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• What library should I use for 2D Geometry? [closed]

  - by Luka

  I've been working on a 2D game in java, but found that java just didn't cut it for me and had forced me to a lot of bad design choices, so I've decided to port all my work to c++. The main reason I've decided change to c++ is that i had reached a point where i had 3 geometry libraries (the native, one from the game engine and one to handle "complex" polygons), none of witch worked very well together and i couldn't keep track of them. I'm new to c++, but i know all the basics. My question is, what would be a good geometry library to use, ideally it should be able to handle integer and decimal data types, have point, line, and polygon classes witch are able to check for intersection and contains. Thanks in advance, Luka

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• What is the simplest way to render video into memory (for drawing to a texture) in .NET?

  - by sebf

  In my project I would like to be able to play back video on surfaces in the world. I intend to do this by having the video frames rendered to a block of memory, then use this to update a texture each frame. Everything is in place - except for the part that actually gets the video. I have looked on Google and found that the video library world is very expansive (and geared towards video processing), and am having trouble finding a suitable one. FFMpeg is very comprehensive, but is an entire suite and would take a good amount of work to integrate. So far the most promising library I've found is the one based on the VLC player libraries - by virtue of it using the same resources as VLC Player it is known to be very capable; it also renders to blocks of memory, but the API (at least of the one on Codeplex) is more of a port of the C++ API rather than a managed wrapper. The 'solution' can be any wrapper/API/library, but with characteristics that make it suitable for use in a rendering engine, namely: Renders the video frame data to memory, so it can be picked up and passed to a texture on the GPU easily. Super simple - all that is needed is a way to load, jump and render a frame programatically - ideally it would use the systems codecs and not require an assortment of plugins. Permissive license (LGPL or more free-er) .NET bindings at least; all the better if it is natively managed Can anyone suggest a lightweight, (.NET) library, that can take a video file, and spit out some frames into a byte[]?

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• Unity: Render 2D textures on a 3D object's face

  - by www.Sillitoy.com

  I am not familiar with 3D graphics and I'd like to know what is the right way to render some 2D figures on different points of a wider face of a 3D object. My 3D object is just a cube representing a poker table. I have 2D png for players placeholders and I'd like to render these figures on the 3D object where needed. An alternative solution would be to render the whole face with a big picture containing all the placeholders figures. However it would be a waste of memory and thus less efficient. What do you suggest me?

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• Sorting for 2D Drawing

  - by Nexian

  okie, looked through quite a few similar questions but still feel the need to ask mine specifically (I know, crazy). Anyhoo: I am drawing a game in 2D (isometric) My objects have their own arrays. (i.e. Tiles[], Objects[], Particles[], etc) I want to have a draw[] array to hold anything that will be drawn. Because it is 2D, I assume I must prioritise depth over any other sorting or things will look weird. My game is turn based so Tiles and Objects won't be changing position every frame. However, Particles probably will. So I am thinking I can populate the draw[] array (probably a vector?) with what is on-screen and have it add/remove object, tile & particle references when I pan the screen or when a tile or object is specifically moved. No idea how often I'm going to have to update for particles right now. I want to do this because my game may have many thousands of objects and I want to iterate through as few as possible when drawing. I plan to give each element a depth value to sort by. So, my questions: Does the above method sound like a good way to deal with the actual drawing? What is the most efficient way to sort a vector? Most of the time it wont require efficiency. But for panning the screen it will. And I imagine if I have many particles on screen moving across multiple tiles, it may happen quite often. For reference, my screen will be drawing about 2,800 objects at any one time. When panning, it will be adding/removing about ~200 elements every second, and each new element will need adding in the correct location based on depth.

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• Algorithm for procedural city generation?

  - by Zove Games

  I am planning on making a (simple) procedural city generator using Java. I need ideas on whan algorithm to use for the layout, and the actual buildings. The city will mostly have skyscrapers, not really much complex stuff. For the layout I already have a simple algorithm implemented: Create a Map with java.awt.Point keys and Integer values. Fill it with all the points in the city's bounds with the value as -1 (unnassigned) Shuffle the map, and assign the 1st 10 of the keys IDs (from 1-10) Loop until all points have IDs: Loop though all points: Assign points next to an assigned point IDs of the point next to them, if 2 or more points border the point, then randomly choose which ID the point will get. You will end up with 10 random regions. Make roads bordering these regions. Fill the inside of each region with a randomly spaced and randomly rotated grid PROBLEM: This is not the fastest way to do it. What algorithm should I use for the layout. And what should I use to make each building's design? I don't even know how I'm going to do that yet (fractals maybe). I just need some ideas, not actual code.

