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  • How to achieve uniform speed of movement on a bezier curve in cocos 2d?

    - by Andrey Chernukha
    I'm an absolute beginner in cocos2 , actually i started dealing with it yesterday. What i'm trying to do is moving an image along Bezier curve. This is how i do it - (void)startFly { [self runAction:[CCSequence actions: [CCBezierBy actionWithDuration:timeFlying bezier:[self getPathWithDirection:currentDirection]], [CCCallFuncN actionWithTarget:self selector:@selector(endFly)], nil]]; } My issue is that the image moves not uniformly. In the beginning it's moving slowly and then it accelerates gradually and at the end it's moving really fast. What should i do to get rid of this acceleration?

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  • Partial recalculation of visibility on a 2D uniform grid

    - by Martin Källman
    Problem Imagine that we have a 2D uniform grid of dimensions N x N. For this grid we have also pre-computed a visibility look-up table, e.g. with DDA, which answers the boolean query is cell X visible from cell Y? The look-up table is a complete graph KN of the cells V in the grid, with each edge E being a binary value denoting the visibility between its vertices. Question If any given cell has its visibility modified, is it possible to extract the subset Edelta of edges which must have their visibility recomputed due to the change, so as to avoid a full-on recomputation for the entire grid? (Which is N(N-1) / 2 or N2 depending on the implementation) Update If is not possible to solve thi in closed form, then maintaining a separate mapping of each cell and every cell pair who's line intersects said cell might also be an option. This obviously consumes more memory, but the data is static. The increased memory requirement could be reduced by introducing a hierarchy, subdividing the grid into smaller parts, and by doing so the above mapping can be reused for each sub-grid. This would come at a cost in terms of increased computation relative to the number of subdivisions; also requiring a resumable ray-casting algorithm.

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  • Turning on collision crashes game

    - by MomentumGaming
    I am getting a null pointer excecption to both my sprite and level. I am working on my mob class, and when I try to move him and the move function is called, the game crashes after checking collision with a null pointer excecption. Taking out the one line that actually checks if the tile located in front of it fixes the problem. Also, if i keep collision ON but don't move the position of the mob (the spider) the game works fine. I will have collision, and the spider appears on the screen, only problem is, getting it to move causes this nasty error that i just can't fix. true Exception in thread "Display" java.lang.NullPointerException at com.apcompsci.game.entity.mob.Mob.collision(Mob.java:67) at com.apcompsci.game.entity.mob.Mob.move(Mob.java:38) at com.apcompsci.game.entity.mob.spider.update(spider.java:58) at com.apcompsci.game.level.Level.update(Level.java:55) at com.apcompsci.game.Game.update(Game.java:128) at com.apcompsci.game.Game.run(Game.java:106) at java.lang.Thread.run(Unknown Source) Here is my renderMob mehtod: public void renderMob(int xp,int yp,Sprite sprite,int flip) { xp -= xOffset; yp-=yOffset; for(int y = 0; y<32; y++) { int ya = y + yp; int ys = y; if(flip == 2||flip == 3)ys = 31-y; for(int x = 0; x<32; x++) { int xa = x + xp; int xs = x; if(flip == 1||flip == 3)xs = 31-x; if(xa < -32 || xa >=width || ya<0||ya>=height) break; if(xa<0) xa =0; int col = sprite.pixels[xs+ys*32]; if(col!= 0x000000) pixels[xa+ya*width] = col; } } } My spider class which determines the sprite and where I control movement, also rendering the spider onto the screen, when I increment ya to move the sprite, I get the crash, but without ya++, it runs flawlessly with a spider sprite on screen: package com.apcompsci.game.entity.mob; import com.apcompsci.game.entity.mob.Mob.Direction; import com.apcompsci.game.graphics.Screen; import com.apcompsci.game.graphics.Sprite; import com.apcompsci.game.level.Level; public class spider extends Mob{ Direction dir; private Sprite sprite; private boolean walking; public spider(int x, int y) { this.x = x <<4; this.y = y <<4; sprite = sprite.spider_forward; } public void update() { int xa = 0, ya = 0; ya++; if(ya<0) { sprite = sprite.spider_forward; dir = Direction.UP; } if(ya>0) { sprite = sprite.spider_back; dir = Direction.DOWN; } if(xa<0) { sprite = sprite.spider_side; dir = Direction.LEFT; } if(xa>0) { sprite = sprite.spider_side; dir = Direction.LEFT; } if(xa!= 0 || ya!= 0) { System.out.println("true"); move(xa,ya); walking = true; } else{ walking = false; } } public void render(Screen screen) { screen.renderMob(x, y, sprite, 0); } } This is th mob class that contains the move() method that is called in the spider class above. This move method calls the collision method. tile and sprite comes up null in the debugger: package com.apcompsci.game.entity.mob; import java.util.ArrayList; import java.util.List; import com.apcompsci.game.entity.Entity; import com.apcompsci.game.entity.projectile.DemiGodProjectile; import com.apcompsci.game.entity.projectile.Projectile; import com.apcompsci.game.graphics.Sprite; public class Mob extends Entity{ protected Sprite sprite; protected boolean moving = false; protected enum Direction { UP,DOWN,LEFT,RIGHT } protected Direction dir; public void move(int xa,int ya) { if(xa != 0 && ya != 0) { move(xa,0); move(0,ya); return; } if(xa>0) dir = Direction.RIGHT; if(xa<0) dir = Direction.LEFT; if(ya>0)dir = Direction.DOWN; if(ya<0)dir = Direction.UP; if(!collision(xa,ya)){ x+= xa; y+=ya; } } public void update() { } public void shoot(int x, int y, double dir) { //dir = Math.toDegrees(dir); Projectile p = new DemiGodProjectile(x, y,dir); level.addProjectile(p); } public boolean collision(int xa,int ya) { boolean solid = false; for(int c = 0; c<4; c++) { int xt = ((x+xa) + c % 2 * 14 - 8 )/16; int yt = ((y+ya) + c / 2 * 12 +3 )/16; if(level.getTile(xt, yt).solid()) solid = true; } return solid; } public void render() { } } Finally, here is the method in which i call the add() method for the spider to add it to the level: protected void loadLevel(String path) { try{ BufferedImage image = ImageIO.read(SpawnLevel.class.getResource(path)); int w = width =image.getWidth(); int h = height = image.getHeight(); tiles = new int[w*h]; image.getRGB(0, 0, w,h, tiles,0, w); } catch(IOException e){ e.printStackTrace(); System.out.println("Exception! Could not load level file!"); } add(new spider(20,45)); } I don't think i need to include the level class but just in case, I have provided a gistHub link for better context. It contains all of the full classes listed above , plus my entity class and maybe another. Thanks for the help if you decide to do so, much appreciated! Also, please tell me if i'm in the wrong section of stackeoverflow, i figured that since this is the gamign section that it belonged but debugging code normally goes into the general section.

