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AndEngine Box2d game

- by OneMoreVladimir

I'm developing a 2d survival shooter using Box2d extension and I've got some questions: I have two AnalogOnScreenControls. Their listeners modify both sprites and bodies. I receive TouchEventPool was exhausted and as their number grows the game crashes accidently. I've tried to put the modification of the bodies and sprites on the UpdateThread but that does not solve the problem. What could be the cause? I have a class that at the beginnig of the game loads all the textures. After I relaunch the game activity several times I receive Unable to find Phys Addr for and "green color" interface. But that doesn't happen if I clear the memory manually through the Task Manager before relaunch What could be the cause? I unload my atlas at the end of the game. The game sometimes crashes at start with NullPointerException in onResumeGame. The solution suggested is to set android:configChanges="orientation|screenSize" but my device is API 10 so it doesn't have screenSize property and orientation only does not seem to help, because the game starts in portrait mode at times (though landscape is set in the code)

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Unity iOS optimization and draw calls

- by vzm

I am curious of what methods I should approach in optimizing my Unity project for iOS hardware. I have very little image effects running (directional light with low res shadows) and I used the combine children script from the standard assets to lessen the load on the CPU. My project currently runs with 45-57 draw calls at non-intensive segments and up to 178 at intensive segments. I heard that static batching relieves some of the stress, but the game has the environment moving around the player instead of the player moving around the environment. Is there any alternative that I may look towards to improving the draw call number?

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Unity3d web player fails to load textures

- by José Franco

I'm having a problem with Unity3d Web Player. I have developed a project and succesfully deployed it in a web app. It works with absolutely no problem on my PC. This app is to be installed on two identical machines. I have installed them in both and it only works properly in one. The issue I have is on a computer it fails to properly load the models and textures, so the game runs but instead of the models I can only see black rectangles on a blue background. It has the same problem with all browsers and I get no errors either by the player or by JavaScript. The only difference between these computers is that one that has the problem is running on Windows 8.1 and the other one on Windows 8 only. Could this be the cause of the issue? It works fine on my computer with Windows 8.1. However both of the other computers have specs that are significantly lower than mine. I have already searched everywhere and it seems that it has to do with the individual games, however I think it may have to do with the computer itself because it runs properly in the other two. The specs on the computes I'm installing the app on are as follows: Intel Celeron 1.40 GHz, 2GB RAM, Intel HD Graphics If anybody could point me in the right direction I would be very grateful I forgot to mention, I'm running Unity Web player 4.3.5 and the version on the other two computers is 4.5.0

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Turn-based Client-Server Card Game - Unicast (TCP) or Multicast (UDP)

- by LDM91

I am currently planning to make a card game project where the clients will communicate with the server in a turn-based and synchronous manner using messages sent over sockets. The problem I have is how to handle the following scenario: (Client takes it turn and sends its action to server) Client sends a message telling the server its move for the turn (e.g. plays the card 5 from its hand which needs to placed onto the table) Server receives messages and updates game state (server will hold all game state). Server iterates through a list of connected clients and sends a message to tell of them change in state Clients all refresh to display the state This is all based on using TCP, and looking at it now it seems a bit like the Observer pattern. The reason this seems to be an issue to me is this message doesn't seem to be point-to-point like the others as I want to send it to all the clients, and doesn't seem very efficient sending the same message in that way. I was thinking about using multicasting with UDP as then I could send the message to all the clients, however wouldn't this mean that the clients would in theory be able to message each other? There is of course the synchronous aspect as well, though this could be put on top of the UDP I guess. Basically, I would like to know what would be good practice as this project is really all about learning, and even though it won't be big enough to encounter performance issues from this I would like to consider them anyway. However, please note I am not interested in using message oriented middleware as a solution (I have experience with using MOM and I'm interested in considering other options excluding MOM if TCP sockets is a bad idea!).

