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  • What is a technique for 2D ray-box intersection that is suitable for old console hardware?

    - by DJCouchyCouch
    I'm working on a Sega Genesis homebrew game (it has a 7mhz 68000 CPU). I'm looking for a way to find the intersection between a particle sprite and a background tile. Particles are represented as a point with a movement vector. Background tiles are 8 x 8 pixels, with an (X,Y) position that is always located at a multiple of 8. So, really, I need to find the intersection point for a ray-box collision; I need to find out where along the edge of the tile the ray/particle hits. I have these two hard constraints: I'm working with pixel locations (integers). Floating point is too expensive. It doesn't have to be super exact, just close enough. Multiplications, divisions, dot products, et cetera, are incredibly expensive and are to be avoided. So I'm looking for an efficient algorithm that would fit those constraints. Any ideas? I'm writing it in C, so that would work, but assembly should be good as well.

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  • Arrive steering behavior

    - by dbostream
    I bought a book called Programming game AI by example and I am trying to implement the arrive steering behavior. The problem I am having is that my objects oscillate around the target position; after oscillating less and less for awhile they finally come to a stop at the target position. Does anyone have any idea why this oscillating behavior occur? Since the examples accompanying the book are written in C++ I had to rewrite the code into C#. Below is the relevant parts of the steering behavior: private enum Deceleration { Fast = 1, Normal = 2, Slow = 3 } public MovingEntity Entity { get; private set; } public Vector2 SteeringForce { get; private set; } public Vector2 Target { get; set; } public Vector2 Calculate() { SteeringForce.Zero(); SteeringForce = SumForces(); SteeringForce.Truncate(Entity.MaxForce); return SteeringForce; } private Vector2 SumForces() { Vector2 force = new Vector2(); if (Activated(BehaviorTypes.Arrive)) { force += Arrive(Target, Deceleration.Slow); if (!AccumulateForce(force)) return SteeringForce; } return SteeringForce; } private Vector2 Arrive(Vector2 target, Deceleration deceleration) { Vector2 toTarget = target - Entity.Position; double distance = toTarget.Length(); if (distance > 0) { //because Deceleration is enumerated as an int, this value is required //to provide fine tweaking of the deceleration.. double decelerationTweaker = 0.3; double speed = distance / ((double)deceleration * decelerationTweaker); speed = Math.Min(speed, Entity.MaxSpeed); Vector2 desiredVelocity = toTarget * speed / distance; return desiredVelocity - Entity.Velocity; } return new Vector2(); } private bool AccumulateForce(Vector2 forceToAdd) { double magnitudeRemaining = Entity.MaxForce - SteeringForce.Length(); if (magnitudeRemaining <= 0) return false; double magnitudeToAdd = forceToAdd.Length(); if (magnitudeToAdd > magnitudeRemaining) magnitudeToAdd = magnitudeRemaining; SteeringForce += Vector2.NormalizeRet(forceToAdd) * magnitudeToAdd; return true; } This is the update method of my objects: public void Update(double deltaTime) { Vector2 steeringForce = Steering.Calculate(); Vector2 acceleration = steeringForce / Mass; Velocity = Velocity + acceleration * deltaTime; Velocity.Truncate(MaxSpeed); Position = Position + Velocity * deltaTime; } If you want to see the problem with your own eyes you can download a minimal example here. Thanks in advance.

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  • Why is Spritebatch drawing my Textures out of order?

