Pre-emptive collision detection

Hi im at the stage where im writing some collision avoidence routines
for a first person shooting game (yes another one hehe)
i was wondering if there is a way to detect if an object or view is going to collide with
another object in the world..
at the moment im a class CollisionDector that extends Behavior
and uses WakeupCriterion.
but it only activates when the objects are inside eachother, at this point its too late.
what i want to do is some thing like this
is object about to collide?
yes - then save transform set collide var to true
no - do nothing
if collided = true then set viewplatform to saved transform
the reason why im saving the transform is because im using a keyboard behavior class
to move the view point and i dont know any way to stop the movement.
any help would be great
thanks

j3d.org has a nice tutorial on how to do this as well as terrain following.
http://www.j3d.org/tutorials/collision/index.html
It took me about an hour to modify their example implementation for my own research.

Similar Messages

Collision detection with rectangles

Hi, I'm making a racing game from the top view. My track is made up of many gif files, each connecting to each other. My cars are also gif files, and the player's car doesn't move, it can only rotate by displaying gif files of the car in different angles. Only the track moves to create the effect of the car moving. I am having trouble with the collision detection when the car hits the side of the road and when it hits other cars. I've looked at the discussion by JTeen but my car are rectangles, not circles. Could someone please help me with the following:
1. What is the best system to define the boundary of the road in the gif files.
2. Should I use the 4 verties of the player's car to detect the collisions and change the co-ordinates whenever I rotate the car.
3. My tracks are never actually curved, they are made up of multiple straight lines to create a turn. Should I use the slope of these lines and then create an equation for the lines for the detection?

sure.
btw this isn't the way of doing it, its simply a way of doing it.
In a Sector based track, the track is represented as 2 polygons.
An inner track edge, and an outer track edge.
Both polygons have the same number of verticies.
a screen shot from my track editor would probably explain it better than words... http://www.pkl.net/~rsc/4KApplet/editorGrab.png
As the car goes around the track, you keep track of which sector it is in by doing a line intersection with either the nextSector or prevSector.
The code will look something like this [taken from the 4KApplet]
                  //check for entry into the next sector
                  while(Line2D.linesIntersect(x,y,newX,newY,
                        trackX[RIGHT][newNext], trackY[RIGHT][newNext],
                        trackX[LEFT][newNext], trackY[LEFT][newNext]))
                     // if you do enter the next sector, this must loop, until you stop going forward in sectors
                     // if this loop wasn't here, a fast traveling car could potencially jump out of its current sector
                     if(newNext==1) lapChange--;//if the car passes the start/finish line, set the lapChange flag
                     newPrev = newNext; //newPrevious sector is now the old Next sector
                     newNext = (newNext+1)%SEGMENT_COUNT; //and the new next sector is the old next sector +1 (modded for track looping)
                     checkPrevious=false; //the car is going forward, so don't check previous sector gate line
                  if(checkPrevious)
                     //does same as above, but for previous sector
                     while(Line2D.linesIntersect(x,y,newX,newY,
                           trackX[RIGHT][newPrev], trackY[RIGHT][newPrev],
                           trackX[LEFT][newPrev], trackY[LEFT][newPrev]))
                        if(newPrev==1) lapChange++; //if the car is going backward, increment the lapCounter
                        newNext = newPrev;
                        newPrev = (newPrev + (SEGMENT_COUNT-1))%SEGMENT_COUNT;//backward looping by using mod as well :) didn't work this out until now!!
                  }Once you have determined which sector the car is in, you must then do 2 more line intersections to determine if the side of the track has been hit.
In a Collision Map based track[n], you pre-calculate the 'inside-ness' of each pixel before hand and store it all in a [][], then, whenever you move the car, you simply look into the collisionMap [][] to see if the new point is track or wall.
This has the advantage that you don't need to keep track of which sector the player is in (though you still have to do 1 line intersection to determine if the start/finish line has been crossed)

Events Triggered By Collision Detection In Shockwave 3D Environment Happen More Than Once?

