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  • Using XNA for a 2D isometric game, but wanna move on

    - by Daniel Ribeiro
    I've been building a 2D isometric game (with learning purposes) in C# using XNA. I found it's really easy to manage sprite sheets loading, collision, basic physics and such with the XNA api. The thing is, I want to move on. My real goal is to learn C++ and develop a game using that language. What engine/library would you guys recommend for me to keep going on that same 2D isometric game direction using pretty much sprite sheets for the graphical part of the game?

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  • Rotation based on x coordinate and x velocity?

    - by Lewis
    -(void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { float deceleration = 0.3f, sensitivity = 8.0f, maxVelocity = 150; // adjust velocity based on current accelerometer acceleration playerVelocity.x = playerVelocity.x * deceleration + acceleration.x * sensitivity; // we must limit the maximum velocity of the player sprite, in both directions (positive & negative values) playerVelocity.x = fmaxf(fminf(playerVelocity.x, maxVelocity), -maxVelocity); } Hi, I want to rotate my sprite based on the velocity and accelerometer input. My sprite can move along the X axis like so: <--------- sprite ----------- But it always faces forwards, if it is moving left I want it to point slightly to the left, the degree of how far it is pointing to be judged from the velocity. This should also work for the right. I tried using atan but as the y velocity and position is always the same the function returns 0, which doesn't rotate it at all. Any ideas? Regards, Lewis.

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  • how to do partial updates in OpenGL?

    - by Will
    It is general wisdom that you redraw the entire viewport on each frame. I would like to use partial updates; what are the various ways can do that, and what are their pros, cons and relative performance? (Using textures, FBOs, the accumulator buffer, any kind of scissors that can affect swapbuffers etc?) A scenario: a scene with a fair few thousand visible trees; although the textures are mipmapped and they are drawn via VBOs roughly front-to-back with so on, its still a lot of polys. Would streaming a single screen-sized texture be better than throwing them at the screen every frame? You'd have to redraw and recapture them only on camera movement or as often as your wind model updates or whatever, which need not be every frame.

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  • 3d vertex translated onto 2d viewport

    - by Dan Leidal
    I have a spherical world defined by simple trigonometric functions to create triangles that are relatively similar in size and shape throughout. What I want to be able to do is use mouse input to target a range of vertices in the area around the mouse click in order to manipulate these vertices in real time. I read a post on this forum regarding translating 3d world coordinates into the 2d viewport.. it recommended that you should multiply the world vector coordinates by the viewport and then the projection, but they didn't include any code examples, and suffice to say i couldn't get any good results. Further information.. I am using a lookat method for the viewport. Does this cause a problem, and if so is there a solution? If this isn't the problem, does anyone have a simple code example illustrating translating one vertex in a 3d world into a 2d viewspace? I am using XNA.

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  • How to bind std::map to Lua with LuaBind

    - by MahanGM
    Is this possible in lua to achieve? player.scripts["movement"].properties["stat"] = "stand" print (player.scripts["movement"].properties["stat"]) I've done getter method in c++ with this approach: luabind::object FakeScript::getProp() { luabind::object obj = luabind::newtable(L); for(auto i = this->properties.begin(); i != this->properties.end(); i++) { obj[i->first] = i->second; } return obj; } But I'm stuck with setter. The first line in lua code which I'm trying to set value "stand" for key "stat" is not going to work and it keep redirecting me to the getter method. Setter method only works when I drop ["stat"] from properties. I can do something like this for setter in my script: player.scripts["movement"].properties = {stat = "stand"} But this isn't what I want because I have to go through my real keys in c++ to determine which key is placed in setter argument table value. This is my map in class: std::map<std::string, std::string> properties;

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  • Algorithm to find average position

    - by Simran kaur
    In the given diagram, I have the extreme left and right points, that is -2 and 4 in this case. So, obviously, I can calculate the width which is 6 in this case. What we know: The number of partitions:3 in this case The partition number at at any point i.e which one is 1st,second or third partition (numbered starting from left) What I want: The position of the purple line drawn which is positio of average of a particular partition So, basically I just want a generalized formula to calculate position of the average at any point.

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  • Why do meshes show up as bones in the Model class?

    - by Itamar Marom
    Right now I'm working on a 3D game and I've come across something very weird. When I created the model in Blender, I added an armature named "MyBone" to the stage and attached a cube ("MyCube") to it, so that when I move the armature, the cube moves with it. I exported this as an FBX and loaded it as a Model object. What I expected to see was: But what I got was this: I'm really confused. Why is the mesh I created showing up in the bone list? And what's Root Node? Here are the .blend and .fbx files: here or here. Thanks.