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• rotate opengl mesh relative to camera

  - by shuall

  I have a cube in opengl. It's position is determined by multiplying it's specific model matrix, the view matrix, and the projection matrix and then passing that to the shader as per this tutorial (http://www.opengl-tutorial.org/beginners-tutorials/tutorial-3-matrices/). I want to rotate it relative to the camera. The only way I can think of getting the correct axis is by multiplying the inverse of the model matrix (because that's where all the previous rotations and tranforms are stored) times the view matrix times the axis of rotation (x or y). I feel like there's got to be a better way to do this like use something other than model, view and projection matrices, or maybe I'm doing something wrong. That's what all the tutorials I've seen use. PS I'm also trying to keep with opengl 4 core stuff. edit: If quaternions would fix my problems, could someone point me to a good tutorial/example for switching from 4x4 matrices to quaternions. I'm a little daunted by the task.

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• Implementing my Entity System. Questions about some problems I have found.

  - by Notbad

  Hi!, Well during this week I have deciding about implementation of my entity system. It is a big topic so it has been difficult to take one option from the whole. This has been my decision: 1) I don't have an entity class it is just an id. 2) I have systems that contain a list of components (the list is homegenous, I mean, RenderSystem will just have RenderComponents). 3) Compones will be just data. 4) There would be some kind of "entity prototypes" in a manager or something from we will create entity instances.Ideally they will define the type of components it has and initialization data. 5) Prototype code to create an entity (this is from the top of my head): int id=World::getInstance()->createEntity("entity template"); 6) This will notify all systems that a new entity has been created, and if the entity needs a component that the system handles it will add it to the entity. Ok, this are the ideas. Let's see if some can help with the problems: 1) The main problem is this templates that are sent to the systems in creation process to populate the entity with needed components. What would you use, an OR(ed) int?, a list of strings?. 2) How to do initialization for components when the entity has been created? How to store this in the template? I have thought about having a function in the template that is virtual and after entity is created an populated, gets the components and sets initialization values. 3) Don't you think this is a lot of work for just an entity creation?. Sorry for the long post, I have tried to expose my ideas and finding in order other could have a start beside exposing my problems. Thanks in advance, Notbad.

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• How to set sprite source coordinates?

  - by ChaosDev

  I am creating own sprite drawer with DX11 on C++. Works fine but I dont know how to apply source rectangle to texture coordinates of rendering surface(for animation sprite sheets) //source = (0,0,32,64); //RECT D3DXVECTOR2 t0 = D3DXVECTOR2( 1.0f, 0.0f); D3DXVECTOR2 t1 = D3DXVECTOR2( 1.0f, 1.0f); D3DXVECTOR2 t2 = D3DXVECTOR2( 0.0f, 1.0f); D3DXVECTOR2 t3 = D3DXVECTOR2( 0.0f, 1.0f); D3DXVECTOR2 t4 = D3DXVECTOR2( 0.0f, 0.0f); D3DXVECTOR2 t5 = D3DXVECTOR2( 1.0f, 0.0f); VertexPositionColorTexture vertices[] = { { D3DXVECTOR3( dest.left+dest.right, dest.top, z),D3DXVECTOR4(1,1,1,1), t0}, { D3DXVECTOR3( dest.left+dest.right, dest.top+dest.bottom, z),D3DXVECTOR4(1,1,1,1), t1}, { D3DXVECTOR3( dest.left, dest.top+dest.bottom, z),D3DXVECTOR4(1,1,1,1), t2}, { D3DXVECTOR3( dest.left, dest.top+dest.bottom, z),D3DXVECTOR4(1,1,1,1), t3}, { D3DXVECTOR3( dest.left , dest.top, z),D3DXVECTOR4(1,1,1,1), t4}, { D3DXVECTOR3( dest.left+dest.right, dest.top, z),D3DXVECTOR4(1,1,1,1), t5}, };

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• Artifacts when draw particles with some alpha

  - by piotrek

  I want to draw in my game some particles. But when I draw one particle above another particle, alpha channel from this above "clear" previous drawed particle. I set in OpenGL blend in this way: glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ); My fragment shader for particle is very simple: precision highp float; precision highp int; uniform sampler2D u_maps[2]; varying vec2 v_texture; uniform float opaque; uniform vec3 colorize; void main() { vec4 texColor = texture2D(u_maps[0], v_texture); gl_FragColor.rgb = texColor.rgb * colorize.rgb; gl_FragColor.a = texColor.a * opaque; } I attach screenshot from this: Do you know what I made wrong ? I use OpenGL ES 2.0.