    - by Andrew
    I just started working with XNA Studio after programming 2D games in java. Because of this, I have absolutely no experience with Spritebatch and sprite sorting. In java, I could just layer the images by calling the draw methods in order. For a while, my Spritebatch was working fine in deferred sorting mode, but when I made a change to one of my textures, it suddenly started drawing them out of order. I have searched for a solution to this problem, but nothing seems to work. I have tried adding layer depths to the sprites and changing the sort mode to BackToFront or FrontToBack or even immediate, but nothing seems to work. Here is my drawing code: protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.Gray); Game1.spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, SamplerState.PointClamp, null, null); for (int x = 0; x < 5; x++) { for (int y = 0; y < 5; y++) { region[x, y].draw(((float)w / aw)); // Draws the Tile-Based background } } player.draw(spriteBatch, ((float)w / aw));//draws the character (This method is where the problem occurs) enemy.draw(spriteBatch, (float)w/aw); // draws a basic enemy Game1.spriteBatch.End(); base.Draw(gameTime); } player.draw method: public void draw(SpriteBatch sb, float ratio){ //draws the player base (The character without hair or equipment) sb.Draw(playerbase[0], new Rectangle((int)(pos.X - (24 * ratio)), (int)(pos.Y - (48 * ratio)), (int)(48 * ratio), (int)(48 * ratio)), new Rectangle(orientation * 48, animFrame * 48, 48, 48), Color.White,0,Vector2.Zero,SpriteEffects.None,0); //draws the player's hair sb.Draw(playerbase[3], new Rectangle((int)(pos.X - (24 * ratio)), (int)(pos.Y - (48 * ratio)), (int)(48 * ratio), (int)(48 * ratio)), new Rectangle(orientation * 48, animFrame * 48, 48, 48), Color.White, 0, Vector2.Zero, SpriteEffects.None, 0); //draws the player's shirt sb.Draw(equipment[0], new Rectangle((int)(pos.X - (24 * ratio)), (int)(pos.Y - (48 * ratio)), (int)(48 * ratio), (int)(48 * ratio)), new Rectangle(orientation * 48, animFrame * 48, 48, 48), Color.White, 0, Vector2.Zero, SpriteEffects.None, 0); //draws the player's pants sb.Draw(equipment[1], new Rectangle((int)(pos.X - (24 * ratio)), (int)(pos.Y - (48 * ratio)), (int)(48 * ratio), (int)(48 * ratio)), new Rectangle(orientation * 48, animFrame * 48, 48, 48), Color.White, 0, Vector2.Zero, SpriteEffects.None, 0); //draws the player's shoes sb.Draw(equipment[2], new Rectangle((int)(pos.X - (24 * ratio)), (int)(pos.Y - (48 * ratio)), (int)(48 * ratio), (int)(48 * ratio)), new Rectangle(orientation * 48, animFrame * 48, 48, 48), Color.White, 0, Vector2.Zero, SpriteEffects.None, 0); } the game has a top-down perspective much like the early legend of zelda games. It draws sections of the texture depending on which direction the character is facing and the animation frame. However, instead of drawing the character in the order the draw methods are called, it ends up drawing the character out of order. Please help me with this problem.

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  • Is there any existing (old) game that released graphic as free or open source?

    - by Alexey Petrushin
    I'd like to (re)create an online version (html5/JS) of some old game, for example something like HoM&M 2. Maybe, some of old games were released as free or open source (I'm interested in the graphical assets only)? I heard something about Red Alert been released as free, but I'm not sure if it's permitted to reuse graphical assets in such manner. Do You know such games? Another question - can You please share Your thoughts, rough estimate - how much it will cost to pay an artist to create graphics similar to HoM&M 2?

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  • Detecting long held keys on keyboard

    - by Robinson Joaquin
    I just want to ask if can I check for "KEY"(keyboard) that is HOLD/PRESSED for a long time, because I am to create a clone of breakout with air hockey for 2 different human players. Here's the list of my concern: Do I need other/ 3rd party library for KEY HOLDS? Is multi-threading needed? I don't know anything about this multi-threading stuff and I don't think about using one(I'm just a NEWBIE). One more thing, what if the two players pressed their respective key at the same time, how can I program to avoid error or worse one player's key is prioritized first before the the key of the other. example: Player 1 = W for UP & S for DOWN Player 2 = O for UP & L for DOWN (example: W & L is pressed at the same time) PS: I use GLUT for the visuals of the game.

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  • Best practices for periodically saving game state to disk

    - by Ben Morris
    I'm working on an MMO. All of the player and environment data lives on a server and is kept in memory. There's a "world" object which keeps track of all of the maps, characters, etc. and their relations to each other. To avoid data loss in case of a crash, I've been periodically serializing the world to disk. The trouble is, this object can be quite large, so when the server starts writing, there's noticeable in-game slowdown for a few seconds, which I'd like to avoid. Any pointers on how to go about this in a more efficient way?