Okay, I've finally managed to get my Director 3D game to move an object to a new random position when collision detection occurs with that object! HOWEVER, sometimes it will work as expected and other times the object seems to move SEVERAL times before settling. Anyone have any idea why it isn't always just moving once and settling as I'd hoped it would...?
To see an example of the problem I'm facing, create a new Director movie then insert a new Shockwave 3D media element into that Director movie named "Scene" and apply the below code to that 3D media element. I've tried to trim the code down as much as possible to get right to the heart of the problem:
=====
property Scene -- reference to 3D cast member
property pSprite    -- referebce to the 3D sprite
property pCharacter -- reference to the yellow in the 3D world
property pTransformgreen01Flag -- reference to the flag which will trigger action to move green01 + increase score on collision
property pTransformgreen02Flag -- reference to the flag which will trigger action to move green02 + increase score on collision
on beginSprite me
-- initiate properties and 3D world
pSprite = sprite(me.spriteNum)
Global Scene
Scene = sprite(me.spriteNum).member
Scene.resetWorld()
Tempobjres = Scene.newmodelresource("sphereRES", #sphere) --create sphere modelresource
Tempobjres.radius = 10     --set sphere modelresrource radius to 20
Tempobjres.resolution = 17   --set the sphere modelresource resolution to 17
Tempobj = scene.newmodel("yellow", tempobjres)   --create a model from the sphere modelresource
Tempshader = scene.newshader("sphereshd", #standard)   --create a new standard shader
Tempshader.diffuse = rgb(250,250,10)   --set the diffuse color (in this case, a light green)
Tempshader.texture = void   --set the texture of the shader to void
Tempobj.transform.position=vector(0,0,0)
Tempobj.shaderlist = tempshader   -- assign the shader to the model
Tempobjres1 = Scene.newmodelresource("sphereRES1", #sphere) --create sphere modelresource
Tempobjres1.radius = 10     --set sphere modelresrource radius to 20
Tempobjres1.resolution = 17   --set the sphere modelresource resolution to 17
Tempobj1 = scene.newmodel("green01", tempobjres1)   --create a model from the sphere modelresource
Tempshader1 = scene.newshader("sphereshd1", #standard)   --create a new standard shader
Tempshader1.diffuse = rgb(100,200,50)   --set the diffuse color (in this case, a light green)
Tempshader1.texture = void   --set the texture of the shader to void
Tempobj1.transform.position = vector(25,25,0)
Tempobj1.shaderlist = tempshader1   -- assign the shader to the model
Tempobjres2 = Scene.newmodelresource("sphereRES2", #sphere) --create sphere modelresource
Tempobjres2.radius = 10     --set sphere modelresrource radius to 20
Tempobjres2.resolution = 17   --set the sphere modelresource resolution to 17
Tempobj2 = scene.newmodel("green02", tempobjres2)   --create a model from the sphere modelresource
Tempshader2 = scene.newshader("sphereshd2", #standard)   --create a new standard shader
Tempshader2.diffuse = rgb(100,200,50)   --set the diffuse color (in this case, a light green)
Tempshader2.texture = void   --set the texture of the shader to void
Tempobj2.transform.position = vector(-25,-25,0)
Tempobj2.shaderlist = tempshader2   -- assign the shader to the model
--the following lines will add collision detection for all three on-screen 3D objects
Tempobj.addModifier(#collision)
Tempobj.collision.enabled=true
Tempobj1.addModifier(#collision)
Tempobj1.collision.enabled=true
Tempobj2.addModifier(#collision)
Tempobj2.collision.enabled=true
Tempobj.collision.resolve=true
Tempobj1.collision.resolve=true
Tempobj2.collision.resolve=true
--the following lines will tell Director what to do with a specific object when it collides with another
Tempobj.collision.setCollisionCallBack(#beepsound, me)
Tempobj1.collision.setCollisionCallBack(#hitgreen01, me)
Tempobj2.collision.setCollisionCallBack(#hitgreen02, me)
pCharacter = Scene.model("yellow")
-- we must define pCharacter after we use the resetWorld() command
-- otherwise this variable object will be deleted
createCollisionDetect
pTransformgreen01Flag = false
pTransformgreen02Flag = false
end
on createCollisionDetect
Global Scene
-- add collision modifier to the character
pCharacter.addmodifier(#collision)
-- set bounding geometry for collision detection to bounding box of model
pCharacter.collision.mode = #mesh
-- resolve collision for character
pCharacter.collision.resolve = TRUE
end
on keyDown
Global Scene
case(chartonum(the keypressed)) of
    30: --up arrow
      scene.model("yellow").translate(0,5,0)
    31: --down arrow
      scene.model("yellow").translate(0,-5,0)
    28: --left arrow
      scene.model("yellow").translate(-5,0,0)
    29: --right arrow
      scene.model("yellow").translate(5,0,0)
end case
end
--when "yellow" (player character) hits another object, this will happen:
on beepsound me, colData
beep --plays sound
end
--when "green01" is hit by another object, this will happen:
on hitgreen01 me, colData
Global Scene
pTransformgreen01Flag=true
end
--when "green02" is hit by another object, this will happen:
on hitgreen02 me, colData
Global Scene
pTransformgreen02Flag=true
end
on enterFrame me
Global Scene
if pTransformgreen01Flag then
    --the following lines will generate new random x and y co-ordinates for green01
    randomx=random(-110,110)
    green01x=randomx
    randomy=random(-90,90)
    green01y=randomy
    Scene = member("Scene")
    Scene.model("green01").transform.position = vector(green01x,green01y,0)
    pTransformgreen01Flag = false
end if
if pTransformgreen02Flag then
    --the following lines will generate new random x and y co-ordinates for green02
    randomx=random(-110,110)
    green02x=randomx
    randomy=random(-90,90)
    green02y=randomy
    Scene = member("Scene")
    Scene.model("green02").transform.position = vector(green02x,green02y,0)
    pTransformgreen02Flag = false
end if
end
=====
I imagine the part that's causing the issue is the "on enterFrame me" part at the end, but can't see any reason why it wouldn't just perform the desired action ONCE every time...?
This is really confusing the hell out of me and is pretty much the final hurdle before I can call my game "finished" so any and all assistance would be GREATLY appreciated!

You can get yourself a used copy of my book http://www.amazon.com/Director-Shockwave-Studio-Developers-Guide/dp/0072132655/ for $0.82 + shipping. Chapter 14 contains 33 pages which deal specifically with the vagaries of the collision modifier.
You can download just the chapter on Collision Detection from http://nonlinear.openspark.com/book/Collisions.zip. This includes the demo movies and the unedited draft of the text for the chapter.
Perhaps you will find this useful.

