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• ways to program glitch style effects

  - by okkk

  Most tutorials for generating glitch art usually has to do with some form of manipulation of the compression of files. Should my goal instead to replicate the look of these glitches in shaders or is it somehow possible to authentically generate the compression artifacts in real time? Example: This effect which I'm particularly interested is referred to as datamoshing. It does "things" using the p-frames of a video (frames that I think store just the change in pixels). I feel like I need a better understanding of both graphics programming and data-compression.

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• Elliptical orbit modeling

  - by Nathon

  I'm playing with orbits in a simple 2-d game where a ship flies around in space and is attracted to massive things. The ship's velocity is stored in a vector and acceleration is applied to it every frame as appropriate given Newton's law of universal gravitation. The point masses don't move (there's only 1 right now) so I would expect an elliptical orbit. Instead, I see this: I've tried with nearly circular orbits, and I've tried making the masses vastly different (a factor of a million) but I always get this rotated orbit. Here's some (D) code, for context: void accelerate(Vector delta) { velocity = velocity + delta; // Velocity is a member of the ship class. } // This function is called every frame with the fixed mass. It's a // method of the ship's. void fall(Well well) { // f=(m1 * m2)/(r**2) // a=f/m // Ship mass is 1, so a = f. float mass = 1; Vector delta = well.position - loc; float rSquared = delta.magSquared; float force = well.mass/rSquared; accelerate(delta * force * mass); }

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• 2D camera perspective projection from 3D coordinates -- HOW?

  - by Jack

  I am developing a camera for a 2D game with a top-down view that has depth. It's almost a 3D camera. Basically, every object has a Z even though it is in 2D, and similarly to parallax layers their position, scale and rotation speed vary based on their Z. I guess this would be a perspective projection. But I am having trouble converting the objects' 3D coordinates into the 2D space of the screen so that everything has correct perspective and scale. I never learned matrices though I did dig the topic a bit today. I tried without using matrices thanks to this article but every attempt gave awkward results. I'm using ActionScript 3 and Flash 11+ (Starling), where the screen coordinates work like this: Left-handed coordinates system illustration I can explain further what I did if you want to help me sort out what's wrong, or you can directly tell me how you would do it properly. In case you prefer the former, read on. These are images showing the formulas I used: upload.wikimedia.org/math/1/c/8/1c89722619b756d05adb4ea38ee6f62b.png upload.wikimedia.org/math/d/4/0/d4069770c68cb8f1aa4b5cfc57e81bc3.png (Sorry new users can't post images, but both are from the wikipedia article linked above, section "Perspective projection". That's where you'll find what all variables mean, too) The long formula is greatly simplified because I believe a normal top-down 2D camera has no X/Y/Z rotation values (correct ?). Then it becomes d = a - c. Still, I can't get it to work. Maybe you could explain what numbers I should put in a(xyz), c(xyz), theta(xyz), and particularly, e(xyz) ? I don't quite get how e is different than c in my case. c.z is also an issue to me. If the Z of the camera's target object is 0, should the camera's Z be something like -600 ? ( = focal length of 600) Whatever I do, it's wrong. I only got it to work when I used arbitrary calculations that "looked" right, like most cameras with parallax layers seem to do, but that's fake! ;) If I want objects to travel between Z layers I might as well do it right. :) Thanks a lot for your help!

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• Efficient existing rating system for multiplayer?

  - by Nikolay Kuznetsov

  I would like to add a rating for online version of a board game. In this game there are many game rooms each normally having 3-4 people. So I expect that player's rating adjustments (RA) should depends on Rating of opponents in the game room Number of players in game room and final place of a player Person gets rating increase if he plays more games and more frequently If a person leaves a game room (disconnect) before the game ends he should get punished with a high rating decrease I have found two related questions in here Developing an ELO like point system for a multiplayer gaming site Simplest most effective way to rank and measure player skill in a multi-player environment? Please, let me know what would be the most appropriate existing rating model to refer.