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  • Collision Resolution

    - by ultifinitus
    Hey all, I'm making a simple side-scrolling game, and I would appreciate some input! My collision detection system is a simple bounding box detection, so it's really easy to implement. However my collision resolution is ridiculous! Currently I have a little formula like this: if (colliding(firstObject,secondObject)) firstObject.resolve_collision(yAxisOffset); if (colliding(firstObject,secondObject)) firstObject.resolve_collision(xAxisOffset); where yAxisOffset is only set if the first object's previous y position was outside the second object's collision frame, respectively xAxisOffset as well. Now this is working great, in general. However there is a single problem. When I have a stack of objects and I push the first object against that stack, the first object get's "stuck," on the stack. What's I think is happening is the object's collision system checks and resolves for collisions based on creation time, so If I check one axis, then the other, the object will "sink" object directly along the checking axis. This sinking action causes the collision detection routine to think there's a gap between our position and the other object's position, and when I finally check the object that I've already sunk into, my object's position is resolved to it's original position... All this is great, and I'm sure if I bang my head against a wall long enough i'll come up with a working algorithm, but I'd rather not =). So what in the heck do you think I should do? How could I change my collision resolution system to fix this? Here's the program (temporary link, not sure how long it'll last) (notes: arrow keys to navigate, click to drop block, x to jump) I'd appreciate any help you can offer!

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  • What makes game sound effects "good"?

    - by you786
    I'm making a small game, and I've found some free sound effects that I'd like to use. The issue is that I can't get the sound effects to sound like they "belong" in my game. I don't know what to look for that can make sound effects match the rest of my game style. I have some ideas on what affects the meshing of audio with graphics. For example, I have a feeling that the current SFX I may be too "realistic" for my graphical style, which is pretty cartoon-like. Also, is there a golden standard for what volume various SFX should be at? (for example, I am thinking that footsteps or other common sounds should be at barely audible volumes, while enemy deaths or something that is a "big deal" should be louder). I found a similar question about graphics, I'm looking for a similar response with sound effects.

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  • Smooth Camera Rotation around 90 degrees

    - by Nicholas
    I'm developing a third person 3D platformer in XNA. My problem is when I try to rotate the camera around the player. I would like to rotate (and animate) the camera 90 degrees around the player. So the camera should rotate until it has reached 90 degrees from the starting position. I cannot figure out how to keep track of the rotation, and when the rotation has made the full 90 degrees. Currently my cameras update: public void Update(Vector3 playerPosition) { if (rotateCamera) { position = Vector3.Transform(position - playerPosition, Matrix.CreateRotationY(0.1f)) + playerPosition; } this.viewMatrix = Matrix.CreateLookAt(position, playerPosition, Vector3.Up); } The initial position of the camera is set in the constructor. The "rotateCamera" bool is set on keypress. Thanks for the help in advance. Cheers.

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  • Physics in carrom like game using cocos2d + Box2D

    - by Raj
    I am working on carrom like game using cocos2d + Box2D. I set world gravity(0,0), want gravity in z-axis. I set following values for coin and striker body: Coin body (circle with radius - 15/PTM_RATIO): density = 20.0f; friction = 0.4f; restitution = 0.6f; Striker body (circle with radius - 15/PTM_RATIO): density = 25.0f; friction = 0.6f; restitution = 0.3f; Output is not smooth. When I apply ApplyLinearImpulse(force,position) the coin movement looks like floating in the air - takes too much time to stop. What values for coin and striker make it look like real carrom?

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  • Django and Google App Engine Helper not finding the ipaddr module.

    - by Phil
    I'm trying to get Django running on GAE using this tutorial. When I run python manage.py runserver I get the stacktrace below. I'm new to both django and python so I don't know what my next steps are (This is Ubuntu Jaunty btw). It seems django isn't finding the GAE module ipaddr which comes with SDK 1.3.1. How do I get django to find this module? /home/username/bin/google_appengine/google/appengine/api/datastore_file_stub.py:40: DeprecationWarning: the md5 module is deprecated; use hashlib instead import md5 /home/username/bin/google_appengine/google/appengine/api/memcache/__init__.py:31: DeprecationWarning: the sha module is deprecated; use the hashlib module instead import sha Traceback (most recent call last): File "manage.py", line 18, in <module> InstallAppengineHelperForDjango() File "/home/username/Development/GAE/myapp/appengine_django/__init__.py", line 543, in InstallAppengineHelperForDjango InstallDjangoModuleReplacements() File "/home/username/Development/GAE/myapp/appengine_django/__init__.py", line 260, in InstallDjangoModuleReplacements import django.db File "/home/username/Development/GAE/myapp/django/db/__init__.py", line 57, in <module> 'TIME_ZONE': settings.TIME_ZONE, File "/home/username/Development/GAE/myapp/appengine_django/db/base.py", line 117, in __init__ self._setup_stubs() File "/home/username/Development/GAE/myapp/appengine_django/db/base.py", line 128, in _setup_stubs from google.appengine.tools import dev_appserver_main File "/home/username/bin/google_appengine/google/appengine/tools/dev_appserver_main.py", line 82, in <module> from google.appengine.tools import appcfg File "/home/username/bin/google_appengine/google/appengine/tools/appcfg.py", line 53, in <module> from google.appengine.api import dosinfo File "/home/username/bin/google_appengine/google/appengine/api/dosinfo.py", line 25, in <module> import ipaddr ImportError: No module named ipaddr

