development process - Page 500

changing body type without change of center of mass

- by philipp

I have an box2d project with some bodies in it, which move around without any user interaction. But if the user selects one of the bodies, he should be able to move it around just like he wants to. To keep it short, I want to change the type of the body to "kinematic" while the user controls it and back to "dynamic" afterwards. If I do so the rotation center of the body changes with the change of the type. How can I reset this? The body's fixture is created of a single b2PolygonShape, with its vertices set via SetAsArray(). Greetings philipp EDIT:: So I looked around about setting the local center of bodies. what brought me to this solution: var md = new b2MassData(); this.body.GetMassData( md ); this.body.SetType( b2body.b2_kinematicBody ); this.body.SetMassData( md ); that did not work, so I had a look at the source and found that SetMassData() always returns if the body is not "dynamic". So I tried this: var md = new b2MassData(); this._body.GetMassData( md ); this._body.SetType( b2Body.b2_kinematicBody ); this._body.m_sweep.localCenter.Set( md.center.x, md.center.y ); what actually is modifying the private data of the body. But it works and no errors appear, but can I really do this without the risk of breaking the application, or in other words, under which circumstances could this solution might cause errors? n.b.: I am using box2dweb of the latest release. Greetings philipp

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Camera lookAt target changes when rotating parent node

- by Michael IV

have the following issue.I have a camera with lookAt method which works fine.I have a parent node to which I parent the camera.If I rotate the parent node while keeping the camera lookAt the target , the camera lookAt changes too.That is nor what I want to achieve.I need it to work like in Adobe AE when you parent camera to a null object:when null object is rotated the camera starts orbiting around the target while still looking at the target.What I do currently is multiplying parent's model matrix with camera model matrix which is calculated from lookAt() method.I am sure I need to decompose (or recompose ) one of the matrices before multiplying them .Parent model or camera model ? Anyone here can show the right way doing it ? UPDATE: The parent is just a node .The child is the camera.The parented camera in AfterEffects works like this: If you rotate the parent node while camera looks at the target , the camera actually starts orbiting around the target based on the parent rotation.In my case the parent rotation changes also Camera's lookAt direction which IS NOT what I want.Hope now it is clear .

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Physics/Graphics Components

- by Brett Powell

I have spent the last 48 hours reading up on Object Component systems, and feel I am ready enough to start implementing it. I got the base Object and Component classes created, but now that I need to start creating the actual components I am a bit confused. When I think of them in terms of HealthComponent or something that would basically just be a property, it makes perfect sense. When it is something more general as a Physics/Graphics component, I get a bit confused. My Object class looks like this so far (If you notice any changes I should make please let me know, still new to this)... typedef unsigned int ID; class GameObject { public: GameObject(ID id, Ogre::String name = ""); ~GameObject(); ID &getID(); Ogre::String &getName(); virtual void update() = 0; // Component Functions void addComponent(Component *component); void removeComponent(Ogre::String familyName); template<typename T> T* getComponent(Ogre::String familyName) { return dynamic_cast<T*>(m_components[familyName]); } protected: // Properties ID m_ID; Ogre::String m_Name; float m_flVelocity; Ogre::Vector3 m_vecPosition; // Components std::map<std::string,Component*> m_components; std::map<std::string,Component*>::iterator m_componentItr; }; Now the problem I am running into is what would the general population put into Components such as Physics/Graphics? For Ogre (my rendering engine) the visible Objects will consist of multiple Ogre::SceneNode (possibly multiple) to attach it to the scene, Ogre::Entity (possibly multiple) to show the visible meshes, and so on. Would it be best to just add multiple GraphicComponent's to the Object and let each GraphicComponent handle one SceneNode/Entity or is the idea to have one of each Component needed? For Physics I am even more confused. I suppose maybe creating a RigidBody and keeping track of mass/interia/etc. would make sense. But I am having trouble thinking of how to actually putting specifics into a Component. Once I get a couple of these "Required" components done, I think it will make a lot more sense. As of right now though I am still a bit stumped.

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How should an object that uses composition set its composed components?