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• How can I get a 2D texture to rotate like a compass in XNA?

  - by IronGiraffe

  I'm working on a small maze puzzle game and I'm trying to add a compass to make it somewhat easier for the player to find their way around the maze. The problem is: I'm using XNA's draw method to rotate the arrow and I don't really know how to get it to rotate properly. What I need it to do is point towards the exit from the player's position, but I'm not sure how I can do that. So does anyone know how I can do this? Is there a better way to do it?

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• Box2D `ApplyLinearImpulse` is not working whereas `SetLinearVelocity` works

  - by Narek

  I need to mimic jumping behavior for the player in my game. Player consists of two fixtures with circle and rectangle shapes. Rectangle I use to detect ground and it is a sensor. Is some point for jumping I do this: float impulseY = body->GetMass() * PLAYER_JUMPING_VEOCITY / PTM_RATIO * std::sin(PLAYER_JUMPING_ANGLE * PI / 180); body->ApplyLinearImpulse(b2Vec2(0, impulseY), body->GetWorldCenter(), true); and player does not jump. But when I do this: body->SetLinearVelocity(b2Vec2(0, PLAYER_JUMPING_VEOCITY / PTM_RATIO * std::sin(PLAYER_JUMPING_ANGLE * PI / 180))); my player jumps. Also when I change the rectangle shape to be normal (not sensor) shape, its works again. Why? Just in case here are the parameters of my rectangular sensor: b2PolygonShape boxShape; boxShape.SetAsBox(width * 0.5/2/PTM_RATIO, height * 0.2/2/PTM_RATIO, b2Vec2(0, -height * 0.4 /PTM_RATIO), 0); b2FixtureDef boxFixtureDef; boxFixtureDef.friction = 0; boxFixtureDef.restitution = 0; boxFixtureDef.density = 1; boxFixtureDef.isSensor = true; boxFixtureDef.userData = static_cast<void*>(PLAYER_GROUP);

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• How do I simplify a 2D game grid for level management while keeping its by-pixel features?

  - by Eric Thoma

  (I cross-posted this from StackOverflow as this seems to be a more appropriate forum. I've looked around a little here and I did not find an answer, so I hope this is not a recurring question.) This is a question dealing with 2D world design. I am playing around by creating a 2D bird's eye view shooter game, and I am looking to make the game sleek and advanced. I hope to be able to write physics so projectiles have momentum and knock-down properties. I am immediately running into the problem of world design. I need a way to have level files that store everything there is about a game. This is easiest by just having a grid of objects. But there are thin-walls and other objects that don't seem to fit into a traditional cell of a grid. I want to be able to fit all these together so I can streamline level design; so I don't have to put in the exact pixel-specific start and end of a wall. There doesn't seem to be an obvious translation from level file to game without forcing myself into a pacman-life scenario, meaning a scenario where the game feels boxy and discrete. There is a contrast between the smoothly (relatively) moving characters and finite jumps in a grid. I would appreciate an answer that would describe implementation options or point me to resources that do. I would also appreciate references to sites that teach game design. The language I am using is Java (although I would love to use C or C++, but I can never find convenient resources in those languages). Thank you for any answers. Please leave any questions in the space below; I will be able to answer them later tonight (28th Nov).

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• Wall avoidance steering

  - by Vodemki

  I making a small steering simulator using the reynolds boid algorythm. Now I want to add a wall avoidance feature. My walls are in 3D and defined using two points like that: ---------. P2 | | P1 .--------- My agents have a velocity, a position, etc... Could you tell me how to make avoidance with my agents ? Vector2D ReynoldsSteeringModel::repulsionFromWalls() { Vector2D force; vector<Wall *> wallsList = walls(); Point2D pos = self()->position(); Vector2D velocity = self()->velocity(); for (unsigned i=0; i<wallsList.size(); i++) { //TODO } return force; } Then I use all the forces returned by my boid functions and I apply it to my agent. I just need to know how to do that with my walls ? Thanks for your help.

