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  • jBullet Collision/Physics not working correctly

    - by Kenneth Bray
    Below is the code for one of my objects in the game I am creating (yes although this is a cube, I am not making anything remotely like MineCraft), and my issue is I while the cube will display and is does follow the physics if the cube falls, it does not interact with any other objects in the game. If I was to have multiple cubes in screen at once they all just sit there, or shoot off in all directions never stopping. Anyway, I am new to jBullet, and any help would be appreciated. package Object; import static org.lwjgl.opengl.GL11.GL_QUADS; import static org.lwjgl.opengl.GL11.glBegin; import static org.lwjgl.opengl.GL11.glColor3f; import static org.lwjgl.opengl.GL11.glEnd; import static org.lwjgl.opengl.GL11.glPopMatrix; import static org.lwjgl.opengl.GL11.glPushMatrix; import static org.lwjgl.opengl.GL11.glVertex3f; import javax.vecmath.Matrix4f; import javax.vecmath.Quat4f; import javax.vecmath.Vector3f; import com.bulletphysics.collision.shapes.BoxShape; import com.bulletphysics.collision.shapes.CollisionShape; import com.bulletphysics.dynamics.RigidBody; import com.bulletphysics.dynamics.RigidBodyConstructionInfo; import com.bulletphysics.linearmath.DefaultMotionState; import com.bulletphysics.linearmath.Transform; public class Cube { // Cube size/shape variables private float size; boolean cubeCollidable; boolean cubeDestroyable; // Position variables - currently this defines the center of the cube private float posX; private float posY; private float posZ; // Rotation variables - should be between 0 and 359, might consider letting rotation go higher though I can't think of a purpose currently private float rotX; private float rotY; private float rotZ; //collision shape is a box shape CollisionShape fallShape; // setup the motion state for the ball DefaultMotionState fallMotionState; Vector3f fallInertia = new Vector3f(0, 1, 0); RigidBodyConstructionInfo fallRigidBodyCI; public RigidBody fallRigidBody; int mass = 1; // Constructor public Cube(float pX, float pY, float pZ, float pSize) { posX = pX; posY = pY; posZ = pZ; size = pSize; rotX = 0; rotY = 0; rotZ = 0; // define the physics based on the values passed in fallShape = new BoxShape(new Vector3f(size, size, size)); fallMotionState = new DefaultMotionState(new Transform(new Matrix4f(new Quat4f(0, 0, 0, 1), new Vector3f(0, 50, 0), 1f))); fallRigidBodyCI = new RigidBodyConstructionInfo(mass, fallMotionState, fallShape, fallInertia); fallRigidBody = new RigidBody(fallRigidBodyCI); } public void Update() { Transform trans = new Transform(); fallRigidBody.getMotionState().getWorldTransform(trans); posY = trans.origin.x; posX = trans.origin.y; posZ = trans.origin.z; } public void Draw() { fallShape.calculateLocalInertia(mass, fallInertia); // center point posX, posY, posZ float radius = size / 2; //top glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,0.0f,0.0f); // red glVertex3f(posX + radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ + radius); glVertex3f(posX + radius, posY + radius, posZ + radius); } glEnd(); glPopMatrix(); //bottom glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,1.0f,0.0f); // ?? color glVertex3f(posX + radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX + radius, posY - radius, posZ - radius); } glEnd(); glPopMatrix(); //right side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,0.0f,1.0f); // ?? color glVertex3f(posX + radius, posY + radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ - radius); glVertex3f(posX + radius, posY + radius, posZ - radius); } glEnd(); glPopMatrix(); //left side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,1.0f,1.0f); // ?? color glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY + radius, posZ + radius); } glEnd(); glPopMatrix(); //front side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,0.0f,1.0f); //blue glVertex3f(posX + radius, posY + radius, posZ + radius); glVertex3f(posX - radius, posY + radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ + radius); } glEnd(); glPopMatrix(); //back side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,1.0f,0.0f); // green glVertex3f(posX + radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX + radius, posY + radius, posZ - radius); } glEnd(); glPopMatrix(); } }

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  • XNA Per-Polygon Collision Check

    - by user22985
    I'm working on a project in XNA for WP7 with a low-poly environment, my problem is I need to setup a working per-polygon collision check between 2 or more 3d meshes. I've checked tons of tutorials but all of them use bounding-boxes, bounding-spheres,rays etc., but what I really need is a VERY precise way of checking if the polygons of two distinct models have intersected or not. If you could redirect me to an example or at least give me some pointers I would be grateful.

