aim for is the ability to create your own fleet of ships with custom shapes and attached modules (propellers, tractor beams...) which would give advantages and disadvantages to each ship, so you have lots of different fleet distributions. E.g., long ship with two propellers at the side would let the ship spin around that plane easily, bigger ships would move slowly unless you place lots of propellers at the back (therefore spending more "construction" points and energy when moving, and it will only move fast towards that direction.) I plan to balance all the game around this feature. The game would revolve around two phases: orders and combat phase. During the orders phase, you command the different ships. When all players finish the order phase, the combat phase begins and the ship orders get resolved in real-time for some time, then the action pauses and there's a new orders phase. The problem comes when I think about player input. To move a ship, you need to turn on or off different propellers if you want to steer, travel forward, brake, rotate in place... These propellers don't have to work at their whole power, so you can achieve more movement combinations with less propellers. I think this approach is a bit boring. The player doesn't want to fiddle with motors or anything, you just want to MOVE and KILL. The way I intend the player to give orders to these ships is by a destination and a rotation, and then the AI would calculate the correct propeller power to achive that movement and rotation. Propulsion doesn't have to be the same throught the entire turn calculation (after the orders have been given) so it would be cool if the ships reacted as they move, adjusting the power of the propellers for their needs dynamically, but it may be too hard to implement and it's not really needed for the game to work. In both cases, how would that AI decide which propellers to activate for the best (or at least not worst) trajectory to be achieved? I though about some approaches: Learning AI: The ship types would learn about their movement by trial and error, adjusting their behaviour with more uses, and finally becoming "smart". I don't want to get involved THAT far in AI coding, and I think it can be frustrating for the player (even if you can let it learn without playing.) Pre-calculated timestep movement: Upon ship creation, ALL possible movements are calculated for each propeller configuration and power for a given delta-time. Memory intensive, ugly, bad. Pre-calculated trajectories: The same as above but not for each delta-time but the whole trajectory, which would then be fitted as much as possible. Requires a fixed propeller configuration for the whole combat phase and is still memory intensive, ugly and bad. Continuous brute forcing: The AI continously checks ALL possible propeller configurations throughout the entire combat phase, precalculates a few time steps and decides which is the best one based on that. Con: what's good now might not be that good later, and it's too CPU intensive, ugly, and bad too. Single brute forcing: Same as above, but only brute forcing at the beginning of the simulation, so it needs constant propeller configuration throughout the entire combat phase. Coninuous angle check: This is not a full movement method, but maybe a way to discard "stupid" propeller configurations. Given the current propeller's normal vector and the final one, you can approximate the power needed for the propeller based on the angle. You must do this continuously throughout the whole combat phase. I figured this one out recently so I didn't put in too much thought. A priori, it has the "what's good now might not be that good later" drawback too, and it doesn't care about the other propellers which may act together to make a better propelling configuration. I'm really stuck here. Any ideas?

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  • Per-vertex animation with VBOs: Stream each frame or use index offset per frame?

    - by charstar
    Scenario Meshes are animated using either skeletons (skinned animation) or some form of morph targets (i.e. per-vertex key frames). However, in either case, the animations are known in full at load-time, that is, there is no physics, IK solving, or any other form of in-game pose solving. The number of character actions (animations) will be limited but rich (hand-animated). There may be multiple characters using a each mesh and its animations simultaneously in-game (they will be at different poses/keyframes at the same time). Assume color and texture coordinate buffers are static. Goal To leverage the richness of well vetted animation tools such as Blender to do the heavy lifting for a small but rich set of animations. I am aware of additive pose blending like that from Naughty Dog and similar techniques but I would prefer to expend a little RAM/VRAM to avoid implementing a thesis-ready pose solver. I would also like to avoid implementing a key-frame + interpolation curve solver (reinventing Blender vertex groups and IPOs). Current Considerations Much like a non-shader-powered pose solver, create a VBO for each character and copy vertex and normal data to each VBO on each frame (VBO in STREAMING). Create one VBO for each animation where each frame (interleaved vertex and normal data) is concatenated onto the VBO. Then each character simply has a buffer pointer offset based on its current animation frame (e.g. pointer offset = (numVertices+numNormals)*frameNumber). (VBO in STATIC) Known Trade-Offs In 1 above: Each VBO would be small but there would be many VBOs and therefore lots of buffer binding and vertex copying each frame. Both client and pipeline intensive. In 2 above: There would be few VBOs therefore insignificant buffer binding and no vertex data getting jammed down the pipe each frame, but each VBO would be quite large. Are there any pitfalls to number 2 (aside from finite memory)? Are there other methods that I am missing?