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collision detection problems - Javascript/canvas game

- by Tom Burman

Ok here is a more detailed version of my question. What i want to do: i simply want the have a 2d array to represent my game map. i want a player sprite and i want that sprite to be able to move around my map freely using the keyboard and also have collisions with certain tiles of my map array. i want to use very large maps so i need a viewport. What i have: I have a loop to load the tile images into an array: /Loop to load tile images into an array var mapTiles = []; for (x = 0; x <= 256; x++) { var imageObj = new Image(); // new instance for each image imageObj.src = "images/prototype/"+x+".jpg"; mapTiles.push(imageObj); } I have a 2d array for my game map: //Array to hold map data var board = [ [1,2,3,4,3,4,3,4,5,6,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [17,18,19,20,19,20,19,20,21,22,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [33,34,35,36,35,36,35,36,37,38,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [49,50,51,52,51,52,51,52,53,54,1,1,1,1,1,1,1,1,1,1,1,1,1,197,198,199,1,1,1,1], [65,66,67,68,146,147,67,68,69,70,1,1,1,1,1,1,1,1,216,217,1,1,1,213,214,215,1,1,1,1], [81,82,83,161,162,163,164,84,85,86,1,1,1,1,1,1,1,1,232,233,1,1,1,229,230,231,1,1,1,1], [97,98,99,177,178,179,180,100,101,102,1,1,1,1,59,1,1,1,248,249,1,1,1,245,246,247,1,1,1,1], [1,1,238,1,1,1,1,239,240,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [216,217,254,1,1,1,1,255,256,1,204,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [232,233,1,1,1,117,118,1,1,1,220,1,1,119,120,1,1,1,1,1,1,1,1,1,1,1,119,120,1,1], [248,249,1,1,1,133,134,1,1,1,1,1,1,135,136,1,1,1,1,1,1,59,1,1,1,1,135,136,1,1], [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,216,217,1,1,1,1,1,1,60,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,232,233,1,1,1,1,1,1,1,1,1,1,1,1,1,1,204,1,1,1,1,1,1,1,1,1,1,1], [1,1,248,249,1,1,1,1,1,1,1,1,1,1,1,1,1,1,220,1,1,1,1,1,1,216,217,1,1,1], [1,1,1,1,1,1,1,1,1,1,1,1,149,150,151,1,1,1,1,1,1,1,1,1,1,232,233,1,1,1], [12,12,12,12,12,12,12,13,1,1,1,1,165,166,167,1,1,1,1,1,1,119,120,1,1,248,249,1,1,1], [28,28,28,28,28,28,28,29,1,1,1,1,181,182,183,1,1,1,1,1,1,135,136,1,1,1,1,1,1,1], [44,44,44,44,44,15,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,1,1,27,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,1,1,27,28,29,1,1,1,1,1,1,1,1,1,59,1,1,197,198,199,1,1,1,1,119,120,1], [1,1,1,1,1,27,28,29,1,1,216,217,1,1,1,1,1,1,1,1,213,214,215,1,1,1,1,135,136,1], [1,1,1,1,1,27,28,29,1,1,232,233,1,1,1,1,1,1,1,1,229,230,231,1,1,1,1,1,1,1], [1,1,1,1,1,27,28,29,1,1,248,249,1,1,1,1,1,1,1,1,245,246,247,1,1,1,1,1,1,1], [1,1,1,197,198,199,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,213,214,215,28,29,1,1,1,1,1,60,1,1,1,1,204,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,229,230,231,28,29,1,1,1,1,1,1,1,1,1,1,220,1,1,1,1,119,120,1,1,1,1,1], [1,1,1,245,246,247,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,135,136,1,1,60,1,1], [1,1,1,1,1,27,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,1,1,27,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1] ]; I have my loop to place the correct tile sin the correct positions: //Loop to place tiles onto screen in correct position for (x = 0; x <= viewWidth; x++){ for (y = 0; y <= viewHeight; y++){ var width = 32; var height = 32; context.drawImage(mapTiles[board[y+viewY][x+viewX]],x*width, y*height); } } I Have my player object : //Place player object context.drawImage(playerImg, (playerX-viewX)*32,(playerY-viewY)*32, 32, 32); I have my viewport setup: //Set viewport pos viewX = playerX - Math.floor(0.5 * viewWidth); if (viewX < 0) viewX = 0; if (viewX+viewWidth > worldWidth) viewX = worldWidth - viewWidth; viewY = playerY - Math.floor(0.5 * viewHeight); if (viewY < 0) viewY = 0; if (viewY+viewHeight > worldHeight) viewY = worldHeight - viewHeight; I have my player movement: canvas.addEventListener('keydown', function(e) { console.log(e); var key = null; switch (e.which) { case 37: // Left if (playerY > 0) playerY--; break; case 38: // Up if (playerX > 0) playerX--; break; case 39: // Right if (playerY < worldWidth) playerY++; break; case 40: // Down if (playerX < worldHeight) playerX++; break; } My Problem: I have my map loading an it looks fine, but my player position thinks it's on a different tile to what it actually is. So for instance, i know that if my player moves left 1 tile, the value of that tile should be 2, but if i print out the value it should be moving to (2), it comes up with a different value. How ive tried to solve the problem: I have tried swap X and Y values for the initialization of my player, for when my map prints. If i swap the x and y values in this part of my code: context.drawImage(mapTiles[board[y+viewY][x+viewX]],x*width, y*height); The map doesnt get draw correctly at all and tiles are placed all in random positions or orientations IF i sway the x and y values for my player in this line : context.drawImage(playerImg, (playerX-viewX)*32,(playerY-viewY)*32, 32, 32); The players movements are inversed, so up and down keys move my player left and right viceversa. My question: Where am i going wrong in my code, and how do i solve it so i have my map looking like it should and my player moving as it should as well as my player returning the correct tileID it is standing on or moving too. Thanks Again ALSO Here is a link to my whole code: prototype