- by Casey

After struggling with various problems and reading up on component-based systems and reading Bob Nystrom's excellent book "Game Programming Patterns" and in particular the chapter on Components I determined that this is a horrible idea: //Class intended to be inherited by all objects. Engine uses Objects exclusively. class Object : public IUpdatable, public IDrawable { public: Object(); Object(const Object& other); Object& operator=(const Object& rhs); virtual ~Object() =0; virtual void SetBody(const RigidBodyDef& body); virtual const RigidBody* GetBody() const; virtual RigidBody* GetBody(); //Inherited from IUpdatable virtual void Update(double deltaTime); //Inherited from IDrawable virtual void Draw(BITMAP* dest); protected: private: }; I'm attempting to refactor it into a more manageable system. Mr. Nystrom uses the constructor to set the individual components; CHANGING these components at run-time is impossible. It's intended to be derived and be used in derivative classes or factory methods where their constructors do not change at run-time. i.e. his Bjorne object is just a call to a factory method with a specific call to the GameObject constructor. Is this a good idea? Should the object have a default constructor and setters to facilitate run-time changes or no default constructor without setters and instead use a factory method? Given: class Object { public: //...See below for constructor implementation concerns. Object(const Object& other); Object& operator=(const Object& rhs); virtual ~Object() =0; //See below for Setter concerns IUpdatable* GetUpdater(); IDrawable* GetRenderer(); protected: IUpdatable* _updater; IDrawable* _renderer; private: }; Should the components be read-only and passed in to the constructor via: class Object { public: //No default constructor. Object(IUpdatable* updater, IDrawable* renderer); //...remainder is same as above... }; or Should a default constructor be provided and then the components can be set at run-time? class Object { public: Object(); //... SetUpdater(IUpdater* updater); SetRenderer(IDrawable* renderer); //...remainder is same as above... }; or both? class Object { public: Object(); Object(IUpdater* updater, IDrawable* renderer); //... SetUpdater(IUpdater* updater); SetRenderer(IDrawable* renderer); //...remainder is same as above... };

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Issue porting Cocos2d-x to Android

- by Anil

I've written a basic game using Cocos2D-x on XCode. It works fine on the iPhone. Now I'm trying to port it to Android. When I run the script ./build_native.sh inside the proj.android folder, it gives me the following error: jni/../../Classes/MemoryModeLayer.cpp: In member function 'void MemoryModeLayer::startNewGame()': jni/../../Classes/MemoryModeLayer.cpp:109:25: error: 'time' is not a member of 'std' jni/../../Classes/MemoryModeLayer.cpp:109:25: note: suggested alternative: /Users/abc/android-ndk-r9d/platforms/android-8/arch-arm/usr/include/time.h:40:17: note: 'time' jni/../../Classes/MemoryModeLayer.cpp:111:5: error: 'random_shuffle' is not a member of 'std' jni/../../Classes/MemoryModeLayer.cpp:112:5: error: 'random_shuffle' is not a member of 'std' make: *** [obj/local/armeabi/objs/cocos2dcpp_shared/__/__/Classes/MemoryModeLayer.o] Error 1 make: Leaving directory `/Users/abc/cocos2d-x-2.2.3/projects/Game/proj.android' In MemoryModeLayer.cpp I have the following: std::srand(unsigned(std::time(0))); std::random_shuffle(_xCod, _xCod + _numberOfRows); std::random_shuffle(_yCod, _yCod + _numberOfColumns); I've included the following headers as well: #include <string> #include <ctime> #include <algorithm> #include <iostream> #include <iomanip> Also added using namespace std in the header file. Is there anything else that I should do?

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XNA Sprite Rotation Matrix - Moving Origin

- by Jon

I am currently grouping sprites together, then applying a rotation transformation on draw: private void UpdateMatrix(ref Vector2 origin, float radians) { Vector3 matrixorigin = new Vector3(origin, 0); _rotationMatrix = Matrix.CreateTranslation(-matrixorigin) * Matrix.CreateRotationZ(radians) * Matrix.CreateTranslation(matrixorigin); } Where the origin is the Centermost point of my group of sprites. I apply this transformation to each sprite in the group. My problem is that when I adjust the point of origin, my entire sprite group will re-position itself on screen. How could I differentiate the point of rotation used in the transformation, from the position of the sprite group? Is there a better way of creating this transformation matrix?