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• Order independent transparency in particle system

  - by Stepan Zastupov

  I'm writing a particle system and would like to find a trick to achieve proper alpha blending without sorting particles because: Each particle is a point sprite in a single mesh and I can't use scene graph ability to sort transparent nodes. The system node should be properly sorted, though. Particle position is computed on shader from initial velocity, acceleration and time. In order to sort the system I would have to perform all this computations on CPU, which is something I want to avoid. Sorting hundreds of particles against camera position and uploading it on GPU each frame seams to be quiet heavy operation. Alpha testing seems to be fast enough on GLES 2.0 and works fine for non-transparent but "masked" textures. Still, it's not enough for semi-transparent particles. How would you handle this?

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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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• The practical cost of swapping effects

  - by sebf

  Hello, I use XNA for my projects and on those forums I sometimes see references to the fact that swapping an effect for a mesh has a relatively high cost, which surprises me as I thought to swap an effect was simply a case of copying the replacement shader program to the GPU along with appropriate parameters. I wondered if someone could explain exactly what is costly about this process? And put, if possible, 'relatively' into context? For example say I wanted to use a short shader to help with picking, I would: Change the effect on every object, calculting a unique color to identify it and providing it to the shader. Draw all the objects to a render target in memory. Get the color from the target and use it to look up the selected object. What portion of the total time taken to complete that process would be spent swapping the shaders? My instincts would say that rendering the scene again, no matter how simple the shader, would be an order of magnitude slower than any other part of the process so why all the concern over effects?

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• Circle-Rectangle collision in a tile map game

  - by furiousd

  I am making a 2D tile map based putt-putt game. I have collision detection working between the ball and the walls of the map, although when the ball collides at the meeting point between 2 tiles I offset it by 0.5 so that it doesn't get stuck in the wall. This aint a huge issue though. if(y % 20 == 0) { y+=0.5; } if(x % 20 == 0) { x+=0.5; } Collisions work as follows Find the closest point between each tile and the center of the ball If distance(ball_x, ball_y, close_x, close_y) <= ball_radius and the closest point belongs to a solid object, collision has occured Invert X/Y speed according to side of object collided with The next thing I tried to do was implement floating blocks in the middle of the map for the ball to bounce off of. When a ball collides with a corner of the block, it gets stuck in it. So I changed my determineRebound() function to treat corners as if they were circles. Here's that functon: `i and j are indexes of the solid object in the 2d map array. x & y are centre point of ball.` void determineRebound(int _i, int _j) { if(y > _i*tile_w && y < _i*tile_w + tile_w) { //Not a corner xs*=-1; } else if(x > _j*tile_w && x < _j*tile_w + tile_w) { //Not a corner ys*=-1; } else { //Corner float nx = x - close_x; float ny = y - close_y; float len = sqrt(nx * nx + ny * ny); nx /= len; ny /= len; float projection = xs * nx + ys * ny; xs -= 2 * projection * nx; ys -= 2 * projection * ny; } } This is where things have gotten messy. Collisions with 'floating' corners work fine, but now when the ball collides near the meeting point of 2 tiles, it detects a corner collision and does not rebound as expected. I'm a bit in over my head at this point. I guess I'm wondering if I'm going about making this sort of game in the right way. Is a 2d tile map the way to go? If so, is there a problem with my collision logic and where am I going wrong? Any advice/feedback would be great.

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• Tips and Tools for creating Spritesheet animations

  - by Spooks

  I am looking for a tool that I can use to create sprite sheet easily. Right now I am using Illustrator, but I can never get the center of the character in the exact position, so it looks like it is moving around(even though its always in one place), while being loop through the sprite sheet. Is there any better tools that I can be using? Also what kind of tips would you give for working with a sprite sheet? Should I create each part of the character in individual layers (left arm, right arm, body, etc.) or everything at once? any other tips would also be helpful! thank you

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• Render a 3D scene in multiple windows - extended panoramic view

  - by teodron

  Is there any resource location on how to view a 3D scene from an application or a game on multiple windows or monitors? Each window should continue drawing from where the neighbouring one left off (in the end, the result should be a mosaic of the scene). My idea is to use a camera for each window and have a reference position and orientation for a meta-camera object that is used to correctly offset the other camera. Since there are quite some elements to consider (window specs, viewport properties, position-orientation of each render camera), what is the correct way to update the individual cameras considering the position and orientation of the central, meta-camera? I currently cannot make the cameras present the scene contiguously (and I am reluctant in working out the transformations without checking whether this is the actual way of doing things).