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  • My grid based collision detection is slow

    - by Fibericon
    Something about my implementation of a basic 2x4 grid for collision detection is slow - so slow in fact, that it's actually faster to simply check every bullet from every enemy to see if the BoundingSphere intersects with that of my ship. It becomes noticeably slow when I have approximately 1000 bullets on the screen (36 enemies shooting 3 bullets every .5 seconds). By commenting it out bit by bit, I've determined that the code used to add them to the grid is what's slowest. Here's how I add them to the grid: for (int i = 0; i < enemy[x].gun.NumBullets; i++) { if (enemy[x].gun.bulletList[i].isActive) { enemy[x].gun.bulletList[i].Update(timeDelta); int bulletPosition = 0; if (enemy[x].gun.bulletList[i].position.Y < 0) { bulletPosition = (int)Math.Floor((enemy[x].gun.bulletList[i].position.X + 900) / 450); } else { bulletPosition = (int)Math.Floor((enemy[x].gun.bulletList[i].position.X + 900) / 450) + 4; } GridItem bulletItem = new GridItem(); bulletItem.index = i; bulletItem.type = 5; bulletItem.parentIndex = x; if (bulletPosition > -1 && bulletPosition < 8) { if (!grid[bulletPosition].Contains(bulletItem)) { for (int j = 0; j < grid.Length; j++) { grid[j].Remove(bulletItem); } grid[bulletPosition].Add(bulletItem); } } } } And here's how I check if it collides with the ship: if (ship.isActive && !ship.invincible) { BoundingSphere shipSphere = new BoundingSphere( ship.Position, ship.Model.Meshes[0].BoundingSphere.Radius * 9.0f); for (int i = 0; i < grid.Length; i++) { if (grid[i].Contains(shipItem)) { for (int j = 0; j < grid[i].Count; j++) { //Other collision types omitted else if (grid[i][j].type == 5) { if (enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].isActive) { BoundingSphere bulletSphere = new BoundingSphere(enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].position, enemy[grid[i][j].parentIndex].gun.bulletModel.Meshes[0].BoundingSphere.Radius); if (shipSphere.Intersects(bulletSphere)) { ship.health -= enemy[grid[i][j].parentIndex].gun.damage; enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].isActive = false; grid[i].RemoveAt(j); break; //no need to check other bullets } } else { grid[i].RemoveAt(j); } } What am I doing wrong here? I thought a grid implementation would be faster than checking each one.

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  • 2D SAT Collision Detection not working when using certain polygons

    - by sFuller
    My SAT algorithm falsely reports that collision is occurring when using certain polygons. I believe this happens when using a polygon that does not contain a right angle. Here is a simple diagram of what is going wrong: Here is the problematic code: std::vector<vec2> axesB = polygonB->GetAxes(); //loop over axes B for(int i = 0; i < axesB.size(); i++) { float minA,minB,maxA,maxB; polygonA->Project(axesB[i],&minA,&maxA); polygonB->Project(axesB[i],&minB,&maxB); float intervalDistance = polygonA->GetIntervalDistance(minA, maxA, minB, maxB); if(intervalDistance >= 0) return false; //Collision not occurring } This function retrieves axes from the polygon: std::vector<vec2> Polygon::GetAxes() { std::vector<vec2> axes; for(int i = 0; i < verts.size(); i++) { vec2 a = verts[i]; vec2 b = verts[(i+1)%verts.size()]; vec2 edge = b-a; axes.push_back(vec2(-edge.y,edge.x).GetNormailzed()); } return axes; } This function returns the normalized vector: vec2 vec2::GetNormailzed() { float mag = sqrt( x*x + y*y ); return *this/mag; } This function projects a polygon onto an axis: void Polygon::Project(vec2* axis, float* min, float* max) { float d = axis->DotProduct(&verts[0]); float _min = d; float _max = d; for(int i = 1; i < verts.size(); i++) { d = axis->DotProduct(&verts[i]); _min = std::min(_min,d); _max = std::max(_max,d); } *min = _min; *max = _max; } This function returns the dot product of the vector with another vector. float vec2::DotProduct(vec2* other) { return (x*other->x + y*other->y); } Could anyone give me a pointer in the right direction to what could be causing this bug?

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  • 2D SAT Collision Detection not working when using certain polygons (With example)

    - by sFuller
    My SAT algorithm falsely reports that collision is occurring when using certain polygons. I believe this happens when using a polygon that does not contain a right angle. Here is a simple diagram of what is going wrong: Here is the problematic code: std::vector<vec2> axesB = polygonB->GetAxes(); //loop over axes B for(int i = 0; i < axesB.size(); i++) { float minA,minB,maxA,maxB; polygonA->Project(axesB[i],&minA,&maxA); polygonB->Project(axesB[i],&minB,&maxB); float intervalDistance = polygonA->GetIntervalDistance(minA, maxA, minB, maxB); if(intervalDistance >= 0) return false; //Collision not occurring } This function retrieves axes from the polygon: std::vector<vec2> Polygon::GetAxes() { std::vector<vec2> axes; for(int i = 0; i < verts.size(); i++) { vec2 a = verts[i]; vec2 b = verts[(i+1)%verts.size()]; vec2 edge = b-a; axes.push_back(vec2(-edge.y,edge.x).GetNormailzed()); } return axes; } This function returns the normalized vector: vec2 vec2::GetNormailzed() { float mag = sqrt( x*x + y*y ); return *this/mag; } This function projects a polygon onto an axis: void Polygon::Project(vec2* axis, float* min, float* max) { float d = axis->DotProduct(&verts[0]); float _min = d; float _max = d; for(int i = 1; i < verts.size(); i++) { d = axis->DotProduct(&verts[i]); _min = std::min(_min,d); _max = std::max(_max,d); } *min = _min; *max = _max; } This function returns the dot product of the vector with another vector. float vec2::DotProduct(vec2* other) { return (x*other->x + y*other->y); } Could anyone give me a pointer in the right direction to what could be causing this bug? Edit: I forgot this function, which gives me the interval distance: float Polygon::GetIntervalDistance(float minA, float maxA, float minB, float maxB) { float intervalDistance; if (minA < minB) { intervalDistance = minB - maxA; } else { intervalDistance = minA - maxB; } return intervalDistance; //A positive value indicates this axis can be separated. } Edit 2: I have recreated the problem in HTML5/Javascript: Demo

