----------------------------------- thoughtful Fri Jan 23, 2004 8:16 pm Tutorial: Basic POOL and realistic collision ----------------------------------- Okay here is my long promised tutorial I have seen a lot of reference to poor tonys tutorial, which has some bugs. That turotial was meant to be a base information, he said in his post that he did not spend all the time figuring all the trig out. So give him a break :D . BTW my tutorial was inspired by somewhat same principle and then i added some stuff. The tutorial is not just on collision but it actually provieds a base package for n e pool game, with a lot of room to expand. I actually took out a old version of my ISP and had to delete some stuff to make it so it doesnt give the whole solution. The collision algorithm is very good, but it might have some problem, such as the balls sticking together, now that i want u to figure on your own (my ISP has an advanced version of the same algorith with no problems :P ). Also you can change the values of the constants to increase ball size, decay, highest speed, lowest speed or number of balls e.t.c. And also i will like to thank tony and catalyst who at the start helped me understand how the realistic collision works. % by Abdullah Ramay a.k.a Thoughtful % some variables may not be used in this tutorial becuase this is taken from my game that i am making for my ISP %click on the white ball and drag to take a shot var white_x : real% positions var white_y : real var white_xsp : real%velocities var white_ysp : real var x, y, but : int var sunk_x, sunk_y : int const totalballs := 3 %change this to change number of balls var balls_x : array 1 .. totalballs of real%positions var balls_y : array 1 .. totalballs of real var balls_xsp : array 1 .. totalballs of real%velocities var balls_ysp : array 1 .. totalballs of real var balls_check : array 1 .. totalballs of int var font : int := Font.New ("verdana:5:bold") var font2 : int := Font.New ("verdana:5") var distance : real var xsp_temp1, ysp_temp1, xsp_temp2, ysp_temp2 : real var movedist1, movedist2, collangle, mass, a1, a2, nX, nY, optimisedP : real const decay := 75 %inversely poportional to stopping, bigger decay= longer moving ball const lowbar := 50 const ballradius := 8 %radius of the ball, try 18 for monster ball ;=) const lowestspeed := .01%lowest possible speed const highestspeed := 10 %highest possible speed const ballcollidedistance := ballradius * 2 %how far does the ball has to be before it collides const pocketcollidedistance := 20 var cuecolor : int := white setscreen ("title:Thoughtful's Pool") setscreen ("offscreenonly") View.Set ("graphics:600;350") sunk_x := 20 sunk_y := 20 mass := 1 for i : 1 .. totalballs %initialises starting positions balls_x (i) := Rand.Int (20 + lowbar, (maxx - 20)) + Rand.Real balls_y (i) := Rand.Int (20, (maxy - 20)) + Rand.Real balls_xsp (i) := 0 balls_ysp (i) := 0 balls_check (i) := 1 end for % ignore these , jus some initial setup values white_x := (maxx div 2) white_y := (maxy div 2) + (lowbar / 2) white_xsp := 0 white_ysp := 0 proc drawfield %draws the field drawfillbox (0, 0, maxx, maxy, brown) drawfillbox (10, 10 + lowbar, maxx - 10, maxy - 10, white) drawfillbox (20, 20 + lowbar, maxx - 20, maxy - 20, green) end drawfield %collision of white ball to balls proc white_collide for i : 1 .. totalballs distance := ((balls_x (i) - white_x) * (balls_x (i) - white_x) + (balls_y (i) - white_y) * (balls_y (i) - white_y)) ** 0.5 if distance < ballcollidedistance then % this the part which controls the ball to ball collision /****************************************************************************************** * the collision part is below * ******************************************************************************************/ collangle := arctand ((balls_y (i) - white_y) / ((balls_x (i) - white_x))) %get