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• Creating a frozen bubble clone

  - by Vaughan Hilts

  This photo illustrates the environment: http://i.imgur.com/V4wbp.png I'll shoot the cannon, it'll bounce off the wall and it's SUPPOSED to stick to the bubble. It does at pretty much every other angle. The problem is always reproduced here, when hit off the wall into those bubbles. It also exists in other cases, but I'm not sure what triggers it. What actually happens: The ball will sometimes set to the wrong cell, and my "dropping" code will detect it as a loner and drop it off the stage. *There are many implementations of "Frozen Bubble" on the web, but I can't for the life of me find a good explanation as to how the algorithm for the "Bubble Sticking" works. * I see this: http://www.wikiflashed.com/wiki/BubbleBobble https://frozenbubblexna.svn.codeplex.com/svn/FrozenBubble/ But I can't figure out the algorithims... could anyone explain possibly the general idea behind getting the balls to stick? Code in question: //Counstruct our bounding rectangle for use var nX = currentBall.x + ballvX * gameTime; var nY = currentBall.y - ballvY * gameTime; var movingRect = new BoundingRectangle(nX, nY, 32, 32); var able = false; //Iterate over the cells and draw our bubbles for (var x = 0; x < 8; x++) { for (var y = 0; y < 12; y++) { //Get the bubble at this layout var bubble = bubbleLayout[x][y]; var rowHeight = 27; //If this slot isn't empty, draw if (bubble != null) { var bx = 0, by = 0; if (y % 2 == 0) { bx = x * 32 + 270; by = y * 32 + 45; } else { bx = x * 32 + 270 + 16; by = y * 32 + 45; } //Check var targetBox = new BoundingRectangle(bx, by, 32, 32); if (targetBox.intersects(movingRect)) { able = true; } } } } cellY = Math.round((currentBall.y - 45) / 32); if (cellY % 2 == 0) cellX = Math.round((currentBall.x - 270) / 32); else cellX = Math.round((currentBall.x - 270 - 16) / 32); Any ideas are very much welcome. Things I've tried: Flooring and Ceiling values Changing the wall bounce to a lower value Slowing down the ball None of these seem to affect it. Is there something in my math I'm not getting?

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• XNA 4.0, Combining model draw calls

  - by MayContainNuts

  I have the following problem: The levels in my game are made up of a Large Quantity of small Models and because of that I am experiencing frame rate problems. I already did some research and came to the conclusion that the amount of draw calls I am making must be the root of my problems. I've looked around for a while now and couldn't quite find a satisfying solution. I can't cull any of those models, in a worst case scenario there could be 1000 of them visible at the same time. I also looked at Hardware geometry Instancing, but I don't think that's quite what I'm looking for, because the level consists of a lot of different parts. So, what I'd like to do is combining 100 or 200 of these Models into a single large one and draw it as a whole 'chunk'. The whole geometry is static so it wouldn't have to be changed after combining, but different parts of it would have to use different textures (I think I can accomplish that with a texture atlas). But I have no idea how to to that, so does anybody have any suggestions?

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• Importing 3d model with multiple skeletons

  - by Sweta Dwivedi

  I have created an animated butterfly in 3ds Max and try to export it in ".fbx" format to use in XNA, however as soon as I compile, i get the following Errors: Warning 1 Multiple skeletons were found in the file. The first skeleton, named "Left.Wing" has been moved to be a child of the scene root. The other, "Right.Wing", will be ignored. Fragment identifier "Right.Wing". Error 2 Vertex is bound to bone "Right.Wing", but this bone is not present in the skeleton. Which is confusing since I have the bone Right.Wing . . and I use it to animate the butterfly I have seen a few possible solution for Blender but none for 3Ds max it would be really helpful if someone could help me out with this

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• Android: how do I switch between game scenes in a game? Any tutorials?