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  • Different bounding volumes for culling and collision detection

    - by Serthy
    Should an object in a 3D-engine use different bounding volumes for collision-detection (broad-phase) and culling? Basically class renderBounds and class physBounds versus class boundingVolume? Each of this classes then could either contain the same type of volumes (AABB's, kDOP's, sphere's etc.) or a special fitting one for the particular object. (note: without considering of using an external physics engine)

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  • Java 2D Tile Collision

    - by opiop65
    I have been working on a way to do collision detection forever, and just can't figure it out. Here's my simple 2D array: for (int x = 0; x < 16; x++) { for (int y = 0; y < 16; y++) { map[x][y] = AIR; if(map[x][y] == AIR) { air.draw(x * tilesize, y * tilesize); } } } for (int x = 0; x < 16; x++) { for (int y = 6; y < 16; y++) { map[x][y] = GRASS; if(map[x][y] == GRASS) { grass.draw(x * tilesize, y * tilesize); } } } for (int x = 0; x < 16; x++) { for (int y = 8; y < 16; y++) { map[x][y] = STONE; if(map[x][y] == STONE) { stone.draw(x * tilesize, y * tilesize); } } } I want to do it with rectangles, and using the intersect() method, but how would I go about adding rectangles to all the tiles? Edit: My player moves like this: if(input.isKeyDown(Input.KEY_W)) { shiftY -= delta * speed; idY = (int) shiftY; if(shift == true) { shiftY -= delta * runspeed; } if(isColliding == true) { shiftY += delta * speed; } } if(input.isKeyDown(Input.KEY_S)) { shiftY += delta * speed; idY = (int) shiftY; if(shift == true) { shiftY += delta * runspeed; } if(isColliding == true) { shiftY -= delta * speed; } } if (input.isKeyDown(Input.KEY_A)) { steve = left; shiftX -= delta * speed; idX = (int) shiftX; if(shift == true) { shiftX -= delta * runspeed; } if(isColliding == true) { shiftX += delta * speed; } } if (input.isKeyDown(Input.KEY_D)) { steve = right; shiftX += delta * speed; idX = (int) shiftX; if(shift == true) { shiftX += delta * runspeed; } if(isColliding == true) { shiftX -= delta * speed; } } (I have tried my own collision code, but its horrible. Doesn't work in the slightest)

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  • Platformer Collision Error [closed]

    - by Connor
    I am currently working on a relatively simple platform game that has an odd bug.You start the game by falling onto the ground (you spawn a few blocks above the ground), but when you land your feet get stuck INSIDE the world and you can't move until you jump. Here's what I mean: The player's feet are a few pixels below the ground level. However, this problem only occurs in 3 places throughout the map and only in those 3 select places. I'm assuming that the problem lies within my collision detection code but I'm not entirely sure, as I don't get an error when it happens. public boolean isCollidingWithBlock(Point pt1, Point pt2) { //Checks x for(int x = (int) (this.x / Tile.tileSize); x < (int) (this.x / Tile.tileSize + 4); x++) { //Checks y for(int y = (int) (this.y / Tile.tileSize); y < (int) (this.y / Tile.tileSize + 4); y++) { if(x >= 0 && y >= 0 && x < Component.dungeon.block.length && y < Component.dungeon.block[0].length) { //If the block is not air if(Component.dungeon.block[x][y].id != Tile.air) { //If the player is in contact with point one or two on the block if(Component.dungeon.block[x][y].contains(pt1) || Component.dungeon.block[x][y].contains(pt2)) { //Checks for specific blocks if(Component.dungeon.block[x][y].id == Tile.portalBlock) { Component.isLevelDone = true; } if(Component.dungeon.block[x][y].id == Tile.spike) { Health.health -= 1; Component.isJumping = true; if(Health.health == 0) { Component.isDead = true; } } return true; } } } } } return false; } What I'm asking is how I would fix the problem. I've looked over my code for quite a while and I'm not sure what's wrong with it. Also, if there's a more efficient way to do my collision checking then please let me know! I hope that is enough information, if it's not just tell me what you need and I'll be sure to add it. Thank you! [EDIT] Jump code: if(!isJumping && !isCollidingWithBlock(new Point((int) x + 2, (int) (y + height)), new Point((int) (x + width + 2), (int) (y + height)))) { y += fallSpeed; //sY is the screen's Y. The game is a side-scroller Component.sY += fallSpeed; } else { if(Component.isJumping) { isJumping = true; } } if(isJumping) { if(!isCollidingWithBlock(new Point((int) x + 2, (int) y), new Point((int) (x + width + 2), (int) y))) { if(jumpCount >= jumpHeight) { isJumping = false; jumpCount = 0; } else { y -= jumpSpeed; Component.sY -= jumpSpeed; jumpCount += 1; } } else { isJumping = false; jumpCount = 0; } }