Camera Collision Detection - Is It Possible?

Hi,
I am making a 3D RPG game and I would like to know if it is possible to get collision detection on a camera created in Adobe Director 11. I have my 3D character running through an underground maze and he detects correctly on the walls of the maze. However, I also have a camera as a child to the character so this moves with him. I have added a bounding-box to this camera but it still doesn't detect whereas the gunBB works fine, as does the characterBB.
This is really confusing and I don't know what I am doing wrong. Any help would be really appreciated!
Thanks, Phil.

Thanks for the reply. It is not exactly what I am looking for as the script is different than the style I am using. This is the script I have got so far, I have also added an extra camera to view what is happening.
property pSprite, p3Dmember -- reference to the 3D member
--property pLevel, maze -- Level
--property pLeftArrow, pRightArrow, pDownArrow, pUpArrow -- arrow keys
--property pCharacter -- character in the 3D world
--property pTofuBB, pGunBB, gun -- character + gun
--property gUseGun, hasGun
--property pCamera, pCameraBoundingBox --camera and bounding box
--property barrier,mountains,exitmaze
--property door1, door2, turret, turretgun
--property keylist, keypresslist -- for keys pressed
--on beginSprite me
-- -- define the 3D cast member
-- p3Dmember = sprite(me.spriteNum).member
-- -- reset the 3D world
-- p3Dmember.resetWorld()
-- pSprite = sprite(me.spriteNum)
-- pCamera = pSprite.camera
-- -- define level as 3DS level Plane - must all be defined after resetWorld()
-- pLevel = p3Dmember.model("landscape")
-- mountains = p3Dmember.model("mountains")
-- turret = p3Dmember.model("turret")
-- turretgun = p3Dmember.model("turretgun")
-- maze = p3Dmember.model("maze")
-- exitmaze = p3Dmember.model("exitmaze")
-- pCharacter = p3Dmember.model("hero")
-- gun = p3Dmember.model("gun")
-- barrier = p3Dmember.model("barrier")
-- door1 = p3Dmember.model("door1")
-- door2 = p3Dmember.model("door2")
-- -- stop hero walking biped animation
-- pCharacter.bonesPlayer.pause()
-- -- below for key control
-- keylist = []
-- keypresslist = []
-- -- this sets up a list of keycodes to track.
-- -- this code covers the arrow keys only, it could be changed to cover a full range of keys
-- repeat with i = 123 to 126
--    keylist[i] = i -- this creates a list of keycodes to track
--    keypresslist[i] = 0 -- this creates a "last state" list that corresponds to the keycode.
--    --keypresslist tracks the last known state of that key, so we can tell when a keypress has changed.
-- end repeat
-- -- key control end
-- createBoundingBoxes
-- createLight
--end
-- code used to create bounding boxes
--on createBoundingBoxes
-- -- create tofu bounding box for character
-- tofuBB_MR = p3Dmember.newModelResource("tofuBox",#box)
-- tofuBB_MR.height = 235
-- tofuBB_MR.width = 235
-- tofuBB_MR.length = 500
-- pTofuBB = p3Dmember.newModel("tofuBox",tofuBB_MR)
-- pTofuBB.worldPosition = pCharacter.worldPosition
-- -- create parent child relationships
-- pCharacter.addChild(pTofuBB, #preserveWorld)
-- invisShader = p3Dmember.newShader("invisShader",#standard)
-- invisShader.transparent = TRUE
-- invisShader.blend = 50
-- pTofuBB.shaderlist = p3Dmember.shader("invisShader")
-- pCamera = p3Dmember.newCamera("camera")
-- frontCam = p3Dmember.newCamera("frontCam")
-- frontCam.fieldOfView = 35
-- frontCam.transform.position = vector(-14150,-3100,-600)
-- frontCam.transform.rotation = vector(90,0,180)
-- pSprite.camera = p3Dmember.camera("frontCam")
-- pCamera.fieldOfView = 75
-- pCamera.transform.position = vector(500,1800,450) --450
-- pCamera.transform.rotation = vector(90,0,180)
-- pSprite.camera = p3Dmember.camera("camera")
-- cameraModRes = p3Dmember.newModelResource("cameraModRes",#sphere)
-- cameraModRes.radius = 200
-- pCameraBoundingBox = p3Dmember.newModel("CameraBoundingBox",cameraModRes)
-- pCameraBoundingBox.worldPosition = pCamera.worldPosition
-- pCameraBoundingBox.shaderList = p3Dmember.shader("invisShader")
-- pCamera.addChild(pCameraBoundingBox, #preserveWorld)
-- pCharacter.addChild(pCamera,#preserveWorld)
-- -- create gun bounding box
-- gun.worldposition.z = gun.worldposition.z + 200
-- gunMR = p3Dmember.newModelResource("gunSphere",#sphere)
-- gunMR.radius = 218
-- pGunBB = p3Dmember.newModel("gunSphere", gunMR)