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  • Direct3d - Code structure

    - by marcg11
    I'm learning directx in a master's degree and they taught us to have a GraphicsLayer class which is the one connecting with the direct3d library. That way this class is completly independent from the other classes (my game classes), meaning changing the renderer to OpenGL wouldn't require much effort but only changing the graphicLayer. This classe has it's LoadAssets, Paint methods, but I have a question, they told us to load all the assets inside this class. This means all these methods will be in the loadAssets method: D3DXCreateTextureFromFileEx(g_pD3DDevice,"tiles.png",0,0,1,0,D3DFMT_UNKNOWN,D3DPOOL_DEFAULT,D3DX_FILTER_NONE,D3DX_FILTER_NONE,NULL,NULL,NULL,&texTiles); // And more resources to load //... texTiles as you see is a LPDIRECT3DTEXTURE9 instance which is declared in the graphicLayer.h. So my question is, how do you manage all the resources? Do I have to declare in the .h all my game textures even if I'm not using them? How would you load only those resources there are in a scene and draw them in a code-strucured way?

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  • XNA - Finding boundaries in isometric tilemap

    - by Yheeky
    I have an issue with my 2D isometric engine. I'm using my own 2D camera class which works with matrices and need to find the tilemaps boundaries so the user always sees the map. Currently my map size is 100x100 (with 128x128 tiles) so the calculation (e.g. for the right boundary) is: var maxX = (TileMap.MapWidth + 1) * (TileMap.TileWidth / 2) - ViewSize.X; var maxX = (100 + 1) * (128 / 2) - 1360; // = 5104 pixels. This works fine while having scale factor of 1.0f but not for any other zoom factor. When I zoom out to 0.9f the right border should be at approx. 4954. I´m using the following code for transformation but I always get a wrong value: var maxXVector = new Vector2(maxX, 0); var maxXTransformed = Vector2.Transform(maxXVector, tempTransform).X; The result is 4593. Does anyone of you have an idea what I´m during wrong? Thanks for your help! Yheeky

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  • How to stop camera from rotating in 2.5d platformer

    - by Artem Suchkov
    I'm stuck with a problem: I can not make my camera stop rotating after character. What I already have tried: using empty game object with rigid body and locked rotation and make it parent of camera, while player being the parent of object. Also, I've tried using few scripts from web, that did not help. Right now I'm bad with using JS in Unity (can handle JS on website, but I dont know how to integrate it for now) and practicing the basics, making easy 2.5d platformer with basic features, so I can not write code for now.

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  • Physics timestep questions

    - by SSL
    I've got a projectile working perfectly using the code below: //initialised in loading screen 60 is the FPS - projectilEposition and velocity are Vector3 types gravity = new Vector3(0, -(float)9.81 / 60, 0); //called every frame projectilePosition += projectileVelocity; This seems to work fine but I've noticed in various projectile examples I've seen that the elapsedtime per update is taken into account. What's the difference between the two and how can I convert the above to take into account the elapsedtime? (I'm using XNA - do I use ElapsedTime.TotalSeconds or TotalMilliseconds)? Edit: Forgot to add my attempt at using elapsedtime, which seemed to break the physics: projectileVelocity.Y += -(float)((9.81 * gameTime.ElapsedGameTime.TotalSeconds * gameTime.ElapsedGameTime.TotalSeconds) * 0.5f); Thanks for the help

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  • Is it possible to construct a cube with fewer than 24 vertices

    - by Telanor
    I have a cube-based world like Minecraft and I'm wondering if there's a way to construct a cube with fewer than 24 vertices so I can reduce memory usage. It doesn't seem possible to me for 2 reasons: the normals wouldn't come out right and per-face textures wouldn't work. Is this the case or am I wrong? Maybe there's some fancy new DX11 tech that can help? Edit: Just to clarify, I have 2 requirements: I need surface normals for each cube face in order to do proper lighting and I need a way to address a different indexes in a texture array for each cube face

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  • A star algorithm implementation problems