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  • how can I specify interleaved vertex attributes and vertex indices

    - by freefallr
    I'm writing a generic ShaderProgram class that compiles a set of Shader objects, passes args to the shader (like vertex position, vertex normal, tex coords etc), then links the shader components into a shader program, for use with glDrawArrays. My vertex data already exists in a VertexBufferObject that uses the following data structure to create a vertex buffer: class CustomVertex { public: float m_Position[3]; // x, y, z // offset 0, size = 3*sizeof(float) float m_TexCoords[2]; // u, v // offset 3*sizeof(float), size = 2*sizeof(float) float m_Normal[3]; // nx, ny, nz; float colour[4]; // r, g, b, a float padding[20]; // padded for performance }; I've already written a working VertexBufferObject class that creates a vertex buffer object from an array of CustomVertex objects. This array is said to be interleaved. It renders successfully with the following code: void VertexBufferObject::Draw() { if( ! m_bInitialized ) return; glBindBuffer( GL_ARRAY_BUFFER, m_nVboId ); glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, m_nVboIdIndex ); glEnableClientState( GL_VERTEX_ARRAY ); glEnableClientState( GL_TEXTURE_COORD_ARRAY ); glEnableClientState( GL_NORMAL_ARRAY ); glEnableClientState( GL_COLOR_ARRAY ); glVertexPointer( 3, GL_FLOAT, sizeof(CustomVertex), ((char*)NULL + 0) ); glTexCoordPointer(3, GL_FLOAT, sizeof(CustomVertex), ((char*)NULL + 12)); glNormalPointer(GL_FLOAT, sizeof(CustomVertex), ((char*)NULL + 20)); glColorPointer(3, GL_FLOAT, sizeof(CustomVertex), ((char*)NULL + 32)); glDrawElements( GL_TRIANGLES, m_nNumIndices, GL_UNSIGNED_INT, ((char*)NULL + 0) ); glDisableClientState( GL_VERTEX_ARRAY ); glDisableClientState( GL_TEXTURE_COORD_ARRAY ); glDisableClientState( GL_NORMAL_ARRAY ); glDisableClientState( GL_COLOR_ARRAY ); glBindBuffer( GL_ARRAY_BUFFER, 0 ); glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, 0 ); } Back to the Vertex Array Object though. My code for creating the Vertex Array object is as follows. This is performed before the ShaderProgram runtime linking stage, and no glErrors are reported after its steps. // Specify the shader arg locations (e.g. their order in the shader code) for( int n = 0; n < vShaderArgs.size(); n ++) glBindAttribLocation( m_nProgramId, n, vShaderArgs[n].sFieldName.c_str() ); // Create and bind to a vertex array object, which stores the relationship between // the buffer and the input attributes glGenVertexArrays( 1, &m_nVaoHandle ); glBindVertexArray( m_nVaoHandle ); // Enable the vertex attribute array (we're using interleaved array, since its faster) glBindBuffer( GL_ARRAY_BUFFER, vShaderArgs[0].nVboId ); glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, vShaderArgs[0].nVboIndexId ); // vertex data for( int n = 0; n < vShaderArgs.size(); n ++ ) { glEnableVertexAttribArray(n); glVertexAttribPointer( n, vShaderArgs[n].nFieldSize, GL_FLOAT, GL_FALSE, vShaderArgs[n].nStride, (GLubyte *) NULL + vShaderArgs[n].nFieldOffset ); AppLog::Ref().OutputGlErrors(); } This doesn't render correctly at all. I get a pattern of white specks onscreen, in the shape of the terrain rectangle, but there are no regular lines etc. Here's the code I use for rendering: void ShaderProgram::Draw() { using namespace AntiMatter; if( ! m_nShaderProgramId || ! m_nVaoHandle ) { AppLog::Ref().LogMsg("ShaderProgram::Draw() Couldn't draw object, as initialization of ShaderProgram is incomplete"); return; } glUseProgram( m_nShaderProgramId ); glBindVertexArray( m_nVaoHandle ); glDrawArrays( GL_TRIANGLES, 0, m_nNumTris ); glBindVertexArray(0); glUseProgram(0); } Can anyone see errors or omissions in either the VAO creation code or rendering code? thanks!

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  • Logarithmic spacing of FFT bins

    - by Mykel Stone
    I'm trying to do the examples within the GameDev.net Beat Detection article ( http://archive.gamedev.net/archive/reference/programming/features/beatdetection/index.html ) I have no issue with performing a FFT and getting the frequency data and doing most of the article. I'm running into trouble though in the section 2.B, Enhancements and beat decision factors. in this section the author gives 3 equations numbered R10-R12 to be used to determine how many bins go into each subband: R10 - Linear increase of the width of the subband with its index R11 - We can choose for example the width of the first subband R12 - The sum of all the widths must not exceed 1024 He says the following in the article: "Once you have equations (R11) and (R12) it is fairly easy to extract 'a' and 'b', and thus to find the law of the 'wi'. This calculus of 'a' and 'b' must be made manually and 'a' and 'b' defined as constants in the source; indeed they do not vary during the song." However, I cannot seem to understand how these values are calculated...I'm probably missing something simple, but learning fourier analysis in a couple of weeks has left me Decimated-in-Mind and I cannot seem to see it.