-- pGunBB.worldPosition = gun.worldPosition
-- pGunBB.shaderList = p3Dmember.shader("invisShader")
-- pGunBB.addChild(gun, #preserveWorld)
--end
-- code below used to light up level
--on createLight
-- -- create a point 'bulb' type light
-- p3Dmember.newLight("Bulb Light", #point )
-- -- position the light
-- p3Dmember.light("Bulb Light").transform.position = vector(0,0,100)
-- -- define light color and intensity
-- p3Dmember.light("Bulb Light").color = rgb(255,255,255)
-- -- Make the character model a parent of the light
-- -- Bulb Light becomes a child of pCharacter
-- -- This is done so that the light will always move
-- -- with the character.
-- pCharacter.addChild(p3Dmember.light("Bulb Light"),#preserveParent)
--end
--on keyUp me
-- --pCharacter.bonesPlayer.pause()
-- --if keypressed("s")
--end
--on keydown me
-- if keypressed("c") then changeCamera
--end
--on changeCamera
-- -- check the sprites camera and switch
-- if pSprite.camera = p3Dmember.camera("frontCam") then
--     pSprite.camera = p3Dmember.camera("camera")
--     else
--     pSprite.camera = p3Dmember.camera("frontcam")
--     end if
--end
--on exitFrame me
-- below detects which keys are pressed
--repeat with i = 1 to keylist.count
--inewstate= keypressed( keylist[i] )
--if keypresslist[i] <> inewstate then -- this means the key changed status from whether it's up or down
--if inewstate= 0 then
-- they key was released
--keyLastReleased = keylist[i]
--if (keyLastReleased=123) then pLeftArrow = 0 -- 123 = left arrow key
--if (keyLastReleased=124) then pRightArrow = 0 -- 124 = right arrow key
--if (keyLastReleased=125) then
--pDownArrow = 0 -- 125 = down arrow key
--pCharacter.bonesPlayer.pause()
--end if
--if (keyLastReleased=126) then
--pUpArrow = 0 -- 126 = up arrow key
--pCharacter.bonesPlayer.pause()
--end if
--else
-- the key was pressed
--keyLastPressed = keylist[i]
--if (keyLastPressed=123) then pLeftArrow = 1 -- 123 = left arrow key
--if (keyLastPressed=124) then pRightArrow = 1 -- 124 = right arrow key
--if (keyLastPressed=125) then pDownArrow = 1 -- 125 = down arrow key
--if (keyLastPressed=126) then pUpArrow = 1 -- 126 = up arrow key
--end if
--keypresslist[i] = inewstate-- update so we remember its new state.
--end if
--end repeat
-- by the time this repeat loop has finished, keypresslist will contain a complete index of what keys
-- are held down, and which aren't.
-- Note: most keyboards have a limit on how many keys they'll track simultaneously.
--checkCollisions
--characterMove
-- gun collision start
--if gUseGun = TRUE then
--pTofuBB.addChild(pGunBB,#preserveParent)
--pGunBB.worldPosition = pTofuBB.worldPosition
--pGunBB.worldPosition.z = 500
--pGunBB.worldPosition.x = pCharacter.worldPosition.x - 150 --50
---pGunBB.worldPosition.y = -860
--pGunBB.rotate(0,0,-240)
--pCharacter.bonesPlayer.pause()
--gUseGun = FALSE
--hasGun = TRUE
--end if
-- gun collision end
--end
--on characterMove
-- if the right arrow is pressed,
-- rotate the character 5 degrees about the z-axis
--if pRightArrow then
-- rotate character and camera
--pCharacter.rotate(0,0,-2)
--end if
--if the left arrow is pressed,
-- rotate character -5 degrees about the z-axis
--if pLeftArrow then
--pCharacter.rotate(0,0,2)
--end if
-- if the up arrow is pressed,
-- move the character 5 pixels along the y-axis
--if pUpArrow then
--if (pcharacter.bonesPlayer.playing = 0) then
--pCharacter.bonesplayer.loop = true
--if (_key.shiftDown) then
--pCharacter.bonesPlayer.playRate = 2
--if (hasGun = TRUE) then -- running
--pCharacter.bonesplayer.play("hero", 1, 6270, 8330, 1)
--else
--pCharacter.bonesplayer.play("hero", 1, 2067, 4130, 1)
--end if
--else
--pCharacter.bonesPlayer.playRate = 1
--if (hasGun = TRUE) then -- walking
--pCharacter.bonesplayer.play("hero", 1, 4200, 6200, 1)
--else
--pCharacter.bonesplayer.play("hero", 1, 0, 2000, 1)
--end if
--end if
--end if -- bonesPlayer playing
--if (_key.shiftDown) then
--pCharacter.translate(120,0,0)
--else
--pCharacter.translate(50,0,0)
--end if
--end if
-- if the down arrow is pressed,
-- move the character -5 pixels along the y-axis
--if pDownArrow then
--if (pcharacter.bonesPlayer.playing = 0) then
--pCharacter.bonesplayer.loop = true
--if (_key.shiftDown) then
--pCharacter.bonesPlayer.playRate = 2
--if (hasGun = TRUE) then -- running
--pCharacter.bonesplayer.play("hero", 1, 6270, 8330, 1)