    - by bryan226
    I’m having some trouble implementing the A* algorithm in a 2D tile based game. The problem is basically that the algorithm gets stuck when something gets in its direct way (e.g. walls) Note that it only allows Horizontal and Vertical movement. Here's a picture as it works fine across the map without something in its direct way: (Green tile = destination, Blue = In closed list, Green = in open list) This is what happens if I try to walk 'around' a wall: I calculate costs with the F = G + H formula: G = 1 Cost per Step H = 10 Cost per Step //Count how many tiles are between current-tile & destination-tile The functions: short c_astar::GuessH(short Startx,short Starty,short Destinationx,short Destinationy) { hgeVector Start, Destination; Start.x = Startx; Start.y = Starty; Destination.x = Destinationx; Destination.y = Destinationy; short a = 0; short b = 0; if(Start.x > Destination.x) a = Start.x - Destination.x; else a = Destination.x - Start.x; if(Start.y > Destination.y) b = Start.y - Destination.y; else b = Destination.y - Start.y; return (a+b)*10; } short c_astar::GuessG(short Startx,short Starty,short Currentx,short Currenty) { hgeVector Start, Destination; Start.x = Startx; Start.y = Starty; Destination.x = Currentx; Destination.y = Currenty; short a = 0; short b = 0; if(Start.x > Destination.x) a = Start.x - Destination.x; else a = Destination.x - Start.x; if(Start.y > Destination.y) b = Start.y - Destination.y; else b = Destination.y - Start.y; return (a+b); } At the end of the loop I check which tile is the cheapest to go according to its F value: Then some quick checks are done for each tile (UP,DOWN,LEFT,RIGHT): //...CX are holding the F value of the TILE specified // Info: C0 = Center (Current) // C1 = UP // C2 = DOWN // C3 = LEFT // C4 = RIGHT //Quick checks if(((C1 < C2) && (C1 < C3) && (C1 < C4))) { Current.y -= 1; bSimilar = false; if(DEBUG) hge->System_Log("C1 < ALL"); } //.. same for C2,C3 & C4 If there are multiple tiles with the same F value: It’s actually a switch for DOWNLEFT,UPRIGHT.. etc. Here’s one of it: case UPRIGHT: { //UP Temporary = Current; Temporary.y -= 1; bTileStatus[0] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[0]) { //Proceed normal we are OK & walkable Tilex.Tile = map.at(Temporary.y).at(Temporary.x); //Search in lists if(SearchInClosedList(Tilex.Tile.ID,C0)) bFoundInClosedList[0] = true; if(SearchInOpenList(Tilex.Tile.ID,C0)) bFoundInOpenList[0] = true; //RIGHT Temporary = Current; Temporary.x += 1; bTileStatus[1] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[1]) { //Proceed normal we are OK & walkable Tilex.Tile = map.at(Temporary.y).at(Temporary.x); //Search in lists if(SearchInClosedList(Tilex.Tile.ID,C0)) bFoundInClosedList[1] = true; if(SearchInOpenList(Tilex.Tile.ID,C0)) bFoundInOpenList[1] = true; //************************************************* // Purpose: ClosedList behavior //************************************************* if(bFoundInClosedList[0] && !bFoundInClosedList[1]) { //UP found in ClosedList. Go RIGHT return RIGHT; } if(!bFoundInClosedList[0] && bFoundInClosedList[1]) { //RIGHT found in ClosedList. Go UP return UP; } if(bFoundInClosedList[0] && bFoundInClosedList[1]) { //Both found in ClosedList. Random value switch(hge->Random_Int(8,9)) { case 8: return UP; break; case 9: return RIGHT; break; } } //************************************************* // Purpose: OpenList behavior //************************************************* if(bFoundInOpenList[0] && !bFoundInOpenList[1]) { //UP found in OpenList. Go RIGHT return RIGHT; } if(!bFoundInOpenList[0] && bFoundInOpenList[1]) { //RIGHT found in OpenList. Go UP return UP; } if(bFoundInOpenList[0] && bFoundInOpenList[1]) { //Both found in OpenList. Random value switch(hge->Random_Int(8,9)) { case 8: return UP; break; case 9: return RIGHT; break; } } } else if(!bTileStatus[1]) { //RIGHT is not walkable OR out of range //Choose UP return UP; } } else if(!bTileStatus[0]) { //UP is not walkable OR out of range //Fast check RIGHT Temporary = Current; Temporary.x += 1; bTileStatus[1] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[1]) { return RIGHT; } else return FAILED; //Failed, no valid path found! } } break; A log for the second picture: (Cut down to ten passes, because it’s just repeating itself) ----------------------------------------------------- PASS: 1 | C1: 211 | C2: 191 | C3: 211 | C4: 191 DOWN + RIGHT SIMILAR Going DOWN ----------------------------------------------------- PASS: 2 | C1: 200 | C2: 182 | C3: 202 | C4: 182 DOWN + RIGHT SIMILAR Going DOWN ----------------------------------------------------- PASS: 3 | C1: 191 | C2: 193 | C3: 193 | C4: 173 C4 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 4 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going UP Tile(12.000000,5.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 5 | C1: 191 | C2: 173 | C3: 191 | C4: 999 C2 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 6 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going UP Tile(12.000000,5.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 7 | C1: 191 | C2: 173 | C3: 191 | C4: 999 C2 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 8 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going LEFT ----------------------------------------------------- PASS: 9 | C1: 191 | C2: 193 | C3: 193 | C4: 173 C4 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 10 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going LEFT ----------------------------------------------------- Its always going after the cheapest F value, which seems to be wrong. If someone could point me to the right direction I'd be thankful. Regards, bryan226

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  • Doing powerups in a component-based system

    - by deft_code
    I'm just starting really getting my head around component based design. I don't know what the "right" way to do this is. Here's the scenario. The player can equip a shield. The the shield is drawn as bubble around the player, it has a separate collision shape, and reduces the damage the player receives from area effects. How is such a shield architected in a component based game? Where I get confused is that the shield obviously has three components associated with it. Damage reduction / filtering A sprite A collider. To make it worse different shield variations could have even more behaviors, all of which could be components: boost player maximum health health regen projectile deflection etc Am I overthinking this? Should the shield just be a super component? I really think this is wrong answer. So if you think this is the way to go please explain. Should the shield be its own entity that tracks the location of the player? That might make it hard to implement the damage filtering. It also kinda blurs the lines between attached components and entities. Should the shield be a component that houses other components? I've never seen or heard of anything like this, but maybe it's common and I'm just not deep enough yet. Should the shield just be a set of components that get added to the player? Possibly with an extra component to manage the others, e.g. so they can all be removed as a group. (accidentally leave behind the damage reduction component, now that would be fun). Something else that's obvious to someone with more component experience?