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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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How to model interentity membership in entity-component architecture?

- by croxis

I'm falling in love with simple grace of entity-component design, although I still have issues breaking from MVC and OOP practices. Some of my game entities have membership relationships with each other (ex: a player is a member of a city, a city is a member of a nation), and I am unsure on the best way to implement it. My initial reaction is to have a a MemberOfCity component that points to the appropriate city component, but components are suppose to have no references to each other. My other option is to have a System do it, but that would require the system to persist data outside of a component. Is there a clean way to do this in an entity-component design, or am I trying to use a hammer on a screw and should use a hybrid/another approach?

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Are there any good guides for making mods for Minecraft?

- by Pureferret

I've been coding in Java for 5 months at work now, and having past experience with programming in other languages, modifying existing code at Uni etc. I feel like I want to get started on (read: continue learning to program by) modding with minecraft. I know what I need, but not exactly how to do so. I once saw some good guides on the minecraft forum, but they all explained how to write in java, hows different classes in the code work etc. I'm more interested in how you decompile the code, write your own separate from the main 'trunk' of minecraft and then package it to install with a tool like 'Magic Loader'. My issue with these guides is that they always relied on being in windows, but I'm primarily a linux user, and the guides on the forums only seemed to assume you were on a Windows box. So is there a good 'walkthrough' for modding for Minecraft? Especially one where it assumes or at least allows for the fact you are in linux?

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determine collision angle on a rotating body