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• Accounting for waves when doing planar reflections

  - by CloseReflector

  I've been studying Nvidia's examples from the SDK, in particular the Island11 project and I've found something curious about a piece of HLSL code which corrects the reflections up and down depending on the state of the wave's height. Naturally, after examining the brief paragraph of code: // calculating correction that shifts reflection up/down according to water wave Y position float4 projected_waveheight = mul(float4(input.positionWS.x,input.positionWS.y,input.positionWS.z,1),g_ModelViewProjectionMatrix); float waveheight_correction=-0.5*projected_waveheight.y/projected_waveheight.w; projected_waveheight = mul(float4(input.positionWS.x,-0.8,input.positionWS.z,1),g_ModelViewProjectionMatrix); waveheight_correction+=0.5*projected_waveheight.y/projected_waveheight.w; reflection_disturbance.y=max(-0.15,waveheight_correction+reflection_disturbance.y); My first guess was that it compensates for the planar reflection when it is subjected to vertical perturbation (the waves), shifting the reflected geometry to a point where is nothing and the water is just rendered as if there is nothing there or just the sky: Now, that's the sky reflecting where we should see the terrain's green/grey/yellowish reflection lerped with the water's baseline. My problem is now that I cannot really pinpoint what is the logic behind it. Projecting the actual world space position of a point of the wave/water geometry and then multiplying by -.5f, only to take another projection of the same point, this time with its y coordinate changed to -0.8 (why -0.8?). Clues in the code seem to indicate it was derived with trial and error because there is redundancy. For example, the author takes the negative half of the projected y coordinate (after the w divide): float waveheight_correction=-0.5*projected_waveheight.y/projected_waveheight.w; And then does the same for the second point (only positive, to get a difference of some sort, I presume) and combines them: waveheight_correction+=0.5*projected_waveheight.y/projected_waveheight.w; By removing the divide by 2, I see no difference in quality improvement (if someone cares to correct me, please do). The crux of it seems to be the difference in the projected y, why is that? This redundancy and the seemingly arbitrary selection of -.8f and -0.15f lead me to conclude that this might be a combination of heuristics/guess work. Is there a logical underpinning to this or is it just a desperate hack? Here is an exaggeration of the initial problem which the code fragment fixes, observe on the lowest tessellation level. Hopefully, it might spark an idea I'm missing. The -.8f might be a reference height from which to deduce how much to disturb the texture coordinate sampling the planarly reflected geometry render and -.15f might be the lower bound, a security measure.

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• How to Point sprite's direction towards Mouse or an Object [duplicate]

