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  • Self learning automated movement

    - by Super1
    I am trying to make a small demo in Javascript, I have a black border and a car the car travels randomly and a line is drawn of its trail. When the user click inside the area it creates an object (we'll call this the wall). If the car hits the wall then it goes back 3 paces and tries a different route. When its hit the wall it needs to log down its location so it does NOT make that mistake again. Here is my example: http://jsfiddle.net/Jtq3E/ How can I get the car to move by itself and create a trail?

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  • How to keep balance / Unlock items / achievement rules

    - by Mark Knol
    I'm working on an engine for a game, too learn javascript and just because its fun. I'm a flashdeveloper, I know how to build websites. Now making games is a different challenge, javascript is a challenge, but I'd love to learn how to structure code and what patterns are common. I dont mind if the game ever finish, I'm mostly interested in the programming part of it. I dont have a particular endresult in mind, so I'll see where it takes me. I currently have a system where you can buy items. The items cost a specified amount of gold, silver, diamonds etc. When you have selected and bought the item, it takes time before getting rewarded. When time is over, you are getting rewarded with other properties (gold, energy, diamonds). For example, you can buy an apple for 50gold, It takes a minute, you get rewarded with 75energy. Or if you take a run, it cost 50energy, it takes 5minutes, reward is 25gold and 25silver. These definitions is what i call actions. Currently I already have a system where this already works and I can define as much actions with as much properties as I want. The definitions I have kinda looks like this: {id:101, category:544, onInit:{gold:-75}, onComplete:{energy:75}, time:2000, name:"Apple", locked: false} {id:102, category:544, onInit:{gold:-135}, onComplete:{energy:145}, time:2000, name:"Banana", locked: false} {id:106, category:302, onInit:{energy:-50, power: -25}, onComplete:{gold:100, diamonds:2}, time:10000, name:"Run", locked: false} {id:107, category:302, onInit:{energy:-70, silver: -55}, onComplete:{gold:100}, time:10000, name:"Dance", locked: false} {id:108, category:302, onInit:{energy:-230, power: -355}, onComplete:{gold:70, silver:70}, time:10000, name:"Fitness", locked: false} Now, I would love to add a system where I can lock/unlock the actions using achievement rules. Lets say, if you buy 10 apples, you unlock a new action, like bananas which cost more, and reward more. In the future I maybe want to restrict achievements and actions to levels. I am kinda stuck how to structure this. I have 2 questions: Which patterns are used to define achievements? How/where are they defined? Should it be part of the action, or should it be a separate controller? Is it a good idea to register all completed actions to it? I think I want multiple types of achievement rules, Id love to hear some ideas how to develop it. How do you create/find a good balance, so the user does not get stuck or can cheat by repeat a pattern of actions to get too much rewards. I know there is not a simple answer and i'm lacking of a good game-concept, but I wonder if anyone created such a game and how you dealed and played with it.

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  • 2d shapes in XNA 4.0?

    - by Lautaro
    Having some experience of XNA but none of 3D programming. I have an idea i want to realize but i have not decided to do it in 3d or 2d. Im not sure which one will be best in XNA. I want to have a shape like a blob that can reshape depending on input. The morphing does not need to be very advanced. It could be a circle (2d) or globe (3d) that just has one point that moves slightly in a random direction. In ASP.NET i have made this through the 2d Draw classes where i can make lines, circles, squares etc and then modify the points that makes them up. But it seems to me that XNA does not have classes for making 2d shapes (can i get this confirmed?). If it had, then this would be the quickest solution for me.

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  • Customize Colors for Sprites in Web Game

    - by NateDSaint
    So I'm working on an html5/javascript/css3-based game. Without going into too much detail, I'm thinking of having the characters be simple 8 or 16-bit style sprites, but I'd like to allow the user to customize the colors of their character. Here are some examples of what I'm talking about : http://jsfiddle.net/simurai/CGmCe/light/ http://www.splashnology.com/article/sprite-animation-in-css3/1485/ So the problem I'm having is two-fold: 1) Should I use something other than a sprite map for my characters, like actually draw them as shapes and animate them in a canvas element? That way I can fill the sprite with colors of the user's choosing? My fear there is that this would be inefficient as far as resources and also waste a lot of time hand-drawing everything, but could allow other customization (like height/width etc). 2) Are there potentially some web apis that would allow you to alter colors inside of a sprite? I suppose I could do it on the back-end with GD, but I'm trying to make it entirely in-browser (including local storage). It's not a definitive one-answer only question, but I'm hoping someone can suggest something they've seen that approaches the same problem from another angle or gives us a way to customize the sprites or manipulate them in some manner. Or avoid them altogether, and use a different method.

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  • How do I draw a single Triangle with XNA and fill it with a Texture?

    - by Deukalion
    I'm trying to wrap my head around: http://msdn.microsoft.com/en-us/library/bb196409.aspx I'm trying to create a method in XNA that renders a single Triangle, then later make a method that takes a list of Triangles and renders them also. But it isn't working. I'm not understanding what all the things does and there's not enough information. My methods: // Triangle is a struct with A, B, C (didn't include) A, B, C = Vector3 public static void Render(GraphicsDevice device, List<Triangle> triangles, Texture2D texture) { foreach (Triangle triangle in triangles) { Render(device, triangle, texture); } } public static void Render(GraphicsDevice device, Triangle triangle, Texture2D texture) { BasicEffect _effect = new BasicEffect(device); _effect.Texture = texture; _effect.VertexColorEnabled = true; VertexPositionColor[] _vertices = new VertexPositionColor[3]; _vertices[0].Position = triangle.A; _vertices[1].Position = triangle.B; _vertices[2].Position = triangle.B; foreach (var pass in _effect.CurrentTechnique.Passes) { pass.Apply(); device.DrawUserIndexedPrimitives<VertexPositionColor> ( PrimitiveType.TriangleList, _vertices, 0, _vertices.Length, new int[] { 0, 1, 2 }, // example has something similiar, no idea what this is 0, 3 // 3 = gives me an error, 1 = works but no results ); } }

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  • Libgdx ParallaxScrolling and TiledMaps