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  • Deserialize inherited classes into the same list in XNA

    - by M0rgenstern
    I am writing a Gui for a game (for what else ...). Therefor I wrote a class GuiElement which has some serializeable fields. From this class I deflect a Class "Button" which has one serializeable field more. Furthermore, I have a Class GuiWindow, which is as well deflected from "GuiElement". An Object of this Class has a Field "HandledElements" of the type "List". To know the layout of the Menues, I use XML-Files, which look like that (for example): <?xml version="1.0" encoding="utf-8" ?> <XnaContent xmlns:Generic="System.Collections.Generic"> <Asset Type="System.Collections.Generic.List[GUI.GuiWindow]"> <Item> <Position>0 0</Position> <AlternativeImagePath></AlternativeImagePath> <IsActive>true</IsActive> <Name>MainMenu</Name> <HandledElements> <Item> <Position>100 100</Position> <AlternativeImagePath></AlternativeImagePath> <IsActive>true</IsActive> <Name>Optionen</Name> <Caption>Optionen</Caption> </Item> </HandledElements> </Item> <Item> <Position>0 0</Position> <AlternativeImagePath></AlternativeImagePath> <IsActive>false</IsActive> <Name>Options</Name> <HandledElements> </HandledElements> </Item> </Asset> </XnaContent> As you can see, the first window has in its "HandledElements" List an Item with the Field . This is a field which only a Button has. The Problem is now: I can't deserialize this XML file, because GuiElement does not have this Field, it only has the few fields above. I thought it would know automatically which Class to use,but it doesn't. Do I really have to give my windows a list for each child class of GuiElement? Or can I do another workaround?

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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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  • Data Structures for Logic Games / Deduction Rules / Sufficient Set of Clues?

    - by taserian
    I've been cogitating about developing a logic game similar to Einstein's Puzzle , which would have different sets of clues for every new game replay. What data structures would you use to handle the different entities (pets, colors of houses, nationalities, etc.), deduction rules, etc. to guarantee that the clues you provide point to a unique solution? I'm having a hard time thinking about how to get the deduction rules to play along with the possible clues; any insight would be appreciated.

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  • Any reliable polygon normal calculation code?

    - by Jenko
    I'm currently calculating the normal vector of a polygon using this code, but for some faces here and there it calculates a wrong normal. I don't really know what's going on or where it fails but its not reliable. Do you have any polygon normal calculation that's tested and found to be reliable? // calculate normal of a polygon using all points var n:int = points.length; var x:Number = 0; var y:Number = 0; var z:Number = 0 // ensure all points above 0 var minx:Number = 0, miny:Number = 0, minz:Number = 0; for (var p:int = 0, pl:int = points.length; p < pl; p++) { var po:_Point3D = points[p] = points[p].clone(); if (po.x < minx) { minx = po.x; } if (po.y < miny) { miny = po.y; } if (po.z < minz) { minz = po.z; } } for (p = 0; p < pl; p++) { po = points[p]; po.x -= minx; po.y -= miny; po.z -= minz; } var cur:int = 1, prev:int = 0, next:int = 2; for (var i:int = 1; i <= n; i++) { // using Newell method x += points[cur].y * (points[next].z - points[prev].z); y += points[cur].z * (points[next].x - points[prev].x); z += points[cur].x * (points[next].y - points[prev].y); cur = (cur+1) % n; next = (next+1) % n; prev = (prev+1) % n; } // length of the normal var length:Number = Math.sqrt(x * x + y * y + z * z); // turn large values into a unit vector if (length != 0){ x = x / length; y = y / length; z = z / length; }else { throw new Error("Cannot calculate normal since triangle has an area of 0"); }

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  • Rotating an object about a point (2D) using box2d

    - by noob
    i just started developing using box2d on flixel and i realise the pivot point of the rotation of an object in box2d is set to the center of an object. i had read on forums and i found out that SetAsBox can change the pivot point of the object, however, i cannot seem to get it work to rotate about a point. what i would like to achieve is to rotate an object about a point like earth revolving around the sun. any one can help me with it? really thanks a lot and sorry for the bad english

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  • Using 2D sprites and 3D models together