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  • Making a game "resize-safe"

    - by CPP_Person
    It's one thing to get the graphics aligned perfectly, it's another to do this for every single resolution and not take too much time and/or make the code unreadable due to size. Games like Battlefield 3 and Minecraft seem to manage this. But what do they do to keep things from stretching or going off the screen? I don't know any algorithms to do this. I'd like some help on this topic. I've always programmed games that only handle a single resolution, so help would be appreciate.

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  • Managing flash animations for a game

    - by LoveMeSomeCode
    Ok, I've been writing C# for a while, but I'm new to ActionScript, so this is a question about best practices. We're developing a simple match game, where the user selects tiles and tries to match various numbers - sort of like memory - and when the match is made we want a series of animations to take place, and when they're done, remove the tile and add a new one. So basically it's: User clicks the MC Animation 1 on the MC starts Animation 1 ends Remove the MC from the stage Add a new MC Start the animation on the new MC The problem I run into is that I don't want to make the same timeline motion tween on each and every tile, when the animation is all the same. It's just the picture in the tile that's different. The other method I've come up with is to just apply the tweens in code on the main stage. Then I attach an event handler for MOTION_FINISH, and in that handler I trigger the next animation and listen for that to finish etc. This works too, but not only do I have to do all the tweening in code, I have a seperate event handler for each stage of the animation. So is there a more structured way of chaining these animations together?

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  • Reasoner Conversion Problems:

    - by Annalyne
    I have this code right here in Java and I wanted to translate it in C++, but I had some problems going: this is the java code: import java.io.*; import java.util.*; public class ClueReasoner { private int numPlayers; private int playerNum; private int numCards; private SATSolver solver; private String caseFile = "cf"; private String[] players = {"sc", "mu", "wh", "gr", "pe", "pl"}; private String[] suspects = {"mu", "pl", "gr", "pe", "sc", "wh"}; private String[] weapons = {"kn", "ca", "re", "ro", "pi", "wr"}; private String[] rooms = {"ha", "lo", "di", "ki", "ba", "co", "bi", "li", "st"}; private String[] cards; public ClueReasoner() { numPlayers = players.length; // Initialize card info cards = new String[suspects.length + weapons.length + rooms.length]; int i = 0; for (String card : suspects) cards[i++] = card; for (String card : weapons) cards[i++] = card; for (String card : rooms) cards[i++] = card; numCards = i; // Initialize solver solver = new SATSolver(); addInitialClauses(); } private int getPlayerNum(String player) { if (player.equals(caseFile)) return numPlayers; for (int i = 0; i < numPlayers; i++) if (player.equals(players[i])) return i; System.out.println("Illegal player: " + player); return -1; } private int getCardNum(String card) { for (int i = 0; i < numCards; i++) if (card.equals(cards[i])) return i; System.out.println("Illegal card: " + card); return -1; } private int getPairNum(String player, String card) { return getPairNum(getPlayerNum(player), getCardNum(card)); } private int getPairNum(int playerNum, int cardNum) { return playerNum * numCards + cardNum + 1; } public void addInitialClauses() { // TO BE IMPLEMENTED AS AN EXERCISE // Each card is in at least one place (including case file). for (int c = 0; c < numCards; c++) { int[] clause = new int[numPlayers + 1]; for (int p = 0; p <= numPlayers; p++) clause[p] = getPairNum(p, c); solver.addClause(clause); } // If a card is one place, it cannot be in another place. // At least one card of each category is in the case file. // No two cards in each category can both be in the case file. } public void hand(String player, String[] cards) { playerNum = getPlayerNum(player); // TO BE IMPLEMENTED AS AN EXERCISE } public void suggest(String suggester, String card1, String card2, String card3, String refuter, String cardShown) { // TO BE IMPLEMENTED AS AN EXERCISE } public void accuse(String accuser, String card1, String card2, String card3, boolean isCorrect) { // TO BE IMPLEMENTED AS AN EXERCISE } public int query(String player, String card) { return solver.testLiteral(getPairNum(player, card)); } public String queryString(int returnCode) { if (returnCode == SATSolver.TRUE) return "Y"; else if (returnCode == SATSolver.FALSE) return "n"; else return "-"; } public void printNotepad() { PrintStream out = System.out; for (String player : players) out.print("\t" + player); out.println("\t" + caseFile); for (String card : cards) { out.print(card + "\t"); for (String player : players) out.print(queryString(query(player, card)) + "\t"); out.println(queryString(query(caseFile, card))); } } public static void main(String[] args) { ClueReasoner cr = new ClueReasoner(); String[] myCards = {"wh", "li", "st"}; cr.hand("sc", myCards); cr.suggest("sc", "sc", "ro", "lo", "mu", "sc"); cr.suggest("mu", "pe", "pi", "di", "pe", null); cr.suggest("wh", "mu", "re", "ba", "pe", null); cr.suggest("gr", "wh", "kn", "ba", "pl", null); cr.suggest("pe", "gr", "ca", "di", "wh", null); cr.suggest("pl", "wh", "wr", "st", "sc", "wh"); cr.suggest("sc", "pl", "ro", "co", "mu", "pl"); cr.suggest("mu", "pe", "ro", "ba", "wh", null); cr.suggest("wh", "mu", "ca", "st", "gr", null); cr.suggest("gr", "pe", "kn", "di", "pe", null); cr.suggest("pe", "mu", "pi", "di", "pl", null); cr.suggest("pl", "gr", "kn", "co", "wh", null); cr.suggest("sc", "pe", "kn", "lo", "mu", "lo"); cr.suggest("mu", "pe", "kn", "di", "wh", null); cr.suggest("wh", "pe", "wr", "ha", "gr", null); cr.suggest("gr", "wh", "pi", "co", "pl", null); cr.suggest("pe", "sc", "pi", "ha", "mu", null); cr.suggest("pl", "pe", "pi", "ba", null, null); cr.suggest("sc", "wh", "pi", "ha", "pe", "ha"); cr.suggest("wh", "pe", "pi", "ha", "pe", null); cr.suggest("pe", "pe", "pi", "ha", null, null); cr.suggest("sc", "gr", "pi", "st", "wh", "gr"); cr.suggest("mu", "pe", "pi", "ba", "pl", null); cr.suggest("wh", "pe", "pi", "st", "sc", "st"); cr.suggest("gr", "wh", "pi", "st", "sc", "wh"); cr.suggest("pe", "wh", "pi", "st", "sc", "wh"); cr.suggest("pl", "pe", "pi", "ki", "gr", null); cr.printNotepad(); cr.accuse("sc", "pe", "pi", "bi", true); } } how can I convert this? there are too many errors I get. for my C++ code (as a commentor asked for) #include <iostream> #include <cstdlib> #include <string> using namespace std; void Scene_Reasoner() { int numPlayer; int playerNum; int cardNum; string filecase = "Case: "; string players [] = {"sc", "mu", "wh", "gr", "pe", "pl"}; string suspects [] = {"mu", "pl", "gr", "pe", "sc", "wh"}; string weapons [] = {"kn", "ca", "re", "ro", "pi", "wr"}; string rooms[] = {"ha", "lo", "di", "ki", "ba", "co", "bi", "li", "st"}; string cards [0]; }; void Scene_Reason_Base () { numPlayer = players.length; // Initialize card info cards = new String[suspects.length + weapons.length + rooms.length]; int i = 0; for (String card : suspects) cards[i++] = card; for (String card : weapons) cards[i++] = card; for (String card : rooms) cards[i++] = card; cardNum = i; }; private int getCardNum (string card) { for (int i = 0; i < numCards; i++) if (card.equals(cards[i])) return i; cout << "Illegal card: " + card <<endl; return -1; }; private int getPairNum(String player, String card) { return getPairNum(getPlayerNum(player), getCardNum(card)); }; private int getPairNum(int playerNum, int cardNum) { return playerNum * numCards + cardNum + 1; }; int main () { return 0; }