    - by kirchhoff
    I implemented ParallaxScrolling for my SideScroller project, everything is working but the tiled map (the most important part!). I've been trying out everything but it doesn't work (see the code below). I'm using ParallaxCamera from GdxTests, it's working perfectly for the background layers. I can't explain myself properly in english, so I recorded 2 videos: Before parallaxScrolling After parallaxScrolling As you can see, now the platforms appear in the middle of the Y-axis. I've got a Map class with 2 tiled maps, so I need two renderers too: private TiledMapRenderer renderer1; private TiledMapRenderer renderer2; public void update(GameCamera camera) { renderer1.setView(camera.calculateParallaxMatrix(1f, 0f), camera.position.x - camera.viewportWidth / 2, **camera.position.y - camera.viewportHeight/2**, camera.viewportWidth, camera.viewportHeight); renderer2.setView(camera.calculateParallaxMatrix(1f, 0f), camera.position.x - camera.viewportWidth / 2, **camera.position.y - camera.viewportHeight/2**, camera.viewportWidth, camera.viewportHeight); } In bold, the code I think I should change. I've tried changing parameters, even adding hardcoded values, etc, but one of two: 1. Nothing happens. 2. Platforms disappear. Here is some aditional code. The render method: world.update(delta); parallaxBackground.update(camera); clear(0.5f, 0.7f, 1.0f, 1); batch.setProjectionMatrix(camera.calculateParallaxMatrix(0, 0)); batch.disableBlending(); batch.begin(); batch.draw(background, -(int)background.getRegionWidth()/2, -(int)background.getRegionHeight()/2); batch.end(); batch.enableBlending(); parallaxBackground.draw(batch, camera); renderer.render(batch);

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  • View matrix question (rotate by 180 degrees)

    - by King Snail
    I am using a third party rendering API on top of OpenGL code and I cannot get my matrices correct. The API states this: We're right handed by default, and we treat y as up by convention. Since IwGx's coordinate system has (0,0) as the top left, you typically need a 180 degree rotation around Z in your view matrix. I think the viewer does this by default. In my OpenGL app I have access to the view and projection matrices separately. How can I convert them to fit the criteria used by my third party rendering API? I don't understand what they mean to rotate 180 degrees around Z, is that in the view matrix itself or something in the camera before making the view matrix. Any code would be helpful, thanks.

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  • Deformation of Sphere using Transformations

    - by Mert Toka
    I have a graphic related question. I need to have a transformation matrix that I have no idea about what it is. The problem is to create right image from the right sphere. I created those images in Maya, but I need some matrices for the graphics course. Here is the image: Our professor told us to use some sine and cosine in our transformations, but I have no idea what he meant. I thought of intersecting a plane from the grid(that is xz plane) and sphere, and then scaling down the resulting circle. Would that work? I also checked this paper, however it looks like a bit advanced for me. Another thing is I guess that paper is not about the same type of information I was looking for. It would be great if you could help me.

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  • Novice prototyping a massive multiplayer webpage based gaming system

    - by Sean Hendlin
    I'm trying to build a website based game in which various pages of the site act as different areas of the game. I am wondering what you would recommended as a design structure. Which languages would be best if building what will hopefully becomes a massive system able to scale to massive amounts of users. I am wondering if and how various elements from differing languages could be meshed to interact with each other. For example could I use html5, javascript, and PHP? What about asp.net how might that factor in? I'm a newbie programmer but I've been working on this idea for years and I want to build it to reality. Your comments and suggestions are appreciated. P.S.: The game is not all graphics and animation (though flash like appearance and some animation would be nice). What I am thinking of is essentially a heavily gamified system of forms. And LOTS of data in many different categories cross referencing each-other. I'm not sure how to go about structuring the collection of data. Also while I know javascript can be used to process some functions, I'm wondering what sort of base system I would need to handle the server side processing of what I am expecting to be some pretty significant algorithm processing. That is to say I expect to have many many many functions and I'm not sure how to mange this using javascript. I feel like they would be forgotten, mixed up, disorganizes as they essentially only exist where they are coded. I guess I need to learn something of libraries? OK, Thank you! Is enough from me for now.

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  • Game Institute Math Courses

    - by W3Geek
    I'm 21 years old and I suck at math, I mean really bad. I don't have the necessary logic to apply it towards programming. I would like to learn the math and logic of applying it. I found Game Institute (http://www.gameinstitute.com) awhile back and heard a lot of praise about them. Are there Math courses any good? Thank you. Edit: My high school was terrible and did not prepare me for any math. I am fairly decent at programming, I just don't have the logic to apply any mathematics to programming, as an example I don't understand the algorithm of finding the size of a user's screen. Yes I have heard of KhanAcademy (http://www.khanacademy.org/) and I have completed a lot of maths on his website but I still don't have the logic to apply any of it to programming.

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  • How AlphaBlend Blendstate works in XNA 4 when accumulighting light into a RenderTarget?

    - by cubrman
    I am using a Deferred Rendering engine from Catalin Zima's tutorial: His lighting shader returns the color of the light in the rgb channels and the specular component in the alpha channel. Here is how light gets accumulated: Game.GraphicsDevice.SetRenderTarget(LightRT); Game.GraphicsDevice.Clear(Color.Transparent); Game.GraphicsDevice.BlendState = BlendState.AlphaBlend; // Continuously draw 3d spheres with lighting pixel shader. ... Game.GraphicsDevice.BlendState = BlendState.Opaque; MSDN states that AlphaBlend field of the BlendState class uses the next formula for alphablending: (source × Blend.SourceAlpha) + (destination × Blend.InvSourceAlpha), where "source" is the color of the pixel returned by the shader and "destination" is the color of the pixel in the rendertarget. My question is why do my colors are accumulated correctly in the Light rendertarget even when the new pixels' alphas equal zero? As a quick sanity check I ran the following code in the light's pixel shader: float specularLight = 0; float4 light4 = attenuation * lightIntensity * float4(diffuseLight.rgb,specularLight); if (light4.a == 0) light4 = 0; return light4; This prevents lighting from getting accumulated and, subsequently, drawn on the screen. But when I do the following: float specularLight = 0; float4 light4 = attenuation * lightIntensity * float4(diffuseLight.rgb,specularLight); return light4; The light is accumulated and drawn exactly where it needs to be. What am I missing? According to the formula above: (source x 0) + (destination x 1) should equal destination, so the "LightRT" rendertarget must not change when I draw light spheres into it! It feels like the GPU is using the Additive blend instead: (source × Blend.One) + (destination × Blend.One)

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  • Improving Click and Drag with C++