  - by Flavio

  I am trying to create a simple game using the Android SDK without using AndEngine (or any other game engine). I have plenty of experience designing games from the past, but I'm having lots of trouble trying to use the Android SDK to make my game. By far my biggest hurdle right now is switching between views. That is, for example, going from the menu to the first level, etc. I am using a traditional model I learned (I think it's called a scene stack or something?) in which you push the current scene onto a stack and the game's main loop runs the top item of the stack. This model seems non-trivial to implement in the Android SDK, mostly because Android seems to be picky about which thread instantiates which view. My issue is that I want the first level to show up when you press a button on the main menu, but when I instantiate the first level (the level class extends SurfaceView and implements SurfaceHolder.Callback) I get a runtime error complaining that the thread that runs the main menu can't instantiate this class. Something about calling Looper.prepare(). I figured at this point I was probably doing things wrong. I'm not sure how to specifically phrase my issue into a question, so maybe I should leave it as either 1) Does anybody know a good way (or the 'proper' way) to switch between scenes in an Android game? or 2) Are there any tutorials out there which show how to create a game that doesn't take place entirely in one scene? (I have googled for a while to no avail... maybe someone else knows of one?) Thanks!

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• graphical interface when using assembly language

  - by Hellbent

  Im looking to use assembly language to make a great game, not just an average game but a really great game. I want to learn a framework to use in assembly. I know thats not possible without learning the framework in c first. So im thinking of learning sdl in c and then learn, teach myself, how to interpret the program and run it as assembly language code which shouldnt be that hard. Then i will have a window and some graphics routines to display the game while using assembly to code everything in. I need to spend some time learning sdl and then some more time learning how to code all those statements using assembly while calling c functions and knowing what registers returned calls use and what they leave etc. My question is , Is this a good way to go or is there something better to get a graphical window display using assembly language? Regards HellBent

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• Issues glVertexAttribPointer last 2 parameters?

  - by NoobScratcher

  Introduction Hello I will start out by explaining my setup, showing samples as I go along explaining the situation. I'm using these tools: OpenGL 3.3 GLSL 330 C++ Problem The problem is when I render the wavefront obj 3d model it gives a very weird visual glitch the model was supposed to be a square but instead its a triangluated mess with parts of the vertexes pointing in a stretched direction in massive amounts towards the bottom left side of the frustum.... Explanation: I'm using std::vectors to store my wavefront .obj model data using sscanf to get the floating point values into the structure members x,y,z and store them into the Points structure variable p; int index = IndexAssigner(1, 1); ifstream file (list[index].c_str() ); points.push_back(Point()); Point p; int face[4]; while (!file.eof() ) { char modelbuffer[10000]; file.getline(modelbuffer, 10000); switch(modelbuffer[0]) { case 'v' : sscanf(modelbuffer, "v %f %f %f", &p.x, &p.y, &p.z); points.push_back(p); break; case 'f': sscanf(modelbuffer, "f %d %d %d %d", face, face+1, face+2, face+3 ); faces.push_back(face[0]); faces.push_back(face[1]); faces.push_back(face[2]); faces.push_back(face[3]); } //Turn on FileReader aka "RENDER CODE" FileReader = true; } then I render the Points vector using the .data() member of std::vectors to the frustum. Other declarations: int numfloats = 4; float* point=reinterpret_cast<float*>(&points[0]); int num_bytes=numfloats*sizeof(float); Vector declarations: struct Point {float x, y , z; }; std::vector<int>faces; std::vector<Point>points; Render code: glGenBuffers(1, &vertexbuffer); glGenTextures(1, &ModelTexture); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); glBindTexture(GL_TEXTURE_3D, ModelTexture); glTexImage2D(GL_TEXTURE_2D, 0,GL_RGBA, ModelSurface->w, ModelSurface->h, 0, GL_BGR, GL_UNSIGNED_BYTE, ModelSurface->pixels); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glBufferData(GL_ARRAY_BUFFER, sizeof(points), points.data(), GL_STATIC_DRAW); glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE,num_bytes ,points.data()); glEnableVertexAttribArray(3); //Translation Process GLfloat TranslationMatrix[] = { 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0, 0.0, 1.0 }; //Send Translation Matrix up to the vertex shader glUniformMatrix4fv(translation, 1, TRUE, TranslationMatrix); glDrawElements( GL_QUADS, faces.size(), GL_UNSIGNED_INT, faces.data()); I tried looking at what was causing this and went through every function every parameter ,etc looked at the man pages. Then found out that it could be my glVertexAttribPointer. Here are the man pages for glVertexAttribPointer http://www.opengl.org/sdk/docs/man/xhtml/glVertexAttribPointer.xml The last 2 parameters is my problem How do I write those 2 last parameters do I try putting the data from Points into it?. glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE,num_bytes ,points.data()); How does it work with vectors? Is it fast?* if you can not be bothered too look at the man pages here is the scripts coming from the man pages directly. Stride Specifies the byte offset between consecutive generic vertex attributes. If stride is 0, the generic vertex attributes are understood to be tightly packed in the array. The initial value is 0. Pointer Specifies a pointer to the first component of the first generic vertex attribute in the array. The initial value is 0. If you want my full source - http://ideone.com/fPfkg Thanks Again if you do read this.