    - by Sweta Dwivedi
    I have gone through a few posts that talks about changing the GraphicsDevice.BlendState and GraphicsDevice.DepthStencilState (SpriteBatch & Render states). . however even after changing the states .. i cant see my 3D model on the screen.. I see the model for a second before i draw my video in the background. . Here is the code: case GameState.InGame: GraphicsDevice.Clear(Color.AliceBlue); spriteBatch.Begin(); if (player.State != MediaState.Stopped) { videoTexture = player.GetTexture(); } Rectangle screen = new Rectangle(GraphicsDevice.Viewport.X, GraphicsDevice.Viewport.Y, GraphicsDevice.Viewport.Width, GraphicsDevice.Viewport.Height); // Draw the video, if we have a texture to draw. if (videoTexture != null) { spriteBatch.Draw(videoTexture, screen, Color.White); if (Selected_underwater == true) { spriteBatch.DrawString(font, "MaxX , MaxY" + maxWidth + "," + maxHeight, new Vector2(400, 10), Color.Red); spriteBatch.Draw(kinectRGBVideo, new Rectangle(0, 0, 100, 100), Color.White); spriteBatch.Draw(butterfly, handPosition, Color.White); foreach (AnimatedSprite a in aSprites) { a.Draw(spriteBatch); } } if(Selected_planet == true) { spriteBatch.Draw(kinectRGBVideo, new Rectangle(0, 0, 100, 100), Color.White); spriteBatch.Draw(butterfly, handPosition, Color.White); spriteBatch.Draw(videoTexture,screen,Color.White); GraphicsDevice.BlendState = BlendState.Opaque; GraphicsDevice.DepthStencilState = DepthStencilState.Default; GraphicsDevice.SamplerStates[0] = SamplerState.LinearWrap; foreach (_3DModel m in Solar) { m.DrawModel(); } } spriteBatch.End(); break;

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  • Dealing with 2D pixel shaders and SpriteBatches in XNA 4.0 component-object game engine?

    - by DaveStance
    I've got a bit of experience with shaders in general, having implemented a couple, very simple, 3D fragment and vertex shaders in OpenGL/WebGL in the past. Currently, I'm working on a 2D game engine in XNA 4.0 and I'm struggling with the process of integrating per-object and full-scene shaders in my current architecture. I'm using a component-entity design, wherein my "Entities" are merely collections of components that are acted upon by discreet system managers (SpatialProvider, SceneProvider, etc). In the context of this question, my draw call looks something like this: SceneProvider::Draw(GameTime) calls... ComponentManager::Draw(GameTime, SpriteBatch) which calls (on each drawable component) DrawnComponent::Draw(GameTime, SpriteBatch) The SpriteBatch is set up, with the default SpriteBatch shader, in the SceneProvider class just before it tells the ComponentManager to start rendering the scene. From my understanding, if a component needs to use a special shader to draw itself, it must do the following when it's Draw(GameTime, SpriteBatch) method is invoked: public void Draw(GameTime gameTime, SpriteBatch spriteBatch) { spriteBatch.End(); spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, null, null, null, EffectShader, ViewMatrix); // Draw things here that are shaded by the "EffectShader." spriteBatch.End(); spriteBatch.Begin(/* same settings that were set by SceneProvider to ensure the rest of the scene is rendered normally */); } My question is, having been told that numerous calls to SpriteBatch.Begin() and SpriteBatch.End() within a single frame was terrible for performance, is there a better way to do this? Is there a way to instruct the currently running SpriteBatch to simply change the Effect shader it is using for this particular draw call and then switch it back before the function ends?

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  • Why is my Simplex Noise appearing in four columns?

    - by Joe the Person
    I'm trying to make a Texture out of Simplex noise, but it keeps appearing like this regardless of how big or small scale is: The following code is used to produce the image's color date: private Color[,] GetSimplex() { Color[,] colors = new Color[800, 600]; float scale = colors.GetLength(0); for (int x = 0; x < 800; x++) { for (int y = 0; y < 600; y++) { byte noise = (byte)(Noise.Generate(x / scale, y / scale) * 255); colors[x, y] = new Color(noise, noise, noise); } } return colors; }

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  • Generating geometry when using VBO

    - by onedayitwillmake
    Currently I am working on a project in which I generate geometry based on the players movement. A glorified very long trail, composed of quads. I am doing this by storing a STD::Vector, and removing the oldest verticies once enough exist, and then calling glDrawArrays. I am interested in switching to a shader based model, usually examples I see the VBO is generated at start and then that's basically it. What is the best route to go about creating geometry in real time, using shader / VBO approach

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  • Developing an ELO like point system for a multiplayer gaming site

    - by Alejandro Piad
    I'm currently working on a gaming site where users will submit virtual players for different games, like Chess, Nash, Backgammon, Go, etc. The idea is that users don't compete themselves, but through their virtual players. There will be leagues, tournaments, and other competition formats. The question is which would be a good rating system for users in this environment. Take into account that every user may have many different virtual players playing in many different games. As a general guideline I would like to guarantee the following properties: Users who have a lot of mediocre players should not score higher than users with a few very good players. A user with a high rating should not be penalized if he adds a new bad player, until he has had enough time to improve his player. Users who don't play often should not score higher than users who play every day. Thanks in advance.

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  • Unity: parallel vectors and cross product, how to compare vectors

    - by Heisenbug
    I read this post explaining a method to understand if the angle between 2 given vectors and the normal to the plane described by them, is clockwise or anticlockwise: public static AngleDir GetAngleDirection(Vector3 beginDir, Vector3 endDir, Vector3 upDir) { Vector3 cross = Vector3.Cross(beginDir, endDir); float dot = Vector3.Dot(cross, upDir); if (dot > 0.0f) return AngleDir.CLOCK; else if (dot < 0.0f) return AngleDir.ANTICLOCK; return AngleDir.PARALLEL; } After having used it a little bit, I think it's wrong. If I supply the same vector as input (beginDir equal to endDir), the cross product is zero, but the dot product is a little bit more than zero. I think that to fix that I can simply check if the cross product is zero, means that the 2 vectors are parallel, but my code doesn't work. I tried the following solution: Vector3 cross = Vector3.Cross(beginDir, endDir); if (cross == Vector.zero) return AngleDir.PARALLEL; And it doesn't work because comparison between Vector.zero and cross is always different from zero (even if cross is actually [0.0f, 0.0f, 0.0f]). I tried also this: Vector3 cross = Vector3.Cross(beginDir, endDir); if (cross.magnitude == 0.0f) return AngleDir.PARALLEL; it also fails because magnitude is slightly more than zero. So my question is: given 2 Vector3 in Unity, how to compare them? I need the elegant equivalent version of this: if (beginDir.x == endDir.x && beginDir.y == endDir.y && beginDir.z == endDir.z) return true;