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  • Isometric Collision Detection

    - by Sleepy Rhino
    I am having some issues with trying to detect collision of two isometric tile. I have tried plotting the lines between each point on the tile and then checking for line intercepts however that didn't work (probably due to incorrect formula) After looking into this for awhile today I believe I am thinking to much into it and there must be a easier way. I am not looking for code just some advise on the best way to achieve detection of overlap

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  • Ubuntu can't find the correct max resolution with Samsung SyncMaster SA300

    - by fatmatto
    i decided to install ubuntu also on my desktop PC (Windows has been exorcised from my life) but i am having some problems i didn't have with previous hardware configurations. My display is a Samsung SyncMaster SA300, on windows vista the maximum resolution (1920x1080) worked well, but now, ubuntu (after installing fglrx drivers) tells me that the maximum resolution is 1600x1200 I googled a lot last night, and i found a lot of people solving this (on different displays though) with xrandr. I was not able to do it, because xrandr keep complaining "you goddamn maximum resolution is 1600x1600". What xranrd clean command say is: mattia@fatdesktop:~$ xrandr Screen 0: minimum 320 x 200, current 1600 x 1200, maximum 1600 x 1600 DFP1 disconnected (normal left inverted right x axis y axis) CRT1 disconnected (normal left inverted right x axis y axis) CRT2 connected 1600x1200+0+0 (normal left inverted right x axis y axis) 0mm x 0mm 1600x1200 60.0*+ 1400x1050 60.0 1280x1024 60.0 47.0 43.0 1440x900 59.9 1280x960 60.0 1280x800 60.0 1152x864 60.0 47.0 43.0 1280x768 59.9 56.0 1280x720 60.0 50.0 1024x768 60.0 43.5 800x600 60.3 56.2 47.0 720x576 50.0 720x480 60.0 640x480 60.0 TV disconnected (normal left inverted right x axis y axis) CV disconnected (normal left inverted right x axis y axis) Then according to other internet posts and forums: mattia@fatdesktop:~$ cvt 1920 1080 60 # 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz Modeline "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync So now i have to add that modeline mattia@fatdesktop:~$ xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync mattia@fatdesktop:~$ xrandr --addmode CRT2 1920x1080_60.00 And here comes the pain: mattia@fatdesktop:~$ xrandr --output CRT2 --mode 1920x1080_60.00 xrandr: **screen cannot be larger than 1600x1600 (desired size 1920x1080)** See? screen cannot be larger than 1600x1600 (desired size 1920x1080) At this point, the 1920x1080 option appears inside the resolution choice menu (the graphical one). But last night, when i tried to select it, my screen went black, and i had to power off the pc. Any clues? am i on the wrong path?

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  • Problems with Intel Video Resolution on Acer Laptop Wide Display

    - by ricstr
    I have an ACER Aspire 5332 laptop which I have just installed Ubuntu 12.04 x64, which is causing some issues with the video display on boot and video resolution. First and foremost, it will only boot past the purple screen if GRUB has been edited to replace 'quick splash' with 'nomodeset'. Secondly, once it has booted with the the 'nomodeset' option, it does not allow me to change the resolution higher or lower from 1024 x 786. Is it OK to use the 'nomodeset' for normal use? Will this compromise performance of other devices? The video card is an on-board one, integrated within the Intel GL40 chip-set. The display is a wide-screen LCD, and under Windows could operate under various resolutions. Ideally I would like it to operate on a resolution to fit the wide-screen display as it a bit stretched out at the moment, and less desktop space as I am used to. I believe the optimal resolution is 1366 x 768. Below is some information from the terminal which may be useful. ricstr@Aspire-5332:~$ lspci | grep -i VGA 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 09) ricstr@Aspire-5332:~$ xrandr xrandr: Failed to get size of gamma for output default Screen 0: minimum 1024 x 768, current 1024 x 768, maximum 1024 x 768 default connected 1024x768+0+0 0mm x 0mm 1024x768 0.0*

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  • Resolution changes when using switch