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• What causes player box/world geometry glitches in old games?

  - by Alexander

  I'm looking to understand and find the terminology for what causes - or allows - players to interfere with geometry in old games. Famously, ID's Quake3 gave birth to a whole community of people breaking the physics by jumping, sliding, getting stuck and launching themselves off points in geometry. Some months ago (though I'd be darned if I can find it again!) I saw a conference held by Bungie's Vic DeLeon and a colleague in which Vic briefly discussed the issues he ran into while attempting to wrap 'collision' objects (please correct my terminology) around environment objects so that players could appear as though they were walking on organic surfaces, while not clipping through them or appear to be walking on air at certain points, due to complexities in the modeling. My aim is to compose a case study essay for University in which I can tackle this issue in games, drawing on early exploits and how techniques have changed to address such exploits and to aid in the gameplay itself. I have 3 current day example of where exploits still exist, however specifically targeting ID Software clearly shows they've massively improved their techniques between Q3 and Q4. So in summary, with your help please, I'd like to gain a slightly better understanding of this issue as a whole (its terminology mainly) so I can use terms and ask the right questions within the right contexts. In practical application, I know what it is, I know how to do it, but I don't have the benefit of level design knowledge yet and its technical widgety knick-knack terms =) Many thanks in advance AJ

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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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• How does gluLookAt work?