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Vector Graphics in DirectX

- by Doug

I'm curious as to people's thoughts on the best way to use vector graphics in a directX game instead of rasterized textures(think Super Meat Boy). I want to remain resolution independent and don't want to downscale/upscale rasterized graphics. Also the idea would be for all assets to be vector graphics(again think Super Meat Boy). I've looked at Valve's paper "Improved Alpha-Tested Magnification for Vector Textures and Special Effects" and also looked at using shaders http://http.developer.nvidia.com/GPUGems3/gpugems3_ch25.html. Wondering if anyone has done something similar or an alternate approach. Cheers

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How do I simplify terrain with tunnels or overhangs?

- by KKlouzal

I'm attempting to store vertex data in a quadtree with C++, such that far-away vertices can be combined to simplify the object and speed up rendering. This works well with a reasonably flat mesh, but what about terrain with overhangs or tunnels? How should I represent such a mesh in a quadtree? After the initial generation, each mesh is roughly 130,000 polygons and about 300 of these meshes are lined up to create the surface of a planetary body. A fully generated planet is upwards of 10,000,000 polygons before applying any culling to the individual meshes. Therefore, this second optimization is vital for the project. The rest of my confusion focuses around my inexperience with vertex data: How do I properly loop through the vertex data to group them into specific quads? How do I conclude from vertex data what a quad's maximum size should be? How many quads should the quadtree include?

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Limiting game loop to exactly 60 tics per second (Android / Java)

- by user22241

So I'm having terrible problems with stuttering sprites. My rendering and logic takes less than a game tic (16.6667ms) However, although my game loop runs most of the time at 60 ticks per second, it sometimes goes up to 61 - when this happens, the sprites stutter. Currently, my variables used are: //Game updates per second final int ticksPerSecond = 60; //Amount of time each update should take final int skipTicks = (1000 / ticksPerSecond); This is my current game loop @Override public void onDrawFrame(GL10 gl) { // TODO Auto-generated method stub //This method will run continuously //You should call both 'render' and 'update' methods from here //Set curTime initial value if '0' //Set/Re-set loop back to 0 to start counting again loops=0; while(System.currentTimeMillis() > nextGameTick && loops < maxFrameskip){ SceneManager.getInstance().getCurrentScene().updateLogic(); //Time correction to compensate for the missing .6667ms when using int values nextGameTick+=skipTicks; timeCorrection += (1000d/ticksPerSecond) % 1; nextGameTick+=timeCorrection; timeCorrection %=1; //Increase loops loops++; } render(); } I realise that my skipTicks is an int and therefore will come out as 16 rather that 16.6667 However, I tried changing it (and ticksPerSecond) to Longs but got the same problem). I also tried to change the timer used to Nanotime and skiptics to 1000000000/ticksPerSecond, but everything just ran at about 300 ticks per seconds. All I'm attempting to do is to limit my game loop to 60 - what is the best way to guarantee that my game updates never happen at more than 60 times a second? Please note, I do realise that very very old devices might not be able to handle 60 although I really don't expect this to happen - I've tested it on the lowest device I have and it easily achieves 60 tics. So I'm not worried about a device not being able to handle the 60 ticks per second, but rather need to limit it - any help would be appreciated.

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Game physics / 2D Collision detection AS3

- by Jery

I know there are some methods you can use like hittestPoint and so on, but I want to see where my movieclip colliedes with another another movieclip. Any other methods I can use? by any chance does somebody know some a good introduction to game physics? Im asking because I coded a small engine and pretty much the whole code is spagetti code thats why I would like to know how you can setup something like this properly

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Rotate model using quaternion

- by ChocoMan

Currently I have this to rotate my 3D model that rotates on it's local axis independent from the world's axis: // Rotate model with Right Thumbstick modelRotation -= pController.ThumbSticks.Right.X * mRotSpeed; // float value What I'm trying to do is rotate the model using quaternion and not by a matrix. I've searched for tutorials, but have found none that explains thoroughly on how to achieve this. Does anyone know how to I can use quaternions to rotate my model or a complete tutorial?

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How to make unit selection circles merge?

- by MaT

I would like to know how to make this effect of merged circle selection. Here are images to illustrate: Basically I'm looking for this effect: How the merge effect of the circles can be achieved ? I didn't found any explanation concerning this effect. I know that to project those texture I can develop a decal system but I don't know how to create the merging effect. If possible, I'm looking for purely shaders solution.

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Monogame - Input secuence game (Scripting?)