    - by Josh
    I'm currently using SFML 2.0 to develop a game in C++. I have a game sprite class that has a click and drag method. The method works, but there is a slight problem. If the mouse moves too fast, the object the user selected can't keep up and is left behind in the spot where the mouse left its bounds. I will share the class definition and the given function implementation. Definition: class codePeg { protected: FloatRect bounds; CircleShape circle; int xPos, yPos, xDiff, yDiff, once; int xBase, yBase; Vector2i mousePos; Vector2f circlePos; public: void init(RenderWindow& Window); void draw(RenderWindow& Window); void drag(RenderWindow& Window); void setPegPosition(int x, int y); void setPegColor(Color pegColor); void mouseOver(RenderWindow& Window); friend int isPegSelected(void); }; Implementation of the "drag" function: void codePeg::drag(RenderWindow& Window) { mousePos = Mouse::getPosition(Window); circlePos = circle.getPosition(); if(Mouse::isButtonPressed(Mouse::Left)) { if(mousePos.x > xPos && mousePos.y > yPos && mousePos.x - bounds.width < xPos && mousePos.y - bounds.height < yPos) { if(once) { xDiff = mousePos.x - circlePos.x; yDiff = mousePos.y - circlePos.y; once = 0; } xPos = mousePos.x - xDiff; yPos = mousePos.y - yDiff; circle.setPosition(xPos, yPos); } } else { once = 1; xPos = xBase; yPos = yBase; xDiff = 0; yDiff = 0; circle.setPosition(xBase, yBase); } Window.draw(circle); } Like I said, the function works, but to me, the code is very ugly and I think it could be improved and could be more efficient. The only thing I can think of as to why the object cannot keep up with the mouse is that there are too many function calls and/or checks. The user does not really have to mouse the mouse "fast" for it to happen, I would say at an average pace the object is left behind. How can I improve the code so that the object remains with the mouse when it is selected? Any help improving this code or giving advice is greatly appreciated.

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  • Circular motion on low powered hardware

    - by Akroy
    I was thinking about platforms and enemies moving in circles in old 2D games, and I was wondering how that was done. I understand parametric equations, and it's trivial to use sin and cos to do it, but could an NES or SNES make real time trig calls? I admit heavy ignorance, but I thought those were expensive operations. Is there some clever way to calculate that motion more cheaply? I've been working on deriving an algorithm from trig sum identities that would only use precalculated trig, but that seems convoluted.

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  • Huge procedurally generated 'wilderness' worlds

    - by The Communist Duck
    I'm sure you all know of games like Dwarf Fortress - massive, procedural generated wilderness and land. Something like this, taken from this very useful article. However, I was wondering how I could apply this to a much larger scale; the scale of Minecraft comes to mind (isn't that something like 8x the size of the Earth's surface?). Pseudo-infinite, I think the best term would be. The article talks about fractal perlin noise. I am no way an expert on it, but I get the general idea (it's some kind of randomly generated noise which is semi-coherent, so not just random pixel values). I could just define regions X by X in size, add some region loading type stuff, and have one bit of noise generating a region. But this would result in just huge amounts of islands. On the other extreme, I don't think I can really generate a supermassive sheet of perlin noise. And it would just be one big island, I think. I am pretty sure Perlin noise, or some noise, would be the answer in some way. I mean, the map is really nice looking. And you could replace the ascii with tiles, and get something very nice looking. Anyone have any ideas? Thanks. :D

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  • Space-efficient data structures for broad-phase collision detection

    - by Marian Ivanov
    As far as I know, these are three types of data structures that can be used for collision detection broadphase: Unsorted arrays: Check every object againist every object - O(n^2) time; O(log n) space. It's so slow, it's useless if n isn't really small. for (i=1;i<objects;i++){ for(j=0;j<i;j++) narrowPhase(i,j); }; Sorted arrays: Sort the objects, so that you get O(n^(2-1/k)) for k dimensions O(n^1.5) for 2d and O(n^1.67) for 3d and O(n) space. Assuming the space is 2D and sortedArray is sorted so that if the object begins in sortedArray[i] and another object ends at sortedArray[i-1]; they don't collide Heaps of stacks: Divide the objects between a heap of stacks, so that you only have to check the bucket, its children and its parents - O(n log n) time, but O(n^2) space. This is probably the most frequently used approach. Is there a way of having O(n log n) time with less space? When is it more efficient to use sorted arrays over heaps and vice versa?

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  • Level of detail algorithm not functioning correctly

    - by Darestium
    I have been working on this problem for months; I have been creating Planet Generator of sorts, after more than 6 months of work I am no closer to finishing it then I was 4 months ago. My problem; The terrain does not subdivide in the correct locations properly, it almost seems as if there is a ghost camera next to me, and the quads subdivide based on the position of this "ghost camera". Here is a video of the broken program: http://www.youtube.com/watch?v=NF_pHeMOju8 The best example of the problem occurs around 0:36. For detail limiting, I am going for a chunked LOD approach, which subdivides the terrain based on how far you are away from it. I use a "depth table" to determine how many subdivisions should take place. void PQuad::construct_depth_table(float distance) { tree[0] = -1; for (int i = 1; i < MAX_DEPTH; i++) { tree[i] = distance; distance /= 2.0f; } } The chuncked LOD relies on the child/parent structure of quads, the depth is determined by a constant e.g: if the constant is 6, there are six levels of detail. The quads which should be drawn go through a distance test from the player to the centre of the quad. void PQuad::get_recursive(glm::vec3 player_pos, std::vector<PQuad*>& out_children) { for (size_t i = 0; i < children.size(); i++) { children[i].get_recursive(player_pos, out_children); } if (this->should_draw(player_pos) || this->depth == 0) { out_children.emplace_back(this); } } bool PQuad::should_draw(glm::vec3 player_position) { float distance = distance3(player_position, centre); if (distance < tree[depth]) { return true; } return false; } The root quad has four children which could be visualized like the following: [] [] [] [] Where each [] is a child. Each child has the same amount of children up until the detail limit, the quads which have are 6 iterations deep are leaf nodes, these nodes have no children. Each node has a corresponding Mesh, each Mesh structure has 16x16 Quad-shapes, each Mesh's Quad-shapes halves in size each detail level deeper - creating more detail. void PQuad::construct_children() { // Calculate the position of the Quad based on the parent's location calculate_position(); if (depth < (int)MAX_DEPTH) { children.reserve((int)NUM_OF_CHILDREN); for (int i = 0; i < (int)NUM_OF_CHILDREN; i++) { children.emplace_back(PQuad(this->face_direction, this->radius)); PQuad *child = &children.back(); child->set_depth(depth + 1); child->set_child_index(i); child->set_parent(this); child->construct_children(); } } else { leaf = true; } } The following function creates the vertices for each quad, I feel that it may play a role in the problem - I just can't determine what is causing the problem. void PQuad::construct_vertices(std::vector<glm::vec3> *vertices, std::vector<Color3> *colors) { vertices->reserve(quad_width * quad_height); for (int y = 0; y < quad_height; y++) { for (int x = 0; x < quad_width; x++) { switch (face_direction) { case YIncreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, quad_height - 1.0f, -(position.y + y * element_width))); break; case YDecreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, 0.0f, -(position.y + y * element_width))); break; case XIncreasing: vertices->emplace_back(glm::vec3(quad_width - 1.0f, position.y + y * element_width, -(position.x + x * element_width))); break; case XDecreasing: vertices->emplace_back(glm::vec3(0.0f, position.y + y * element_width, -(position.x + x * element_width))); break; case ZIncreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, position.y + y * element_width, 0.0f)); break; case ZDecreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, position.y + y * element_width, -(quad_width - 1.0f))); break; } // Position the bottom, right, front vertex of the cube from being (0,0,0) to (-16, -16, 16) (*vertices)[vertices->size() - 1] -= glm::vec3(quad_width / 2.0f, quad_width / 2.0f, -(quad_width / 2.0f)); colors->emplace_back(Color3(255.0f, 255.0f, 255.0f, false)); } } switch (face_direction) { case YIncreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, quad_height - 1.0f, -(position.y + quad_height / 2.0f)); break; case YDecreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, 0.0f, -(position.y + quad_height / 2.0f)); break; case XIncreasing: this->centre = glm::vec3(quad_width - 1.0f, position.y + quad_height / 2.0f, -(position.x + quad_width / 2.0f)); break; case XDecreasing: this->centre = glm::vec3(0.0f, position.y + quad_height / 2.0f, -(position.x + quad_width / 2.0f)); break; case ZIncreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, position.y + quad_height / 2.0f, 0.0f); break; case ZDecreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, position.y + quad_height / 2.0f, -(quad_height - 1.0f)); break; } this->centre -= glm::vec3(quad_width / 2.0f, quad_width / 2.0f, -(quad_width / 2.0f)); } Any help in discovering what is causing this "subdivding in the wrong place" would be greatly appreciated.