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  • Draw a never-ending line in XNA

    - by user2236165
    I am drawing a line in XNA which I want to never end. I also have a tool that moves forward in X-direction and a camera which is centered at this tool. However, when I reach the end of the viewport the lines are not drawn anymore. Here are some pictures to illustrate my problem: At the start the line goes across the whole screen, but as my tool moves forward, we reach the end of the line. Here are the method which draws the lines: private void DrawEvenlySpacedSprites (Texture2D texture, Vector2 point1, Vector2 point2, float increment) { var distance = Vector2.Distance (point1, point2); // the distance between two points var iterations = (int)(distance / increment); // how many sprites with be drawn var normalizedIncrement = 1.0f / iterations; // the Lerp method needs values between 0.0 and 1.0 var amount = 0.0f; if (iterations == 0) iterations = 1; for (int i = 0; i < iterations; i++) { var drawPoint = Vector2.Lerp (point1, point2, amount); spriteBatch.Draw (texture, drawPoint, Color.White); amount += normalizedIncrement; } } Here are the draw method in Game. The dots are my lines: protected override void Draw (GameTime gameTime) { graphics.GraphicsDevice.Clear(Color.Black); nyVector = nextVector (gammelVector); GraphicsDevice.SetRenderTarget (renderTarget); spriteBatch.Begin (); DrawEvenlySpacedSprites (dot, gammelVector, nyVector, 0.9F); spriteBatch.End (); GraphicsDevice.SetRenderTarget (null); spriteBatch.Begin (SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null, null, camera.transform); spriteBatch.Draw (renderTarget, new Vector2 (), Color.White); spriteBatch.Draw (tool, new Vector2(toolPos.X - (tool.Width/2), toolPos.Y - (tool.Height/2)), Color.White); spriteBatch.End (); gammelVector = new Vector2 (nyVector.X, nyVector.Y); base.Draw (gameTime); } Here's the next vector-method, It just finds me a new point where the line should be drawn with a new X-coordinate between 100 and 200 pixels and a random Y-coordinate between the old vector Y-coordinate and the height of the viewport: Vector2 nextVector (Vector2 vector) { return new Vector2 (vector.X + r.Next(100, 200), r.Next ((int)(vector.Y - 100), viewport.Height)); } Can anyone point me in the right direction here? I'm guessing it has to do with the viewport.width, but I'm not quite sure how to solve it. Thank you for reading!

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  • Missing z-axis rotation for transforming between two vectors

    - by Steve Baughman
    I'm trying to rotate a cube so that it's facing up, but am getting hung up on the final implementation details. It now reliably will rotate the x,y axis to the correct side, but the z-axis is never rotating (See photos of before and after rotation). When I'm using the code below I always get '0' for my rotationVector.z. What am I missing here? // Define lookAt vector lookAtVector = GLKVector3Make(0,0,1); // Define axes vectors axes[0] = GLKVector3Make(0,0,1); axes[1] = GLKVector3Make(-1,0,0); axes[2] = GLKVector3Make(0,1,0); axes[3] = GLKVector3Make(1,0,0); axes[4] = GLKVector3Make(0,-1,0); axes[5] = GLKVector3Make(0,0,-1); CGFloat highest_dot = -1.0; GLKVector3 closest_axis; for(int i = 0; i < 6; i++) { // multiply cube's axes by existing matrix GLKVector3 axis = GLKMatrix4MultiplyVector3(matrix, axes[i]); CGFloat dot = GLKVector3DotProduct(axis, lookAtVector); if(dot > highest_dot) { closest_axis = axis; highest_dot = dot; } } GLKVector3 rotationVector = GLKVector3CrossProduct(closest_axis, lookAtVector); // Get angle between vectors CGFloat angle = atan2(GLKVector3Length(rotationVector), GLKVector3DotProduct(closest_axis, lookAtVector)); // normalize the rotation vector rotationVector = GLKVector3Normalize(rotationVector); // Create transform CATransform3D rotationTransform = CATransform3DMakeRotation(angle, rotationVector.x, rotationVector.y, rotationVector.z); // add rotation transform to existing transformation baseTransform = CATransform3DConcat(baseTransform, rotationTransform); return baseTransform; Before 3d Rotation After 3d Rotation Implementation based on this post