  - by Chan

  From my understanding, gluLookAt( eye_x, eye_y, eye_z, center_x, center_y, center_z, up_x, up_y, up_z ); is equivalent to: glRotatef(B, 0.0, 0.0, 1.0); glRotatef(A, wx, wy, wz); glTranslatef(-eye_x, -eye_y, -eye_z); But when I print out the ModelView matrix, the call to glTranslatef() doesn't seem to work properly. Here is the code snippet: #include <stdlib.h> #include <stdio.h> #include <GL/glut.h> #include <iomanip> #include <iostream> #include <string> using namespace std; static const int Rx = 0; static const int Ry = 1; static const int Rz = 2; static const int Ux = 4; static const int Uy = 5; static const int Uz = 6; static const int Ax = 8; static const int Ay = 9; static const int Az = 10; static const int Tx = 12; static const int Ty = 13; static const int Tz = 14; void init() { glClearColor(0.0, 0.0, 0.0, 0.0); glEnable(GL_DEPTH_TEST); glShadeModel(GL_SMOOTH); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); GLfloat lmodel_ambient[] = { 0.8, 0.0, 0.0, 0.0 }; glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient); } void displayModelviewMatrix(float MV[16]) { int SPACING = 12; cout << left; cout << "\tMODELVIEW MATRIX\n"; cout << "--------------------------------------------------" << endl; cout << setw(SPACING) << "R" << setw(SPACING) << "U" << setw(SPACING) << "A" << setw(SPACING) << "T" << endl; cout << "--------------------------------------------------" << endl; cout << setw(SPACING) << MV[Rx] << setw(SPACING) << MV[Ux] << setw(SPACING) << MV[Ax] << setw(SPACING) << MV[Tx] << endl; cout << setw(SPACING) << MV[Ry] << setw(SPACING) << MV[Uy] << setw(SPACING) << MV[Ay] << setw(SPACING) << MV[Ty] << endl; cout << setw(SPACING) << MV[Rz] << setw(SPACING) << MV[Uz] << setw(SPACING) << MV[Az] << setw(SPACING) << MV[Tz] << endl; cout << setw(SPACING) << MV[3] << setw(SPACING) << MV[7] << setw(SPACING) << MV[11] << setw(SPACING) << MV[15] << endl; cout << "--------------------------------------------------" << endl; cout << endl; } void reshape(int w, int h) { float ratio = static_cast<float>(w)/h; glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0, ratio, 1.0, 425.0); } void draw() { float m[16]; glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glGetFloatv(GL_MODELVIEW_MATRIX, m); gluLookAt( 300.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f ); glColor3f(1.0, 0.0, 0.0); glutSolidCube(100.0); glGetFloatv(GL_MODELVIEW_MATRIX, m); displayModelviewMatrix(m); glutSwapBuffers(); } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(400, 400); glutInitWindowPosition(100, 100); glutCreateWindow("Demo"); glutReshapeFunc(reshape); glutDisplayFunc(draw); init(); glutMainLoop(); return 0; } No matter what value I use for the eye vector: 300, 0, 0 or 0, 300, 0 or 0, 0, 300 the translation vector is the same, which doesn't make any sense because the order of code is in backward order so glTranslatef should run first, then the 2 rotations. Plus, the rotation matrix, is completely independent of the translation column (in the ModelView matrix), then what would cause this weird behavior? Here is the output with the eye vector is (0.0f, 300.0f, 0.0f) MODELVIEW MATRIX -------------------------------------------------- R U A T -------------------------------------------------- 0 0 0 0 0 0 0 0 0 1 0 -300 0 0 0 1 -------------------------------------------------- I would expect the T column to be (0, -300, 0)! So could anyone help me explain this? The implementation of gluLookAt from http://www.mesa3d.org void GLAPIENTRY gluLookAt(GLdouble eyex, GLdouble eyey, GLdouble eyez, GLdouble centerx, GLdouble centery, GLdouble centerz, GLdouble upx, GLdouble upy, GLdouble upz) { float forward[3], side[3], up[3]; GLfloat m[4][4]; forward[0] = centerx - eyex; forward[1] = centery - eyey; forward[2] = centerz - eyez; up[0] = upx; up[1] = upy; up[2] = upz; normalize(forward); /* Side = forward x up */ cross(forward, up, side); normalize(side); /* Recompute up as: up = side x forward */ cross(side, forward, up); __gluMakeIdentityf(&m[0][0]); m[0][0] = side[0]; m[1][0] = side[1]; m[2][0] = side[2]; m[0][1] = up[0]; m[1][1] = up[1]; m[2][1] = up[2]; m[0][2] = -forward[0]; m[1][2] = -forward[1]; m[2][2] = -forward[2]; glMultMatrixf(&m[0][0]); glTranslated(-eyex, -eyey, -eyez); }

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• Incorrect lighting results with deferred rendering