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  • How to move a directional light according to the camera movement?

    - by Andrea Benedetti
    Given a light direction, how can I move it according to the camera movement, in a shader? Think that an artist has setup a scene (e.g., in 3DSMax) with a mesh in center of that and a directional light with a position and a target. From this position and target I've calculated the light direction. Now I want to use the same direction in my lighting equation but, obviously, I want that this light moves correctly with the camera. Thanks.

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  • Processing component pools problem - Entity Subsystem

    - by mani3xis
    Architecture description I'm creating (designing) an entity system and I ran into many problems. I'm trying to keep it Data-Oriented and efficient as much as possible. My components are POD structures (array of bytes to be precise) allocated in homogeneous pools. Each pool has a ComponentDescriptor - it just contains component name, field types and field names. Entity is just a pointer to array of components (where address acts like an entity ID). EntityPrototype contains entity name and array of component names. Finally Subsystem (System or Processor) which works on component pools. Actual problem The problem is that some components dependents on others (Model, Sprite, PhysicalBody, Animation depends on Transform component) which makes a lot of problems when it comes to processing them. For example, lets define some entities using [S]prite, [P]hysicalBody and [H]ealth: Tank: Transform, Sprite, PhysicalBody BgTree: Transform, Sprite House: Transform, Sprite, Health and create 4 Tanks, 5 BgTrees and 2 Houses and my pools will look like: TTTTTTTTTTT // Transform pool SSSSSSSSSSS // Sprite pool PPPP // PhysicalBody pool HH // Health component There is no way to process them using indices. I spend 3 days working on it and I still don't have any ideas. In previous designs TransformComponent was bound to the entity - but it wasn't a good idea. Can you give me some advices how to process them? Or maybe I should change the overall design? Maybe I should create pools of entites (pools of component pools) - but I guess it will be a nightmare for CPU caches. Thanks

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  • How can I resolve collisions at different speeds, depending on the direction?

    - by Raven Dreamer
    I have, for all intents and purposes, a Triangle class that objects in my scene can collide with (In actuality, the right side of a parallelogram). My collision detection and resolution code works fine for the purposes of preventing a gameobject from entering into the space of the Triangle, instead directing the movement along the edge. The trouble is, the maximum speed along the x and y axis is not equivalent in my game, and moving along the Y axis (up or down) should take twice as long as an equivalent distance along the X axis (left or right). Unfortunately, these speeds apply to the collision resolution too, and movement along the blue path above progresses twice as fast. What can I do in my collision resolution to make sure that the speedlimit for Y axis movement is obeyed in the latter case? Collision Resolution for this case below (vecInput and velocity are the position and velocity vectors of the game object): // y = mx+c // solve for y. M = 2, x = input's x coord, c = rightYIntercept lowY = 2*vecInput.x + parag.rightYIntercept ; ... else { // y = mx+c // vecInput.y = 2(x) + RightYIntercept // (vecInput.y - RightYIntercept) / 2 = x; //if velocity.Y (positive) greater than velocity.X (negative) //pushing from bottom, so push right. if(velocity.y > -1*velocity.x) { //change the input vector's x position to match the //y position on the shape's edge. Formula for line: Y = MX+C // M is 2, C is rightYIntercept, y is the input y, solve for X. vecInput = new Vector2((vecInput.y - parag.rightYIntercept)/2, vecInput.y); Debug.Log("adjusted rightwards"); } else { vecInput = new Vector2( vecInput.x, lowY); Debug.Log("adjusted downwards"); } }

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  • How do I get the correct values from glReadPixels in OpenGL 3.0?

    - by NoobScratcher
    I'm currently trying to Implement mouse selection into my game editor and I ran into a little problem when I look at the values stored in &pixel[0],&pixel[1],&pixel[2],&pixel[3]; I get r: 0 g: 0 b: 0 a: 0 As you can see I'm not able to get the correct values from glReadPixels(); My 3D models are red colored using glColor3f(255,0,0); I was hoping someone could help me figure this out. Here is the source code: case WM_LBUTTONDOWN: { GetCursorPos(&pos); ScreenToClient(hwnd, &pos); GLenum err = glGetError(); while (glGetError() != GL_NO_ERROR) {cerr << err << endl;} glReadPixels(pos.x, SCREEN_HEIGHT - 1 - pos.y, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, &pixel[0] ); cerr << "r: "<< (int)pixel[0] << endl; cerr << "g: "<< (int)pixel[1] << endl; cerr << "b: "<< (int)pixel[2] << endl; cerr << "a: "<< (int)pixel[3] << endl; cout << pos.x << endl; cout << pos.y << endl; } break; I use : WIN32 API OPENGL 3.0 C++

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  • Remove box2d bodies after collision deduction android?