  - by Irfan Dahir

  This question already has an answer here: Rotating To Face a Point 1 answer I need some help with rotating sprites towards the mouse. I'm currently using the library allegro 5.XX. The rotation of the sprite works but it's constantly inaccurate. It's always a few angles off from the mouse to the left. Can anyone please help me with this? Thank you. P.S I got help with the rotating function from here: http://www.gamefromscratch.com/post/2012/11/18/GameDev-math-recipes-Rotating-to-face-a-point.aspx Although it's by javascript, the maths function is the same. And also, by placing: if(angle < 0) { angle = 360 - (-angle); } doesn't fix it. The Code: #include <allegro5\allegro.h> #include <allegro5\allegro_image.h> #include "math.h" int main(void) { int width = 640; int height = 480; bool exit = false; int shipW = 0; int shipH = 0; ALLEGRO_DISPLAY *display = NULL; ALLEGRO_EVENT_QUEUE *event_queue = NULL; ALLEGRO_BITMAP *ship = NULL; if(!al_init()) return -1; display = al_create_display(width, height); if(!display) return -1; al_install_keyboard(); al_install_mouse(); al_init_image_addon(); al_set_new_bitmap_flags(ALLEGRO_MIN_LINEAR | ALLEGRO_MAG_LINEAR); //smoother rotate ship = al_load_bitmap("ship.bmp"); shipH = al_get_bitmap_height(ship); shipW = al_get_bitmap_width(ship); int shipx = width/2 - shipW/2; int shipy = height/2 - shipH/2; int mx = width/2; int my = height/2; al_set_mouse_xy(display, mx, my); event_queue = al_create_event_queue(); al_register_event_source(event_queue, al_get_mouse_event_source()); al_register_event_source(event_queue, al_get_keyboard_event_source()); //al_hide_mouse_cursor(display); float angle; while(!exit) { ALLEGRO_EVENT ev; al_wait_for_event(event_queue, &ev); if(ev.type == ALLEGRO_EVENT_KEY_UP) { switch(ev.keyboard.keycode) { case ALLEGRO_KEY_ESCAPE: exit = true; break; /*case ALLEGRO_KEY_LEFT: degree -= 10; break; case ALLEGRO_KEY_RIGHT: degree += 10; break;*/ case ALLEGRO_KEY_W: shipy -=10; break; case ALLEGRO_KEY_S: shipy +=10; break; case ALLEGRO_KEY_A: shipx -=10; break; case ALLEGRO_KEY_D: shipx += 10; break; } }else if(ev.type == ALLEGRO_EVENT_MOUSE_AXES) { mx = ev.mouse.x; my = ev.mouse.y; angle = atan2(my - shipy, mx - shipx); } // al_draw_bitmap(ship,shipx, shipy, 0); //al_draw_rotated_bitmap(ship, shipW/2, shipH/2, shipx, shipy, degree * 3.142/180,0); al_draw_rotated_bitmap(ship, shipW/2, shipH/2, shipx, shipy,angle, 0); //I directly placed the angle because the allegro library calculates radians, and if i multiplied it by 180/3. 142 the rotation would go hawire, not would, it actually did. al_flip_display(); al_clear_to_color(al_map_rgb(0,0,0)); } al_destroy_bitmap(ship); al_destroy_event_queue(event_queue); al_destroy_display(display); return 0; } EDIT: This was marked duplicate by a moderator. I'd like to say that this isn't the same as that. I'm a total beginner at game programming, I had a view at that other topic and I had difficulty understanding it. Please understand this, thank you. :/ Also, while I was making a print of what the angle is I got this... Here is a screenshot:http://img34.imageshack.us/img34/7396/fzuq.jpg Which is weird because aren't angles supposed to be 360 degrees only?

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• BoundingSpheres move when they should not

  - by NDraskovic

  I have a XNA 4.0 project in which I load a file that contains type and coordinates of items I need to draw to the screen. Also I need to check if one particular type (the only movable one) is passing in front or trough other items. This is the code I use to load the configuration: if (ks.IsKeyDown(Microsoft.Xna.Framework.Input.Keys.L)) { this.GraphicsDevice.Clear(Color.CornflowerBlue); Otvaranje.ShowDialog(); try { using (StreamReader sr = new StreamReader(Otvaranje.FileName)) { String linija; while ((linija = sr.ReadLine()) != null) { red = linija.Split(','); model = red[0]; x = red[1]; y = red[2]; z = red[3]; elementi.Add(Convert.ToInt32(model)); podatci.Add(new Vector3(Convert.ToSingle(x), Convert.ToSingle(y), Convert.ToSingle(z))); sfere.Add(new BoundingSphere(new Vector3(Convert.ToSingle(x), Convert.ToSingle(y), Convert.ToSingle(z)), 1f)); } } } catch (Exception ex) { Window.Title = ex.ToString(); } } The "Otvaranje" is an OpenFileDialog object, "elementi" is a List (determines the type of item that would be drawn), podatci is a List (determines the location where the items will be drawn) and sfere is a List. Now I solved the picking algorithm (checking for ray and bounding sphere intersection) and it works fine, but the collision detection does not. I noticed, while using picking, that BoundingSphere's move even though the objects that they correspond to do not. The movable object is drawn to the world1 Matrix, and the static objects are drawn into the world2 Matrix (world1 and world2 have the same values, I just separated them so that the static elements would not move when the movable one does). The problem is that when I move the item I want, all boundingSpheres move accordingly. How can I move only the boundingSphere that corresponds to that particular item, and leave the rest where they are?

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• Re-sizing the form without scaling the GUI

  - by Bmoore

  I am writing a turn based strategy game in C#. My GUI implementation consists of class that extends Form containing a class that extends Panel. When I render the GUI I draw to the paint method in the panel. I am trying to figure out what is the best way for handling form re-size events. I know I want a minimum window size, but I would prefer to not have a maximum or a set size. Ideally the GUI would reveal more/less of the map as the user changes the window size. I would like to avoid scaling the graphics if at all possible. What is the best way to handle re-size events?