    - by Edward D
    So, the "real" resolution of my monitor is 1024x768. That's what I'd use on my docked Windows laptop, and what I'd use on my Xubuntu desktop connected directly. When I connect a switch, to switch between the two, however, the ubuntu machine's resolution changes. Everything's still proportional, and it still thinks it's doing 1024x768, but the icons and fonts appear larger. Not 800x600 larger, but still big. When I used Xubuntu Precise, I created an xorg.conf file to set a resolution of 1280x1024 which made it look the way it does without the switch ... as a workaround. When I upgraded to Trusty, I lost this. I tried to re-create it, but doesn't seem to load my file. Ideally, I'd like to correct the original problem, but I'd settle for being able to up the resolution. I searched for a while, and tried to do it, but I'm giving up ... please help me out. Controller: Intel Corporation 82915G/P/GV/GL/PL/910GL Memory Controller Hub (rev 04) Monitor: NEC MultiSync LCD 1850e http://www.necdisplay.com/documents/UserManuals/LCD1850E_manual.pdf OS: Xubuntu 14.04 Trusty /etc/X11/xorg.conf: # YOU CREATED THIS FILE # sudo leafpad /etc/X11/xorg.conf Section "Device" Identifier "Configured Video Device" EndSection Section "Monitor" Identifier "NEC LCD1850E" # I found Synchronization Range at: # http://www.necdisplay.com/documents/UserManuals/LCD1850E_manual.pdf HorizSync 31.0-82.0 VertRefresh 55.0-85.0 EndSection Section "Screen" Identifier "Default Screen" Monitor "NEC LCD1850E" Device "Configured Video Device" SubSection "Display" Depth 24 Modes "1280x1024" "1280x960" "1024x768" "800x600" "848x480" "640x480" EndSubSection EndSection

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  • Wrong resolution for Lightdm/GDM on Ubuntu 13.04 using HDMI

    - by f03lipe
    I've tried all the solution I could find on the matter so far, but the error persists. My problem is that the login screen (both under gdm and lightdm) runs with the wrong resolution, even though all is fine when I log in. The error occurs solely when I have my HDMI cable connected to my other screen. The login screen resolution becomes 1024x768 (for my 1366x768 laptop screen) and mirrored on my screen, which is 1920x1080. I've had this issue on version 12.04 (the last one before I upgraded to 13.04), but I got it fixed by adding the xrandr commands on the begining of the /etc/gdm/Init/Default file. This doesn't seem to work anymore. I've also tried telling lightdm to run a script fixing the resolution with xrandr (by editing /etc/lightdm/lightdm.conf), but lightdm crashes, and I'm forced to log in with low graphic settigs. Hint: when ubuntu is loading, the resolution starts OK, then goes bad right before the login screen is initialized. Does that mean that there's nothing wrong with my graphic cards? What do you think? Cheers!

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  • How do 2D physics engines solve the problem of resolving collisions along tiled walls/floors in non-grid-based worlds?

    - by ssb
    I've been working on implementing my SAT algorithm which has been coming along well, but I've found that I'm at a wall when it comes to its actual use. There are plenty of questions regarding this issue on this site, but most of them either have no clear, good answer or have a solution based on checking grid positions. To restate the problem that I and many others are having, if you have a tiled surface, like a wall or a floor, consisting of several smaller component rectangles, and you traverse along them with another rectangle with force being applied into that structure, there are cases where the object gets caught on a false collision on an edge that faces the inside of the shape. I have spent a lot of time thinking about how I could possibly solve this without having to resort to a grid-based system, and I realized that physics engines do this properly. What I want to know is how they do this. What do physics engines do beyond basic SAT that allows this kind of proper collision resolution in complex environments? I've been looking through the source code to Box2D trying to find out how they do it but it's not quite as easy as looking at a Collision() method. I think I'm not good enough at physics to know what they're doing mathematically and not good enough at programming to know what they're doing programmatically. This is what I aim to fix.

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  • Help finding time of collision

    - by WannaBe
    I am making a simple game right now and am struggling with collision response. My goal is to someday be able to turn it into a 2D platformer but I have a long way to go. I am currently making this in JavaScript and using the canvas element so (0,0) is in the top left and positive X is to the right and positive Y is down. I read a helpful post on StackExchange that got me started on this but I can't seem to get the algorithm 100% correct. How to deal with corner collisions in 2D? I can detect the collision fine but I can't seem to get the response right. The goal is to detect which side the player hit first since minimum displacement doesn't always work. The X response seems to work fine but the Y only works when I am far from the corners. Here is a picture showing what happens Here is the code var bx = box.x; var by = box.y; var bw = box.width; var bh = box.height; var boxCenterX = bx + (bw/2); var boxCenterY = by + (bh/2); var playerCenterX = player.x + player.xvel + (player.width/2); var playerCenterY = player.y + player.yvel + (player.height/2); //left = negative and right = positve, 0 = middle var distanceXin = playerCenterX - boxCenterX; var distanceYin = playerCenterY - boxCenterY; var distanceWidth = Math.abs(distanceXin); var distanceHeight = Math.abs(distanceYin); var halfWidths = (bw/2) + (player.width/2); var halfHeights = (bh/2) + (player.height/2); if(distanceWidth < halfWidths){ //xcollision if(distanceHeight < halfHeights){ //ycollision if(player.xvel == 0){ //adjust y if(distanceYin > 0){ //bottom player.y = by + bh; player.yvel = 0; }else{ player.y = by - player.height; player.yvel = 0; } }else if(player.yvel == 0){ //adjust x if(distanceXin > 0){ //right player.x = bx + bw; player.xvel = 0; }else{ //left player.x = bx - player.width; player.xvel = 0; } }else{ var yTime = distanceYin / player.yvel; var xTime = distanceXin / player.xvel; if(xTime < yTime){ //adjust the x it collided first if(distanceXin > 0){ //right player.x = bx + bw; player.xvel = 0; }else{ //left player.x = bx - player.width; player.xvel = 0; } }else{ //adjust the y it collided first if(distanceYin > 0){ //bottom player.y = by + bh; player.yvel = 0; }else{ player.y = by - player.height; player.yvel = 0; } } } } } And here is a JSFiddle if you would like to see the problem yourself. http://jsfiddle.net/dMumU/ To recreate this move the player to here And press up and left at the same time. The player will jump to the right for some reason. Any advice? I know I am close but I can't seem to get xTime and yTime to equal what I want every time.