    - by jubin
    Can any one explain me how to destroy box2d body when collide i have tried but my application crashed.First i have checked al collisions then add all the bodies in array who i want to destroy.I am trying to learning this tutorial My all the bodies are falling i want these bodies should destroy when these bodies will collide my actor monkey but when it collide it destroy but my aplication crashed.I have googled and from google i got the application crash reasons we should not destroy body in step funtion but i am removing body in the last of tick method. could any one help me or provide me code aur check my code why i am getting this prblem or how can i destroy box2d bodies. This is my code what i am doing. Please could any one check my code and tell me what is i am doing wrong for removing bodies. The code is for multiple box2d objects falling on my actor monkey it should be destroy when it will fall on the monkey.It is destroing but my application crahes. static class Box2DLayer extends CCLayer { protected static final float PTM_RATIO = 32.0f; protected static final float WALK_FACTOR = 3.0f; protected static final float MAX_WALK_IMPULSE = 0.2f; protected static final float ANIM_SPEED = 0.3f; int isLeft=0; String dir=""; int x =0; float direction; CCColorLayer objectHint; // protected static final float PTM_RATIO = 32.0f; protected World _world; protected static Body spriteBody; CGSize winSize = CCDirector.sharedDirector().winSize(); private static int count = 200; protected static Body monkey_body; private static Body bodies; CCSprite monkey; float animDelay; int animPhase; CCSpriteSheet danceSheet = CCSpriteSheet.spriteSheet("phases.png"); CCSprite _block; List<Body> toDestroy = new ArrayList<Body>(); //CCSpriteSheet _spriteSheet; private static MyContactListener _contactListener = new MyContactListener(); public Box2DLayer() { this.setIsAccelerometerEnabled(true); CCSprite bg = CCSprite.sprite("jungle.png"); addChild(bg,0); bg.setAnchorPoint(0,0); bg.setPosition(0,0); CGSize s = CCDirector.sharedDirector().winSize(); // Use scaled width and height so that our boundaries always match the current screen float scaledWidth = s.width/PTM_RATIO; float scaledHeight = s.height/PTM_RATIO; Vector2 gravity = new Vector2(0.0f, -30.0f); boolean doSleep = false; _world = new World(gravity, doSleep); // Create edges around the entire screen // Define the ground body. BodyDef bxGroundBodyDef = new BodyDef(); bxGroundBodyDef.position.set(0.0f, 0.0f); // The body is also added to the world. Body groundBody = _world.createBody(bxGroundBodyDef); // Register our contact listener // Define the ground box shape. PolygonShape groundBox = new PolygonShape(); Vector2 bottomLeft = new Vector2(0f,0f); Vector2 topLeft = new Vector2(0f,scaledHeight); Vector2 topRight = new Vector2(scaledWidth,scaledHeight); Vector2 bottomRight = new Vector2(scaledWidth,0f); // bottom groundBox.setAsEdge(bottomLeft, bottomRight); groundBody.createFixture(groundBox,0); // top groundBox.setAsEdge(topLeft, topRight); groundBody.createFixture(groundBox,0); // left groundBox.setAsEdge(topLeft, bottomLeft); groundBody.createFixture(groundBox,0); // right groundBox.setAsEdge(topRight, bottomRight); groundBody.createFixture(groundBox,0); CCSprite floorbg = CCSprite.sprite("grassbehind.png"); addChild(floorbg,1); floorbg.setAnchorPoint(0,0); floorbg.setPosition(0,0); CCSprite floorfront = CCSprite.sprite("grassfront.png"); floorfront.setTag(2); this.addBoxBodyForSprite(floorfront); addChild(floorfront,3); floorfront.setAnchorPoint(0,0); floorfront.setPosition(0,0); addChild(danceSheet); //CCSprite monkey = CCSprite.sprite(danceSheet, CGRect.make(0, 0, 48, 73)); //addChild(danceSprite); monkey = CCSprite.sprite("arms_up.png"); monkey.setTag(2); monkey.setPosition(200,100); BodyDef spriteBodyDef = new BodyDef(); spriteBodyDef.type = BodyType.DynamicBody; spriteBodyDef.bullet=true; spriteBodyDef.position.set(200 / PTM_RATIO, 300 / PTM_RATIO); monkey_body = _world.createBody(spriteBodyDef); monkey_body.setUserData(monkey); PolygonShape spriteShape = new PolygonShape(); spriteShape.setAsBox(monkey.getContentSize().width/PTM_RATIO/2, monkey.getContentSize().height/PTM_RATIO/2); FixtureDef spriteShapeDef = new FixtureDef(); spriteShapeDef.shape = spriteShape; spriteShapeDef.density = 2.0f; spriteShapeDef.friction = 0.70f; spriteShapeDef.restitution = 0.0f; monkey_body.createFixture(spriteShapeDef); //Vector2 force = new Vector2(10, 10); //monkey_body.applyLinearImpulse(force, spriteBodyDef.position); addChild(monkey,10000); this.schedule(tickCallback); this.schedule(createobjects, 2.0f); objectHint = CCColorLayer.node(ccColor4B.ccc4(255,0,0,128), 200f, 100f); addChild(objectHint, 15000); objectHint.setVisible(false); _world.setContactListener(_contactListener); } private UpdateCallback tickCallback = new UpdateCallback() { public void update(float d) { tick(d); } }; private UpdateCallback createobjects = new UpdateCallback() { public void update(float d) { secondUpdate(d); } }; private void secondUpdate(float dt) { this.addNewSprite(); } public void addBoxBodyForSprite(CCSprite sprite) { BodyDef spriteBodyDef = new BodyDef(); spriteBodyDef.type = BodyType.StaticBody; //spriteBodyDef.bullet=true; spriteBodyDef.position.set(sprite.getPosition().x / PTM_RATIO, sprite.getPosition().y / PTM_RATIO); spriteBody = _world.createBody(spriteBodyDef); spriteBody.setUserData(sprite); Vector2 verts[] = { new Vector2(-11.8f / PTM_RATIO, -24.5f / PTM_RATIO), new Vector2(11.7f / PTM_RATIO, -24.0f / PTM_RATIO), new Vector2(29.2f / PTM_RATIO, -14.0f / PTM_RATIO), new Vector2(28.7f / PTM_RATIO, -0.7f / PTM_RATIO), new Vector2(8.0f / PTM_RATIO, 18.2f / PTM_RATIO), new Vector2(-29.0f / PTM_RATIO, 18.7f / PTM_RATIO), new Vector2(-26.3f / PTM_RATIO, -12.2f / PTM_RATIO) }; PolygonShape spriteShape = new PolygonShape(); spriteShape.set(verts); //spriteShape.setAsBox(sprite.getContentSize().width/PTM_RATIO/2, //sprite.getContentSize().height/PTM_RATIO/2); FixtureDef spriteShapeDef = new