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  • Fixed timestep with interpolation in AS3

    - by Jim Sreven
    I'm trying to implement Glenn Fiedler's popular fixed timestep system as documented here: http://gafferongames.com/game-physics/fix-your-timestep/ In Flash. I'm fairly sure that I've got it set up correctly, along with state interpolation. The result is that if my character is supposed to move at 6 pixels per frame, 35 frames per second = 210 pixels a second, it does exactly that, even if the framerate climbs or falls. The problem is it looks awful. The movement is very stuttery and just doesn't look good. I find that the amount of time in between ENTER_FRAME events, which I'm adding on to my accumulator, averages out to 28.5ms (1000/35) just as it should, but individual frame times vary wildly, sometimes an ENTER_FRAME event will come 16ms after the last, sometimes 42ms. This means that at each graphical redraw the character graphic moves by a different amount, because a different amount of time has passed since the last draw. In theory it should look smooth, but it doesn't at all. In contrast, if I just use the ultra simple system of moving the character 6px every frame, it looks completely smooth, even with these large variances in frame times. How can this be possible? I'm using getTimer() to measure these time differences, are they even reliable?

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  • Is there a way to prevent users from adjusting their gamma correction to 'cheat' their way out of a 'dark' area?

    - by Athix
    In almost every game I've come across that includes a dark situation designed to change the way a user interacts with the environment, there are always some players who turn up their monitor's gamma correction in order to negate the desired effect. Is there a way to prevent users from adjusting their gamma correction to 'cheat' their way out of a challenge? (the darkness) I'd imagine if you could reliably retrieve the current gamma correction of the user's monitor, you could use that to more or less prevent the advantage it would otherwise grant without causing the normal users any inconvenience.

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  • Playing part of a sfx audio file in HTML5 using WebAudio

    - by Matthew James Davis
    I have compiled all of my sound effects into one sequenced .ogg file. I have the start and stop times for each sound effect. How do I play the individual effects? That is, how do I play part of an audio file. More specificially, I've created a dictionary { 'sword_hit': { src: 'sfx.ogg', start: 265, // ms length: 212 // ms } } that my play_sound() function can use to look up 'sword_hit' and play the correct audio file at the correct start time for the correct duration. I simply need to know how to tell the WebAudio API to start playing at start ms and only play for length ms.

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  • OpenGL position from depth is wrong

    - by CoffeeandCode
    My engine is currently implemented using a deferred rendering technique, and today I decided to change it up a bit. First I was storing 5 textures as so: DEPTH24_STENCIL8 - Depth and stencil RGBA32F - Position RGBA10_A2 - Normals RGBA8 x 2 - Specular & Diffuse I decided to minimize it and reconstruct positions from the depth buffer. Trying to figure out what is wrong with my method currently has not been fun :/ Currently I get this: which changes whenever I move the camera... weird Vertex shader really simple #version 150 layout(location = 0) in vec3 position; layout(location = 1) in vec2 uv; out vec2 uv_f; void main(){ uv_f = uv; gl_Position = vec4(position, 1.0); } Fragment shader Where the fun (and not so fun) stuff happens #version 150 uniform sampler2D depth_tex; uniform sampler2D normal_tex; uniform sampler2D diffuse_tex; uniform sampler2D specular_tex; uniform mat4 inv_proj_mat; uniform vec2 nearz_farz; in vec2 uv_f; ... other uniforms and such ... layout(location = 3) out vec4 PostProcess; vec3 reconstruct_pos(){ float z = texture(depth_tex, uv_f).x; vec4 sPos = vec4(uv_f * 2.0 - 1.0, z, 1.0); sPos = inv_proj_mat * sPos; return (sPos.xyz / sPos.w); } void main(){ vec3 pos = reconstruct_pos(); vec3 normal = texture(normal_tex, uv_f).rgb; vec3 diffuse = texture(diffuse_tex, uv_f).rgb; vec4 specular = texture(specular_tex, uv_f); ... do lighting ... PostProcess = vec4(pos, 1.0); // Just for testing } Rendering code probably nothing wrong here, seeing as though it always worked before this->gbuffer->bind(); gl::Clear(gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT); gl::Enable(gl::DEPTH_TEST); gl::Enable(gl::CULL_FACE); ... bind geometry shader and draw models and shiz ... gl::Disable(gl::DEPTH_TEST); gl::Disable(gl::CULL_FACE); gl::Enable(gl::BLEND); ... bind textures and lighting shaders shown above then draw each light ... gl::BindFramebuffer(gl::FRAMEBUFFER, 0); gl::Clear(gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT); gl::Disable(gl::BLEND); ... bind screen shaders and draw quad with PostProcess texture ... Rinse_and_repeat(); // not actually a function ;) Why are my positions being output like they are?