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  • Designing Videogame Character Parodies [duplicate]

    - by David Dimalanta
    This question already has an answer here: Is it legal to add a cameo appearance of a known video game character in my game? 2 answers Was it okay to make a playable character when making a videogame despite its resemblance? For example, I'm making a 3rd-person action-platform genre and I have to make a character design resembling like Megaman but not exactly the same as him since there is little alternate in color, details, and facial features.

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  • Viewport / Camera Calculation in 2D Game

    - by Dave
    we have a 2D game with some sprites and tiles and some kind of camera/viewport, that "moves" around the scene. so far so good, if we wouldn't had some special behaviour for your camera/viewport translation. normally you could stick the camera to your player figure and center it, resulting in a very cheap, undergraduate, translation equation, like : vec_translation -/+= speed (depending in what keys are pressed. WASD as default.) buuuuuuuuuut, we want our player figure be able to actually reach the bounds, when the viewport/camera has reached a maximum translation. we came up with the following solution (only keys a and d are the shown here, the rest is just adaption of calculation or maybe YOUR super-cool and elegant solution :) ): if(keys[A]) { playerX -= speed; if(playerScreenX <= width / 2 && tx < 0) { playerScreenX = width / 2; tx += speed; } else if(playerScreenX <= width / 2 && (tx) >= 0) { playerScreenX -= speed; tx = 0; if(playerScreenX < 0) playerScreenX = 0; } else if(playerScreenX >= width / 2 && (tx) < 0) { playerScreenX -= speed; } } if(keys[D]) { playerX += speed; if(playerScreenX >= width / 2 && (-tx + width) < sceneWidth) { playerScreenX = width / 2; tx -= speed; } if(playerScreenX >= width / 2 && (-tx + width) >= sceneWidth) { playerScreenX += speed; tx = -(sceneWidth - width); if(playerScreenX >= width - player.width) playerScreenX = width - player.width; } if(playerScreenX <= width / 2 && (-tx + width) < sceneWidth) { playerScreenX += speed; } } i think the code is rather self explaining: keys is a flag container for currently active keys, playerX/-Y is the position of the player according to world origin, tx/ty are the translation components vital to background / npc / item offset calculation, playerOnScreenX/-Y is the actual position of the player figure (sprite) on screen and width/height are the dimensions of the camera/viewport. this all looks quite nice and works well, but there is a very small and nasty calculation error, which in turn sums up to some visible effect. let's consider following piece of code: if(playerScreenX <= width / 2 && tx < 0) { playerScreenX = width / 2; tx += speed; } it can be translated into plain english as : if the x position of your player figure on screen is less or equal the half of your display / camera / viewport size AND there is enough space left LEFT of your viewport/camera then set players x position on screen to width half, increase translation (because we subtract the translation from something we want to move). easy, right?! doing this will create a small delta between playerX and playerScreenX. after so much talking, my question appears now here at the bottom of this document: how do I stick the calculation of my player-on-screen to the actual position of the player AND having a viewport that is not always centered aroung the players figure? here is a small test-case in processing: http://pastebin.com/bFaTauaa thank you for reading until now and thank you in advance for probably answering my question.