- by jorb

update: new diagram and updated description I have a contact listener set up to try and determine the side that a collision happened at relative to the a bodies rotation. One way to solve this is to find the value of the yellow angle between the red and blue vectors drawn above. The angle can be found by taking the arc cosine of the dot product of the two vectors (Evan pointed this out). One of my points of confusion is the difference in domain of the atan2 function html canvas coordinates and the Box2d rotation information. I know I have to account for this somehow... SS below questions: Does Box2D provide these angles more directly in the collision information? Am I even on the right track? If so, any hints? I have the following javascript so far: Ship.prototype.onCollide = function (other_ent,cx,cy) { var pos = this.body.GetPosition(); //collision position relative to body var d_cx = pos.x - cx; var d_cy = pos.y - cy; //length of initial vector var len = Math.sqrt(Math.pow(pos.x -cx,2) + Math.pow(pos.y-cy,2)); //body angle - can over rotate hence mod 2*Pi var ang = this.body.GetAngle() % (Math.PI * 2); //vector representing body's angle - same magnitude as the first var b_vx = len * Math.cos(ang); var b_vy = len * Math.sin(ang); //dot product of the two vectors var dot_prod = d_cx * b_vx + d_cy * b_vy; //new calculation of difference in angle - NOT WORKING! var d_ang = Math.acos(dot_prod); var side; if (Math.abs(d_ang) < Math.PI/2 ) side = "front"; else side = "back"; console.log("length",len); console.log("pos:",pos.x,pos.y); console.log("offs:",d_cx,d_cy); console.log("body vec",b_vx,b_vy); console.log("body angle:",ang); console.log("dot product",dot_prod); console.log("result:",d_ang); console.log("side",side); console.log("------------------------"); }

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FBX Importer - Texture Name

- by CmasterG

I have a problem with the FBX SDK. I read in the data for the vertex position and the uv coordinates. It works fine, but now I want to read for each polygon to which texture it belongs, so that I can have models with multiple textures. Can anyone tell me how I can get the texture name (file name) for my polygon. My code to read in vertex position and uv coordinates is the following: int i, j, lPolygonCount = pMesh->GetPolygonCount(); FbxVector4* lControlPoints = pMesh->GetControlPoints(); int vertexId = 0; for (i = 0; i < lPolygonCount; i++) { int lPolygonSize = pMesh->GetPolygonSize(i); for (j = 0; j < lPolygonSize; j++) { int lControlPointIndex = pMesh->GetPolygonVertex(i, j); FbxVector4 pos = lControlPoints[lControlPointIndex]; current_model[vertex_index].x = pos.mData[0] - pivot_offset[0]; current_model[vertex_index].y = pos.mData[1] - pivot_offset[1]; current_model[vertex_index].z = pos.mData[2]- pivot_offset[2]; FbxVector4 vertex_normal; pMesh->GetPolygonVertexNormal(i,j, vertex_normal); current_model[vertex_index].nx = vertex_normal.mData[0]; current_model[vertex_index].ny = vertex_normal.mData[1]; current_model[vertex_index].nz = vertex_normal.mData[2]; //read in UV data FbxStringList lUVSetNameList; pMesh->GetUVSetNames(lUVSetNameList); //get lUVSetIndex-th uv set const char* lUVSetName = lUVSetNameList.GetStringAt(0); const FbxGeometryElementUV* lUVElement = pMesh->GetElementUV(lUVSetName); if(!lUVElement) continue; // only support mapping mode eByPolygonVertex and eByControlPoint if( lUVElement->GetMappingMode() != FbxGeometryElement::eByPolygonVertex && lUVElement->GetMappingMode() != FbxGeometryElement::eByControlPoint ) return; //index array, where holds the index referenced to the uv data const bool lUseIndex = lUVElement->GetReferenceMode() != FbxGeometryElement::eDirect; const int lIndexCount= (lUseIndex) ? lUVElement->GetIndexArray().GetCount() : 0; FbxVector2 lUVValue; //get the index of the current vertex in control points array int lPolyVertIndex = pMesh->GetPolygonVertex(i,j); //the UV index depends on the reference mode //int lUVIndex = lUseIndex ? lUVElement->GetIndexArray().GetAt(lPolyVertIndex) : lPolyVertIndex; int lUVIndex = pMesh->GetTextureUVIndex(i, j); lUVValue = lUVElement->GetDirectArray().GetAt(lUVIndex); current_model[vertex_index].tu = (float)lUVValue.mData[0]; current_model[vertex_index].tv = (float)lUVValue.mData[1]; vertex_index ++; } } float v1[3], v2[3], v3[3]; v1[0] = current_model[vertex_index - 3].x; v1[1] = current_model[vertex_index - 3].y; v1[2] = current_model[vertex_index - 3].z; v2[0] = current_model[vertex_index - 2].x; v2[1] = current_model[vertex_index - 2].y; v2[2] = current_model[vertex_index - 2].z; v3[0] = current_model[vertex_index - 1].x; v3[1] = current_model[vertex_index - 1].y; v3[2] = current_model[vertex_index - 1].z; collision_model->addTriangle(v1,v2,v3);