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  • Multiple textures on a mesh created in blender and imported in xna

    - by alecnash
    I created a cube in blender which has multiple images applied to its faces. I am trying to import the model into xna and get the same results as shown when rendering the model in blender. I go through every mesh (for the cube its only one) and through every part but only the first image used in blender is displayed in every face. The code I am using to fetch the texture looks like that: foreach (ModelMesh m in model.Meshes) { foreach (Effect e in m.Effects) { foreach (var part in m.MeshParts) { e.CurrentTechnique = e.Techniques["Lambert"]; e.Parameters["view"].SetValue(camera.viewMatrix); e.Parameters["projection"].SetValue(camera.projectionMatrix); e.Parameters["colorMap"].SetValue(modelTextures[part.GetHashCode()]); } } m.Draw(); } Am I missing something?

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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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  • How do I create a third Person View using DXUTCamera in DX10?

    - by David
    I am creating a 3d flying game and using DXUTCamera for my view. I can get the camera to take on the characters position, But I would like to view my character in the 3rd person. Here is my code for first person view: //Put the camera on the object. D3DXVECTOR3 viewerPos; D3DXVECTOR3 lookAtThis; D3DXVECTOR3 up ( 5.0f, 1.0f, 0.0f ); D3DXVECTOR3 newUp; D3DXMATRIX matView; //Set the viewer's position to the position of the thing. viewerPos.x = character->x; viewerPos.y = character->y; viewerPos.z = character->z; // Create a new vector for the direction for the viewer to look character->setUpWorldMatrix(); D3DXVECTOR3 newDir, lookAtPoint; D3DXVec3TransformCoord(&newDir, &character->initVecDir, &character->matAllRotations); // set lookatpoint D3DXVec3Normalize(&lookAtPoint, &newDir); lookAtPoint.x += viewerPos.x; lookAtPoint.y += viewerPos.y; lookAtPoint.z += viewerPos.z; g_Camera.SetViewParams(&viewerPos, &lookAtPoint); So does anyone have an ideas how I can move the camera to the third person view? preferably timed so there is a smooth action in the camera movement. (I'm hoping I can just edit this code instead of bringing in another camera class)

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  • Moving AI in a multiplayer game

    - by Smallbro
    I've been programming a multiplayer game and its coming together very nicely. It uses both TCP and UDP (UDP for movement and TCP for just about everything else). What I was wondering was how I would go about sending multiple moving AI without much lag. At first I used TCP for everything and it was very slow when people moved. I'm currently using a butchered version of this http://corvstudios.com/tutorials/udpMultiplayer.php for my movement system and I'm wondering what the best method of sending AI movements is. By movements I mean the AI chooses left/right/up/down and the player can see this happening. Thanks.

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  • Moving from XNA/C# to DirectX/C++ quite confused

    - by misiMe
    I made some game with XNA/C# for Windows Phone and Windows 8, since XNA is dead and Visual studio doesn't support it (I have to target Windows Phone 7.1 to build with XNA), I want to start learning something more "consistent in time" and improve my skills. I'm a little confused about the possibilities, because C++/DirectX alone seems difficult, so I found some high-level classes to help: DirectX Toolkit Cocos2D My questions are: What will happen when they will "die" like XNA? Is C++'s approces more "professional" than C#/XNA and why? Is C++'s approces more "portable"? Is C++'s approces more resistant in terms of time? Is there any consideration about DirectX TK and Cocos2D in terms of performance? I ask that because I found that every Game software house in my country looks for skilled C++ programmers.

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  • The how of a collision engine

    - by JXPheonix
    This is a very, very broad question - what is the general algorithm of how a collision engine works? No code in specific, but rather, just a general idea of how a collision engine does what it does, constantly refreshing the points of an object and comparing it to other objects? (see, I have the general gist of it here.) A collision engine is basically an engine used in games (generally) so that your player (call him Bob), whenever bob moves into a wall, Bob stops, Bob does not walk through the wall. They also generally handle the gravity in a game and environmental things like that.