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  • Ogre3D : seeking advices about game files management

    - by Tibor
    I'm working on a new game, and its related level editor, based on Ogre3D. I was thinking about how i could manage the game files, knowing that Ogre use .mesh files for models, .material for materials/texture information etc... . At first i thought about a common .zip folder decompressed at runtime (the same way Torchlight and Ogre samples do). But this way the game assets become a monolithic archive, loading takes time, and could be difficult to eventually patch them. So, let's say i have a game object named "Cube" i want to load in my program. Going for modularity, what if i create a compressed file (using zlib compression routines) named Cube.extname, containing its sub-files Cube.mesh, Cube.material and so on ? Are there any alternatives or should i stick with compressed objects? PS: Just to clear things, the answer is unrelated to my program code, at the moment i'm using "resources.cfg" pointing to the OgreSDK media directory.

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  • Adaptive Characters: AI Solution Needs a Problem

    - by Roger F. Gay
    Have sophisticated adaptive programming, will travel - so to speak. I'm part of a group that developed sophisticated learning / adaptive software for robotics. The system "thinks" via its simulator, building and adapting code on its own; and then carries out the best solution. The software can also adapt to new situations, etc. http://mensnewsdaily.com/2007/05/16/robobusiness-robots-with-imagination/ It's easy to imagine using it with automated game characters that will adapt to the players moves and style - the easiest example would be fighting. The more the simulated fighter fights with the human player, the more it learns to counter that players fighting skills. But there should be more. Anyone have any ideas as to how adaptive characters might be interesting in games?

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  • How to transform mesh components?

    - by Lea Hayes
    I am attempting to transform the components of a mesh directly using a 4x4 matrix. This is working for the vertex positions, but it is not working for the normals (and probably not the tangents either). Here is what I have: // Transform vertex positions - Works like a charm! vertices = mesh.vertices; for (int i = 0; i < vertices.Length; ++i) vertices[i] = transform.MultiplyPoint(vertices[i]); // Does not work, lighting is messed up on mesh normals = mesh.normals; for (int i = 0; i < normals.Length; ++i) normals[i] = transform.MultiplyVector(normals[i]); Note: The input matrix converts from local to world space and is needed to combine multiple meshes together.

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  • Adding tolerance to a point in polygon test

    - by David Gouveia
    I've been using this method which was taken from Game Coding Complete to detect whether a point is inside of a polygon. It works in almost every case, but is failing on a few edge cases, and I can't figure out the reason. For example, given a polygon with vertices at (0,0) (0,100) and (100,100), the algorithm is returning: True for any point strictly inside the polygon False for any of the vertices False for (0, 50) which lies on one of the edges of the polygon True (?) for (50,50) which is also on one of the edges of the polygon I'd actually like to relax the algorithm so that it returns true in all of these cases. In other words, it should return true for points that are strictly inside, for the vertices themselves, and for points on the edges of the polygon. If possible I'd also like to give it enough tolerance so that it always tend towards "true" in face of floating point fluctuations. For example, I have another method, that given a line segment and a point, returns the closest location on the line segment to the given point. Currently, given any point outside the polygon and one of its edges, there are cases where the result is categorized as being inside by the method above, while other points are considered outside. I'd like to give it enough tolerance so that it always returns true in this situation. The way I've currently solved the problem is an hack, which consists of using an external library to inflate the polygon by a few pixels, and performing the tests on the inflated polygon, but I'd really like to replace this with a proper solution.

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  • Super-quick MIDI generator with nonrestrictive license?

    - by Ricket
    I'm working on my Ludum Dare entry and trying to figure out how in the world I'm ever going to get background music. I found WolframTones, but the license is too restrictive: Unless otherwise specified, this Site and content presented on this Site are for your personal and noncommercial use. You may not modify, copy, distribute, transmit, display, perform, reproduce, publish, license, create derivative works from, transfer, or sell any information or content obtained from this Site. For commercial and other uses, contact us. But I really like the interface! It's a lot like sfxr - click a genre and download a song. That's so cool. Is there another program that does this same sort of thing but without a restrictive license, so that I can generate a bgm and use it in my game?