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Simpler alternative to AngelScript

- by Vee

I want to give players the ability to create and share bullet patterns for a shoot'em up. The pattern scripts should have all the common programming stuff like loops, if/else, variables, and so on. But in the end, I just want them to call a "spawn bullet at X, Y with Z angle and A speed" in the C++ game. To spawn a circle of bullets, the user should only have to write a script with a for loop that goes from 0 to 360 and calls the spawn bullet function on every iteration. I tried integrating AngelScript, but I am getting nowhere - it looks way to complex for a simple task like this one. Is there an easy to integrate library that can solve my problem? Thanks.

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Managing constant buffers without FX interface

- by xcrypt

I am aware that there is a sample on working without FX in the samplebrowser, and I already checked that one. However, some questions arise: In the sample: D3DXMATRIXA16 mWorldViewProj; D3DXMATRIXA16 mWorld; D3DXMATRIXA16 mView; D3DXMATRIXA16 mProj; mWorld = g_World; mView = g_View; mProj = g_Projection; mWorldViewProj = mWorld * mView * mProj; VS_CONSTANT_BUFFER* pConstData; g_pConstantBuffer10->Map( D3D10_MAP_WRITE_DISCARD, NULL, ( void** )&pConstData ); pConstData->mWorldViewProj = mWorldViewProj; pConstData->fTime = fBoundedTime; g_pConstantBuffer10->Unmap(); They are copying their D3DXMATRIX'es to D3DXMATRIXA16. Checked on msdn, these new matrices are 16 byte aligned and optimised for intel pentium 4. So as my first question: 1) Is it necessary to copy matrices to D3DXMATRIXA16 before sending them to the constant buffer? And if no, why don't we just use D3DXMATRIXA16 all the time? I have another question about managing multiple constant buffers within one shader. Suppose that, within your shader, you have multiple constant buffers that need to be updated at different times: cbuffer cbNeverChanges { matrix View; }; cbuffer cbChangeOnResize { matrix Projection; }; cbuffer cbChangesEveryFrame { matrix World; float4 vMeshColor; }; Then how would I set these buffers all at different times? g_pd3dDevice->VSSetConstantBuffers( 0, 1, &g_pConstantBuffer10 ); gives me the possibility to set multiple buffers, but that is within one call. 2) Is that okay even if my constant buffers are updated at different times? And do I suppose I have to make sure the constantbuffers are in the same position in the array as the order they appear in the shader?

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OpenGL ES 2.0: Mixing 2D with 3D

- by Bunkai.Satori

Is it possible to mix 2D and 3D graphics in a single OpenGL ES 2.0 game, please? I have plenty of 2D graphics in my game. The 2D graphics is represented by two triangular polygons (making up a rectangle) with texture on them. I use orthographic matrix to render the whole scene. However, I need to add some 3D effects into my game. Threfore, I wish to use perspective camera to render the meshes. Is it possible to mix orthographic and perspective camera in one scene? If yes, is there going to be a large performance cost for this? Is there any recommended approach to do this effectively? I wil have 90% of 2D graphics and only 10% of 3D. Target platform is OpenGL ES 2.0 (iOS, Android). I use C++ to develop. Thank you.

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Compressing 2D level data

- by Lucius

So, I'm developing a 2D, tile based game and a map maker thingy - all in Java. The problem is that recently I've been having some memory issues when about 4 maps are loaded. Each one of these maps are composed of 128x128 tiles and have 4 layers (for details and stuff). I already spent a good amount of time searching for solutions and the best thing I found was run-length enconding (RLE). It seems easy enough to use with static data, but is there a way to use it with data that is constantly changing, without a big drop in performance? In my maps, supposing I'm compressing the columns, I would have 128 rows, each with some amount of data (hopefully less than it would be without RLE). Whenever I change a tile, that whole row would have to be checked and I'm affraid that would slow down too much the production (and I'm in a somewhat tight schedule). Well, worst case scenario I work on each map individually, and save them using RLE, but it would be really nice if I could avoind that. EDIT: What I'm currently using to store the data for the tiles is a 2D array of HashMaps that use the layer as key and store the id of the tile in that position - like this: private HashMap< Integer, Integer [][]

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Projectiles in tile mapped turn-based tactics game?