--else
--pCharacter.bonesplayer.play("hero", 1, 2067, 4130, 1)
--end if
--else
--pCharacter.bonesPlayer.playRate = 1
--if (hasGun = TRUE) then -- walking
--pCharacter.bonesplayer.play("hero", 1, 4200, 6200, 1)
--else
--pCharacter.bonesplayer.play("hero", 1, 0, 2000, 1)
--end if
--end if
--end if -- bonesPlayer playing
--if (_key.shiftDown) then
--pCharacter.translate(-120,0,0)
--else
--pCharacter.translate(-50,0,0)
--end if
--end if
-- floor collision
--thisPosn = pTofuBB.worldPosition
-----thisPosn.z = 1000
--tModelList = [pLevel, maze, door1, door2] -- removed wall as its no longer on level
--tOptionsList = [#levelOfDetail: #detailed, #modelList: tModelList]
--thisData = p3Dmember.modelsUnderRay(thisPosn,vector(0,0,-1),tOptionsList)
--if thisData.count then
--totalCount = thisData.count
--repeat with dataIndex = 1 to totalCount
--terrainPosn = thisData[dataIndex].isectPosition
--- if (thisData[dataIndex].model = pLevel) then
--tDiff = (terrainPosn.z - pTofuBB.worldPosition.z) + 375
--pCharacter.translate(0,0,tDiff,#world)
--exit repeat
--end repeat
--end if
--end
--on checkCollisions
--tModelList = [pGunBB, barrier, mountains, maze, exitmaze, turret, turretgun]
--tOptionsList = [#maxNumberOfModels: 2, #levelOfDetail: #detailed, #modelList: tModelList, #maxDistance: 300]
-- make 4 rays around character checking for collisions, 90 degrees apart
--repeat with i = 1 to 18
--pCharacter.rotate(0,0,20,#self)
--returnData = p3Dmember.modelsUnderRay(pCharacter.worldPosition,pCharacter.transform.xAxis,tOptionsList )
--if (returnData.count) then
-- first in array is closest
--checkObjectFoundDistance(returnData[1])
--end if
--end repeat
--end
--on checkObjectFoundDistance thisData -- check distance from collision with objects
--dist = thisData.distance
-- check if distance is less than width of bounding box
--if (dist < 150) then
--case thisData[#model].name of
--"gunSphere":
--gUseGun = TRUE
--"barrier":
-- get distance of penetration
--diff = 150 - dist
-- calculate vector perpend icular to the wall's surface to move the character
-- using the #isectNormal property
--tVector = thisData.isectNormal * diff
-- move the character in order to resolve the collision
--pCharacter.translate(tVector,#world)
--end case
--end if
--if (dist < 150) then
--case thisData[#model].name of
--"gunSphere":
--gUseGun = TRUE
--"mountains":
-- get distance of penetration
--diff = 150 - dist
-- calculate vector perpend icular to the wall's surface to move the character
-- using the #isectNormal property
--tVector = thisData.isectNormal * diff
-- move the character in order to resolve the collision
--pCharacter.translate(tVector,#world)
--end case
--end if
--if (dist < 150) then
--case thisData[#model].name of
--"gunSphere":
--gUseGun = TRUE
--"maze":
-- get distance of penetration
--diff = 150 - dist
-- calculate vector perpend icular to the wall's surface to move the character
-- using the #isectNormal property
--tVector = thisData.isectNormal * diff
-- move the character in order to resolve the collision
--pCharacter.translate(tVector,#world)
--end case
--end if
--if (dist < 150) then
--case thisData[#model].name of
--"gunSphere":
--gUseGun = TRUE
--"exitmaze":
-- get distance of penetration
--diff = 150 - dist
-- calculate vector perpend icular to the wall's surface to move the character
-- using the #isectNormal property
--tVector = thisData.isectNormal * diff
-- move the character in order to resolve the collision
--pCharacter.translate(tVector,#world)
--end case
--end if
--if (dist < 150) then
--case thisData[#model].name of
--"gunSphere":
--gUseGun = TRUE
--"turret":
-- get distance of penetration
--diff = 150 - dist
-- calculate vector perpend icular to the wall's surface to move the character
-- using the #isectNormal property
--tVector = thisData.isectNormal * diff
-- move the character in order to resolve the collision
--pCharacter.translate(tVector,#world)
--end case
--end if
--if (dist < 150) then
--case thisData[#model].name of
--"gunSphere":
--gUseGun = TRUE
--"turretgun":
-- get distance of penetration
--diff = 150 - dist
-- calculate vector perpend icular to the wall's surface to move the character
-- using the #isectNormal property
--tVector = thisData.isectNormal * diff
-- move the character in order to resolve the collision
--pCharacter.translate(tVector,#world)
--end case
--end if
--end