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  • PCF shadow shader math causing artifacts

    - by user2971069
    For a while now I used PCSS for my shadow technique of choice until I discovered a type of percentage closer filtering. This method creates really smooth shadows and with hopes of improving performance, with only a fraction of texture samples, I tried to implement PCF into my shader. This is the relevant code: float c0, c1, c2, c3; float f = blurFactor; float2 coord = ProjectedTexCoords; if (receiverDistance - tex2D(lightSampler, coord + float2(0, 0)).x > 0.0007) c0 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(f, 0)).x > 0.0007) c1 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(0, f)).x > 0.0007) c2 = 1; if (receiverDistance - tex2D(lightSampler, coord + float2(f, f)).x > 0.0007) c3 = 1; coord = (coord % f) / f; return 1 - (c0 * (1 - coord.x) * (1 - coord.y) + c1 * coord.x * (1 - coord.y) + c2 * (1 - coord.x) * coord.y + c3 * coord.x * coord.y); This is a very basic implementation. blurFactor is initialized with 1 / LightTextureSize. So the if statements fetch the occlusion values for the four adjacent texels. I now want to weight each value based on the actual position of the texture coordinate. If it's near the bottom-right pixel, that occlusion value should be preferred. The weighting itself is done with a simple bilinear interpolation function, however this function takes a 2d vector in the range [0..1] so I have to convert my texture coordinate to get the distance from my first pixel to the second one in range [0..1]. For that I used the mod operator to get it into [0..f] range and then divided by f. This code makes sense to me, and for specific blurFactors it works, producing really smooth one pixel wide shadows, but not for all blurFactors. Initially blurFactor is (1 / LightTextureSize) to sample the 4 adjacent texels. I now want to increase the blurFactor by factor x to get a smooth interpolation across maybe 4 or so pixels. But that is when weird artifacts show up. Here is an image: Using a 1x on blurFactor produces a good result, 0.5 is as expected not so smooth. 2x however doesn't work at all. I found that only a factor of 1/2^n produces an good result, every other factor produces artifacts. I'm pretty sure the error lies here: coord = (coord % f) / f; Maybe the modulo is not calculated correctly? I have no idea how to fix that. Is it even possible for pixel that are further than 1 pixel away?