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  • Camera doesnt move on opengl qt

    - by hugo
    Here is my code, as my subject indicates i have implemented a camera but i couldnt make it move,Thanks in advance. #define PI_OVER_180 0.0174532925f define GL_CLAMP_TO_EDGE 0x812F include "metinalifeyyaz.h" include include include include include include include metinalifeyyaz::metinalifeyyaz(QWidget *parent) : QGLWidget(parent) { this->setFocusPolicy(Qt:: StrongFocus); time = QTime::currentTime(); timer = new QTimer(this); timer->setSingleShot(true); connect(timer, SIGNAL(timeout()), this, SLOT(updateGL())); xpos = yrot = zpos = 0; walkbias = walkbiasangle = lookupdown = 0.0f; keyUp = keyDown = keyLeft = keyRight = keyPageUp = keyPageDown = false; } void metinalifeyyaz::drawBall() { //glTranslatef(6,0,4); glutSolidSphere(0.10005,300,30); } metinalifeyyaz:: ~metinalifeyyaz(){ glDeleteTextures(1,texture); } void metinalifeyyaz::initializeGL(){ glShadeModel(GL_SMOOTH); glClearColor(1.0,1.0,1.0,0.5); glClearDepth(1.0f); glEnable(GL_DEPTH_TEST); glEnable(GL_TEXTURE_2D); glDepthFunc(GL_LEQUAL); glClearColor(1.0,1.0,1.0,1.0); glShadeModel(GL_SMOOTH); GLfloat mat_specular[]={1.0,1.0,1.0,1.0}; GLfloat mat_shininess []={30.0}; GLfloat light_position[]={1.0,1.0,1.0}; glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT,GL_SHININESS,mat_shininess); glLightfv(GL_LIGHT0, GL_POSITION, light_position); glEnable(GL_LIGHT0); glEnable(GL_LIGHTING); QImage img1 = convertToGLFormat(QImage(":/new/prefix1/halisaha2.bmp")); QImage img2 = convertToGLFormat(QImage(":/new/prefix1/white.bmp")); glGenTextures(2,texture); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img1.width(), img1.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img1.bits()); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img2.width(), img2.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img2.bits()); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really nice perspective calculations } void metinalifeyyaz::resizeGL(int w, int h){ if(h==0) h=1; glViewport(0,0,w,h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0f, static_cast<GLfloat>(w)/h,0.1f,100.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } void metinalifeyyaz::paintGL(){ movePlayer(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); GLfloat xtrans = -xpos; GLfloat ytrans = -walkbias - 0.50f; GLfloat ztrans = -zpos; GLfloat sceneroty = 360.0f - yrot; glLoadIdentity(); glRotatef(lookupdown, 1.0f, 0.0f, 0.0f); glRotatef(sceneroty, 0.0f, 1.0f, 0.0f); glTranslatef(xtrans, ytrans+50, ztrans-130); glLoadIdentity(); glTranslatef(1.0f,0.0f,-18.0f); glRotatef(45,1,0,0); drawScene(); int delay = time.msecsTo(QTime::currentTime()); if (delay == 0) delay = 1; time = QTime::currentTime(); timer->start(qMax(0,10 - delay)); } void metinalifeyyaz::movePlayer() { if (keyUp) { xpos -= sin(yrot * PI_OVER_180) * 0.5f; zpos -= cos(yrot * PI_OVER_180) * 0.5f; if (walkbiasangle >= 360.0f) walkbiasangle = 0.0f; else walkbiasangle += 7.0f; walkbias = sin(walkbiasangle * PI_OVER_180) / 10.0f; } else if (keyDown) { xpos += sin(yrot * PI_OVER_180)*0.5f; zpos += cos(yrot * PI_OVER_180)*0.5f ; if (walkbiasangle <= 7.0f) walkbiasangle = 360.0f; else walkbiasangle -= 7.0f; walkbias = sin(walkbiasangle * PI_OVER_180) / 10.0f; } if (keyLeft) yrot += 0.5f; else if (keyRight) yrot -= 0.5f; if (keyPageUp) lookupdown -= 0.5; else if (keyPageDown) lookupdown += 0.5; } void metinalifeyyaz::keyPressEvent(QKeyEvent *event) { switch (event->key()) { case Qt::Key_Escape: close(); break; case Qt::Key_F1: setWindowState(windowState() ^ Qt::WindowFullScreen); break; default: QGLWidget::keyPressEvent(event); case Qt::Key_PageUp: keyPageUp = true; break; case Qt::Key_PageDown: keyPageDown = true; break; case Qt::Key_Left: keyLeft = true; break; case Qt::Key_Right: keyRight = true; break; case Qt::Key_Up: keyUp = true; break; case Qt::Key_Down: keyDown = true; break; } } void metinalifeyyaz::changeEvent(QEvent *event) { switch (event->type()) { case QEvent::WindowStateChange: if (windowState() == Qt::WindowFullScreen) setCursor(Qt::BlankCursor); else unsetCursor(); break; default: break; } } void metinalifeyyaz::keyReleaseEvent(QKeyEvent *event) { switch (event->key()) { case Qt::Key_PageUp: keyPageUp = false; break; case Qt::Key_PageDown: keyPageDown = false; break; case Qt::Key_Left: keyLeft = false; break; case Qt::Key_Right: keyRight = false; break; case Qt::Key_Up: keyUp = false; break; case Qt::Key_Down: keyDown = false; break; default: QGLWidget::keyReleaseEvent(event); } } void metinalifeyyaz::drawScene(){ glBegin(GL_QUADS); glNormal3f(0.0f,0.0f,1.0f); // glColor3f(0,0,1); //back glVertex3f(-6,0,-4); glVertex3f(-6,-0.5,-4); glVertex3f(6,-0.5,-4); glVertex3f(6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(0.0f,0.0f,-1.0f); //front