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  • Turn-based games [closed]

    - by Blue
    I've been looking for tutorials on turn-based games. I found an incomplete tutorial series by InsugentX about turn-based games. I haven't looked through it, but since it's incomplete, I worry that I won't be able to finish the scripts. I'm looking for tutorials or some good tips or advice to create turn-based games(similar to Worms). Recently I finished watching the WalkerBoys' tutorials so I am familiar with code. Where can I find some info and/or tutorials on creating Turn-based games? I'd prefer it to be video format. How can I create turn-based games (not the entire thing, only the set-up) or a turn-based event like in Worms? To explain more, How do I create 2 parties(1st player, 2nd player) exchanging turns(turn-based games and/or hotseat). While parties have characters similar to Worms(having more than 1 character within each party)? Do I use an array, an enum? I don't have any experience in turn-based games, so I would like to know how to actually make turn-based games. I can't find any reference to help me with construction of a turn-based game code similar to Worms in a programming language I can understand.

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  • Image with FadeIn effect blinks when added to scene

    - by Ef Es
    I am trying to add an image to the scene, but it should just be added to the scene invisible, FadeIn and then be deleted when the effect finishes. My problem is that the images blink once when they are added to the scene, then they do the intended effect. My best guess is that when they are added they show on the scene for a split second before starting the animation. I though of making them invisible for a split second before activating them, but I am not sure how to code it. const bool Sunbeams::add() { const CCSize kSceenSize = CCDirector::sharedDirector()->getWinSize(); const int nRayType = random( m_kRays.size()); const CCPoint kPosition( random( static_cast < int >( kSceenSize.width)), 0.0f); const float fDuration = random( m_fDurationVariance) + m_fDurationMin; CCSprite* pkLightBeam = CCSprite::spriteWithTexture( m_kRays[nRayType]); if ( !pkLightBeam) { msg::debug( "Sunbeams::add", "Failed to create sprite from ray '%d'!\n", m_kRays[nRayType]); return false; } pkLightBeam->setAnchorPoint( CCPointZero); pkLightBeam->setPosition( kPosition); m_kActiveBeams.push_back( pkLightBeam); CCDirector::sharedDirector()->getRunningScene()->addChild( pkLightBeam); CCActionInterval* pkAction = CCFadeIn::actionWithDuration( fDuration); CCActionInterval* pkActionBack = pkAction->reverse(); pkLightBeam->runAction( CCSequence::actions( pkAction, pkActionBack, 0)); return true; }

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  • Migration from XNA to SharpDX

    - by Wouter
    My fear is that XNA has reached the end of the road. To keep up with the latest technology a shift to another game framework might be needed. We have many games in a large codebase, all based on XNA. My question is, how much work would it be to migrate to SharpDX and are there other possibilities? Our code base mainly uses basic 3D rendering and the SpriteBatch, no fancy shader stuff. Update: I should have mentioned we only use 2.5D, we have a simple engine that builds textured quads to render text and animated sprites. Also for sound we use XACT (what else..) with some effects.

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  • Automated texture mapping

    - by brandon
    I have a set of seamless tiling textures. I want to be able to take an arbitrary model and create a UV map with these properties: No stretching (all textures tile appropriately so there is no stretching and sheering of the texture) The textures display on the correct axis relative to the model it's mapping to (if you look at the example, you can see some of the letters on the front are tilted, the y axis of the texture should be matching up with the y axis of the object. Some other faces have upside down letters too) the texture is as continuous as possible on the surface of the model (if two faces are adjacent, the texture continues on the adjacent face where it left off) the model is closed (all faces are completely enclosed by other faces) A few notes. This mapping will occur before triangulation. I realize there are ways to do this by hand and it's probably a hard problem to automatically map textures in general, but since these textures are seamless and I just need uniform coverage it seems like an easier problem. I'm looking for an algorithmic approach to this that I can apply in general, not a tool that does it. What approach would work for this, is there an existing one? (I assume so)

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  • Moving my sprite in XNA using classes

