----------------------------------- Dan Tue Sep 24, 2002 3:06 pm [Tutorial] Collision Detection ----------------------------------- Collision Detection Ok I am show you how to use a common method of collision detection which is some times called rectangle collision detection. What it dose is uses if statements to make a theoretical rectangles arrowed the objects and then dose some tings if the rectangles hit. Well here is an example of how to do this. This example uses two ovals which we wont to bounce off everything. (sorry for the bad spelling if I get time I will spell check it :oops: ) var x, y : int %var for the 1st ovals quadents var x2, y2 : int %var for the 2nd ovals quadents var nx, ny, nx2, ny2 : int := 1 %vars for the chage in qroadents var s : int := 10 %var for the size of the ovals x := Rand.Int (10, 100) %set the x quadent for the 1st oval y := Rand.Int (10, 100) %set the y quadent for the 1st oval x2 := Rand.Int (10, 100) %set the x quadent for the 2nd oval y2 := Rand.Int (10, 100) %set the y quadent for the 2nd oval %main loop loop Draw.Oval (x, y, s, s, red) %draws the 1st oval Draw.Oval (x2, y2, s, s, green) %draws the 2nd one %check to see if oval gose off the screen %for oval 1 if x = maxy then %check to see if it gose off to the right ny := - 1 %chages the direction end if %check to see if oval gose off the screen %for oval 2 if x2 = maxy then %check to see if it gose off to the right ny2 := - 1 %chages the direction end if %this if checks to see if the ovals have hit each other if x + s > x2 - s and x - s < x2 + s and y + s > y2 - s and y - s < y2 + s then put "the balls hit" delay (500) %chages the direction of all the ovals nx := nx * - 1 ny := ny * - 1 nx2 := nx2 * - 1 ny2 := ny2 * - 1 end if %this part adds the chage in qroadents to the %quradents and makes the ovals move x += nx y += ny x2 += nx2 y2 += ny2 delay (10) cls end loop Also i think tony has some stuff to add to this about other methods of doing this. P.S. if there is anything you dont understand (or cant read becuse of my spelling) plz feal free to post and let us know. :wink: ----------------------------------- Tony Wed Sep 25, 2002 12:28 pm ----------------------------------- Oval Collision Detection Well Dan explained how to use rectangle collision Detection... sord off... Anyway, that is good enough for some cases, but in sertain games oval detection might prove better. Especially if you deal with circles :wink: The idea behind it is to find the distance between the centers of the circles and see if its less then sum of radiuses. If so, they have collided. To make a collision Detection function, you need to know pythagorian theorem (C^2 = A^2 + B^2) Here's how you use it: distance = ((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1))**0.5 %you take the square of differences of X coordinates and add %a square of differences of Y coordinates then take a square %root of the sum %%%%%% %I did (x)*(x) instead of x**2 because exponents is a function %and it takes up more resourses then *, thus its faster %Also **0.5 is the same as sqrt() - learn your math guys if distance < radious1 + radious2 %might be a good idea to save radious1+radious2 as const/var then collision = true end if I hope this little tutorial helped. If something is still unclear, or you want to know how to do other types of detections, please post. ----------------------------------- R.W.Z Fri Oct 04, 2002 5:05 pm Try This ----------------------------------- This would be a good tutorial but I didn't label much but this is almost the same thing as the other one but with this you can change the number of bouncing balls by changing BALLCOUNT but only the first two balls say if they collided with each other. const BALLCOUNT : int := 2 var ballX : array 1 .. BALLCOUNT of int var ballY : array 1 .. BALLCOUNT of int var directionX : array 1 .. BALLCOUNT of int var directionY : array 1 .. BALLCOUNT of int const RADIUS : int := 20 % Set random values for the x and y of each ball also the % x and y direction for each ball for i : 1 .. BALLCOUNT randint (ballX (i), RADIUS * 2, maxx - RADIUS * 2) randint (ballY (i), RADIUS * 2, maxy - RADIUS * 2) loop randint (directionX (i), -3, 3) randint (directionY (i), -3, 3) exit when directionX (i) not= 0 and directionY (i) not= 0 end loop end for loop for i : 1 .. BALLCOUNT drawfilloval (ballX (i), ballY (i), RADIUS, RADIUS, 0) ballX (i) := ballX (i) + directionX (i) ballY (i) := ballY (i) + directionY (i) if ballX (i) < RADIUS or ballX (i) > maxx - RADIUS then directionX (i) := -directionX (i) end if if ballY (i) < RADIUS or ballY (i) > maxy - RADIUS then directionY (i) := -directionY (i) end if drawfilloval (ballX (i), ballY (i), RADIUS, RADIUS, 12) end for if ballX (1) + RADIUS > ballX (2) - RADIUS and ballX (1) - RADIUS < ballX (2) + RADIUS and ballY (1) + RADIUS > ballY (2) - RADIUS and ballY (1) - RADIUS < ballY (2) + RADIUS then