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• Models from 3ds max lose their transformations when input into XNA

  - by jacobian

  I am making models in 3ds max. However when I export them to .fbx format and then input them into XNA, they lose their scaling. -It is most likely something to do with not using the transforms from the model correctly, is the following code correct -using xna 3.0 Matrix[] transforms=new Matrix[playerModel.Meshes.Count]; playerModel.CopyAbsoluteBoneTransformsTo(transforms); // Draw the model. int count = 0; foreach (ModelMesh mesh in playerModel.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = transforms[count]* Matrix.CreateScale(scale) * Matrix.CreateRotationX((float)MathHelper.ToRadians(rx)) * Matrix.CreateRotationY((float)MathHelper.ToRadians(ry)) * Matrix.CreateRotationZ((float)MathHelper.ToRadians(rz))* Matrix.CreateTranslation(position); effect.View = view; effect.Projection = projection; effect.EnableDefaultLighting(); } count++; mesh.Draw(); }

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• Understanding the Microsoft Permissive License

  - by cable729

  I want to use certain parts of the Game State Management Example in a game I'm making, but I'm not sure how to do this legally. It says in the license that I'm supposed to include a copy of the license with it. So if I make a Visual Studio Solution, I just add the license.txt to the solution? Also, if I use a class and change it, do I have to keep the license info at the top or add that I changed it or what?

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• Where i must put .xnb files in mono game project using VS2010?

  - by user23899

  Hello there my problem was describe below In the "The Content Pipeline" paragraph http://blogs.msdn.com/b/bobfamiliar/archive/2012/08/07/windows-8-xna-and-monogame-part-3-code-migration-and-windows-8-feature-support.aspx#comments Author describe how fix it using VS2012 put xnb files to \AppX\Content folder but i use VS2010 and mono game templates for it and there is no folders like this so where i must put this asstes to run game correctly

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• Should I be using a game engine?

  - by Kyle

  I'm an experienced programmer, but I'm completely new to making games. I'm thinking of making an iPhone game that is similar to a 2d tower defense type game. In the web programming world, it would be a big waste of time to make a website without using some sort of web framework (eg ruby on rails). Is that the same for making games? Do people mostly use some sort of framework/game engine for making a game? If so, what are the popular ones for iOS?

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• In 3D camera math, calculate what Z depth is pixel unity for a given FOV

  - by badweasel

  I am working in iOS and OpenGL ES 2.0. Through trial and error I've figured out a frustum to where at a specific z depth pixels drawn are 1 to 1 with my source textures. So 1 pixel in my texture is 1 pixel on the screen. For 2d games this is good. Of course it means that I also factor in things like the size of the quad and the size of the texture. For example if my sprite is a quad 32x32 pixels. The quad size is 3.2 units wide and tall. And the texcoords are 32 / the size of the texture wide and tall. Then the frustum is: matrixFrustum(-(float)backingWidth/frustumScale,(float)backingWidth/frustumScale, -(float)backingHeight/frustumScale, (float)backingHeight/frustumScale, 40, 1000, mProjection); Where frustumScale is 800 for a retina screen. Then at a distance of 800 from camera the sprite is pixel for pixel the same as photoshop. For 3d games sometimes I still want to be able to do this. But depending on the scene I sometimes need the FOV to be different things. I'm looking for a way to figure out what Z depth will achieve this same pixel unity for a given FOV. For this my mProjection is set using: matrixPerspective(cameraFOV, near, far, (float)backingWidth / (float)backingHeight, mProjection); With testing I found that at an FOV of 45.0 a Z of 38.5 is very close to pixel unity. And at an FOV of 30.0 a Z of 59.5 is about right. But how can I calculate a value that is spot on? Here's my matrixPerspecitve code: void matrixPerspective(float angle, float near, float far, float aspect, mat4 m) { //float size = near * tanf(angle / 360.0 * M_PI); float size = near * tanf(degreesToRadians(angle) / 2.0); float left = -size, right = size, bottom = -size / aspect, top = size / aspect; // Unused values in perspective formula. m[1] = m[2] = m[3] = m[4] = 0; m[6] = m[7] = m[12] = m[13] = m[15] = 0; // Perspective formula. m[0] = 2 * near / (right - left); m[5] = 2 * near / (top - bottom); m[8] = (right + left) / (right - left); m[9] = (top + bottom) / (top - bottom); m[10] = -(far + near) / (far - near); m[11] = -1; m[14] = -(2 * far * near) / (far - near); } And my mView is set using: lookAtMatrix(cameraPos, camLookAt, camUpVector, mView); * UPDATE * I'm going to leave this here in case anyone has a different solution, can explain how they do it, or why this works. This is what I figured out. In my system I use a 10th scale unit to pixels on non-retina displays and a 20th scale on retina displays. The iPhone is 640 pixels wide on retina and 320 pixels wide on non-retina (obsolete). So if I want something to be the full screen width I divide by 20 to get the OpenGL unit width. Then divide that by 2 to get the left and right unit position. Something 32 units wide centered on the screen goes from -16 to +16. Believe it or not I have an excel spreadsheet do all this math for me and output all the vertex data for my sprite sheet. It's an arbitrary thing I made up to do .1 units = 1 non-retina pixel or 2 retina pixels. I could have made it .01 units = 2 pixels and someday I might switch to that. But for now it's the other. So the width of the screen in units is 32.0, and that means the left most pixel is at -16.0 and the right most is at 16.0. After messing a bit I figured out that if I take the [0] value of an identity modelViewProjection matrix and multiply it by 16 I get the depth required to get 1:1 pixels. I don't know why. I don't know if the 16 is related to the screen size or just a lucky guess. But I did a test where I placed a sprite at that calculated depth and varied the FOV through all the valid values and the object stays steady on screen with 1:1 pixels. So now I'm just calculating the unityDepth that way. If someone gives me a better answer I'll checkmark it.