FixtureDef(); spriteShapeDef.shape = spriteShape; spriteShapeDef.density = 2.0f; spriteShapeDef.friction = 0.70f; spriteShapeDef.restitution = 0.0f; spriteShapeDef.isSensor=true; spriteBody.createFixture(spriteShapeDef); } public void addNewSprite() { count=0; Random rand = new Random(); int Number = rand.nextInt(10); switch(Number) { case 0: _block = CCSprite.sprite("banana.png"); break; case 1: _block = CCSprite.sprite("backpack.png");break; case 2: _block = CCSprite.sprite("statue.png");break; case 3: _block = CCSprite.sprite("pineapple.png");break; case 4: _block = CCSprite.sprite("bananabunch.png");break; case 5: _block = CCSprite.sprite("hat.png");break; case 6: _block = CCSprite.sprite("canteen.png");break; case 7: _block = CCSprite.sprite("banana.png");break; case 8: _block = CCSprite.sprite("statue.png");break; case 9: _block = CCSprite.sprite("hat.png");break; } int padding=20; //_block.setPosition(CGPoint.make(100, 100)); // Determine where to spawn the target along the Y axis CGSize winSize = CCDirector.sharedDirector().displaySize(); int minY = (int)(_block.getContentSize().width / 2.0f); int maxY = (int)(winSize.width - _block.getContentSize().width / 2.0f); int rangeY = maxY - minY; int actualY = rand.nextInt(rangeY) + minY; // Create block and add it to the layer float xOffset = padding+_block.getContentSize().width/2+((_block.getContentSize().width+padding)*count); _block.setPosition(CGPoint.make(actualY, 750)); _block.setTag(1); float w = _block.getContentSize().width; objectHint.setVisible(true); objectHint.changeWidth(w); objectHint.setPosition(actualY-w/2, 460); this.addChild(_block,10000); // Create ball body and shape BodyDef ballBodyDef1 = new BodyDef(); ballBodyDef1.type = BodyType.DynamicBody; ballBodyDef1.position.set(actualY/PTM_RATIO, 480/PTM_RATIO); bodies = _world.createBody(ballBodyDef1); bodies.setUserData(_block); PolygonShape circle1 = new PolygonShape(); Vector2 verts[] = { new Vector2(-11.8f / PTM_RATIO, -24.5f / PTM_RATIO), new Vector2(11.7f / PTM_RATIO, -24.0f / PTM_RATIO), new Vector2(29.2f / PTM_RATIO, -14.0f / PTM_RATIO), new Vector2(28.7f / PTM_RATIO, -0.7f / PTM_RATIO), new Vector2(8.0f / PTM_RATIO, 18.2f / PTM_RATIO), new Vector2(-29.0f / PTM_RATIO, 18.7f / PTM_RATIO), new Vector2(-26.3f / PTM_RATIO, -12.2f / PTM_RATIO) }; circle1.set(verts); FixtureDef ballShapeDef1 = new FixtureDef(); ballShapeDef1.shape = circle1; ballShapeDef1.density = 10.0f; ballShapeDef1.friction = 0.0f; ballShapeDef1.restitution = 0.1f; bodies.createFixture(ballShapeDef1); count++; //Remove(); } @Override public void ccAccelerometerChanged(float accelX, float accelY, float accelZ) { //Apply the directional impulse /*float impulse = monkey_body.getMass()*accelY*WALK_FACTOR; Vector2 force = new Vector2(impulse, 0); monkey_body.applyLinearImpulse(force, monkey_body.getWorldCenter());*/ walk(accelY); //Remove(); } private void walk(float accelY) { // TODO Auto-generated method stub direction = accelY; } private void Remove() { for (Iterator<MyContact> it1 = _contactListener.mContacts.iterator(); it1.hasNext();) { MyContact contact = it1.next(); Body bodyA = contact.fixtureA.getBody(); Body bodyB = contact.fixtureB.getBody(); // See if there's any user data attached to the Box2D body // There should be, since we set it in addBoxBodyForSprite if (bodyA.getUserData() != null && bodyB.getUserData() != null) { CCSprite spriteA = (CCSprite) bodyA.getUserData(); CCSprite spriteB = (CCSprite) bodyB.getUserData(); // Is sprite A a cat and sprite B a car? If so, push the cat // on a list to be destroyed... if (spriteA.getTag() == 1 && spriteB.getTag() == 2) { //Log.v("dsfds", "dsfsd"+bodyA); //_world.destroyBody(bodyA); // removeChild(spriteA, true); toDestroy.add(bodyA); } // Is sprite A a car and sprite B a cat? If so, push the cat // on a list to be destroyed... else if (spriteA.getTag() == 2 && spriteB.getTag() == 1) { //Log.v("dsfds", "dsfsd"+bodyB); toDestroy.add(bodyB); } } } // Loop through all of the box2d bodies we want to destroy... for (Iterator<Body> it1 = toDestroy.iterator(); it1.hasNext();) { Body body = it1.next(); // See if there's any user data attached to the Box2D body // There should be, since we set it in addBoxBodyForSprite if (body.getUserData() != null) { // We know that the user data is a sprite since we set // it that way, so cast it... CCSprite sprite = (CCSprite) body.getUserData(); // Remove the sprite from the scene _world.destroyBody(body); removeChild(sprite, true); } // Destroy the Box2D body as well // _contactListener.mContacts.remove(0); } } public synchronized void tick(float delta) { synchronized (_world) { _world.step(delta, 8, 3); //_world.clearForces(); //addNewSprite(); } CCAnimation danceAnimation = CCAnimation.animation("dance", 1.0f); // Iterate over the bodies in the physics world Iterator<Body> it = _world.getBodies(); while(it.hasNext()) { Body b = it.next(); Object userData = b.getUserData(); if (userData != null && userData instanceof CCSprite) { //Synchronize the Sprites position and rotation with the corresponding body CCSprite sprite = (CCSprite)userData; if(sprite.getTag()==1) { //b.applyLinearImpulse(force, pos); sprite.setPosition(b.getPosition().x * PTM_RATIO, b.getPosition().y * PTM_RATIO); sprite.setRotation(-1.0f * ccMacros.CC_RADIANS_TO_DEGREES(b.getAngle())); } else { //Apply the directional impulse float impulse = monkey_body.getMass()*direction*WALK_FACTOR; Vector2 force = new Vector2(impulse, 0); b.applyLinearImpulse(force, b.getWorldCenter()); sprite.setPosition(b.getPosition().x * PTM_RATIO, b.getPosition().y * PTM_RATIO); animDelay -= 1.0f/60.0f; if(animDelay <= 0) { animDelay = ANIM_SPEED; animPhase++; if(animPhase > 2) { animPhase = 1; } } if(direction < 0 ) { isLeft=1; } else { isLeft=0; } if(isLeft==1) { dir = "left"; } else { dir = "right"; } float standingLimit = (float) 0.1f; float vX = monkey_body.getLinearVelocity().x; if((vX > -standingLimit)&& (vX < standingLimit)) { // Log.v("sasd", "standing"); } else { } } } } Remove(); } } Sorry for my english. Thanks in advance.