locatexy (maxx div 2, maxy div 2) put "Balls Hit" delay(100) cls end if delay (10) end loop R.W.Z Martin was here. Use code tags ----------------------------------- JayLo Tue Nov 26, 2002 11:46 pm for the rectangle collision... ----------------------------------- I'm trying out a pool program... thanks for the rectangle collision program... However, I would like to make the collision more realistic as in a "real" pool bounce... I tried out the oval collision, but it seems as if the program only tells when it hits! I would like to find out if the balls can realistically bounce off each other in a real way. Please post any sort of help. ----------------------------------- Tony Wed Nov 27, 2002 12:35 am ----------------------------------- ya, you can do that... you need to apply some physics and trig for it though... you should have no problem with grade11 knowledge of math and physics. I will shortly post a new tutorial on this topic. Check out tutorial section for [trig] ----------------------------------- void Mon Apr 07, 2003 8:00 pm collison detection ----------------------------------- when i click on a certain spot i want it to check if there is something within a certain radius of the point, say i click on (x,y)...i want to check if there is something within a 40 pixel radius of the spot :? ...any ideas are welcome....can u try to explain it to me because i dont wanna just see code and copy it (im lazy :oops: so if its there, i'll copy it :twisted: ), if you hafta tho ..i dont mind... :D thanks alot.....this site is really helpful...and its a good oppurtunity for me to test my own skills by debuggin and helping others and receive help from you crazzy programmmers.......if i had a job i might give you pplz money for such an amazing site...its one of the very few on the net that have a point to them...alongside google and shockwave.com :wink: GOOD JOB!!!! i know its commentss like this that make your day j/k :P im out...pz ----------------------------------- Blade Mon Apr 07, 2003 8:05 pm ----------------------------------- use an if statement... lets say if you have a ball.... xy will be the mouse... so you make the forign object enter the radius of the mouse click.... then use an if statement to see if its there.. .such as if forignobject < xy of ball + 40 then the object has entered the radius understand? ----------------------------------- void Mon Apr 07, 2003 8:18 pm ----------------------------------- thanks alot ....i think i get it...but the thing is...what if its at like a 45 degree angle from the center (using a horizontal plane as 0 degreees and 180)...then how do you check it? lets say its a line headed at a circle at a 45 degree angle from the center of the circle....how would you check that?...because the xy only check the horizontal and vertical values does it not? the diagonals are completely ignored ----------------------------------- Blade Mon Apr 07, 2003 8:38 pm ----------------------------------- what happens if you add 40 to x, and y, then find the distance between the both then get the midpoint from that.... would that work? ----------------------------------- Catalyst Tue Apr 08, 2003 6:08 am ----------------------------------- use this function to find out if its in the circle function distance (x1, y1, x2, y2 : real) : real result ((x1 - x2) ** 2 + (y1 - y2) ** 2) ** 0.5 end distance ----------------------------------- void Tue Apr 08, 2003 6:45 am ----------------------------------- thanks man...that helped alot...im just wondering how come everyone uses **0.5 instead of sqrt...is it betta proggramming? or is it just kinda what ur used ta doing? ----------------------------------- Catalyst Tue Apr 08, 2003 7:25 am ----------------------------------- might me a little faster since its not a function like sqrt, but i mainly just use by habit and that i can do cube roots and such by doing **0.3333,etc. ----------------------------------- void Tue Apr 08, 2003 6:33 pm ----------------------------------- var x, y, button : int function distance (x1, y1, x2, y2 : real) : real result ( (x1 - x2) ** 2 - ( y1 - y1) ** 2) ** 0.5 end distance loop Mouse.Where (x, y, button) locate (13, 13) put distance (6, 4, x, y) delay (5) end loop okay....heres what im attempting to do....i wanna see what the distance is....by radius from the mouse and the point that i randomly set in there.....but the thing is....i get a value of 0 (which should mean im directly over the point) far too many...how many different (6,4)'s can there be.....i've tried switching the (x,y) to x1 and y1 positions istead of their current x2,y2 possition...but the result is still the same..... :evil: ----------------------------------- Catalyst Tue Apr 08, 2003 9:14 pm ----------------------------------- u messed the code up.. result ( (x1 - x2) ** 2 - ( y1 - y1) ** 2) ** 0.5 should be result ( (x1 - x2) ** 2 - ( y1 - y2 )** 2) ** 0.5 ----------------------------------- void