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  • slick2d missiles

    - by kirchhoff
    Hey I'm making a game in java with slick2d and I want to create planes which shoots: int maxBullets = 40; static int bullet = 0; Missile missile[] = new Missile[maxBullets]; I want to create/move my missiles in the most efficient way, I would appreciate your advises: public void shoot() throws SlickException{ if(bullet<maxBullets){ if(missile[bullet] != null){ missile[bullet].resetLocation(plane.getCentreX(), plane.getCentreY(), plane.image.getRotation()); }else{ missile[bullet] = new Missile("resources/missile.png", plane.getCentreX(), plane.getCentreY(), plane.image.getRotation()); } }else{ bullet = 0; missile[bullet].resetLocation(plane.getCentreX(), plane.getCentreY(), plane.image.getRotation()); } bullet++; } I created the method "resetLocation" in my Missile class in order to avoid loading again the resource. Is it correct? In the update method I've got this to move all the missiles: if(bullet > 0 && bullet < maxBullets){ float hyp = 0.4f * delta; if(bullet == 1){ missile[0].move(hyp); }else{ for(int x = 0; x<bullet; x++){ missile[x].move(hyp); } } }

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  • Error X3650 when compiling shader in XNA

    - by Saikai
    I'm attempting to convert the XBDEV.NET Mosaic Shader for use in my XNA project and having trouble. The compiler errors out because of the half globals. At first I tried replacing the globals and just writing the variables explicitly in the code, but that garbles the Output. Next I tried replacing all the half with float vars, but that still garbles the resulting Image. I call the effect file from SpriteBatch.Begin(). Is there a way to convert this shader to the new pixel shader conventions? Are there any good tutorials for this topic? Here is the shader file for reference: /*****************************************************************************/ /* File: tiles.fx Details: Modified version of the NVIDIA Composer FX Demo Program 2004 Produces a tiled mosaic effect on the output. Requires: Vertex Shader 1.1 Pixel Shader 2.0 Modified by: [email protected] (www.xbdev.net) */ /*****************************************************************************/ float4 ClearColor : DIFFUSE = { 0.0f, 0.0f, 0.0f, 1.0f}; float ClearDepth = 1.0f; /******************************** TWEAKABLES *********************************/ half NumTiles = 40.0; half Threshhold = 0.15; half3 EdgeColor = {0.7f, 0.7f, 0.7f}; /*****************************************************************************/ texture SceneMap : RENDERCOLORTARGET < float2 ViewportRatio = { 1.0f, 1.0f }; int MIPLEVELS = 1; string format = "X8R8G8B8"; string UIWidget = "None"; >; sampler SceneSampler = sampler_state { texture = <SceneMap>; AddressU = CLAMP; AddressV = CLAMP; MIPFILTER = NONE; MINFILTER = LINEAR; MAGFILTER = LINEAR; }; /***************************** DATA STRUCTS **********************************/ struct vertexInput { half3 Position : POSITION; half3 TexCoord : TEXCOORD0; }; /* data passed from vertex shader to pixel shader */ struct vertexOutput { half4 HPosition : POSITION; half2 UV : TEXCOORD0; }; /******************************* Vertex shader *******************************/ vertexOutput VS_Quad( vertexInput IN) { vertexOutput OUT = (vertexOutput)0; OUT.HPosition = half4(IN.Position, 1); OUT.UV = IN.TexCoord.xy; return OUT; } /********************************** pixel shader *****************************/ half4 tilesPS(vertexOutput IN) : COLOR { half size = 1.0/NumTiles; half2 Pbase = IN.UV - fmod(IN.UV,size.xx); half2 PCenter = Pbase + (size/2.0).xx; half2 st = (IN.UV - Pbase)/size; half4 c1 = (half4)0; half4 c2 = (half4)0; half4 invOff = half4((1-EdgeColor),1); if (st.x > st.y) { c1 = invOff; } half threshholdB = 1.0 - Threshhold; if (st.x > threshholdB) { c2 = c1; } if (st.y > threshholdB) { c2 = c1; } half4 cBottom = c2; c1 = (half4)0; c2 = (half4)0; if (st.x > st.y) { c1 = invOff; } if (st.x < Threshhold) { c2 = c1; } if (st.y < Threshhold) { c2 = c1; } half4 cTop = c2; half4 tileColor = tex2D(SceneSampler,PCenter); half4 result = tileColor + cTop - cBottom; return result; } /*****************************************************************************/ technique tiles { pass p0 { VertexShader = compile vs_1_1 VS_Quad(); ZEnable = false; ZWriteEnable = false; CullMode = None; PixelShader = compile ps_2_0 tilesPS(); } }