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  • Read only array, deep copy or retrieve copies one by one? (Performance and Memory)

    - by Arthur Wulf White
    In a garbage collection based system, what is the most effective way to handle a read only array if such a structure does not exist natively in the language. Is it better to return a copy of an array or allow other classes to retrieve copies of the objects stored in the array one by one? @JustinSkiles: It is not very broad. It is performance related and can actually be answered specifically for two general cases. You only need very few items: in this situation it's more effective to retrieve copies of the objects one by one. You wish to iterate over 30% or more objects. In this cases it is superior to retrieve all the array at once. This saves on functions calls. Function calls are very expansive when compared to reading directly from an array. A good specific answer could include performance, reading from an array and reading indirectly through a function. It is a simple performance related question.

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  • Why is GL_TEXTURE_MAX_ANISOTROPY_EXT undefined?

    - by Haydn
    So I'm writing my texture class in my opengl game, I get to the part where I would normally set GL_TEXTURE_MAX_ANISOTROPY_EXT, and I'm shocked to discover that it's undefined! This exact same extensions worked perfectly in a different application, so I know it's not a typo or something. It's worth noting that I'm getting my extensions using glcorearb.h, instead of glext.h, because I have no intention of supporting the compatibility profile. Could this be my problem, and if so, how do I work around it?

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  • How to port animation from one skeleton to another?

    - by shawn
    While I need to do this in a Blender3D modeler script, the math should be similar for other modelers or realtime engines. Blender3D specific terminology: Armature = skeleton EditBone = rest pose bone (stores the rest pose matrix) PoseBone = can store a different pose (animation matrix) for each frame of your animation I need to share animations (Blender Actions) between Armatures which have EditBones with same names and which have the same positions, but can have different (rest pose) angles and scales. Plus the Armatures might have different bone hierarchy (bone parenting/ no bone parenting). Why I need this: I've made an importer/exporter for a 3d format for a game. The format doesn't store enough info to connect/parent the bones, which makes posing/animating character models in a 3d modeller nearly impossible (original model files for the 3d modeler don't exist, this is for modding). As there are only 2 character skeleton types in the game, I decided to optionally allow to generate the bone from a hardcoded data in the model importer and undo that in the exporter. This allows to easily pose the model for checking weights, easily create weights, makes it easier for Blender to generate automatic weights and of course makes animating possible. This worked perfectly: the importer optionally generated the Armature itself and the exporter removed those changes, so the exported model works with existing animations in the game. But now I'm writing an importer and exporter for the game's animation format and here come the problems of: Trying to make original animations work in Blender with my "custom" (modified) Armature Trying to make animations created by using the "custom" (modified) Armature work with the original models in the game (and Blender). Constraints or bone snapping inside Blender won't work as they don't care that the bones have different angles in the rest pose, they will still face the same direction. It seems I just need to get the "difference" between the EditBone matrices of all EditBones for the two Armatures somehow and apply that difference to PoseBone matrices of all PoseBones, for all frames of my animation. I need to know how to get that difference and how to apply it. BTW, PoseBone matrices are relative to rest pose, they are by default [1.000000, 0.000000, 0.000000, 0.000000](matrix [row 0]) [0.000000, 1.000000, 0.000000, 0.000000](matrix [row 1]) [0.000000, 0.000000, 1.000000, 0.000000](matrix [row 2]) [0.000000, 0.000000, 0.000000, 1.000000](matrix [row 3]) So the question is: How to get the difference between two bone (EditBone) matrices to apply that difference to the animation matrices (PoseBone matrices)? Please be easy on the matrix math.

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  • Looking for literature about graphics pipeline optimization

    - by zacharmarz
    I am looking for some books, articles or tutorials about graphics architecture and graphics pipeline optimizations. It shouldn't be too old (2008 or newer) - the newer, the better. I have found something in [Optimising the Graphics Pipeline, NVIDIA, Koji Ashida] - too old, [Real-time rendering, Akenine Moller], [OpenGL Bindless Extensions, NVIDIA, Jeff Bolz], [Efficient multifragment effects on graphics processing units, Louis Frederic Bavoil] and some internet discussions. But there is not too much information and I want to read more. It should contain something about application, driver, memory and shader units communication and data transfers. About vertices and attributes. Also pre and post T&L cache (if they still exist in nowadays architectures) etc. I don't need anything about textures, frame buffers and rasterization. It can also be about OpenGL (not about DirecX) and optimizing extensions (not old extensions like VBOs, but newer like vertex_buffer_unified_memory).