- by user2662567

I'm starting to program my very first game, it's a clone of DDR/Stepmania done for research purposes and learning. I (at this early stage) get most of the UI/Music/input work that should be done, but what i still can't grasp is scripting, i've read about Lua and that you shouldn't use it with XNA/Monogame as C# is capable enough, but i cannot get the utility of it. Assuming the needs of my game, ¿What would be the ideal way to implement the input secuences it needs?, i thought of XML/Json, let's say Stage 1 <game> <level id="1"> <step id="1" key="up" time="00:00:01"/> <step id="2" key="left" time="00:00:02"/> </level> </game> Is that a correct implementation? or are there better ways with more benefits?

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Mobile 3D engine renders alpha as full-object transparency

- by Nils Munch

I am running a iOS project using the isgl3d framework for showing pod files. I have a stylish car with 0.5 alpha windows, that I wish to render on a camera background, seeking some augmented reality goodness. The alpha on the windows looks okay, but when I add the object, I notice that it renders the entire object transparently, where the windows are. Including interior of the car. Like so (in example, keyboard can be seen through the dashboard, seats and so on. should be solid) The car interior is a seperate object with alpha 1.0. I would rather not show a "ghost car" in my project, but I haven't found a way around this. Have anyone encountered the same issue, and eventually reached a solution ?

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Adding interactive graphical elements to text-based browser game with HTML5

- by st9

I'm re-writing an old virtual world/browser based game. It is text and HTML form based with some static graphics. The client is HTML and JS. I want to introduce some interactive graphical elements to certain parts of the game, for example a 'customise character' page, with hooks to server side and local data storage. I want to use HTML5/JS, what is the best approach to designing the web-site? For example could I use Boilerplate and then embed these interactive elements in the page? Thanks

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Tile-based maps in AS3

- by Ashley

I want to make a tile-based platformer in AS3. I want my game to read an external maps file (in xml or json or somethimg similar) to draw a tile-based map. I've seen loads of tutorials for this in AS2 and other languages, and the few I've found in AS3 are either incomplete or filled with extra unnecessary features. I just want to be able to draw a basic map from sprites in Flash. Any links or information to point me in the right direction would be appreciated.

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Game actions that take multiple frames to complete

- by CantTetris

I've never really done much game programming before, pretty straightforward question. Imagine I'm building a Tetris game, with the main loop looking something like this. for every frame handle input if it's time to make the current block move down a row if we can move the block move the block else remove all complete rows move rows down so there are no gaps if we can spawn a new block spawn a new current block else game over Everything in the game so far happens instantly - things are spawned instantly, rows are removed instantly etc. But what if I don't want things to happen instantly (i.e animate things)? for every frame handle input if it's time to make the current block move down a row if we can move the block move the block else ?? animate complete rows disappearing (somehow, wait over multiple frames until the animation is done) ?? animate rows moving downwards (and again, wait over multiple frames) if we can spawn a new block spawn a new current block else game over In my Pong clone this wasn't an issue, as every frame I was just moving the ball and checking for collisions. How can I wrap my head around this issue? Surely most games involves some action that takes more than a frame, and other things halt until the action is done.

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Strange mesh import problem with Assimp and OpenGL

- by Morgan

Using the assimp library for importing 3D data into an OpenGL application. I get some strange problems regarding indexing of the vertices: If I use the following code for importing vertex indices: for (unsigned int t = 0; t < mesh->mNumFaces; ++t) { const struct aiFace * face = &mesh->mFaces[t]; if (face->mNumIndices == 3) { indices->push_back(face->mIndices[0]); indices->push_back(face->mIndices[1]); indices->push_back(face->mIndices[2]); } } I get the following result: Instead, if I use the following code: for(int k = 0; k < 2 ; k++) { for (unsigned int t = 0; t < mesh->mNumFaces; ++t) { const struct aiFace * face = &mesh->mFaces[t]; if (face->mNumIndices == 3) { indices->push_back(face->mIndices[0]); indices->push_back(face->mIndices[1]); indices->push_back(face->mIndices[2]); } } } I get the correct result: Hence adding the indices twice, renders the correct result? The OpenGL buffer is populated, like so: glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices->size() * sizeof(unsigned int), indices->data(), GL_STATIC_DRAW); And rendered as follows: glDrawElements(GL_TRIANGLES, vertexCount*3, GL_UNSIGNED_INT, indices->data());

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Open source level editor for HTML5 platform game?