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  • 2D water with dynamic waves

    - by user1103457
    New Super Mario Bros has really cool 2D water that I'd like to learn how to create. Here's a video showing it. When something hits the water, it creates a wave. There are also constant "background" waves. You can get a good look at the constant waves just after 00:50 when the camera isn't moving. I assume the splashes in NSMB work as in the first part of this tutorial. But in NSMB the water also has constant waves on the surface, and the splashes look very different. Another difference is that in the tutorial, if you create a splash, it first creates a deep "hole" in the water at the origin of the splash. In new super mario bros this hole is absent or much smaller. I am referring to the splashes that the player creates when jumping in and out of the water. How do they create the constant waves and the splashes? I am especially interested in the splashes, and how they work together with the constant waves. I am programming in XNA. I've tried this myself, but couldn't really get it all to work well together. Bonus questions: How do they create the light spots just under the surface of the waves and how do they texture the deeper parts of the water? This is the first time I try to create water like this. EDIT: I assume the constant waves are created using a sine function. The splashes are probably created in a way like in the tutorial. (But they are not the same, so I am still interested in how to make this kind of splashes) But I have a lot of trouble combining those things. I know I can use the sine function to set the height of a specific watercolumn but the splashes are using the speed, to determine the new height. I can't figure out how to combine those. Not that I am not asking how the developers of new super mario bros did this exactly. I am just interested in ways to recreate an effect like it. This week I have an examweek so I don't have time to work on the code. After this week I will spend a lot of time on it. But I am constantly thinking about it, so that's why I will be checking comments etc. I just won't be looking at the code since it might be too time-consuming.

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  • Efficiency concerning thread granularity

    - by MaelmDev
    Lately, I've been thinking of ways to use multithreading to improve the speed of different parts of a game engine. What confuses me is the appropriate granularity of threads, especially when dealing with single-instruction-multiple-data (SIMD) tasks. Let's use line-of-sight detection as an example. Each AI actor must be able to detect objects of interest around them and mark them. There are three basic ways to go about this with multithreading: Don't use threading at all. Create a thread for each actor. Create a thread for each actor-object combination. Option 1 is obviously going to be the least efficient method. However, choosing between the next two options is more difficult. Only using one thread per actor is still running through every object in series instead of in parallel. However, are CPU's able to create and join threads in the granularity posed in Option 3 efficiently? It seems like that many calls to the OS could be really slow, and varying enormously between different hardware.

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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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  • Is there a good way to get pixel-perfect collision detection in XNA?

    - by ashes999
    Is there a well-known way (or perhaps reusable bit of code) for pixel-perfect collision detection in XNA? I assume this would also use polygons (boxes/triangles/circles) for a first-pass, quick-test for collisions, and if that test indicated a collision, it would then search for a per-pixel collision. This can be complicated, because we have to account for scale, rotation, and transparency. WARNING: If you're using the sample code from the link from the answer below, be aware that the scaling of the matrix is commented out for good reason. You don't need to uncomment it out to get scaling to work.

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  • Designing rules to fight smallpox in Civ-style TBS games

    - by Williham Totland
    TL;DR: How do you design a ruleset for a Civ-style TBS game that prevents city smallpox from being a profitable or viable strategy? Long version: Civ-style games are pretty great. Bringing a civilization from cradle to grave is a great endeavor, and practicing diplomacy with hard-line human players is fun and challenging. In theory. In practice, however, many of these games has, especially in multiplayer, exactly one viable strategy: City smallpox, a.k.a. infinite city spread, a.k.a. covering all available space with 1-citizen cities, packed as tight as they will go. I suppose this could count as emergent gameplay, but still; it could hardly be considered to be in the spirit of the class of game. The Civilization series, of course, is stuck in their more or less fixed rule sets, established with Civilization. Yes, there have been major changes in some respects, but the rules pertaining to city building and maintenance have stayed pretty similar. So the question, then: If you build a ruleset for a TBS from the ground up; what rules should be in place to prevent Infinite City Sprawl from being a viable strategy? Or should ICS be a viable strategy?