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  • Determining explosion radius damage - Circle to Rectangle 2D

    - by Paul Renton
    One of the Cocos2D games I am working on has circular explosion effects. These explosion effects need to deal a percentage of their set maximum damage to all game characters (represented by rectangular bounding boxes as the objects in question are tanks) within the explosion radius. So this boils down to circle to rectangle collision and how far away the circle's radius is from the closest rectangle edge. I took a stab at figuring this out last night, but I believe there may be a better way. In particular, I don't know the best way to determine what percentage of damage to apply based on the distance calculated. Note : All tank objects have an anchor point of (0,0) so position is according to bottom left corner of bounding box. Explosion point is the center point of the circular explosion. TankObject * tank = (TankObject*) gameSprite; float distanceFromExplosionCenter; // IMPORTANT :: All GameCharacter have an assumed (0,0) anchor if (explosionPoint.x < tank.position.x) { // Explosion to WEST of tank if (explosionPoint.y <= tank.position.y) { //Explosion SOUTHWEST distanceFromExplosionCenter = ccpDistance(explosionPoint, tank.position); } else if (explosionPoint.y >= (tank.position.y + tank.contentSize.height)) { // Explosion NORTHWEST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x, tank.position.y + tank.contentSize.height)); } else { // Exp center's y is between bottom and top corner of rect distanceFromExplosionCenter = tank.position.x - explosionPoint.x; } // end if } else if (explosionPoint.x > (tank.position.x + tank.contentSize.width)) { // Explosion to EAST of tank if (explosionPoint.y <= tank.position.y) { //Explosion SOUTHEAST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x + tank.contentSize.width, tank.position.y)); } else if (explosionPoint.y >= (tank.position.y + tank.contentSize.height)) { // Explosion NORTHEAST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x + tank.contentSize.width, tank.position.y + tank.contentSize.height)); } else { // Exp center's y is between bottom and top corner of rect distanceFromExplosionCenter = explosionPoint.x - (tank.position.x + tank.contentSize.width); } // end if } else { // Tank is either north or south and is inbetween left and right corner of rect if (explosionPoint.y < tank.position.y) { // Explosion is South distanceFromExplosionCenter = tank.position.y - explosionPoint.y; } else { // Explosion is North distanceFromExplosionCenter = explosionPoint.y - (tank.position.y + tank.contentSize.height); } // end if } // end outer if if (distanceFromExplosionCenter < explosionRadius) { /* Collision :: Smaller distance larger the damage */ int damageToApply; if (self.directHit) { damageToApply = self.explosionMaxDamage + self.directHitBonusDamage; [tank takeDamageAndAdjustHealthBar:damageToApply]; CCLOG(@"Explsoion-> DIRECT HIT with total damage %d", damageToApply); } else { // TODO adjust this... turning out negative for some reason... damageToApply = (1 - (distanceFromExplosionCenter/explosionRadius) * explosionMaxDamage); [tank takeDamageAndAdjustHealthBar:damageToApply]; CCLOG(@"Explosion-> Non direct hit collision with tank"); CCLOG(@"Damage to apply is %d", damageToApply); } // end if } else { CCLOG(@"Explosion-> Explosion distance is larger than explosion radius"); } // end if } // end if Questions: 1) Can this circle to rect collision algorithm be done better? Do I have too many checks? 2) How to calculate the percentage based damage? My current method generates negative numbers occasionally and I don't understand why (Maybe I need more sleep!). But, in my if statement, I ask if distance < explosion radius. When control goes through, distance/radius must be < 1 right? So 1 - that intermediate calculation should not be negative. Appreciate any help/advice!

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  • Largest sphere inside a frustum

    - by Will
    How do you find the largest sphere that you can draw in perspective? Viewed from the top, it'd be this: Added: on the frustum on the right, I've marked four points I think we know something about. We can unproject all eight corners of the frusum, and the centres of the near and far ends. So we know point 1, 3 and 4. We also know that point 2 is the same distance from 3 as 4 is from 3. So then we can compute the nearest point on the line 1 to 4 to point 2 in order to get the centre? But the actual math and code escapes me. I want to draw models (which are approximately spherical and which I have a miniball bounding sphere for) as large as possible. Update: I've tried to implement the incircle-on-two-planes approach as suggested by bobobobo and Nathan Reed : function getFrustumsInsphere(viewport,invMvpMatrix) { var midX = viewport[0]+viewport[2]/2, midY = viewport[1]+viewport[3]/2, centre = unproject(midX,midY,null,null,viewport,invMvpMatrix), incircle = function(a,b) { var c = ray_ray_closest_point_3(a,b); a = a[1]; // far clip plane b = b[1]; // far clip plane c = c[1]; // camera var A = vec3_length(vec3_sub(b,c)), B = vec3_length(vec3_sub(a,c)), C = vec3_length(vec3_sub(a,b)), P = 1/(A+B+C), x = ((A*a[0])+(B*a[1])+(C*a[2]))*P, y = ((A*b[0])+(B*b[1])+(C*b[2]))*P, z = ((A*c[0])+(B*c[1])+(C*c[2]))*P; c = [x,y,z]; // now the centre of the incircle c.push(vec3_length(vec3_sub(centre[1],c))); // add its radius return c; }, left = unproject(viewport[0],midY,null,null,viewport,invMvpMatrix), right = unproject(viewport[2],midY,null,null,viewport,invMvpMatrix), horiz = incircle(left,right), top = unproject(midX,viewport[1],null,null,viewport,invMvpMatrix), bottom = unproject(midX,viewport[3],null,null,viewport,invMvpMatrix), vert = incircle(top,bottom); return horiz[3]<vert[3]? horiz: vert; } I admit I'm winging it; I'm trying to adapt 2D code by extending it into 3 dimensions. It doesn't compute the insphere correctly; the centre-point of the sphere seems to be on the line between the camera and the top-left each time, and its too big (or too close). Is there any obvious mistakes in my code? Does the approach, if fixed, work?