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  • Opposite Force to Apply to a Collided Rigid Body?

    - by Milo
    I'm working on the physics for my GTA2-like game so I can learn more about game physics. The collision detection and resolution are working great. I'm now just unsure how to compute the force to apply to a body after it collides with a wall. My rigid body looks like this: /our simulation object class RigidBody extends Entity { //linear private Vector2D velocity = new Vector2D(); private Vector2D forces = new Vector2D(); private float mass; private Vector2D v = new Vector2D(); //angular private float angularVelocity; private float torque; private float inertia; //graphical private Vector2D halfSize = new Vector2D(); private Bitmap image; private Matrix mat = new Matrix(); private float[] Vector2Ds = new float[2]; private Vector2D tangent = new Vector2D(); private static Vector2D worldRelVec = new Vector2D(); private static Vector2D relWorldVec = new Vector2D(); private static Vector2D pointVelVec = new Vector2D(); private static Vector2D acceleration = new Vector2D(); public RigidBody() { //set these defaults so we don't get divide by zeros mass = 1.0f; inertia = 1.0f; setLayer(LAYER_OBJECTS); } protected void rectChanged() { if(getWorld() != null) { getWorld().updateDynamic(this); } } //intialize out parameters public void initialize(Vector2D halfSize, float mass, Bitmap bitmap) { //store physical parameters this.halfSize = halfSize; this.mass = mass; image = bitmap; inertia = (1.0f / 20.0f) * (halfSize.x * halfSize.x) * (halfSize.y * halfSize.y) * mass; RectF rect = new RectF(); float scalar = 10.0f; rect.left = (int)-halfSize.x * scalar; rect.top = (int)-halfSize.y * scalar; rect.right = rect.left + (int)(halfSize.x * 2.0f * scalar); rect.bottom = rect.top + (int)(halfSize.y * 2.0f * scalar); setRect(rect); } public void setLocation(Vector2D position, float angle) { getRect().set(position.x,position.y, getWidth(), getHeight(), angle); rectChanged(); } public Vector2D getPosition() { return getRect().getCenter(); } @Override public void update(float timeStep) { doUpdate(timeStep); } public void doUpdate(float timeStep) { //integrate physics //linear acceleration.x = forces.x / mass; acceleration.y = forces.y / mass; velocity.x += (acceleration.x * timeStep); velocity.y += (acceleration.y * timeStep); //velocity = Vector2D.add(velocity, Vector2D.scalarMultiply(acceleration, timeStep)); Vector2D c = getRect().getCenter(); v.x = getRect().getCenter().getX() + (velocity.x * timeStep); v.y = getRect().getCenter().getY() + (velocity.y * timeStep); setCenter(v.x, v.y); forces.x = 0; //clear forces forces.y = 0; //angular float angAcc = torque / inertia; angularVelocity += angAcc * timeStep; setAngle(getAngle() + angularVelocity * timeStep); torque = 0; //clear torque } //take a relative Vector2D and make it a world Vector2D public Vector2D relativeToWorld(Vector2D relative) { mat.reset(); Vector2Ds[0] = relative.x; Vector2Ds[1] = relative.y; mat.postRotate(JMath.radToDeg(getAngle())); mat.mapVectors(Vector2Ds); relWorldVec.x = Vector2Ds[0]; relWorldVec.y = Vector2Ds[1]; return relWorldVec; } //take a world Vector2D and make it a relative Vector2D public Vector2D worldToRelative(Vector2D world) { mat.reset(); Vector2Ds[0] = world.x; Vector2Ds[1] = world.y; mat.postRotate(JMath.radToDeg(-getAngle())); mat.mapVectors(Vector2Ds); worldRelVec.x = Vector2Ds[0]; worldRelVec.y = Vector2Ds[1]; return worldRelVec; } //velocity of a point on body public Vector2D pointVelocity(Vector2D worldOffset) { tangent.x = -worldOffset.y; tangent.y = worldOffset.x; pointVelVec.x = (tangent.x * angularVelocity) + velocity.x; pointVelVec.y = (tangent.y * angularVelocity) + velocity.y; return pointVelVec; } public void applyForce(Vector2D worldForce, Vector2D worldOffset) { //add linear force forces.x += worldForce.x; forces.y += worldForce.y; //add associated torque torque += Vector2D.cross(worldOffset, worldForce); } @Override public void draw( GraphicsContext c) { c.drawRotatedScaledBitmap(image, getPosition().x, getPosition().y, getWidth(), getHeight(), getAngle()); } public Vector2D getVelocity() { return velocity; } public void setVelocity(Vector2D velocity) { this.velocity = velocity; } } The way it is given force is by the applyForce method, this method considers angular torque. I'm just not sure how to come up with the vectors in the case where: RigidBody hits static entity RigidBody hits other RigidBody that may or may not be in motion. Would anyone know a way (without too complex math) that I could figure out the opposite force I need to apply to the car? I know the normal it is colliding with and how deep it collided. My main goal is so that say I hit a building from the side, well the car should not just stay there, it should slowly rotate out of it if I'm more than 45 degrees. Right now when I hit a wall I only change the velocity directly which does not consider angular force. Thanks!

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  • How to proceed on the waypoint path?

    - by Alpha Carinae
    I'm using Dijkstra algorithm to find shortest path and I'm drawing this path on the screen. As the character object moves on, path updates itself(shortens as the object approaches the target and gets longer as the object moves away from it.) I tried to visualize my problem. This is the beginning state. 'A' node is the target, path is the blue and the object is the green one. I draw this path, from object to the closest node. In this case my problem occurs. Because 'D' node is more closer to the object than 'C' node, something like this happens: So, how can i decide that the object passed the 'D' node? Path should be look like this: One thing comes to my mind is that I use some distance variables between the two closest nodes in the route path. (In this example these are 'C' and 'D' nodes.) As the object approaches 'C' and moves away from the 'D' node at the same time, this means character passed the 'D'. However, I think there are some standardized and easy ways to solve this. What approach should I take?

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  • Bouncing off a circular Boundary with multiple balls?