- by Lai Yu-Hsuan

A natty GUI editor is very helpful to create level map. I want to use some open-source choices rather than build my own from scratch. I found Tiled Map Editor but it doesn't work for what I want. Though I'm building HTML5 game, I don't have to use a HTML5 level editor as long as it can output well-formatted map files which my javascript can read. Edit: Sorry for the confusion. Tiled does not work for me because to make the player perform a 'tricky' jump, sometimes I want to set the distance between two platforms to, say, 7/3 or 8/3 tiles. But in Tiled I get only 2 or 3. If Tiled can do this, please teach me.

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Collision between sprites in game programming?

- by Lyn Maxino

I've since just started coding for an android game using eclipse. I've read Beginning Android Game Programming and various other e-books. Recently, I've encountered a problem with collision between sprites. I've used this code template for my program. package com.project.CAI_test; import java.util.Random; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Rect; public class Sprite { // direction = 0 up, 1 left, 2 down, 3 right, // animation = 3 back, 1 left, 0 front, 2 right int[] DIRECTION_TO_ANIMATION_MAP = { 3, 1, 0, 2 }; private static final int BMP_ROWS = 4; private static final int BMP_COLUMNS = 3; private static final int MAX_SPEED = 5; private GameView gameView; private Bitmap bmp; private int x = 0; private int y = 0; private int xSpeed; private int ySpeed; private int currentFrame = 0; private int width; private int height; public Sprite(GameView gameView, Bitmap bmp) { this.width = bmp.getWidth() / BMP_COLUMNS; this.height = bmp.getHeight() / BMP_ROWS; this.gameView = gameView; this.bmp = bmp; Random rnd = new Random(); x = rnd.nextInt(gameView.getWidth() - width); y = rnd.nextInt(gameView.getHeight() - height); xSpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED; ySpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED; } private void update() { if (x >= gameView.getWidth() - width - xSpeed || x + xSpeed <= 0) { xSpeed = -xSpeed; } x = x + xSpeed; if (y >= gameView.getHeight() - height - ySpeed || y + ySpeed <= 0) { ySpeed = -ySpeed; } y = y + ySpeed; currentFrame = ++currentFrame % BMP_COLUMNS; } public void onDraw(Canvas canvas) { update(); int srcX = currentFrame * width; int srcY = getAnimationRow() * height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bmp, src, dst, null); } private int getAnimationRow() { double dirDouble = (Math.atan2(xSpeed, ySpeed) / (Math.PI / 2) + 2); int direction = (int) Math.round(dirDouble) % BMP_ROWS; return DIRECTION_TO_ANIMATION_MAP[direction]; } public boolean isCollition(float x2, float y2) { return x2 > x && x2 < x + width && y2 > y && y2 < y + height; } } The above code only detects collision between the generated sprites and the surface border. What I want to achieve is a collision detection that is controlled by the update function without having to change much of the coding. Probably several lines placed in the update() function. Tnx for any comment/suggestion.

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LWJGL - Continuous key press event without delay

- by Zarkopafilis

I am checking for key presses and then based on the keys pressed I am moving a square around the screen. I am setting booleans for the keys WASD. But , Whenever I try to keep the key down , it takes a while till it moves continuously (Just a half second stop after a single move.) Any way to get rid of that and make it be "smooth"? Code: up = false; down = false; left = false; right = false; reset = false; while(Keyboard.next()){ if (Keyboard.getEventKeyState()) { if(Keyboard.isKeyDown(Keyboard.KEY_SPACE)){ reset = false; } if(Keyboard.isKeyDown(Keyboard.KEY_W)){ up = true; } if(Keyboard.isKeyDown(Keyboard.KEY_S)){ down = true; } if(Keyboard.isKeyDown(Keyboard.KEY_A)){ left = true; } if(Keyboard.isKeyDown(Keyboard.KEY_D)){ right = true; } } }

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Organising levels / rooms in a MUD-style text based world