    - by Tom
    Hey, im a newbie at this programming lark and its really frustrating me. I'm trying to move a snake in all directions while using classes. Ive created a vector2 for speed and ive attempted creating a method which moves the snake within the snake class. Now I'm confused and not sure what to do next. Appreciate any help. Thanks :D This is what i've done in terms of the method... public Vector2 direction() { Vector2 inputDirection = Vector2.Zero; if (Keyboard.GetState().IsKeyDown(Keys.Left)) inputDirection.X -= -1; if (Keyboard.GetState().IsKeyDown(Keys.Right)) inputDirection.X += 1; if (Keyboard.GetState().IsKeyDown(Keys.Up)) inputDirection.Y -= -1; if (Keyboard.GetState().IsKeyDown(Keys.Down)) inputDirection.Y += 1; return inputDirection * snakeSpeed; } Appreciate any help. Thanks :D EDIT: Well let me make everything clear. Im making a small basic game for an assignment. The game is similar to the old snake game on the old Nokia phones. I've created a snake class (even though I'm not sure whether this is needed because im only going to be having one moving sprite within the game). After I written the code above (in the snake class), the game ran with no errors but I couldn't actually move the image :( EDIT2: Thanks so much for everyones responses!!

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  • LWJGL glRotatef() without rotating axes?

    - by Brandon oubiub
    Okay so, I noticed when you rotate around an axis, say you do this: glRotatef(90.0f, 1.0f, 0.0f, 0.0f); That will rotate things 90 degrees around the x-axis. However, it also sort of rotates the y and z axes as well. So now the y-axis is pointing in and out of the screen, instead of up and down. So when I try to do stuff like this: glRotatef(90.0f, 1.0f, 0.0f, 0.0f); glRotatef(whatever, 0.0f, 1.0f, 0.0f); glRotatef(whatever2, 0.0f, 0.0f, 1.0f); The rotations around the y and z-axes end up not how I want them. I was wondering if there is any way I can sort of rotate just the axes back to their initial position after using glRotatef(), without rotating the object back. Or something like that, just so that when I rotate around the y-axis, it rotates around a vertical axis.

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  • How to run the pixel shader effcet??

    - by Yashwinder
    Below stated is the code for my pixel shader which I am rendering after the vertex shader. I have set the wordViewProjection matrix in my program but I don't know to set the progress variable i.e in my pixel shader file which will make the image displayed by the help of a quad to give out transition effect. Here is the code for my pixel shader program::: As my pixel shader is giving a static effect and now I want to use it to give some effect. So for this I have to add a progress variable in my pixel shader and initialize to the Constant table function i.e constantTable.SetValue(D3DDevice,"progress",progress ); I am having the problem in using this function for progress in my program. Anybody know how to set this variable in my program. And my new pixel Shader code is float progress : register(C0); sampler2D implicitInput : register(s0); sampler2D oldInput : register(s1); struct VS_OUTPUT { float4 Position : POSITION; float4 Color : COLOR0; float2 UV : TEXCOORD 0; }; float4 Blinds(float2 uv) { if(frac(uv.y * 5) < progress) { return tex2D(implicitInput, uv); } else { return tex2D(oldInput, uv); } } // Pixel Shader { return Blinds(input.UV); }

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  • ray collision with rectangle and floating point accuracy

    - by phq
    I'm trying to solve a problem with a ray bouncing on a box. Actually it is a sphere but for simplicity the box dimensions are expanded by the sphere radius when doing the collision test making the sphere a single ray. It is done by projecting the ray onto all faces of the box and pick the one that is closest. However because I'm using floating point variables I fear that the projected point onto the surface might be interpreted as being below in the next iteration, also I will later allow the sphere to move which might make that scenario more likely. Also the bounce coefficient might be as low as zero, making the sphere continue along the surface. So my naive solution is to project not only forwards but backwards to catch those cases. That is where I got into problems shown in the figure: In the first iteration the first black arrow is calculated and we end up at a point on the surface of the box. In the second iteration the "back projection" hits the other surface making the second black arrow bounce on the wrong surface. If there are several boxes close to each other this has further consequences making the sphere fall through them all. So my main question is how to handle possible floating point accuracy when placing the sphere on the box surface so it does not fall through. In writing this question I got the idea to have a threshold to only accept back projections a certain amount much smaller than the box but larger than the possible accuracy limitation, this would only cause the "false" back projection when the sphere hit the box on an edge which would appear naturally. To clarify my original approach, the arrows shown in the image is not only the path the sphere travels but is also representing a single time step in the simulation. In reality the time step is much smaller about 0.05 of the box size. The path traveled is projected onto possible sides to avoid traveling past a thinner object at higher speeds. In normal situations the floating point accuracy is not an issue but there are two situations where I have the concern. When the new position at the end of the time step is located very close to the surface, very unlikely though. When using a bounce factor of 0, here it happens every time the sphere hit a box. To add some loss of accuracy, the motivation for my concern, is that the sphere and box are in different coordinate systems and thus the sphere location is transformed for every test. This last one is why I'm not willing to stand on luck that one floating point value lying on top of the box always will be interpreted the same. I did not know voronoi regions by name, but looking at it I'm not sure how it would be used in a projection scenario that I'm using here.