    - by Anarkie
    I am making a game like this : Yellow Smiley has to escape from red smileys, when yellow smiley hits the boundary game is over, when red smileys hit the boundary they should bounce back with the same angle they came, like shown below: Every 10 seconds a new red smiley comes in the big circle, when red smiley hits yellow, game is over, speed and starting angle of red smileys should be random. I control the yellow smiley with arrow keys. The biggest problem I have reflecting the red smileys from the boundary with the angle they came. I don't know how I can give a starting angle to a red smiley and bouncing it with the angle it came. I would be glad for any tips! My js source code : var canvas = document.getElementById("mycanvas"); var ctx = canvas.getContext("2d"); // Object containing some global Smiley properties. var SmileyApp = { radius: 15, xspeed: 0, yspeed: 0, xpos:200, // x-position of smiley ypos: 200 // y-position of smiley }; var SmileyRed = { radius: 15, xspeed: 0, yspeed: 0, xpos:350, // x-position of smiley ypos: 65 // y-position of smiley }; var SmileyReds = new Array(); for (var i=0; i<5; i++){ SmileyReds[i] = { radius: 15, xspeed: 0, yspeed: 0, xpos:350, // x-position of smiley ypos: 67 // y-position of smiley }; SmileyReds[i].xspeed = Math.floor((Math.random()*50)+1); SmileyReds[i].yspeed = Math.floor((Math.random()*50)+1); } function drawBigCircle() { var centerX = canvas.width / 2; var centerY = canvas.height / 2; var radiusBig = 300; ctx.beginPath(); ctx.arc(centerX, centerY, radiusBig, 0, 2 * Math.PI, false); // context.fillStyle = 'green'; // context.fill(); ctx.lineWidth = 5; // context.strokeStyle = '#003300'; // green ctx.stroke(); } function lineDistance( positionx, positiony ) { var xs = 0; var ys = 0; xs = positionx - 350; xs = xs * xs; ys = positiony - 350; ys = ys * ys; return Math.sqrt( xs + ys ); } function drawSmiley(x,y,r) { // outer border ctx.lineWidth = 3; ctx.beginPath(); ctx.arc(x,y,r, 0, 2*Math.PI); //red ctx.fillStyle="rgba(255,0,0, 0.5)"; ctx.fillStyle="rgba(255,255,0, 0.5)"; ctx.fill(); ctx.stroke(); // mouth ctx.beginPath(); ctx.moveTo(x+0.7*r, y); ctx.arc(x,y,0.7*r, 0, Math.PI, false); // eyes var reye = r/10; var f = 0.4; ctx.moveTo(x+f*r, y-f*r); ctx.arc(x+f*r-reye, y-f*r, reye, 0, 2*Math.PI); ctx.moveTo(x-f*r, y-f*r); ctx.arc(x-f*r+reye, y-f*r, reye, -Math.PI, Math.PI); // nose ctx.moveTo(x,y); ctx.lineTo(x, y-r/2); ctx.lineWidth = 1; ctx.stroke(); } function drawSmileyRed(x,y,r) { // outer border ctx.lineWidth = 3; ctx.beginPath(); ctx.arc(x,y,r, 0, 2*Math.PI); //red ctx.fillStyle="rgba(255,0,0, 0.5)"; //yellow ctx.fillStyle="rgba(255,255,0, 0.5)"; ctx.fill(); ctx.stroke(); // mouth ctx.beginPath(); ctx.moveTo(x+0.4*r, y+10); ctx.arc(x,y+10,0.4*r, 0, Math.PI, true); // eyes var reye = r/10; var f = 0.4; ctx.moveTo(x+f*r, y-f*r); ctx.arc(x+f*r-reye, y-f*r, reye, 0, 2*Math.PI); ctx.moveTo(x-f*r, y-f*r); ctx.arc(x-f*r+reye, y-f*r, reye, -Math.PI, Math.PI); // nose ctx.moveTo(x,y); ctx.lineTo(x, y-r/2); ctx.lineWidth = 1; ctx.stroke(); } // --- Animation of smiley moving with constant speed and bounce back at edges of canvas --- var tprev = 0; // this is used to calculate the time step between two successive calls of run function run(t) { requestAnimationFrame(run); if (t === undefined) { t=0; } var h = t - tprev; // time step tprev = t; SmileyApp.xpos += SmileyApp.xspeed * h/1000; // update position according to constant speed SmileyApp.ypos += SmileyApp.yspeed * h/1000; // update position according to constant speed for (var i=0; i<SmileyReds.length; i++){ SmileyReds[i].xpos += SmileyReds[i].xspeed * h/1000; // update position according to constant speed SmileyReds[i].ypos += SmileyReds[i].yspeed * h/1000; // update position according to constant speed } // change speed direction if smiley hits canvas edges if (lineDistance(SmileyApp.xpos, SmileyApp.ypos) + SmileyApp.radius > 300) { alert("Game Over"); } // redraw smiley at new position ctx.clearRect(0,0,canvas.height, canvas.width); drawBigCircle(); drawSmiley(SmileyApp.xpos, SmileyApp.ypos, SmileyApp.radius); for (var i=0; i<SmileyReds.length; i++){ drawSmileyRed(SmileyReds[i].xpos, SmileyReds[i].ypos, SmileyReds[i].radius); } } // uncomment these two lines to get every going // SmileyApp.speed = 100; run(); // --- Control smiley motion with left/right arrow keys function arrowkeyCB(event) { event.preventDefault(); if (event.keyCode === 37) { // left arrow SmileyApp.xspeed = -100; SmileyApp.yspeed = 0; } else if (event.keyCode === 39) { // right arrow SmileyApp.xspeed = 100; SmileyApp.yspeed = 0; } else if (event.keyCode === 38) { // up arrow SmileyApp.yspeed = -100; SmileyApp.xspeed = 0; } else if (event.keyCode === 40) { // right arrow SmileyApp.yspeed = 100; SmileyApp.xspeed = 0; } } document.addEventListener('keydown', arrowkeyCB, true); JSFiddle : http://jsfiddle.net/gj4Q7/

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  • Dynamic audio score/music

    - by Joel Martinez
    I'm interested in developing a game who's background music changes with the mood and scenario of the game's action. Of course many existing games do this (halo for example), but I was interested in any resources/papers/articles talking about the techniques to develop a system like this. I have some ideas, and I understand that this will be equally challenging to implement at the code level as it will be to come up or acquire music that fits this model. Any links or, answers with ideas in them would he appreciated. Edit: this is the kind of info I'm looking for :) http://halo.bungie.org/misc/gdc.2002.music/

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