- by Petteri Hietavirta

I am planning to make a Laser Squad clone and I think I have most of the aspects covered. But the major headache is the projectiles shot/thrown. The easy way would be to figure out the probability of hit and just mark miss/hit. But I want to be able to have the projectile to hit something eventually (collateral damage!). Currently everything is flat 2D tile map and there would be full (wall, door) and half height (desk, chair, window) obstacles. My idea is to draw an imaginary line from the shooter to the target and add some horizontal&vertical error based on the player skills. Then I would trace the modified path until it hits something. This is basically what the original Laser Squad seems to do. Can you recommend any algorithms or other approaches for this?

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What is the practical use of IBOs / degenerate vertex in OpenGL?

- by 0xFAIL

Vertices in 3D models CAN get cut in the process of optimizing 3D geometry, (degenerate vertices) by 3D graphics software (Blender, ...) when exporting because they aren't needed when reusing a vertex for multiple triangles. (In the current case 3D data is exported from Blender as .ply and read by a simple application that displays the 3D model) Every vertex has a few attributes like position, color, normal, tangent,... But the data for each vertex that is cut through the vertex sharing is lost and is missing in the vertex shader. Modern shader techniques like Bump or Normal mapping require normals/tangents per vertex which are also cut. To use complex shader techniques IBOs must not be used? Or is there a way to use IBOs and retain the data per vertex that was origionally lost?

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Using SQL tables for storing user created level stats. Is there a better way?

- by Ivan

I am developing a racing game in which players can create their own tracks and upload them to a server. Players will be able to compare their best track times to their friends and see world records. I was going to generate a table for each track submitted to store the best times of each player who plays the track. However, I can't predict how many will be uploaded and I imagine too many tables might cause problems, or is this a valid method? I considered saving each player's best times in a string in a single table field like so: level1:00.45;level2:00.43;level3:00.12 If I did this I wouldn't need a separate table for each level (each level could just have a row in a 'WorldRecords' table). However, this just causes another problem because the text would eventually reach the limit for varchar length. I also considered storing the times data in XML files. This would avoid database issues and server disk space can be increased if needed. But I imagine this would be very slow. To update one players best time on one level, I would have to check every node in the file to find their time record to update. Apologies for the wall of text. Any suggestions would be appreciated.

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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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Pixmaps, ByteBuffers, and Textures....Oh my

- by odaymichael

My ultimate goal is to take a specific region of the screen, and redraw it somewhere else. For example, take a square from the upper left hand corner of the screen and redraw it on the lower right hand corner, so that it is basically a copy of that screen section; kind of like a minimap, but at the same scale as the original. I have looked in to pixmaps and bytebuffers. Also maybe copying that region from the backbuffer somehow. Wondering the best way to go about this. Any help is appreciated. I am using opengl es and libgdx for what it's worth.

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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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Smooth waypoint traversing

- by TheBroodian

There are a dozen ways I could word this question, but to keep my thoughts in line, I'm phrasing it in line with my problem at hand. So I'm creating a floating platform that I would like to be able to simply travel from one designated point to another, and then return back to the first, and just pass between the two in a straight line. However, just to make it a little more interesting, I want to add a few rules to the platform. I'm coding it to travel multiples of whole tile values of world data. So if the platform is not stationary, then it will travel at least one whole tile width or tile height. Within one tile length, I would like it to accelerate from a stop to a given max speed. Upon reaching one tile length's distance, I would like it to slow to a stop at given tile coordinate and then repeat the process in reverse. The first two parts aren't too difficult, essentially I'm having trouble with the third part. I would like the platform to stop exactly at a tile coordinate, but being as I'm working with acceleration, it would seem easy to simply begin applying acceleration in the opposite direction to a value storing the platform's current speed once it reaches one tile's length of distance (assuming that the tile is traveling more than one tile-length, but to keep things simple, let's just assume it is)- but then the question is what would the correct value be for acceleration to increment from to produce this effect? How would I find that value?