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  • Surface normal to screen angle

    - by Tannz0rz
    I've been struggling to get this working. I simply wish to take a surface normal and convert it to a screen angle. As an example, assuming we're working with the highlighted surface on the sphere below, where the arrow is the normal, the 2D angle would obviously be PI/4 radians. Here's one of the many things I've tried to no avail: float4 A = v.vertex; float4 B = v.vertex + float4(v.normal, 0.0); A = mul(VP, A); B = mul(VP, B); A.xy = (0.5 * (A.xy / A.w)) + 0.5; B.xy = (0.5 * (B.xy / B.w)) + 0.5; o.theta = atan2(B.y - A.y, B.x - A.x); I'm finally at my wit's end. Thanks for any and all help.

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  • XNA Skinned Model - Keyframe.Bone out of range exception

    - by idlackage
    I'm getting an IndexOutOfRangeException on this line of AnimationPlayer.cs: boneTransforms[keyframe.Bone] = keyframe.Transform; I don't get what it's really referring to. The error happens when keyframe.Bone is 14, but I have no idea what that's supposed to mean. The 14th bone of my model? What would that even be? I read this thread, but nothing there seemed to work. I don't have many bones, stray edges/verts, unassigned verts, unparented/non-root bones, or bones with dots in the name. What else can I be missing? Thank you for any help!

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  • Writing to a structured buffer with a compute shader (D3D11)

    - by Vertexwahn
    I have some problems writing to a structured buffer. First I create a structured buffer that is filled with float values beginning from 0 to 99. Afterwards a copy the structured buffer to a CPU accessible buffer is made to print the content of the structured buffer to the console. The output is as expected (Numbers 0 to 99 appear on the console). Afterwards I use a compute shader that should change the contents of the structured buffer: RWStructuredBuffer<float> Result : register( u0 ); [numthreads(1, 1, 1)] void CS_main( uint3 GroupId : SV_GroupID ) { Result[GroupId.x] = GroupId.x * 10; } But the compute shader does not change the contents of the structured buffer. The source code can be found here (main.cpp): https://bitbucket.org/Vertexwahn/cmakedemos/src/4abb067afd5781b87a553c4c720956668adca22a/D3D11ComputeShader/src/main.cpp?at=default FillCS.hlsl: https://bitbucket.org/Vertexwahn/cmakedemos/src/4abb067afd5781b87a553c4c720956668adca22a/D3D11ComputeShader/src/FillCS.hlsl?at=default

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  • What are good JS libraries for game dev?

    - by acidzombie24
    If I decide to write a simple game both text and graphical (2d) what libraries would I use? (Assume we are using a HTML5 compatible browser) The main things I can think of Rendering text on screen Animating sprites (using images/css) Input (capturing the arrow keys and getting relative mouse positions) Perhaps some preloading resource or dynamically loading resources and choosing order Sound (but I am unsure how important this will be to me at first). Perhaps with mixing and chaining sounds or looping forever until stop. Networking (low priority) to connect a user to another or to continuously GET data without multiple request (I know this exist but I don't know how easy it is to setup or use. But this isn't important to me. Its for the question).

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  • Simple collision detection for pong

    - by Dave Voyles
    I'm making a simple pong game, and things are great so far, but I have an odd bug which causes my ball (well, it's a box really) to get stuck on occasion when detecting collision against the ceiling or floor. It looks as though it is trying to update too frequently to get out of the collision check. Basically the box slides against the top or bottom of the screen from one paddle to the other, and quickly bounces on and off the wall while doing so, but only bounces a few pixels from the wall. What can I do to avoid this problem? It seems to occur at random. Below is my collision detection for the wall, as well as my update method for the ball. public void UpdatePosition() { size.X = (int)position.X; size.Y = (int)position.Y; position.X += speed * (float)Math.Cos(direction); position.Y += speed * (float)Math.Sin(direction); CheckWallHit(); } // Checks for collision with the ceiling or floor. // 2*Math.pi = 360 degrees // TODO: Change collision so that ball bounces from wall after getting caught private void CheckWallHit() { while (direction > 2 * Math.PI) { direction -= 2 * Math.PI; } while (direction < 0) { direction += 2 * Math.PI; } if (position.Y <= 0 || (position.Y > resetPos.Y * 2 - size.Height)) { direction = 2 * Math.PI - direction; } }

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  • HedgeWar code confusion

    - by BluFire
    I looked at an open source project(HedgeWars) that was built using many programming languages such as C++ and Java. While I was looking through the code, I couldn't help noticing that all the math and physics were gone from the Java code. HedgeWars I imported the project file called "SDL-android-project" which was a sub folder to "android build" and project files. My question is where is all the math and physics inside the code? Do I have to look at the C++ code in order to see it? I think Hedgewars was originally programmed in C++ but the files are confusing be because of its size and the fact that it has several programming languages inside.