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  • 2D Tile Based Collision Detection

    - by MrPlosion1243
    There are a lot of topics about this and it seems each one addresses a different problem, this topic does the same. I was looking into tile collision detection and found this where David Gouveia explains a great way to get around the person's problem by separating the two axis. So I implemented the solution and it all worked perfectly from all the testes I through at it. Then I implemented more advanced platforming physics and the collision detection broke down. Unfortunately I have not been able to get it to work again which is where you guys come in :)! I will present the code first: public void Update(GameTime gameTime) { if(Input.GetKeyDown(Keys.A)) { velocity.X -= moveAcceleration; } else if(Input.GetKeyDown(Keys.D)) { velocity.X += moveAcceleration; } if(Input.GetKeyDown(Keys.Space)) { if((onGround && isPressable) || (!onGround && airTime <= maxAirTime && isPressable)) { onGround = false; airTime += (float)gameTime.ElapsedGameTime.TotalSeconds; velocity.Y = initialJumpVelocity * (1.0f - (float)Math.Pow(airTime / maxAirTime, Math.PI)); } } else if(Input.GetKeyReleased(Keys.Space)) { isPressable = false; } if(onGround) { velocity.X *= groundDrag; velocity.Y = 0.0f; } else { velocity.X *= airDrag; velocity.Y += gravityAcceleration; } velocity.Y = MathHelper.Clamp(velocity.Y, -maxFallSpeed, maxFallSpeed); velocity.X = MathHelper.Clamp(velocity.X, -maxMoveSpeed, maxMoveSpeed); position += velocity * (float)gameTime.ElapsedGameTime.TotalSeconds; position = new Vector2((float)Math.Round(position.X), (float)Math.Round(position.Y)); if(Math.Round(velocity.X) != 0.0f) { HandleCollisions2(Direction.Horizontal); } if(Math.Round(velocity.Y) != 0.0f) { HandleCollisions2(Direction.Vertical); } } private void HandleCollisions2(Direction direction) { int topTile = (int)Math.Floor((float)Bounds.Top / Tile.PixelTileSize); int bottomTile = (int)Math.Ceiling((float)Bounds.Bottom / Tile.PixelTileSize) - 1; int leftTile = (int)Math.Floor((float)Bounds.Left / Tile.PixelTileSize); int rightTile = (int)Math.Ceiling((float)Bounds.Right / Tile.PixelTileSize) - 1; for(int x = leftTile; x <= rightTile; x++) { for(int y = topTile; y <= bottomTile; y++) { Rectangle tileBounds = new Rectangle(x * Tile.PixelTileSize, y * Tile.PixelTileSize, Tile.PixelTileSize, Tile.PixelTileSize); Vector2 depth; if(Tile.IsSolid(x, y) && Intersects(tileBounds, direction, out depth)) { if(direction == Direction.Horizontal) { position.X += depth.X; } else { onGround = true; isPressable = true; airTime = 0.0f; position.Y += depth.Y; } } } } } From the code you can see when velocity.X is not equal to zero the HandleCollisions() Method is called along the horizontal axis and likewise for the vertical axis. When velocity.X is not equal to zero and velocity.Y is equal to zero it works fine. When velocity.Y is not equal to zero and velocity.X is equal to zero everything also works fine. However when both axis are not equal to zero that's when it doesn't work and I don't know why. I basically teleport to the left side of a tile when both axis are not equal to zero and there is a air block next to me. Hopefully someone can see the problem with this because I sure don't as far as I'm aware nothing has even changed from what I'm doing to what the linked post's solution is doing. Thanks.