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• Java 2D World question

  - by Munkybunky

  I have a 2D world background made up of a Grid of graphics, which I display on screen with a viewport (800x600) and it all works. My question is I have the following code to convert the mouse co-ordinates to world co-ordinates then World co-ordinates to grid co-ordinates then grid co-ordinates to screen co-ordinates. //Add camerax to mouse screen co-ords to convert to world co-ords. int cursorx_world=(int)camerax+(int)GameInput.mousex; int cursorx_grid=(int)cursorx_world/blocksize; // World Co-ords / gridsize give grid co-ords int cursorx_screen=-(int)camerax+(cursorx_grid*blocksize); So is there anyway I can convert straight from mouse screen co-ords to screen co-ordinates?

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• Circular class dependency

  - by shad0w

  Is it bad design to have 2 classes which need each other? I'm writing a small game in which I have a GameEngine class which has got a few GameState objects. To access several rendering methods, these GameState objects also need to know the GameEngine class - so it's a circular dependency. Would you call this bad design? I am just asking, because I am not quite sure and at this time I am still able to refactor these things.

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• snapping an angle to the closest cardinal direction

  - by Josh E

  I'm developing a 2D sprite-based game, and I'm finding that I'm having trouble with making the sprites rotate correctly. In a nutshell, I've got spritesheets for each of 5 directions (the other 3 come from just flipping the sprite horizontally), and I need to clamp the velocity/rotation of the sprite to one of those directions. My sprite class has a pre-computed list of radians corresponding to the cardinal directions like this: protected readonly List<float> CardinalDirections = new List<float> { MathHelper.PiOver4, MathHelper.PiOver2, MathHelper.PiOver2 + MathHelper.PiOver4, MathHelper.Pi, -MathHelper.PiOver4, -MathHelper.PiOver2, -MathHelper.PiOver2 + -MathHelper.PiOver4, -MathHelper.Pi, }; Here's the positional update code: if (velocity == Vector2.Zero) return; var rot = ((float)Math.Atan2(velocity.Y, velocity.X)); TurretRotation = SnapPositionToGrid(rot); var snappedX = (float)Math.Cos(TurretRotation); var snappedY = (float)Math.Sin(TurretRotation); var rotVector = new Vector2(snappedX, snappedY); velocity *= rotVector; //...snip private float SnapPositionToGrid(float rotationToSnap) { if (rotationToSnap == 0) return 0.0f; var targetRotation = CardinalDirections.First(x => (x - rotationToSnap >= -0.01 && x - rotationToSnap <= 0.01)); return (float)Math.Round(targetRotation, 3); } What am I doing wrong here? I know that the SnapPositionToGrid method is far from what it needs to be - the .First(..) call is on purpose so that it throws on no match, but I have no idea how I would go about accomplishing this, and unfortunately, Google hasn't helped too much either. Am I thinking about this the wrong way, or is the answer staring at me in the face?

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