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  • Efficiently separating Read/Compute/Write steps for concurrent processing of entities in Entity/Component systems

    - by TravisG
    Setup I have an entity-component architecture where Entities can have a set of attributes (which are pure data with no behavior) and there exist systems that run the entity logic which act on that data. Essentially, in somewhat pseudo-code: Entity { id; map<id_type, Attribute> attributes; } System { update(); vector<Entity> entities; } A system that just moves along all entities at a constant rate might be MovementSystem extends System { update() { for each entity in entities position = entity.attributes["position"]; position += vec3(1,1,1); } } Essentially, I'm trying to parallelise update() as efficiently as possible. This can be done by running entire systems in parallel, or by giving each update() of one system a couple of components so different threads can execute the update of the same system, but for a different subset of entities registered with that system. Problem In reality, these systems sometimes require that entities interact(/read/write data from/to) each other, sometimes within the same system (e.g. an AI system that reads state from other entities surrounding the current processed entity), but sometimes between different systems that depend on each other (i.e. a movement system that requires data from a system that processes user input). Now, when trying to parallelize the update phases of entity/component systems, the phases in which data (components/attributes) from Entities are read and used to compute something, and the phase where the modified data is written back to entities need to be separated in order to avoid data races. Otherwise the only way (not taking into account just "critical section"ing everything) to avoid them is to serialize parts of the update process that depend on other parts. This seems ugly. To me it would seem more elegant to be able to (ideally) have all processing running in parallel, where a system may read data from all entities as it wishes, but doesn't write modifications to that data back until some later point. The fact that this is even possible is based on the assumption that modification write-backs are usually very small in complexity, and don't require much performance, whereas computations are very expensive (relatively). So the overhead added by a delayed-write phase might be evened out by more efficient updating of entities (by having threads work more % of the time instead of waiting). A concrete example of this might be a system that updates physics. The system needs to both read and write a lot of data to and from entities. Optimally, there would be a system in place where all available threads update a subset of all entities registered with the physics system. In the case of the physics system this isn't trivially possible because of race conditions. So without a workaround, we would have to find other systems to run in parallel (which don't modify the same data as the physics system), other wise the remaining threads are waiting and wasting time. However, that has disadvantages Practically, the L3 cache is pretty much always better utilized when updating a large system with multiple threads, as opposed to multiple systems at once, which all act on different sets of data. Finding and assembling other systems to run in parallel can be extremely time consuming to design well enough to optimize performance. Sometimes, it might even not be possible at all because a system just depends on data that is touched by all other systems. Solution? In my thinking, a possible solution would be a system where reading/updating and writing of data is separated, so that in one expensive phase, systems only read data and compute what they need to compute, and then in a separate, performance-wise cheap, write phase, attributes of entities that needed to be modified are finally written back to the entities. The Question How might such a system be implemented to achieve optimal performance, as well as making programmer life easier? What are the implementation details of such a system and what might have to be changed in the existing EC-architecture to accommodate this solution?

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  • Precision loss when transforming from cartesian to isometric

    - by Justin Skiles
    My goal is to display a tile map in isometric projection. This tile map has 25 tiles across and 25 tiles down. Each tile is 32x32. See below for how I'm accomplishing this. World Space World Space to Screen Space Rotation (45 degrees) Using a 2D rotation matrix, I use the following: double rotation = Math.PI / 4; double rotatedX = ((tileWorldX * Math.Cos(rotation)) - ((tileWorldY * Math.Sin(rotation))); double rotatedY = ((tileWorldX * Math.Sin(rotation)) + (tileWorldY * Math.Cos(rotation))); World Space to Screen Space Scale (Y-axis reduced by 50%) Here I simply scale down the Y value by a factor of 0.5. Problem And it works, kind of. There are some tiny 1px-2px gaps between some of the tiles when rendering. I think there's some precision loss somewhere, or I'm not understanding how to get these tiles to fit together perfectly. I'm not truncating or converting my values to non-decimal types until I absolutely have to (when I pass to the render method, which only takes integers). I'm not sure how to guarantee pixel perfect rendering precision when I'm rotating and scaling on a level of higher precision. Any advice? Do I need to supply for information?

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