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  • Switching my collision detection to array lists caused it to stop working

    - by Charlton Santana
    I have made a collision detection system which worked when I did not use array list and block generation. It is weird why it's not working but here's the code, and if anyone could help I would be very grateful :) The first code if the block generation. private static final List<Block> BLOCKS = new ArrayList<Block>(); Random rnd = new Random(System.currentTimeMillis()); int randomx = 400; int randomy = 400; int blocknum = 100; String Title = "blocktitle" + blocknum; private Block block; public void generateBlocks(){ if(blocknum > 0){ int offset = rnd.nextInt(250) + 100; //500 is the maximum offset, this is a constant randomx += offset;//ofset will be between 100 and 400 int randomyoff = rnd.nextInt(80); //500 is the maximum offset, this is a constant randomy = platformheighttwo - 6 - randomyoff;//ofset will be between 100 and 400 block = new Block(BitmapFactory.decodeResource(getResources(), R.drawable.block2), randomx, randomy); BLOCKS.add(block); blocknum -= 1; } The second is where the collision detection takes place note: the block.draw(canvas); works perfectly. It's the blocks that don't work. for(Block block : BLOCKS) { block.draw(canvas); if (sprite.bottomrx < block.bottomrx && sprite.bottomrx > block.bottomlx && sprite.bottomry < block.bottommy && sprite.bottomry > block.topry ){ Log.d(TAG, "Collided!!!!!!!!!!!!1"); } // bottom left touching block? if (sprite.bottomlx < block.bottomrx && sprite.bottomlx > block.bottomlx && sprite.bottomly < block.bottommy && sprite.bottomly > block.topry ){ Log.d(TAG, "Collided!!!!!!!!!!!!1"); } // top right touching block? if (sprite.toprx < block.bottomrx && sprite.toprx > block.bottomlx && sprite.topry < block.bottommy && sprite.topry > block.topry ){ Log.d(TAG, "Collided!!!!!!!!!!!!1"); } //top left touching block? if (sprite.toprx < block.bottomrx && sprite.toprx > block.bottomlx && sprite.topry < block.bottommy && sprite.topry > block.topry ){ Log.d(TAG, "Collided!!!!!!!!!!!!1"); } } The values eg bottomrx are in the block.java file..

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  • Change Desktop Resolution With a Keyboard Shortcut

    - by Matthew Guay
    Do you find yourself changing your monitor resolution several times a day?  If so, you might like this handy way to set a keyboard shortcut for your most-used resolutions. Most users rarely have to change their screen resolution often, as LCD monitors usually only look best at their native resolution.  But netbooks present a unique situation, as their native resolution is usually only 1024×600.  Some newer netbooks offer higher resolutions which may not looks as crisp as the native resolution but can be handy for using a program that expects a higher resolution.  This is the perfect situation for a keyboard shortcut to help you change the resolution without having to hassle with dialogs and menus each time, and HRC – HotKey Resolution Changer makes it easy to do. Create Keyboard Shortcuts Download the HRC – HotKey Resolution Changer (link below), unzip, and then run HRC.exe in the folder. This will start a tray icon, and will not automatically open the HRC window.  You don’t have to install HRC.  Double-click the tray icon to open it.  Note: Windows 7 automatically hides new tray icons, so if you can’t see it, click the arrow to see the hidden tray icons. By default, HRC will show two entries with your default resolutions, color depth, and refresh rate. Add a keyboard shortcut by clicking the Change button over the resolution.  Press the keyboard shortcut you want to press to switch to that resolution; we entered Ctrl+Alt+1 for our default resolution.  Make sure not to use a keyboard shortcut you use in another application, as this will override it.  Click Set when you’ve entered the hotkey(s) you want. Now, on the second entry, select the resolution you want for your alternate resolution.  The drop-down list will only show your monitor’s supported resolutions, so you don’t have to worry about choosing an incorrect resolution.  You can also set a different color depth or refresh rate for this resolution.  Now add a keyboard shortcut for this resolution as well. You can set keyboard shortcuts for up to 9 different resolutions with HRC.  Click the Select number of HotKeys button on the left, and choose the number of resolutions you want to set.  Here we have unique keyboard shortcuts for our three most-used resolutions on our netbook. HRC must be kept running to use the keyboard shortcuts, so click the Minimize to tray icon which is the second icon to the right.  This will keep it running in the tray. If you want to be able to change your resolution anytime, you’ll want HRC to automatically start with Windows.  Create a shortcut to HRC, and paste it into your Windows startup folder.  You can easily open this folder by entering the following in the Run command or in the address bar in Explorer: %appdata%\Microsoft\Windows\Start Menu\Programs\Startup   Conclusion HRC- HotKey Resolution Changer gives you a great way to quickly change your screen resolution with a keyboard shortcut.  Whether or not you love keyboard shortcuts, this is still a much easier way to switch between your most commonly used resolutions. Download HRC – HotKey Resolution Changer Similar Articles Productive Geek Tips Create a Keyboard Shortcut to Access Hidden Desktop Icons and FilesGet Mac’s Hide Others (cmd+opt+H) Keyboard Shortcut for WindowsHide Desktop Icon Text on Windows 7 or VistaShow Keyboard Shortcut Access Keys in Windows VistaKeyboard Ninja: 21 Keyboard Shortcut Articles TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips VMware Workstation 7 Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Use Flixtime To Create Video Slideshows Creating a Password Reset Disk in Windows Bypass Waiting Time On Customer Service Calls With Lucyphone MELTUP – "The Beginning Of US Currency Crisis And Hyperinflation" Enable or Disable the Task Manager Using TaskMgrED Explorer++ is a Worthy Windows Explorer Alternative

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  • How to set resolution higher than maximum shown?