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How to move from home page screen to the next menu screen on clicking a particular image in XNA4.0?

- by Raj

I m new 2 XNA game pgming(also C#)....I want 2 create a main page with some buttons and on clicking a particular button, it should goto another screen whr there r some buttons to select which should inturn goto the game screen on clicking....Whether I can put all the codes in the "game1.cs" or create new class for every page....Pls help... I've jus went through some pages in "Learning xna4.0" by o'reilly...If there s any other gud tutorials, pls suggest me...

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OpenGL 3 and the Radeon HD 4850x2

- by rotard

A while ago, I picked up a copy of the OpenGL SuperBible fifth edition and slowly and painfully started teaching myself OpenGL the 3.3 way, after having been used to the 1.0 way from school way back when. Making things more challenging, I am primarily a .NET developer, so I was working in Mono with the OpenTK OpenGL wrapper. On my laptop, I put together a program that let the user walk around a simple landscape using a couple shaders that implemented per-vertex coloring and lighting and texture mapping. Everything was working brilliantly until I ran the same program on my desktop. Disaster! Nothing would render! I have chopped my program down to the point where the camera sits near the origin, pointing at the origin, and renders a square (technically, a triangle fan). The quad renders perfectly on my laptop, coloring, lighting, texturing and all, but the desktop renders a small distorted non-square quadrilateral that is colored incorrectly, not affected by the lights, and not textured. I suspect the graphics card is at fault, because I get the same result whether I am booted into Ubuntu 10.10 or Win XP. I did find that if I pare the vertex shader down to ONLY outputting the positional data and the fragment shader to ONLY outputting a solid color (white) the quad renders correctly. But as SOON as I start passing in color data (whether or not I use it in the fragment shader) the output from the vertex shader is distorted again. The shaders follow. I left the pre-existing code in, but commented out so you can get an idea what I was trying to do. I'm a noob at glsl so the code could probably be a lot better. My laptop is an old lenovo T61p with a Centrino (Core 2) Duo and an nVidia Quadro graphics card running Ubuntu 10.10 My desktop has an i7 with a Radeon HD 4850 x2 (single card, dual GPU) from Saphire dual booting into Ubuntu 10.10 and Windows XP. The problem occurs in both XP and Ubuntu. Can anyone see something wrong that I am missing? What is "special" about my HD 4850x2? string vertexShaderSource = @" #version 330 precision highp float; uniform mat4 projection_matrix; uniform mat4 modelview_matrix; //uniform mat4 normal_matrix; //uniform mat4 cmv_matrix; //Camera modelview. Light sources are transformed by this matrix. //uniform vec3 ambient_color; //uniform vec3 diffuse_color; //uniform vec3 diffuse_direction; in vec4 in_position; in vec4 in_color; //in vec3 in_normal; //in vec3 in_tex_coords; out vec4 varyingColor; //out vec3 varyingTexCoords; void main(void) { //Get surface normal in eye coordinates //vec4 vEyeNormal = normal_matrix * vec4(in_normal, 0); //Get vertex position in eye coordinates //vec4 vPosition4 = modelview_matrix * vec4(in_position, 0); //vec3 vPosition3 = vPosition4.xyz / vPosition4.w; //Get vector to light source in eye coordinates //vec3 lightVecNormalized = normalize(diffuse_direction); //vec3 vLightDir = normalize((cmv_matrix * vec4(lightVecNormalized, 0)).xyz); //Dot product gives us diffuse intensity //float diff = max(0.0, dot(vEyeNormal.xyz, vLightDir.xyz)); //Multiply intensity by diffuse color, force alpha to 1.0 //varyingColor.xyz = in_color * diff * diffuse_color.xyz; varyingColor = in_color; //varyingTexCoords = in_tex_coords; gl_Position = projection_matrix * modelview_matrix * in_position; }"; string fragmentShaderSource = @" #version 330 //#extension GL_EXT_gpu_shader4 : enable precision highp float; //uniform sampler2DArray colorMap; //in vec4 varyingColor; //in vec3 varyingTexCoords; out vec4 out_frag_color; void main(void) { out_frag_color = vec4(1,1,1,1); //out_frag_color = varyingColor; //out_frag_color = vec4(varyingColor, 1) * texture(colorMap, varyingTexCoords.st); //out_frag_color = vec4(varyingColor, 1) * texture(colorMap, vec3(varyingTexCoords.st, 0)); //out_frag_color = vec4(varyingColor, 1) * texture2DArray(colorMap, varyingTexCoords); }"; Note that in this code the color data is accepted but not actually used. The geometry is outputted the same (wrong) whether the fragment shader uses varyingColor or not. Only if I comment out the line varyingColor = in_color; does the geometry output correctly. Originally the shaders took in vec3 inputs, I only modified them to take vec4s while troubleshooting.