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  • How do you pack resources in a game when you have too many of them?

    - by ThePlan
    I've recently made a basic space invaders clone in C++ using the Allegro 5 framework. It took me a long time, but after I finished, I realized I had about 10 sprites, and 13MB worth of DLLs (Some of the people didn't even have the mingW dlls) which were making people who played the game very confused. How can I "pack" all my resources in a way that I can easily add-remove data to my game, and to reduce the size taken by the resource, basically placing them in 1 spot? I'm using codeblocks.

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  • Strange and erratic transformations when using OpenGL VBOs to render scene

    - by janoside
    I have an existing iOS game with fairly simple scenes (all textured quads) and I'm using Apple's "Texture2D" class. I'm trying to convert this class to use VBOs since the vertices of my objects basically never change so I may as well not re-create them for every object every frame. I have the scene rendering using VBOs but the sizes and orientations of all rendered objects are strange and erratic - though locations seem generally correct. I've been toying with this code for a few days now, and I've found something odd: if I re-create all of my VBOs each frame, everything looks correct, even though I'm almost certain my vertices are not changing. Other notes I'm basing my work on this tutorial, and therefore am also using "IBOs" I create my buffers before rendering begins My buffers include vertex and texture data I'm using OpenGL ES 1.1 Fearing some strange effect of the current matrix GL state at the time of buffer creation I've also tried wrapping my buffer-setup code in a "pushMatrix-loadIdentity-popMatrix" block which (as expected) had no effect I'm aware that various articles have been published demonstrating that VBOs may not help performance, but I want to understand this problem and at least have the option to use them. I realize this is a shot in the dark, but has anyone else experienced this type of strange behavior? What might I be doing to result in this behavior? It's rather difficult for me to isolate the problem since I'm working in an existing, moderately complex project, so suggestions about how to approach the problem are also quite welcome.

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  • Variables in static library are never initialized. Why?

    - by Coyote
    I have a bunch of variables that should be initialized then my game launches, but must of them are never initialized. Here is an example of the code: MyClass.h class MyClass : public BaseObject { DECLARE_CLASS_RTTI(MyClass, BaseObject); ... }; MyClass.cpp REGISTER_CLASS(MyClass) Where REGISTER_CLASS is a macro defined as follow #define REGISTER_CLASS(className)\ class __registryItem##className : public __registryItemBase {\ virtual className* Alloc(){ return NEW className(); }\ virtual BaseObject::RTTI& GetRTTI(){ return className::RTTI; }\ }\ \ const __registryItem##className __registeredItem##className(#className); and __registryItemBase looks like this: class __registryItemBase { __registryItemBase(const _string name):mName(name){ ClassRegistry::Register(this); } const _string mName; virtual BaseObject* Alloc() = 0; virtual BaseObject::RTTI& GetRTTI() = 0; } Now the code is similar to what I currently have and what I have works flawlessly, all the registered classes are registered to a ClassManager before main(...) is called. I'm able to instantiate and configure components from scripts and auto-register them to the right system etc... The problem arrises when I create a static library (currently for the iPhone, but I fear it will happen with android as well). In that case the code in the .cpp files is never registered. Why is the resulting code not executed when it is in the library while the same code in the program's binary is always executed? Bonus questions: For this to work in the static library, what should I do? Is there something I am missing? Do I need to pass a flag when building the lib? Should I create another structure and init all the __registeredItem##className using that structure?