glVertex3f(6,0,4); glVertex3f(6,-0.5,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,0,4); glEnd(); glBegin(GL_QUADS); glNormal3f(-1.0f,0.0f,0.0f); // glColor3f(0,0,1); //left glVertex3f(-6,0,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,-0.5,-4); glVertex3f(-6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(1.0f,0.0f,0.0f); // glColor3f(0,0,1); //right glVertex3f(6,0,-4); glVertex3f(6,-0.5,-4); glVertex3f(6,-0.5,4); glVertex3f(6,0,4); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[0]); glBegin(GL_QUADS); glNormal3f(0.0f,1.0f,0.0f);//top glTexCoord2f(1.0f,0.0f); glVertex3f(6,0,-4); glTexCoord2f(1.0f,1.0f); glVertex3f(6,0,4); glTexCoord2f(0.0f,1.0f); glVertex3f(-6,0,4); glTexCoord2f(0.0f,0.0f); glVertex3f(-6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(0.0f,-1.0f,0.0f); //glColor3f(0,0,1); //bottom glVertex3f(6,-0.5,-4); glVertex3f(6,-0.5,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,-0.5,-4); glEnd(); // glPushMatrix(); glBindTexture(GL_TEXTURE_2D, texture[1]); glBegin(GL_QUADS); glNormal3f(1.0f,0.0f,0.0f); glTexCoord2f(1.0f,0.0f); //right far goal post front face glVertex3f(5,0.5,-0.95); glTexCoord2f(1.0f,1.0f); glVertex3f(5,0,-0.95); glTexCoord2f(0.0f,1.0f); glVertex3f(5,0,-1); glTexCoord2f(0.0f,0.0f); glVertex3f(5, 0.5, -1); glColor3f(1,1,1); //right far goal post back face glVertex3f(5.05,0.5,-0.95); glVertex3f(5.05,0,-0.95); glVertex3f(5.05,0,-1); glVertex3f(5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post left face glVertex3f(5,0.5,-1); glVertex3f(5,0,-1); glVertex3f(5.05,0,-1); glVertex3f(5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post right face glVertex3f(5.05,0.5,-0.95); glVertex3f(5.05,0,-0.95); glVertex3f(5,0,-0.95); glVertex3f(5, 0.5, -0.95); glColor3f(1,1,1); //right near goal post front face glVertex3f(5,0.5,0.95); glVertex3f(5,0,0.95); glVertex3f(5,0,1); glVertex3f(5,0.5, 1); glColor3f(1,1,1); //right near goal post back face glVertex3f(5.05,0.5,0.95); glVertex3f(5.05,0,0.95); glVertex3f(5.05,0,1); glVertex3f(5.05,0.5, 1); glColor3f(1,1,1); //right near goal post left face glVertex3f(5,0.5,1); glVertex3f(5,0,1); glVertex3f(5.05,0,1); glVertex3f(5.05,0.5, 1); glColor3f(1,1,1); //right near goal post right face glVertex3f(5.05,0.5,0.95); glVertex3f(5.05,0,0.95); glVertex3f(5,0,0.95); glVertex3f(5,0.5, 0.95); glColor3f(1,1,1); //right crossbar front face glVertex3f(5,0.55,-1); glVertex3f(5,0.55,1); glVertex3f(5,0.5,1); glVertex3f(5,0.5,-1); glColor3f(1,1,1); //right crossbar back face glVertex3f(5.05,0.55,-1); glVertex3f(5.05,0.55,1); glVertex3f(5.05,0.5,1); glVertex3f(5.05,0.5,-1); glColor3f(1,1,1); //right crossbar bottom face glVertex3f(5.05,0.5,-1); glVertex3f(5.05,0.5,1); glVertex3f(5,0.5,1); glVertex3f(5,0.5,-1); glColor3f(1,1,1); //right crossbar top face glVertex3f(5.05,0.55,-1); glVertex3f(5.05,0.55,1); glVertex3f(5,0.55,1); glVertex3f(5,0.55,-1); glColor3f(1,1,1); //left far goal post front face glVertex3f(-5,0.5,-0.95); glVertex3f(-5,0,-0.95); glVertex3f(-5,0,-1); glVertex3f(-5, 0.5, -1); glColor3f(1,1,1); //right far goal post back face glVertex3f(-5.05,0.5,-0.95); glVertex3f(-5.05,0,-0.95); glVertex3f(-5.05,0,-1); glVertex3f(-5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post left face glVertex3f(-5,0.5,-1); glVertex3f(-5,0,-1); glVertex3f(-5.05,0,-1); glVertex3f(-5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post right face glVertex3f(-5.05,0.5,-0.95); glVertex3f(-5.05,0,-0.95); glVertex3f(-5,0,-0.95); glVertex3f(-5, 0.5, -0.95); glColor3f(1,1,1); //left near goal post front face glVertex3f(-5,0.5,0.95); glVertex3f(-5,0,0.95); glVertex3f(-5,0,1); glVertex3f(-5,0.5, 1); glColor3f(1,1,1); //right near goal post back face glVertex3f(-5.05,0.5,0.95); glVertex3f(-5.05,0,0.95); glVertex3f(-5.05,0,1); glVertex3f(-5.05,0.5, 1); glColor3f(1,1,1); //right near goal post left face glVertex3f(-5,0.5,1); glVertex3f(-5,0,1); glVertex3f(-5.05,0,1); glVertex3f(-5.05,0.5, 1); glColor3f(1,1,1); //right near goal post right face glVertex3f(-5.05,0.5,0.95); glVertex3f(-5.05,0,0.95); glVertex3f(-5,0,0.95); glVertex3f(-5,0.5, 0.95); glColor3f(1,1,1); //left crossbar front face glVertex3f(-5,0.55,-1); glVertex3f(-5,0.55,1); glVertex3f(-5,0.5,1); glVertex3f(-5,0.5,-1); glColor3f(1,1,1); //right crossbar back face glVertex3f(-5.05,0.55,-1); glVertex3f(-5.05,0.55,1); glVertex3f(-5.05,0.5,1); glVertex3f(-5.05,0.5,-1); glColor3f(1,1,1); //right crossbar bottom face glVertex3f(-5.05,0.5,-1); glVertex3f(-5.05,0.5,1); glVertex3f(-5,0.5,1); glVertex3f(-5,0.5,-1); glColor3f(1,1,1); //right crossbar top face glVertex3f(-5.05,0.55,-1); glVertex3f(-5.05,0.55,1); glVertex3f(-5,0.55,1); glVertex3f(-5,0.55,-1); glEnd(); // glPopMatrix(); // glPushMatrix(); // glTranslatef(0,0,0); // glutSolidSphere(0.10005,500,30); // glPopMatrix(); }