  - by Lasse

  I am trying to render a light-pass to a texture which I will later apply on the scene. But I seem to calculate the light position wrong. I am working on view-space. In the image above, I am outputting the attenuation of a point light which is currently covering the whole screen. The light is at 0,10,0 position, and I transform it to view-space first: Vector4 pos; Vector4 tmp = new Vector4 (light.Position, 1); // Transform light position for shader Vector4.Transform (ref tmp, ref Camera.ViewMatrix, out pos); shader.SendUniform ("LightViewPosition", ref pos); Now to me that does not look as it should. What I think it should look like is that the white area should be on the center of the scene. The camera is at the corner of the scene, and it seems as if the light would move along with the camera. Here's the fragment shader code: void main(){ // default black color vec3 color = vec3(0); // Pixel coordinates on screen without depth vec2 PixelCoordinates = gl_FragCoord.xy / ScreenSize; // Get pixel position using depth from texture vec4 depthtexel = texture( DepthTexture, PixelCoordinates ); float depthSample = unpack_depth(depthtexel); // Get pixel coordinates on camera-space by multiplying the // coordinate on screen-space by inverse projection matrix vec4 world = (ImP * RemapMatrix * vec4(PixelCoordinates, depthSample, 1.0)); // Undo the perspective calculations vec3 pixelPosition = (world.xyz / world.w) * 3; // How far the light should reach from it's point of origin float lightReach = LightColor.a / 2; // Vector in between light and pixel vec3 lightDir = (LightViewPosition.xyz - pixelPosition); float lightDistance = length(lightDir); vec3 lightDirN = normalize(lightDir); // Discard pixels too far from light source //if(lightReach < lightDistance) discard; // Get normal from texture vec3 normal = normalize((texture( NormalTexture, PixelCoordinates ).xyz * 2) - 1); // Half vector between the light direction and eye, used for specular component vec3 halfVector = normalize(lightDirN + normalize(-pixelPosition)); // Dot product of normal and light direction float NdotL = dot(normal, lightDirN); float attenuation = pow(lightReach / lightDistance, LightFalloff); // If pixel is lit by the light if(NdotL > 0) { // I have moved stuff from here to above so I can debug them. // Diffuse light color color += LightColor.rgb * NdotL * attenuation; // Specular light color color += LightColor.xyz * pow(max(dot(halfVector, normal), 0.0), 4.0) * attenuation; } RT0 = vec4(color, 1); //RT0 = vec4(pixelPosition, 1); //RT0 = vec4(depthSample, depthSample, depthSample, 1); //RT0 = vec4(NdotL, NdotL, NdotL, 1); RT0 = vec4(attenuation, attenuation, attenuation, 1); //RT0 = vec4(lightReach, lightReach, lightReach, 1); //RT0 = depthtexel; //RT0 = 100 / vec4(lightDistance, lightDistance, lightDistance, 1); //RT0 = vec4(lightDirN, 1); //RT0 = vec4(halfVector, 1); //RT0 = vec4(LightColor.xyz,1); //RT0 = vec4(LightViewPosition.xyz/100, 1); //RT0 = vec4(LightPosition.xyz, 1); //RT0 = vec4(normal,1); } What am I doing wrong here?

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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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• Loading levels from .txt or .XML for XNA

  - by Dave Voyles

  I'm attemptin to add multiple levels to my pong game. I'd like to simply exchange a few elements with each level, nothing crazy. Just the background texture, the color of the AI paddle (the one on the right side), and the music. It seems that the best way to go about this is by utilizing the StreamReader to read and write the files from XML. If there is a better, or more efficient alternative way then I'm all for it. In looking over the XNA Starter Platformer Kit provided by MS it seems that they've done it in this manner as well. I'm perplexed by a few things, however, namely parts within the Level class which aren't commented. /// <summary> /// Iterates over every tile in the structure file and loads its /// appearance and behavior. This method also validates that the /// file is well-formed with a player start point, exit, etc. /// </summary> /// <param name="fileStream"> /// A stream containing the tile data. /// </param> private void LoadTiles(Stream fileStream) { // Load the level and ensure all of the lines are the same length. int width; List<string> lines = new List<string>(); using (StreamReader reader = new StreamReader(fileStream)) { string line = reader.ReadLine(); width = line.Length; while (line != null) { lines.Add(line); if (line.Length != width) throw new Exception(String.Format("The length of line {0} is different from all preceeding lines.", lines.Count)); line = reader.ReadLine(); } } What does width = line.Length mean exactly? I mean I know how it reads the line, but what difference does it make if one line is longer than any of the others? Finally, their levels are simply text files that look like this: .................... .................... .................... .................... .................... .................... .................... .........GGG........ .........###........ .................... ....GGG.......GGG... ....###.......###... .................... .1................X. #################### It can't be that easy..... Can it?