Wed Apr 09, 2003 6:56 am ----------------------------------- hehehehehehe :oops: ooopsssiiies......dont i feel like an idiot.... :lol: ----------------------------------- FwuffyTheBunny Wed Apr 09, 2003 10:11 am ----------------------------------- Hey man, i like the bouncing ball program, ill probly use sum of it to help me in making my projects in school, so all in all thanks ----------------------------------- Homer_simpson Fri Apr 25, 2003 11:04 pm ----------------------------------- here's is what i used in my custom created GUI to detect if mouse is over buttons or not function mouseover (x, y, x1, y1, x2, y2 : int) : boolean if x >= x1 and x = y1 and y = x1 and x = y1 and y = maxx then shot := false end if View.Update delay (10) cls end loop reply quick ----------------------------------- [Gandalf] Sun Jun 05, 2005 12:43 pm ----------------------------------- heck, I know this is proabbyl an assignment and I'm not supposed to help you. I'm also sure that you should be listening to Dan and posting this is the Help sections. I'm also sure that you shouldn't post things multiple times to get help. But what the hey... What you need is a whatdotcolour check for the bullet's x and y cordinates as well as the coordinates of you (big dot). *edit* use [ code] tags next time when posting code. ----------------------------------- Paper*Mate Sun Jun 05, 2005 1:06 pm ----------------------------------- im sorry to bug u again... but can u put up the actual code cause i dont understand what u r trying to tell me... its just that im a newbie at writting codes ----------------------------------- Bacchus Sun Jun 05, 2005 6:27 pm ----------------------------------- Well, then start to program smaller and easier to understand program until your able to program larger more complex ones instead of relying on others to give you the code, because if you just 'mooch' off of other you won't learn anything. ----------------------------------- Jujeff Mon May 12, 2008 12:01 pm Re: [Tutorial] Collision Detection ----------------------------------- Hello! I'm new to here, and Turing (sort of) so I'm sorry if I appear a noob. I wanted to make a platformer for a school project, so I realized I needed to make my character jump. I found the highly-helpful Mazer Jump Tutorial, copied and pasted (there are some numbers I couldn't figure out the use of), and tweaked it to my needs. After putting in a platform, I discovered that this messed everything up (the character cannot jump once on a platform), I tried to fix it as best as I could, and added in a boolean variable by recommendation of a friend, however as it is not clear to me the use of this, I will paste the code that I had before the boolean variable. (The problem of the jumping of the platform, as far as I can see, is that the Yvelocity must be 0 to be able to jump, but the character can only be on the platform if Yvelocity is above the value of "gravity".) Code: setscreen ("graphics:1011;699;nobuttonbar;offscreenonly") % VARIABLES! var keystroke : array char of boolean var height : int := 1 var LeftWall : int := 1 var RightWall : int := 1011 var movespeed : int := 10 var jumpspeed : int := 30 var gravity : int := 2 var Xposition, Yposition : int var Xvelocity, Yvelocity : real Xposition := 20 Yposition := 400 Xvelocity := 0 Yvelocity := 0 % game loop loop Input.KeyDown (keystroke) % horizontal movement if keystroke ('a') then Xvelocity := -movespeed elsif keystroke ('d') then Xvelocity := movespeed else Xvelocity := 0 end if % jump movement if keystroke ('w') and Yposition = height then Yvelocity := jumpspeed end if % world (lines and where you can walk and such) drawline (0, height, maxx, height, blue) drawline (245, 146, 384, 146, blue) % line (if you're on the middle line, stay on it) if Xposition >= 245 and Xposition = 140 then Yposition := 140 Yvelocity := 10 end if % reinstate gravity every loop Yvelocity -= gravity Xposition += round (Xvelocity) Yposition += round (Yvelocity) % don't fall through the ground or go past the edges if Yposition RightWall then Xposition := 1010 end if % character (square for now) drawfillbox (Xposition - 10, Yposition, Xposition + 10, Yposition + 20, green) drawfillbox (Xposition - 10, Yposition, Xposition + 10, Yposition + 20, red) % animation View.Update delay (25) cls end loop ----------------------------------- Jujeff Mon May 12, 2008 7:48 pm Re: [Tutorial] Collision Detection ----------------------------------- EDIT:::: don't worry, it's been figured out ----------------------------------- DaveAngus Tue May 20, 2008 12:39 pm Re: [Tutorial] Collision Detection ----------------------------------- This is great Dan! Another easy way to detect colour could be whatdotcolor you could do something like if whatdotcolor (posx + 25, posy) = black then % What ever you want inside here end if I think this would work. Let me know if it wouldnt. Take care