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  • What is the benefit of triple buffering?

    - by user782220
    I read everything written in a previous question. From what I understand in double buffering the program must wait until the finished drawing is copied or swapped before starting the next drawing. In triple buffering the program has two back buffers and can immediately start drawing in the one that is not involved in such copying. But with triple buffering if you're in a situation where you can take advantage of the third buffer doesn't that suggest that you are drawing frames faster than the monitor can refresh. So then you don't actually get a higher frame rate. So what is the benefit of triple buffering then?

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  • What's a good way to programmatically manage a cloneable entity?

    - by bobobobo
    Say you have missiles or rockets that a player can fire. What's a good way to programmatically manage the cloning of a base rocket, for example? I can think of 2 ways to do it: Player has a currently selected weapon (which is an int) When player shoots, the selectedWeapon member is looked at, and the correct instance of rocket is created (with some base parameters) Or Player has a currently selected weapon (which is a pointer, to a "base instance" of the rocket object) When player shoots, the base instance rocket is cloned, transformed, and shot into the game world

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  • Lighting get darker when texture is aplied

    - by noah
    Im using OpenGL ES 1.1 for iPhone. I'm attempting to implement a skybox in my 3d world and started out by following one of Jeff Lamarches tutorials on creating textures. Heres the tutorial: iphonedevelopment.blogspot.com/2009/05/opengl-es-from-ground-up-part-6_25.html Ive successfully added the image to my 3d world but am not sure why the lighting on the other shapes has changed so much. I want the shapes to be the original color and have the image in the background. Before: https://www.dropbox.com/s/ojmb8793vj514h0/Screen%20Shot%202012-10-01%20at%205.34.44%20PM.png After: https://www.dropbox.com/s/8v6yvur8amgudia/Screen%20Shot%202012-10-01%20at%205.35.31%20PM.png Heres the init OpenGL: - (void)initOpenGLES1 { glShadeModel(GL_SMOOTH); // Enable lighting glEnable(GL_LIGHTING); // Turn the first light on glEnable(GL_LIGHT0); const GLfloat lightAmbient[] = {0.2, 0.2, 0.2, 1.0}; const GLfloat lightDiffuse[] = {0.8, 0.8, 0.8, 1.0}; const GLfloat matAmbient[] = {0.3, 0.3, 0.3, 0.5}; const GLfloat matDiffuse[] = {1.0, 1.0, 1.0, 1.0}; const GLfloat matSpecular[] = {1.0, 1.0, 1.0, 1.0}; const GLfloat lightPosition[] = {0.0, 0.0, 1.0, 0.0}; const GLfloat lightShininess = 100.0; //Configure OpenGL lighting glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, matAmbient); glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiffuse); glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, matSpecular); glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, lightShininess); glLightfv(GL_LIGHT0, GL_AMBIENT, lightAmbient); glLightfv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse); glLightfv(GL_LIGHT0, GL_POSITION, lightPosition); // Define a cutoff angle glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, 40.0); // Set the clear color glClearColor(0, 0, 0, 1.0f); // Projection Matrix config glMatrixMode(GL_PROJECTION); glLoadIdentity(); CGSize layerSize = self.view.layer.frame.size; // Swapped height and width for landscape mode gluPerspective(45.0f, (GLfloat)layerSize.height / (GLfloat)layerSize.width, 0.1f, 750.0f); [self initSkyBox]; // Modelview Matrix config glMatrixMode(GL_MODELVIEW); glLoadIdentity(); // This next line is not really needed as it is the default for OpenGL ES glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glDisable(GL_BLEND); // Enable depth testing glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LESS); glDepthMask(GL_TRUE); } Heres the drawSkybox that gets called in the drawFrame method: -(void)drawSkyBox { glDisable(GL_LIGHTING); glDisable(GL_DEPTH_TEST); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_NORMAL_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); static const SSVertex3D vertices[] = { {-1.0, 1.0, -0.0}, { 1.0, 1.0, -0.0}, {-1.0, -1.0, -0.0}, { 1.0, -1.0, -0.0} }; static const SSVertex3D normals[] = { {0.0, 0.0, 1.0}, {0.0, 0.0, 1.0}, {0.0, 0.0, 1.0}, {0.0, 0.0, 1.0} }; static const GLfloat texCoords[] = { 0.0, 0.5, 0.5, 0.5, 0.0, 0.0, 0.5, 0.0 }; glLoadIdentity(); glTranslatef(0.0, 0.0, -3.0); glBindTexture(GL_TEXTURE_2D, texture[0]); glVertexPointer(3, GL_FLOAT, 0, vertices); glNormalPointer(GL_FLOAT, 0, normals); glTexCoordPointer(2, GL_FLOAT, 0, texCoords); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glDisableClientState(GL_VERTEX_ARRAY); glDisableClientState(GL_NORMAL_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glEnable(GL_LIGHTING); glEnable(GL_DEPTH_TEST); } Heres the init Skybox: -(void)initSkyBox { // Turn necessary features on glEnable(GL_TEXTURE_2D); glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_SRC_COLOR); // Bind the number of textures we need, in this case one. glGenTextures(1, &texture[0]); // create a texture obj, give unique ID glBindTexture(GL_TEXTURE_2D, texture[0]); // load our new texture name into the current texture glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); NSString *path = [[NSBundle mainBundle] pathForResource:@"space" ofType:@"jpg"]; NSData *texData = [[NSData alloc] initWithContentsOfFile:path]; UIImage *image = [[UIImage alloc] initWithData:texData]; GLuint width = CGImageGetWidth(image.CGImage); GLuint height = CGImageGetHeight(image.CGImage); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); void *imageData = malloc( height * width * 4 ); // times 4 because will write one byte for rgb and alpha CGContextRef cgContext = CGBitmapContextCreate( imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big ); // Flip the Y-axis CGContextTranslateCTM (cgContext, 0, height); CGContextScaleCTM (cgContext, 1.0, -1.0); CGColorSpaceRelease( colorSpace ); CGContextClearRect( cgContext, CGRectMake( 0, 0, width, height ) ); CGContextDrawImage( cgContext, CGRectMake( 0, 0, width, height ), image.CGImage ); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData); CGContextRelease(cgContext); free(imageData); [image release]; [texData release]; } Any help is greatly appreciated.