    - by Olivier Lalonde
    I just bought an external monitor for my laptop (Asus VH242H) but cannot set its resolution to anything higher than 1600x900. I tried both from System/Administration/Monitors and the ATI Catalyst Control Center. There was a CD that came with the monitor but it only contains a Windows installer. According to the monitor's specifications: 23.6” 16:9 widescreen with 1920×1080 resolution enables borderless Full HD 1080p full-screen video display. My graphic card is an ATI Mobility Radeon HD 4670 and the monitor is currently connected to my laptop with a VGA cable. How can I set my external monitor to its maximum resolution?

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  • adjust resolution on Ubuntu Server 10.04?

    - by Mike Grace
    Installed Ubuntu Server 10.04 on an old laptop and I noticed that the system is trying to show the CLI below my screen. This means that if I run a script or a program with a bunch of output, once it is done, I have to press return several times to bring the output to the point where I can actually see it on the screen. I also have to clear the screen to be able to see what I am typing at the current command prompt. The laptop is an EliteGroup 536S with a native screen resolution of 1024 x 768 How can I adjust the resolution for Ubuntu Server 10.04? What file do I need to edit if editing a file is the solution? I've seen posts on how to change the resolution on the desktop version of Ubuntu but not the server version.

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  • Ubuntu doesn't give the intended screen resolution

    - by JMCF125
    I have recently created a Ubuntu 12.04.2 64 bit virtual machine on VirtualBox, and I am not very used to Linux (I used Linux Mint for a few weeks some time ago), so please refer the full name of stuff, not just "the what-not-command". The problem is I can't set the full resolution my computer supports (I think it is 1366 by 768), I have found similar questions and tried most of the respective solutions, thy did not work. If I type xrandr to the terminal I get: xrandr: Failed to get size of gamma for output default Screen 0: minimum 640 x 480, current 1024 x 768, maximum 1024 x 768 default connected 1024x768+0+0 0mm x 0mm 1024x768 61.0* 800x600 61.0 640x480 60.0 As you can see, the maximum is too low. And in the settings of the screen (I mean, with GUI) only 1024x768 and 800x600 appear. I don't remember exactly which answer of those questions, but it was one in the terminal (again, with xrandr) that made the resolution I wanted appear (although it gave an error when selected, not even changing to the 1366x768 resolution first and then back to 1024x768).

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  • GUI Application Resolution from Text Mode OS

    - by brettw
    I'm trying to turn a computer into a Linux thin client via Ubuntu. I have a Dell OptiPlex 755 loaded with Ubuntu 14.04 installed and fully patched. I've configured the OS to run in text mode and automatically launch the VMWare Horizon's client, which works. The issue is that when the Horizon client launches, its resolution is only 1/4 of the screen. I've played with the resolution settings in grub which appears to modify the text environment but not the application environment for Horizon's. Can someone point me in the right direction on how to increase the resolution for a GUI application launch from text mode so it's full screen. Thanks!

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  • Screen resolution higher than monitor specs

    - by bisi
    Is there any magical or non-magical way to increase screen resolution for my monitor that officially does 1366 x 768? With my graphics card, I could do 1920, and when I actually do that, the image is very "unclean" on the screen... I run Ubuntu 10.10, on an HP Pavilion with a GeForce 315. My monitor is a HD ready Samsung LE32C450... my smaller previous monitor had no problem showing a 1920 resolution, and my obvious mishap was to assume a much bigger screen would support at least this same resolution... Any tips would be greatly appreciated!

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  • can not get Toshiba tv to full resolution

    - by Tloc2077
    I have a 23inch Toshiba model#23L1350U that I am using as a computer monitor via VGA plug; it is a full 1080P resolution TV but in Ubuntu it shows up as a Toshiba 72inch Television and wont go past the resolution 1366 by 1768. Has anyone came up with a solution to this problem..I used to get full 1080 resolution with my Insignia 32 inch TV so I know my hardware can push the signal, I am running a Radeon x1550 graphics cars 3200+ processor on a 756 chip set 64bit version of Ubuntu 13.04 your help is greatly appreciated and you may or may not be compensated for your time

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  • Ubuntu 11.10 Desktop Sharing resolution

    - by Zuma123
    I have 11.10 running on a Netbook with Unity2D @ 1024x600 resolution. I VNC into my Ubuntu Netbook from Win7 @ 1920x1200. Is there a way make Desktop Sharing on 11.10 run at a resolution higher than the hardware resolution? I am not too worried about speed/lag. 1440x900 would be perfect. I like to keep my machine as clean as possible, I could add eg. vnc4server but I'd prefer not to do that. I have looked for but cannot find an appropriate vino-server config file. Thank you.

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