- by Polynomial

I'm thinking of writing a small text-based adventure game, but I'm not particularly sure how I should design the world from a technical standpoint. My first thought is to do it in XML, designed something like the following. Apologies for the huge pile of XML, but I felt it important to fully explain what I'm doing. <level> <start>  <room>Kitchen</room> <inventory></inventory> </start> <rooms> <room> <name>Kitchen</name> <description>A small kitchen that looks like it hasn't been used in a while. It has a table in the middle, and there are some cupboards. There is a door to the north, which leads to the garden.</description>  <objects> <object>Cupboards</object> <object>Knife</object> <object>Batteries</object> </objects> </room> <room> <name>Garden</name> <description>The garden is wild and full of prickly bushes. To the north there is a path, which leads into the trees. To the south there is a house.</description> <objects> </objects> </room> <room> <name>Woods</name> <description>The woods are quite dark, with little light bleeding in from the garden. It is eerily quiet.</description> <objects> <object>Trees01</object> </objects> </room> </rooms> <doors>  <door> <type>door</type> <direction>N</direction> <from>Kitchen</from> <to>Garden</to> </door> <door> <type>path</type> <direction>N</direction> <from>Garden</type> <to>Woods</type> </door> </doors> <variables>  <variable name="cupboard_open">0</variable> </variables> <objects>  <object> <name>Trees01</name> <displayName>Trees</displayName> <actions>  <action> <command>EXAMINE</command> <message>The trees are tall and thick. There aren't any low branches, so it'd be difficult to climb them.</message> </action> </actions> </object> <object> <name>Cupboards</name> <displayName>Cupboards</displayName> <actions> <action>  <requirements>  <require operation="equal" value="1">cupboard_open</require> </requirements> <command>EXAMINE</command>  <failMessage>The cupboard is closed.</failMessage> <message>The cupboard contains some batteires.</message> </action> <action> <requirements> <require operation="equal" value="0">cupboard_open</require> </requirements> <command>OPEN</command> <failMessage>The cupboard is already open.</failMessage> <message>You open the cupboard. It contains some batteries.</message>  <assigns> <assign operation="set" value="1">cupboard_open</assign> </assigns> </action> <action> <requirements> <require operation="equal" value="1">cupboard_open</require> </requirements> <command>CLOSE</command> <failMessage>The cupboard is already closed.</failMessage> <message>You closed the cupboard./message> <assigns> <assign operation="set" value="0">cupboard_open</assign> </assigns> </action> </actions> </object> <object> <name>Batteries</name> <displayName>Batteries</displayName>  <inventory>1</inventory> <actions> <action> <requirements> <require operation="equal" value="1">cupboard_open</require> </requirements> <command>GET</command>  <message>You picked up the batteries.</message> </action> </actions> </object> </objects> </level> Obviously there'd need to be more to it than this. Interaction with people and enemies as well as death and completion are necessary additions. Since the XML is quite difficult to work with, I'd probably create some sort of world editor. I'd like to know if this method has any downfalls, and if there's a "better" or more standard way of doing it.

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Box2D: How to get the Exact Collision Point and ignore the collision (from 2 "ghost bodies")

- by Moritz

I have a very basic problem with Box2D. For a arenatype game where you can throw scriptable "missiles" at other players I decided to use Box2D for the collision detection between the players and the missiles. Players and missiles have their own circular shape with a specific size (varying). But I don´t want to use dynamic bodies because the missiles need to move themselve in any way they want to (defined in the script) and shouldnt be resolved unless the script wants it. The behavior I look for is as following (for each time step): velocity of missiles is set by the specific missile script each missile is moved according to that velocity if a collision accurs now, I want to get the exact position of impact, and now I need a mechanism to decide if the missile should just ignore the collision (for example collision between two fireballs which shouldnt interact) or take it (so they are resolved and dont overlap anymore) So is there a way in Box2D to create Ghost bodies and listen to collisions from them, then deciding if they should ignore the collision or should take them and resolve their position? I hope I was clear enough and would be happy about any help!

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How to I get a rotated sprite to move left or right?