URGENT: Collision Detection In Tiled Map

HELP!!!!! I am creating a tile map of size 32*32. And the character image size is also 32*32. Now i am stuck in making collision with the walls. I have tried my own method but to no avail. Has anyone tried to doing collision detection? Need a simple logic method to detect the collision...
(Using keyevent to control the character moving around)
Pls I really appreciate your help!!!!!!!
Thanks.....

I assume you have some way of knowing that you need to display a wall tile on the map, so before you move a particular direction check to see if the square you will move to is an acceptable move (no wall, door, mountain, water etc). If it is unacceptable play a little sound or display a message, otherwise do the move.

2D Pixel Collision detection on XML tiled map

Hello,
I'm designing a game where the player can move through a city composed of 2D image tiles. Right now we have successfully got the pixel collision detection to work on a large single image consisting of an invisible mask image and a visible image that shows a cluster of buildings and objects. The mask overlays the visible buildings and blocks / allows movement based on the color of the mask. Black is a collision, white is open space, etc.
But this technique won't work for the game, since there will be many cities and vastly larger than this little testbed. I cannot create multiple huge cities into one file - the file would be several megs large, and I'm looking at dozens of cities.
My idea is to create tiled maps, which will save the coordinates for the various building/object tiles in an XML file. However, I do not know how to make the collision detection work with such a tiled map. Moreover, I don't know if constructing a mosaic city using XML coordinates is the best way to go - I'm open for suggestions. My goal is to simply be able to assemble a city from individual tiles of buildings and masks, and drive/walk my character through the city with pixel collision detection, without using the current setup of a single image and a single mask.
Any advice/suggestions offered will be GREATLY appreciated! This is our first Java project, but hopefully we can make this work.
Thank you so much!
Message was edited by:
Gateway2007 - clarifying that this is a collision detection based on pixels, not planes or other method.

Sound like this might be too late of a suggestion, but have you looked at Slick at all?
http://slick.cokeandcode.com/static.php?page=features
It might help with the tiling and collision aspects.

Please i need help in Collision detection

i want to make collision detection system
but i have no good papers or examples about collision to can make simple collision if anyone can give me good link please

http://www.flipcode.com/articles/article_basiccollisions.shtml
regards

KeyPressed / collision detection

I have a tile based platformer I am making and am having some trouble with the collision detection. I have it so that the game detects a collision before it actually occurs so that it wont happen in the game. However, it only appears to works right if i tap the arrow key into the wall, and if i hold the arrow key down i fly right through the tile until i let go (if i let go inside a block the hero gets stuck because it detects a collision anywhere i try to move after that). At this time i had the new coordinate to detect collision based on which direction i was moving gotten from keyPressed. Since this didnt work (assumed it was because the game loop and keyPressed dont take turns performing their actions) I made the new coordinate collision be detected from a method called in the main game loop and the result was that if I held down the key and flew into a wall, it doesnt stop exactly at the right spot (but I cant go through an entire row of tiles) but when I go the opposite direction from the collision (open space should work fine) it works fine until a point where in mid air it acts like a collision occured.
I have tried very hard to find the error in my code concerning the collision detection and need to make sure these problems arent a result of limitations of keyPressed or something, but rather just the code i've written

ok well I now have it set up so that before the hero moves it checks to see if the move is valid from each pixel starting at the hero to the length the hero moves in 1 directional press (using a rectangle that is the size of the hero, then has width 1 pixel larger etc until reaches the length of a move). The collision detection method returns true if there is a collision at any point, false otherwise. I tried to put the method in both the keyPressed method (for each case of a directional key pressed) as well as in the main game loop (not both at the same time) and neither worked perfectly and both worked about the same. Now the problem is that as long as the hero approaches the tile from a far away distance it works perfectly (a tile is 40 pixels in width and hero is 30), it appears that if the hero approaches from around 40 pixels out it will work but anything less and it will go through the tile as far from the 40 pixel mark it started (ie if hero starts at 37 pixels from tile and moves, it will go through the tile 3 pixels) then it can only travel back to the position it started even if there is no collision detected. Again, it appears that the hero must be about 40 pixels out (not sure if this is coincidence or it is exactly the length of the tile for a reason). Really can't figure this out, dont think there is a problem with the code i have written but probably i'm approaching the solution wrong