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  • XNA clip plane effect makes models black

    - by user1990950
    When using this effect file: float4x4 World; float4x4 View; float4x4 Projection; float4 ClipPlane0; void vs(inout float4 position : POSITION0, out float4 clipDistances : TEXCOORD0) { clipDistances.x = dot(position, ClipPlane0); clipDistances.y = 0; clipDistances.z = 0; clipDistances.w = 0; position = mul(mul(mul(position, World), View), Projection); } float4 ps(float4 clipDistances : TEXCOORD0) : COLOR0 { clip(clipDistances); return float4(0, 0, 0, 0); } technique { pass { VertexShader = compile vs_2_0 vs(); PixelShader = compile ps_2_0 ps(); } } all models using this are rendered black. Is it possible to render them correctly?

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  • OpenGL ES rotate texture

    - by 0xSina
    I just got started with OpenGL ES... I have a fragment: const char * sFragment = _STRINGIFY( varying highp vec2 coordinate; precision mediump float; uniform vec4 maskC; uniform float threshold; uniform sampler2D videoframe; uniform sampler2D videosprite; uniform vec4 mask; uniform vec4 maskB; uniform int recording; vec3 normalize(vec3 color, float meanr) { return color*vec3(0.75 + meanr, 1., 1. - meanr); } void main() { float d; float dB; float dC; float meanr; float meanrB; float meanrC; float minD; vec4 pixelColor; vec4 spriteColor; pixelColor = texture2D(videoframe, coordinate); spriteColor = texture2D(videosprite, coordinate); meanr = (pixelColor.r + mask.r)/8.; meanrB = (pixelColor.r + maskB.r)/8.; meanrC = (pixelColor.r + maskC.r)/8.; d = distance(normalize(pixelColor.rgb, meanr), normalize(mask.rgb, meanr)); dB = distance(normalize(pixelColor.rgb, meanrB), normalize(maskB.rgb, meanrB)); dC = distance(normalize(pixelColor.rgb, meanrC), normalize(maskC.rgb, meanrC)); minD = min(d, dB); minD = min(minD, dC); gl_FragColor = spriteColor; if (minD > threshold) { gl_FragColor = pixelColor; } } Now, depending on wether recording is 0 or 1, I want to rotate uniform sampler2D videosprite 180 degrees (reflection in x-axis, flip vertically). How can I do that? I found the function glRotatef(), but how do i specify that I want to rotate video sprite and not videoframe? Thanks

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  • Postgres: clear entire database before re-creating / re-populating from bash script

    - by Hoff
    hi folks, I'm writing a shell script (will become a cronjob) that will: 1: dump my production database 2: import the dump into my development database Between step 1 and 2, I need to clear the development database (drop all tables?). How is this best accomplished from a shell script? So far, it looks like this: #!/bin/bash time=`date '+%Y'-'%m'-'%d'` # 1. export(dump) the current production database pg_dump -U production_db_name > /backup/dir/backup-${time}.sql # missing step: drop all tables from development database so it can be re-populated # 2. load the backup into the development database psql -U development_db_name < backup/dir/backup-${time}.sql Many thanks in advance! Martin

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  • 2D Car Simulation with Throttle Linear Physics

    - by James
    I'm trying to make a simulation game for an automatic cruise control system. The system simulates a car on varying inclinations and throttle speeds. I've coded up to the car physics but these do note make sense. The dynamics of the simulation are specified as follows: a = V' - V T = (k1)V + ?(k2) + ma V' = (1 - (k1 / m) V) + T - ( k2 / m) * ? Where T = throttle position k1 = viscous friction V = speed V' = next speed ? = angle of incline k2 = m g sin ? a = acceleration m = mass Notice that the angle of incline in the equation is not chopped up by sin or cos. Even the equation for acceleration isn't right. Can anyone correct them or am I misinterpreting the physics?