- by rphello101

Using Java/Slick 2D, I'm using the mouse to rotate a sprite on the screen and the directional keys (in this case, WASD) to move the spite. Forwards and backwards is easy, just position += cos(ang)*speed or position -= cos(ang)*speed. But how do I get the sprite to move left or right? I'm thinking it has something to do with adding 90 degrees to the angle or something. Any ideas? Rotation code: int mX = Mouse.getX(); int mY = HEIGHT - Mouse.getY(); int pX = sprite.x+sprite.image.getWidth()/2; int pY = sprite.y+sprite.image.getHeight()/2; double mAng; if(mX!=pX){ mAng = Math.toDegrees(Math.atan2(mY - pY, mX - pX)); if(mAng==0 && mX<=pX) mAng=180; } else{ if(mY>pY) mAng=90; else mAng=270; } sprite.angle = mAng; sprite.image.setRotation((float) mAng); And the movement code (delta is change in time): Input input = gc.getInput(); Vector2f direction = new Vector2f(); Vector2f velocity = new Vector2f(); direction.x = (float) Math.cos(Math.toRadians(sprite.angle)); direction.y = (float) Math.sin(Math.toRadians(sprite.angle)); if(direction.length()>0) direction = direction.normalise(); //On a separate note, what does this line of code do? velocity.x = (float) (direction.x * sprite.moveSpeed); velocity.y = (float) (direction.y * sprite.moveSpeed); if(input.isKeyDown(sprite.up)){ sprite.x += velocity.x*delta; sprite.y += velocity.y*delta; }if (input.isKeyDown(sprite.down)){ sprite.x -= velocity.x*delta; sprite.y -= velocity.y*delta; }if (input.isKeyDown(sprite.left)){ //??? }if (input.isKeyDown(sprite.right)){ //??? }

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Problems implementing a screen space shadow ray tracing shader

- by Grieverheart

Here I previously asked for the possibility of ray tracing shadows in screen space in a deferred shader. Several problems were pointed out. One of the most important problem is that only visible objects can cast shadows and objects between the camera and the shadow caster can interfere. Still I thought it'd be a fun experiment. The idea is to calculate the view coordinates of pixels and cast a ray to the light. The ray is then traced pixel by pixel to the light and its depth is compared with the depth at the pixel. If a pixel is in front of the ray, a shadow is casted at the original pixel. At first I thought that I could use the DDA algorithm in 2D to calculate the distance 't' (in p = o + t d, where o origin, d direction) to the next pixel and use it in the 3D ray equation to find the ray's z coordinate at that pixel's position. For the 2D ray, I would use the projected and biased 3D ray direction and origin. The idea was that 't' would be the same in both 2D and 3D equations. Unfortunately, this is not the case since the projection matrix is 4D. Thus, some tweak needs to be done to make this work this way. I would like to ask if someone knows of a way to do what I described above, i.e. from a 2D ray in texture coordinate space to get the 3D ray in screen space. I did implement a simple version of the idea which you can see in the following video: video here Shadows may seem a bit pixelated, but that's mostly because of the size of the step in 't' I chose. And here is the shader: #version 330 core uniform sampler2D DepthMap; uniform vec2 projAB; uniform mat4 projectionMatrix; const vec3 light_p = vec3(-30.0, 30.0, -10.0); noperspective in vec2 pass_TexCoord; smooth in vec3 viewRay; layout(location = 0) out float out_AO; vec3 CalcPosition(void){ float depth = texture(DepthMap, pass_TexCoord).r; float linearDepth = projAB.y / (depth - projAB.x); vec3 ray = normalize(viewRay); ray = ray / ray.z; return linearDepth * ray; } void main(void){ vec3 origin = CalcPosition(); if(origin.z < -60) discard; vec2 pixOrigin = pass_TexCoord; //tex coords vec3 dir = normalize(light_p - origin); vec2 texel_size = vec2(1.0 / 600.0); float t = 0.1; ivec2 pixIndex = ivec2(pixOrigin / texel_size); out_AO = 1.0; while(true){ vec3 ray = origin + t * dir; vec4 temp = projectionMatrix * vec4(ray, 1.0); vec2 texCoord = (temp.xy / temp.w) * 0.5 + 0.5; ivec2 newIndex = ivec2(texCoord / texel_size); if(newIndex != pixIndex){ float depth = texture(DepthMap, texCoord).r; float linearDepth = projAB.y / (depth - projAB.x); if(linearDepth > ray.z + 0.1){ out_AO = 0.2; break; } pixIndex = newIndex; } t += 0.5; if(texCoord.x < 0 || texCoord.x > 1.0 || texCoord.y < 0 || texCoord.y > 1.0) break; } } As you can see, here I just increment 't' by some arbitrary factor, calculate the 3D ray and project it to get the pixel coordinates, which is not really optimal. Hopefully, I would like to optimize the code as much as possible and compare it with shadow mapping and how it scales with the number of lights. PS: Keep in mind that I reconstruct position from depth by interpolating rays through a full screen quad.

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