Using ModelsUnderRay Collision detection

Ok first things first. I know you guys who have been reading
my other post is going to get confused after reading this post so
let me make myself clear. First yes I was previously trying to
Havok, but I could not get my car to work with it. So This is why I
am now asking stuff about ModelsUnderRay collision detection.
Second, I found this tutorial at
http://www.fbe.unsw.edu.au/learning/director/,
and all things seem to go pretty good with using the max File the
tutorial uses. Meaning I have not tried this on my car as of yet.
In addition, considering that things seem to work with the
tutorial, I now came up with a new question. Basically, if I am
correct, I think by using the code below, this is not going to work
with my car when the car is going up a hill. I conclude this by
knowing that the tutorial just uses a character, meaning it is not
like a using something like a car that has a chassis and 4 wheels.
So my question is this... How can I get the chassis to follow the
angle of the hill if I am using a behaviour that looks something
like this...
on collisionDetect me
-- create a list to store collision data created by
modelsUnderRay
-- cast ray to left
collisionList =
p3Dmember.modelsUnderRay(pCharacter.worldPosition, \
-pCharacter.transform.yAxis,#detailed)
-- if models picked up by ray, then activate checkForCollion
-- handler and send the collisionList as a parameter
if (collisionList.count) then
me.checkForCollision(collisionList[1])
-- cast ray to right
collisionList =
p3Dmember.modelsUnderRay(pCharacter.worldPosition, \
pCharacter.transform.yAxis,#detailed)
-- if models picked up by ray, then check for collision
if (collisionList.count) then
me.checkForCollision(collisionList[1])
-- cast ray forward
collisionList =
p3Dmember.modelsUnderRay(pCharacter.worldPosition, \
pCharacter.transform.xAxis,#detailed)
-- if models picked up by ray, then check for collision
if (collisionList.count) then
me.checkForCollision(collisionList[1])
-- cast ray backward
collisionList =
p3Dmember.modelsUnderRay(pCharacter.worldPosition, \
-pCharacter.transform.xAxis,#detailed)
-- if models picked up by ray, then check for collision
if (collisionList.count) then
me.checkForCollision(collisionList[1])
end
on checkForCollision me, collisData
-- grab the #distance value from the CollisionList
dist = collisData.distance
-- check if distance is less than width of bounding box
if (dist < pCharBoundingBox.resource.width ) then
-- get distance of penetration
diff = pCharBoundingBox.resource.width - dist
-- calculate vector perpendicular to the wall's surface to
move the character
-- using the #isectNormal property
tVector = collisData.isectNormal * diff
-- move the character in order to resolve the collision
pCharacter.translate(tVector,#world)
end if
end
on keyDown
-- check to see which key has been pressed
-- and set the property relating to that key to TRUE
if keypressed(123) then pLeftArrow = TRUE -- 123 = left
arrow key
if keypressed(124) then pRightArrow = TRUE -- 124 = right
arrow key
if keypressed(125) then pDownArrow = TRUE -- 125 = down
arrow key
if keypressed(126) then pUpArrow = TRUE -- 125 = up arrow
key
-- if 'r' key pressed, return character to starting position
if keypressed("r") then resetCharacter
-- if 'c' key is pressed, then switch camera
if keypressed("c") then changeCamera
end
on keyUp
-- when the arrow keys are released, set the properties to
FALSE
pLeftArrow = FALSE
pRightArrow = FALSE
pUpArrow = FALSE
pDownArrow = FALSE
end
on exitFrame
characterMove
end
on characterMove
-- if the right arrow is pressed,
-- rotate the character 5 degrees about the z-axis
if pRightArrow then pCharacter.rotate(0,0,-5)
--if the right arrow is pressed,
-- rotate character -5 degrees about the z-axis
if pLeftArrow then pCharacter.rotate(0,0,5)
-- if the up arrow is pressed,
-- move the character 5 pixels along the y-axis
if pUpArrow then pCharacter.translate(0,5,0)
-- if the down arrow is pressed,
-- move the character -5 pixels along the y-axis
if pDownArrow then pCharacter.translate(0,-5,0)
-- move along terrain
-- create reference for terrain (ground)
terrain = p3Dmember.model("Terrain")
-- store character's position
charPos = pCharacter.worldPosition
charPos.y = charPos.y - 20
-- cast a ray down
collisData =
p3Dmember.modelsUnderRay(charPos,vector(0,0,-1),#detailed)
-- if model is picked up on ray.
if collisData.count then
-- store total no of models detected by the ray
totalCount = collisData.count
repeat with modelNo = 1 to totalCount
-- check if over the terrain model
if (collisData[modelNo].model = terrain) then
terrainPos = collisData[modelNo].isectPosition
-- find out the distance the character should move up or
down
diff = (terrainPos.z - pCharacter.worldPosition.z)+45
-- move the character
pCharacter.translate(0,0,diff,#world)
end if
end repeat
end if
end

ok,
I have been trying to work this out for ahwile and I got
pretty close on getting this correct but there are still some
glitches. So far I did a little research in the help files to see
what the dot product does and this is how I got my calculations
going so far
--the code
on beginSprite me
I created 2 spheres and a box. Next, I then positioned them
so that the first sphere is alligned with the front end of the box
and then I aligned the second sphere to back of the box. I will not
show you the code of beginSprite because all this does is for
creating the models and there are no calculations going inside this
handler. In addition, with these 3 models, my purpose is to say
lets prtend that the box is the chasis of the car and the sphere
that is placed at the frent end of the chassis are to represemt the
2 front wheels and the othere sphere is to represent the 2 back
wheels of the car. Also, I initlalised a timer to the following
below
pTimer = (the milliseconds)
end beginSprite
... note The timere is just for purposes of simulating a
pretend upward movement for the wheels. See below which should
explain it better then I can say it in words.
--the code below is the calculations. The translations is for
saying that I am pretending that the wheels are inclining up a
hill. However, the wheels in the true game will be getting
calculated by finding the distance of collion by using the
modelsUnderRay function just like you normally would. By the way,
all models and the camera are set to y is the up vector
on exitFrame
if ((the milliseconds) - pTimer) > 1000 then -- increment
the calculations every one second
pBall1.translate(0, 0.125, 0) -- This is for saying that
this is the calculations that I am calculating the front wheels
need to move up when they incline up the hill.
pBall2.translate(0, -0.125, 0) -- Just like the front wheel
pretend calulations but for the back wheels, and use a negative
translate.
pos1 = pBall1.transform.position -- get the calculated
position for the front wheels
pos2 = pBall2.transform.position -- get the calculated
position for the back wheels
norm1 = pos1.getnormalized() -- not sure I understand this,
but in the help files, it says that when you calculate the dot
product of 2 vectors that have been normalized, you then get their
cosine
norm2 = pos2.getNormalized() -- normalize the back wheels
position
dotProduct = norm1.dot(norm2) -- calculate the dot product
of the 2 vectors
pBox.rotate(dotAngle, 0, 0) -- I took a guess and thought
that using the dotProduct will allow me to correctly rotate the
chassis but the chassis is quite not rotating correctlly
pTimer = (the milliseconds) -- update the timer so that we
can recyle the above code again
end if
end exitFrame
... Ok, now like I said previously, the chassis is rotating
almost correctlly, but if you continue to do this, and by after the
third cycle, the front end wheels start to collide with the
chassis. So in other words, the rotations look correct untill
exitFrame is called for the third time and after which then the
front wheels start to collide with the chassis.
So I am wondering if anyone could help me out to fix this and
explain what I am doing wrong?