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  • Bullet Physics - Casting a ray straight down from a rigid body (first person camera)

    - by Hydrocity
    I've implemented a first person camera using Bullet--it's a rigid body with a capsule shape. I've only been using Bullet for a few days and physics engines are new to me. I use btRigidBody::setLinearVelocity() to move it and it collides perfectly with the world. The only problem is the Y-value moves freely, which I temporarily solved by setting the Y-value of the translation vector to zero before the body is moved. This works for all cases except when falling from a height. When the body drops off a tall object, you can still glide around since the translate vector's Y-value is being set to zero, until you stop moving and fall to the ground (the velocity is only set when moving). So to solve this I would like to try casting a ray down from the body to determine the Y-value of the world, and checking the difference between that value and the Y-value of the camera body, and disable or slow down movement if the difference is large enough. I'm a bit stuck on simply casting a ray and determining the Y-value of the world where it struck. I've implemented this callback: struct AllRayResultCallback : public btCollisionWorld::RayResultCallback{ AllRayResultCallback(const btVector3& rayFromWorld, const btVector3& rayToWorld) : m_rayFromWorld(rayFromWorld), m_rayToWorld(rayToWorld), m_closestHitFraction(1.0){} btVector3 m_rayFromWorld; btVector3 m_rayToWorld; btVector3 m_hitNormalWorld; btVector3 m_hitPointWorld; float m_closestHitFraction; virtual btScalar addSingleResult(btCollisionWorld::LocalRayResult& rayResult, bool normalInWorldSpace) { if(rayResult.m_hitFraction < m_closestHitFraction) m_closestHitFraction = rayResult.m_hitFraction; m_collisionObject = rayResult.m_collisionObject; if(normalInWorldSpace){ m_hitNormalWorld = rayResult.m_hitNormalLocal; } else{ m_hitNormalWorld = m_collisionObject->getWorldTransform().getBasis() * rayResult.m_hitNormalLocal; } m_hitPointWorld.setInterpolate3(m_rayFromWorld, m_rayToWorld, m_closestHitFraction); return 1.0f; } }; And in the movement function, I have this code: btVector3 from(pos.x, pos.y + 1000, pos.z); // pos is the camera's rigid body position btVector3 to(pos.x, 0, pos.z); // not sure if 0 is correct for Y AllRayResultCallback callback(from, to); Base::getSingletonPtr()->m_btWorld->rayTest(from, to, callback); So I have the callback.m_hitPointWorld vector, which seems to just show the position of the camera each frame. I've searched Google for examples of casting rays, as well as the Bullet documentation, and it's been hard to just find an example. An example is really all I need. Or perhaps there is some method in Bullet to keep the rigid body on the ground? I'm using Ogre3D as a rendering engine, and casting a ray down is quite straightforward with that, however I want to keep all the ray casting within Bullet for simplicity. Could anyone point me in the right direction? Thanks.

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  • What makes games responsive to user input?

    - by zaftcoAgeiha
    Many games have been praised for its responsive gameplay, where each user action input correspond to a quick and precise character movement (eg: super meat boy, shank...) What makes those games responsive? and what prevents other games from achieving the same? How much of it is due to the game framework used to queue mouse/keyboard events and render/update the game and how much is attributed to better coding?

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  • fast java2d translucency

    - by mdriesen
    I'm trying to draw a bunch of translucent circles on a Swing JComponent. This isn't exactly fast, and I was wondering if there is a way to speed it up. My custom JComponent has the following paintComponent method: public void paintComponent(Graphics g) { Rectangle view = g.getClipBounds(); VolatileImage image = createVolatileImage(view.width, view.height); Graphics2D buffer = image.createGraphics(); // translate to camera location buffer.translate(-cx, -cy); // renderables contains all currently visible objects for(Renderable r : renderables) { r.paint(buffer); } g.drawImage(image.getSnapshot(), view.x, view.y, this); } The paint method of my circles is as follows: public void paint(Graphics2D graphics) { graphics.setPaint(paint); graphics.fillOval(x, y, radius, radius); } The paint is just an rgba color with a < 255: Color(int r, int g, int b, int a) It works fast enough for opaque objects, but is there a simple way to speed this up for translucent ones?

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