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• Particle effect after the bullet

  - by Siddharth

  In my game, I fire a bullet from the gun along with that I generate a particle behind the bullet so that I look like fire effect after the bullet. But my problem is that the position I got from the bullet was distance in place. So basically I want to say that the bullet speed was high for that reason I got coordinate for the particle generation was far from each other like dot dot effect. But I want continuous flow of particle behind the bullet. So please provide any guidance for my problem

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• Isometric layer moving inside map

  - by gronzzz

  i'm created isometric map and now trying to limit layer moving. Main idea, that i have left bottom, right bottom, left top, right top points, that camera can not move outside, so player will not see map out of bounds. But i can not understand algorithm of how to do that. It's my layer scale/moving code. - (void)touchBegan:(UITouch *)touch withEvent:(UIEvent *)event { _isTouchBegin = YES; } - (void)touchMoved:(UITouch *)touch withEvent:(UIEvent *)event { NSArray *allTouches = [[event allTouches] allObjects]; UITouch *touchOne = [allTouches objectAtIndex:0]; CGPoint touchLocationOne = [touchOne locationInView: [touchOne view]]; CGPoint previousLocationOne = [touchOne previousLocationInView: [touchOne view]]; // Scaling if ([allTouches count] == 2) { _isDragging = NO; UITouch *touchTwo = [allTouches objectAtIndex:1]; CGPoint touchLocationTwo = [touchTwo locationInView: [touchTwo view]]; CGPoint previousLocationTwo = [touchTwo previousLocationInView: [touchTwo view]]; CGFloat currentDistance = sqrt( pow(touchLocationOne.x - touchLocationTwo.x, 2.0f) + pow(touchLocationOne.y - touchLocationTwo.y, 2.0f)); CGFloat previousDistance = sqrt( pow(previousLocationOne.x - previousLocationTwo.x, 2.0f) + pow(previousLocationOne.y - previousLocationTwo.y, 2.0f)); CGFloat distanceDelta = currentDistance - previousDistance; CGPoint pinchCenter = ccpMidpoint(touchLocationOne, touchLocationTwo); pinchCenter = [self convertToNodeSpace:pinchCenter]; CGFloat predictionScale = self.scale + (distanceDelta * PINCH_ZOOM_MULTIPLIER); if([self predictionScaleInBounds:predictionScale]) { [self scale:predictionScale scaleCenter:pinchCenter]; } } else { // Dragging _isDragging = YES; CGPoint previous = [[CCDirector sharedDirector] convertToGL:previousLocationOne]; CGPoint current = [[CCDirector sharedDirector] convertToGL:touchLocationOne]; CGPoint delta = ccpSub(current, previous); self.position = ccpAdd(self.position, delta); } } - (void)touchEnded:(UITouch *)touch withEvent:(UIEvent *)event { _isDragging = NO; _isTouchBegin = NO; // Check if i need to bounce _touchLoc = [touch locationInNode:self]; } #pragma mark - Update - (void)update:(CCTime)delta { CGPoint position = self.position; float scale = self.scale; static float friction = 0.92f; //0.96f; if(_isDragging && !_isScaleBounce) { _velocity = ccp((position.x - _lastPos.x)/2, (position.y - _lastPos.y)/2); _lastPos = position; } else { _velocity = ccp(_velocity.x * friction, _velocity.y *friction); position = ccpAdd(position, _velocity); self.position = position; } if (_isScaleBounce && !_isTouchBegin) { float min = fabsf(self.scale - MIN_SCALE); float max = fabsf(self.scale - MAX_SCALE); int dif = max > min ? 1 : -1; if ((scale > MAX_SCALE - SCALE_BOUNCE_AREA) || (scale < MIN_SCALE + SCALE_BOUNCE_AREA)) { CGFloat newSscale = scale + dif * (delta * friction); [self scale:newSscale scaleCenter:_touchLoc]; } else { _isScaleBounce = NO; } } }

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• Is it legal to develop a game using D&D rules?

  - by Max

  For a while now I've been thinking about trying my hand at creating a game similar in spirit and execution to Baldur's Gate, Icewind Dale and offshoots. I'd rather not face the full bulk of work in implementing my own RPG system - I'd like to use D&D rules. Now, reading about the subject it seems there is something called "The License" which allows a company to brand a game as D&D. This license seems to be exclusive, and let's just say I don't have the money to buy it :p. Is it still legal for me to implement and release such a game? Commercially or open-source? I'm not sure exactly which edition would fit the best, but since Baldur's Gate is based of 2nd edition, could I go ahead an implement that? in short: what are the issues concerning licensing and publishing when it comes to D&D? Also: Didn't see any similar question...

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