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  • Shadows shimmer when camera moves

    - by Chad Layton
    I've implemented shadow maps in my simple block engine as an exercise. I'm using one directional light and using the view volume to create the shadow matrices. I'm experiencing some problems with the shadows shimmering when the camera moves and I'd like to know if it's an issue with my implementation or just an issue with basic/naive shadow mapping itself. Here's a video: http://www.youtube.com/watch?v=vyprATt5BBg&feature=youtu.be Here's the code I use to create the shadow matrices. The commented out code is my original attempt to perfectly fit the view frustum. You can also see my attempt to try clamping movement to texels in the shadow map which didn't seem to make any difference. Then I tried using a bounding sphere instead, also to no apparent effect. public void CreateViewProjectionTransformsToFit(Camera camera, out Matrix viewTransform, out Matrix projectionTransform, out Vector3 position) { BoundingSphere cameraViewFrustumBoundingSphere = BoundingSphere.CreateFromFrustum(camera.ViewFrustum); float lightNearPlaneDistance = 1.0f; Vector3 lookAt = cameraViewFrustumBoundingSphere.Center; float distanceFromLookAt = cameraViewFrustumBoundingSphere.Radius + lightNearPlaneDistance; Vector3 directionFromLookAt = -Direction * distanceFromLookAt; position = lookAt + directionFromLookAt; viewTransform = Matrix.CreateLookAt(position, lookAt, Vector3.Up); float lightFarPlaneDistance = distanceFromLookAt + cameraViewFrustumBoundingSphere.Radius; float diameter = cameraViewFrustumBoundingSphere.Radius * 2.0f; Matrix.CreateOrthographic(diameter, diameter, lightNearPlaneDistance, lightFarPlaneDistance, out projectionTransform); //Vector3 cameraViewFrustumCentroid = camera.ViewFrustum.GetCentroid(); //position = cameraViewFrustumCentroid - (Direction * (camera.FarPlaneDistance - camera.NearPlaneDistance)); //viewTransform = Matrix.CreateLookAt(position, cameraViewFrustumCentroid, Up); //Vector3[] cameraViewFrustumCornersWS = camera.ViewFrustum.GetCorners(); //Vector3[] cameraViewFrustumCornersLS = new Vector3[8]; //Vector3.Transform(cameraViewFrustumCornersWS, ref viewTransform, cameraViewFrustumCornersLS); //Vector3 min = cameraViewFrustumCornersLS[0]; //Vector3 max = cameraViewFrustumCornersLS[0]; //for (int i = 1; i < 8; i++) //{ // min = Vector3.Min(min, cameraViewFrustumCornersLS[i]); // max = Vector3.Max(max, cameraViewFrustumCornersLS[i]); //} //// Clamp to nearest texel //float texelSize = 1.0f / Renderer.ShadowMapSize; //min.X -= min.X % texelSize; //min.Y -= min.Y % texelSize; //min.Z -= min.Z % texelSize; //max.X -= max.X % texelSize; //max.Y -= max.Y % texelSize; //max.Z -= max.Z % texelSize; //// We just use an orthographic projection matrix. The sun is so far away that it's rays are essentially parallel. //Matrix.CreateOrthographicOffCenter(min.X, max.X, min.Y, max.Y, -max.Z, -min.Z, out projectionTransform); } And here's the relevant part of the shader: if (CastShadows) { float4 positionLightCS = mul(float4(position, 1.0f), LightViewProj); float2 texCoord = clipSpaceToScreen(positionLightCS) + 0.5f / ShadowMapSize; float shadowMapDepth = tex2D(ShadowMapSampler, texCoord).r; float distanceToLight = length(LightPosition - position); float bias = 0.2f; if (shadowMapDepth < (distanceToLight - bias)) { return float4(0.0f, 0.0f, 0.0f, 0.0f); } } The shimmer is slightly better if I drastically reduce the view volume but I think that's mostly just because the texels become smaller and it's harder to notice them flickering back and forth. I'd appreciate any insight, I'd very much like to understand what's going on before I try other techniques.