Java 3d collision detection

i loaded some villas models(.obj ) and i want to implement simple collision detection to prevent the user from walking through the villa models

Note: The powerups do move around too, so, if the powerup and the character are in the middle of a translation (in between predefined grid positions), then I need to find out if their paths cross and react appropriately.

Better way of collision detection?

right now I'm experiencing problems with using the same speed
in reverse for collision detection (such as +=5 being countered by
-= 5). While this works most of the time, if the velocity of the
moving object changes, or on occasion, is out of sync with the map,
the moving object gets stuck like glue to the "wall".
Is there some other method of stopping the velocity when
colliding, without freezing the object in place?

I changed the = manspeed to = manspeed +1 and now the avatar
is now "moonwalking"???
for (i=1;i<49;i++){
the_wall = this["brick_mc"+i];
if(Key.isDown(Key.LEFT) &&
avatar_mc.body_mc.hitTest(the_wall)){
avatar_mc._x += manspeed +1;
if(Key.isDown(Key.RIGHT) &&
avatar_mc.body_mc.hitTest(the_wall)){
avatar_mc._x -= manspeed +1;
if(Key.isDown(Key.DOWN) &&
avatar_mc.body_mc.hitTest(the_wall)){
avatar_mc._y -= manspeed +1;
if(Key.isDown(Key.UP) &&
avatar_mc.body_mc.hitTest(the_wall)){
avatar_mc._y += manspeed +1;
}

Good collision detection?

I have been looking into quadtrees since it is a way to detect collisions. Is there another better way to do this? My game also has a system of sorting sprites in an array based on there relative locations on the map. ie: my character can appear in front of a tree or behind it. I have a complex system to do this which tests polygons however I was wondering if there is an expert way to do this.

well my tank game has two levels of collision detection. Well, I guess in a way it handles all the items in 3 levels.
First level, I have a Vector storing the items on the screen. They're only evaluated in any way if they're in the Vector. I refresh that vector every 10 frames by testing all the objects in the game to see if they're in a rectangle that surrounds the screen.
After that, to check collisions I have a simple distance formula check that finds the distance between the centers of two objects (ie. bullet and tank) and compares them to the sum of the largest dimensions (width for both) to see if they're close enough to collide.
If that check returns true, it calls a third level of collision checking. This check intersects the areas I've created from polygons that outline my objects. This way even if they're rotated in any way, the check only returns true if there's an honest to goodness real accurate collision. This check takes much longer than the previous one, but since it has the first check behind it, this check isn't called very often.

Collision Detections in Tilemaps

I need some help with collision detection with tilemaps. I have the following code for the tilemap:
import java.awt.*;
public class TileMap {
     final int EMPTY = 0;
     final int WALL = 1;
     private static final int WIDTH = 30;
     private static final int HEIGHT = 40;
     public static final int TILE_SIZE = 15;
     private int[][] map = new int[WIDTH][HEIGHT];
     public TileMap() {
          for (int i=0;i<HEIGHT;i++) {
               map[0] = WALL;
               map[29][i] = WALL;
          for (int i=0;i<WIDTH;i++) {
               map[i][0] = WALL;
               map[i][39] = WALL;
     public void paint(Graphics g) {
          for (int x=0;x<WIDTH;x++) {
               for (int y=0;y<HEIGHT;y++) {
                    if (map[x][y] == WALL) {
                         g.setColor(Color.RED);
                         g.fillRect(x*TILE_SIZE,y*TILE_SIZE,TILE_SIZE,TILE_SIZE);
Im finding it hard to find a good tutorial on simple collision detection. Can anyone explain how i would work out some simple collision detection. For example, lets say there is one sprite, how would i figure out which tile the sprite is on? How would i detect the next sprite? Just need the concept.
Thanks very much.
Edited by: Java_Jenius on Jun 28, 2009 8:34 PM

Take a look at http://www.13thmonkey.org/~boris/jgame/ for example.
It is an open source gaming engine and features sprites and collision detection.

How do i set up or remove pre-emptive text?

how do i set up and remove pre-emptive text?
== This happened ==
Every time Firefox opened

The Mail app does not provide that funtion. Check with your email provider. They may provide such a feature through a web interface.

Managing multiple collision detection between objects(not necessarily circles)

Hi.
I´d like to know if there´s any good tutorial, or if somebody knows, a way, to manage a multiple collision detection with pixel level detection, for objects, not necessarily circles, irregular objects.
Any help?

Yes, and what about the speeds of each object?
I was thinking something like this:
var _currentObj1SpeedX = obj1.speedX
var _currentObj1SpeedY = obj1.speedY
obj1.speedX = obj1.speedX - obj2.speedX
obj1.speedY = obj1.speedY - obj2.speedY
obj2.speedX = obj2.speedX - _currentObj1SpeedX
obj2.speedY = obj2.speedY - _currentObj1SpeedY
Is it right?

Pre-emptive collision detection

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