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  • How to design good & continuous tiles

    - by Mikalichov
    I have trouble designing tiles so that when assembled, they don't look like tiles, but look like an homogeneous thing. For example on the image below: even though the main part of the grass is only one tile, you don't "see" the grid; you know where it is if you look a bit carefully, but it is not obvious. Whereas when I design tiles, you can only see "oh, jeez, 64 times the same tile". A bit like on that image: (taken from a gamedev.stackexchange question, sorry; no critic about the game, but it proves my point, and actually has better tile design that what I manage) I think the main problem is that I design them so they are independent, there is no junction between two tiles if put closed to each other. I think having the tiles more "continuous" would have a smoother effect, but can't manage to do it, it seems overly complex to me. I think it is probably simpler than I think once you know how to do it, but couldn't find a tutorial on that specific point. Is there a known method to design continuous / homogeneous tiles? (my terminology might be totally wrong, don't hesitate to correct me)

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  • Unity 3d (Using Blender) - anime/manga/cel-shaded style characters

    - by David Archer
    Making a game using Blender for 3D models and Unity for the game engine. Just wondering if anyone knows any links to pages that give a tutorial on Japanese anime style 3D modelling, texturing and shading through blender. I'm actually looking to create a cel-shaded look eventually (read: Okami/Jet Set Radio style) and I'm kind of stuck with the design stuff. I'm not a Blender expert by any means, and still kind of new to the design side of things (I'm a programmer by trade), so please don't vote me down too hard. I've tried googling, but there doesn't seem to be much in the way of what I'm after. The only thing I've found really is a plugin for blender called freestyle, or using the ToonShader shading tool. If there are any good tutorials or anything, I'm really happy to sit through them - just want to learn :) Thanks for any help :)

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  • How to do geometric projection shadows?

    - by John Murdoch
    I have decided that since my game world is mostly flat I don't need better shadows than geometric projections - at least for now. The only problem is I don't even know how to do those properly - that is to produce a 4x4 matrix which would render shadows for my objects (that is, I guess, project them on a horizontal XZ plane). I would like a light source at infinity (e.g., the sun at some point in the sky) and thus parallel projection. My current code does something that looks almost right for small flying objects, but actually is a very rude approximation, as it doesn't project the objects onto the ground, but simply moves them there (I think). Also it always wrongly assumes the sun is always on the zenith (projecting straight down). Gdx.gl20.glEnable(GL10.GL_BLEND); Gdx.gl20.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA); //shells shellTexture.bind(); shader.begin(); for (ShellState state : shellStates.values()) { transform.set(camera.combined); transform.mul(state.transform); shader.setUniformMatrix("u_worldView", transform); shader.setUniformi("u_texture", 0); shellMesh.render(shader, GL10.GL_TRIANGLES); } shader.end(); // shadows shader.begin(); for (ShellState state : shellStates.values()) { transform.set(camera.combined); m4.set(state.transform); state.transform.getTranslation(v3); m4.translate(0, -v3.y + 0.5f, 0); // TODO HACK: + 0.5f is a hack to ensure the shadow appears above the ground; this is overall a hack as we are just moving the shell to the surface instead of projecting it on the surface! transform.mul(m4); shader.setUniformMatrix("u_worldView", transform); shader.setUniformi("u_texture", 0); // TODO: make shadow black somehow shellMesh.render(shader, GL10.GL_TRIANGLES); } shader.end(); Gdx.gl.glDisable(GL10.GL_BLEND); So my questions are: a) What is the proper way to produce a Matrix4 to pass to openGL which would render the shadows for my objects? b) I am supposed to use another fragment shader for the shadows which would paint them in semi-transparent grey, correct? c) The limitation of this simplistic approach is that whenever there is some object on the ground (it is not flat) the shadows will not be drawn, correct? d) Do I need to add something very small to the y (up) coordinate to avoid z-fighting with ground textures? Or is the fact they will be semi-transparent enough to resolve that problem?

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