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  • First Person Camera strafing at angle

    - by Linkandzelda
    I have a simple camera class working in directx 11 allowing moving forward and rotating left and right. I'm trying to implement strafing into it but having some problems. The strafing works when there's no camera rotation, so when the camera starts at 0, 0, 0. But after rotating the camera in either direction it seems to strafe at an angle or inverted or just some odd stuff. Here is a video uploaded to Dropbox showing this behavior. https://dl.dropboxusercontent.com/u/2873587/IncorrectStrafing.mp4 And here is my camera class. I have a hunch that it's related to the calculation for camera position. I tried various different calculations in strafe and they all seem to follow the same pattern and same behavior. Also the m_camera_rotation represents the Y rotation, as pitching isn't implemented yet. #include "camera.h" camera::camera(float x, float y, float z, float initial_rotation) { m_x = x; m_y = y; m_z = z; m_camera_rotation = initial_rotation; updateDXZ(); } camera::~camera(void) { } void camera::updateDXZ() { m_dx = sin(m_camera_rotation * (XM_PI/180.0)); m_dz = cos(m_camera_rotation * (XM_PI/180.0)); } void camera::Rotate(float amount) { m_camera_rotation += amount; updateDXZ(); } void camera::Forward(float step) { m_x += step * m_dx; m_z += step * m_dz; } void camera::strafe(float amount) { float yaw = (XM_PI/180.0) * m_camera_rotation; m_x += cosf( yaw ) * amount; m_z += sinf( yaw ) * amount; } XMMATRIX camera::getViewMatrix() { updatePosition(); return XMMatrixLookAtLH(m_position, m_lookat, m_up); } void camera::updatePosition() { m_position = XMVectorSet(m_x, m_y, m_z, 0.0); m_lookat = XMVectorSet(m_x + m_dx, m_y, m_z + m_dz, 0.0); m_up = XMVectorSet(0.0, 1.0, 0.0, 0.0); }

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  • Deferred rendering with both Clockwise and CounterClockwise culling

    - by user1423893
    I have a deferred rendering system that works well with objects that appear solid and drawn using CounterClockwise culling. I have a problem with Clockwise culled objects that are supposed to represent hollow that display their inside faces only. The image below shows a CounterClockwise culled object (left) Clockwise culled object (right). The Clockwise culled object faces display what would be displayed on the CounterClockwise face. How can I get the lighting to light the inner faces for Clockwise culled objects and continue lighting the outer CounterClockwise faces as normal? My lighting method is below private void DeferredLighting(GameTime gameTime) { // Set the render target for the lights game.GraphicsDevice.SetRenderTarget(lightMap); // Clear the render target to (0, 0, 0, 0) game.GraphicsDevice.Clear(Color.Transparent); // Set the render states game.GraphicsDevice.BlendState = BlendState.Additive; game.GraphicsDevice.DepthStencilState = DepthStencilState.None; game.GraphicsDevice.RasterizerState = RasterizerState.CullCounterClockwise; // Set sampler state to Point as the Surface type requires it in XNA 4.0 game.GraphicsDevice.SamplerStates[0] = SamplerState.PointClamp; // Set the camera properties for all lights BaseLight.SetCameraProperties(game.ActiveCamera); // Draw the lights int numLights = lights.Count; for (int i = 0; i < numLights; ++i) { if (lights[i].Diffuse.W > 0f) { lights[i].Render(gameTime, ref normalMap, ref depthMap, ref sgrMap); } } // Resolve the render target game.GraphicsDevice.SetRenderTarget(null); } I have tried adjusting the render states but no combination works for both objects.

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  • How do I efficiently code both the client and server at the same time?

    - by liamzebedee
    I'm coding my game using a client-server model. When playing on singleplayer, the game starts a local server, and interacts with it just like a remote server (multiplayer). I have done this to avoid coding separate singleplayer and multiplayer code. I have just started coding and have encountered a major problem. Currently I'm developing the game in Eclipse, having all the game classes organized into packages. Then, in my server code, I just use all the classes in the client packages. The problem is, these client classes have variables that are specific to rendering, which obviously wouldn't be performed on a server. Should I create modified versions of the client classes to use in the server? Or should I just modify the client classes with a boolean, to indicate if its the client/server using it. Are there any other options I have? I just had a thought about maybe using the server class as the core class, then extending it with rendering stuff?

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