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Creating smooth lighting transitions using tiles in HTML5/JavaScript game

- by user12098

I am trying to implement a lighting effect in an HTML5/JavaScript game using tile replacement. What I have now is kind of working, but the transitions do not look smooth/natural enough as the light source moves around. Here's where I am now: Right now I have a background map that has a light/shadow spectrum PNG tilesheet applied to it - going from darkest tile to completely transparent. By default the darkest tile is drawn across the entire level on launch, covering all other layers etc. I am using my predetermined tile sizes (40 x 40px) to calculate the position of each tile and store its x and y coordinates in an array. I am then spawning a transparent 40 x 40px "grid block" entity at each position in the array The engine I'm using (ImpactJS) then allows me to calculate the distance from my light source entity to every instance of this grid block entity. I can then replace the tile underneath each of those grid block tiles with a tile of the appropriate transparency. Currently I'm doing the calculation like this in each instance of the grid block entity that is spawned on the map: var dist = this.distanceTo( ig.game.player ); var percentage = 100 * dist / 960; if (percentage < 2) { // Spawns tile 64 of the shadow spectrum tilesheet at the specified position ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 64 ); } else if (percentage < 4) { ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 63 ); } else if (percentage < 6) { ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 62 ); } // etc... (sorry about the weird spacing, I still haven't gotten the hang of pasting code in here properly) The problem is that like I said, this type of calculation does not make the light source look very natural. Tile switching looks too sharp whereas ideally they would fade in and out smoothly using the spectrum tilesheet (I copied the tilesheet from another game that manages to do this, so I know it's not a problem with the tile shades. I'm just not sure how the other game is doing it). I'm thinking that perhaps my method of using percentages to switch out tiles could be replaced with a better/more dynamic proximity forumla of some sort that would allow for smoother transitions? Might anyone have any ideas for what I can do to improve the visuals here, or a better way of calculating proximity with the information I'm collecting about each tile? (PS: I'm reposting this from Stack Overflow at someone's suggestion, sorry about the duplicate!)

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Apply bone tranforms when importing FBX in XNA

- by hichaeretaqua

Preconditions: I have some models, that does only contain some meshes and one texture. There is no animation within the model. An example: a model of a table. I want to draw the Model with a custom effect, so I have to swap the effect after loading the model. In order to draw them correctly, I have to apply the bone transformation manually on each draw for each mesh and effect as can be seen here. So there are two questions: Is there a option during import that allows my to apply the bone transformation on all vertices, so that during draw call I should not have to do this? Is there a option during import that merges all vertices into a Vertex- and IndexBuffer, that allows me to draw the whole model with just one call? I'm pretty sure that the build-in "Autodesk FBX - XNA Framework" does not support this features, but maybe there is an other imported available or an other possibility I missed. The aim is to speed up rendering a little bit especially by using instancing. So having one VertexBuffer to draw at one time would be pretty nice.

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