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  • Structure gameobjects and call events

    - by waco001
    I'm working on a 2D tile based game in which the player interacts with other game objects (chests, AI, Doors, Houses etc...). The entire map will be stored in a file which I can read. When loading the tilemap, it will find any tile with the ID that represents a gameobject and store it in a hashmap (right data structure I think?). private static HashMap<Integer, Class<GameObject>> gameObjects = new HashMap<Integer, Class<GameObject>>(); How exactly would I go about calling, and checking for events? I figure that I would just call the update, render and input methods of each gameobject using the hashmap. Should I got towards a Minecraft/Bukkit approach (sorry only example I can think of), where the user registers an event, and it gets called whenever that event happens, and where should I go as in resources to learn about that type of programming, (Java, LWJGL). Or should I just loop through the entire hashmap looking for an event that fits? Thanks waco

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  • (Quaternion based) Trouble moving foward based on model rotation

    - by ChocoMan
    Using quaternions, I'm having trouble moving my model in its facing direction. Currently the model moves can move in all cardinal directions with no problems. The problem comes when I rotate the move as it still travelling in the direction of world space. Meaning, if I'm moving forward, backward or any other direction while rotating the model, the model acts like its a figure skater spinning while traveling in the same direction. How do I update the direction of travel proper with the facing direction of the model? Rotates model on Y-axis: Yaw = pController.ThumbSticks.Right.X * MathHelper.ToRadians(speedAngleMAX); AddRotation = Quaternion.CreateFromYawPitchRoll(yaw, 0, 0); ModelLoad.MRotation *= AddRotation; MOrientation = Matrix.CreateFromQuaternion(ModelLoad.MRotation); Moves model forward: // Move Forward if (pController.IsButtonDown(Buttons.LeftThumbstickUp)) { SpeedX = (float)(Math.Sin(ModelLoad.ModelRotation)) * FWDSpeedMax * pController.ThumbSticks.Left.Y * (float)gameTime.ElapsedGameTime.TotalSeconds; SpeedZ = (float)(Math.Cos(ModelLoad.ModelRotation)) * FWDSpeedMax * pController.ThumbSticks.Left.Y * (float)gameTime.ElapsedGameTime.TotalSeconds; // Update model position ModelLoad._modelPos += Vector3.Forward * SpeedZ; ModelLoad._modelPos += Vector3.Left * SpeedX; }

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  • Xna model parts are overlying others

    - by Federico Chiaravalli
    I am trying to import in XNA an .fbx model exported with blender. Here is my drawing code public void Draw() { Matrix[] modelTransforms = new Matrix[Model.Bones.Count]; Model.CopyAbsoluteBoneTransformsTo(modelTransforms); foreach (ModelMesh mesh in Model.Meshes) { foreach (BasicEffect be in mesh.Effects) { be.EnableDefaultLighting(); be.World = modelTransforms[mesh.ParentBone.Index] * GameCamera.World * Translation; be.View = GameCamera.View; be.Projection = GameCamera.Projection; } mesh.Draw(); } } The problem is that when I start the game some model parts are overlying others instead of being behind. I've tried to download other models from internet but they have the same problem.

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