angle nX := cosd (collangle) %x vector nY := sind (collangle) %y vector a2 := balls_xsp (i) * nX + balls_ysp (i) * nY%figure out reultant velcoities a1 := white_xsp * nX + white_ysp * nY %resultants optimisedP := (2.0 * (a1 - a2)) / (mass + mass) %you can have different masses, i am using same masses for all balls balls_xsp (i) := balls_xsp (i) + (optimisedP * mass * nX) %finally initialises the x and y velocoities to the balls balls_ysp (i) := balls_ysp (i) + (optimisedP * mass * nY) white_xsp := white_xsp - (optimisedP * mass * nX) white_ysp := white_ysp - (optimisedP * mass * nY) /****************************************************************************************** * the collision part ends * ******************************************************************************************/ end if end for end white_collide %collision of balls to balls proc balls_collide for i : 1 .. totalballs for k : i .. totalballs if k not= i then distance := (((balls_x (i) - balls_x (k)) * (balls_x (i) - balls_x (k))) + ((balls_y (i) - balls_y (k)) * (balls_y (i) - balls_y (k)))) ** 0.5 if distance < ballcollidedistance then collangle := arctand ((balls_y (k) - balls_y (i)) / ((balls_x (k) - balls_x (i)))) nX := cosd (collangle) nY := sind (collangle) a1 := balls_xsp (i) * nX + balls_ysp (i) * nY a2 := balls_xsp (k) * nX + balls_ysp (k) * nY optimisedP := (2.0 * (a1 - a2)) / (mass + mass) balls_xsp (i) := balls_xsp (i) - (optimisedP * mass * nX) balls_ysp (i) := balls_ysp (i) - (optimisedP * mass * nY) balls_xsp (k) := balls_xsp (k) + (optimisedP * mass * nX) balls_ysp (k) := balls_ysp (k) + (optimisedP * mass * nY) % moves the balls forward a step so they dont get stuck with each other( but the balls will still stick) balls_x (i) += balls_xsp (i) balls_y (i) += balls_ysp (i) balls_x (k) += balls_xsp (k) balls_y (k) += balls_ysp (k) end if end if end for end for end balls_collide % controls the motion& collision with the side bars, also decays the speed so it slows proc balls_mov for i : 1 .. totalballs if balls_check (i) not= 0 then balls_x (i) += balls_xsp (i) balls_y (i) += balls_ysp (i) if balls_x (i) < (20 + ballradius) then balls_x (i) := 20 + ballradius balls_xsp (i) := - (balls_xsp (i)) end if if balls_x (i) > (maxx - (20 + ballradius)) then balls_x (i) := maxx - (20 + ballradius) balls_xsp (i) := - (balls_xsp (i)) end if if balls_y (i) < (20 + ballradius) + lowbar then balls_y (i) := (20 + ballradius) + lowbar balls_ysp (i) := - (balls_ysp (i)) end if if balls_y (i) > (maxy - (20 + ballradius)) then balls_y (i) := maxy - (20 + ballradius) balls_ysp (i) := - (balls_ysp (i)) end if if balls_xsp (i) > 0 then balls_xsp (i) := balls_xsp (i) - (balls_xsp (i) / decay) end if if balls_ysp (i) > 0 then balls_ysp (i) := balls_ysp (i) - (balls_ysp (i) / decay) end if if balls_xsp (i) < 0 then balls_xsp (i) := balls_xsp (i) + (- (balls_xsp (i) / decay)) end if if balls_ysp (i) < 0 then balls_ysp (i) := balls_ysp (i) + (- (balls_ysp (i) / decay)) end if if balls_ysp (i) > - (lowestspeed) and balls_ysp (i) < (lowestspeed) then balls_ysp (i) := 0 end if if balls_xsp (i) > - (lowestspeed) and balls_xsp (i) < (lowestspeed) then balls_xsp (i) := 0 end if end if end for for i : 1 .. totalballs %draws the balls drawfilloval (round (balls_x (i)), round (balls_y (i)), ballradius, ballradius, i) drawfilloval (round (balls_x (i)), round (balls_y (i)), ballradius - 4, ballradius - 4, white) drawoval (round (balls_x (i)), round (balls_y (i)), ballradius, ballradius, black) Font.Draw (intstr (i), round (balls_x (i)) - 2, round (balls_y (i)) - 2, font, 7) end for end balls_mov proc whiteball_mov %controls the moving of the white ball white_x += white_xsp white_y += white_ysp Mouse.Where (x, y, but) % bouncing of the wall if white_x < (20 + ballradius) then white_x := 20 + ballradius white_xsp := - (white_xsp) end if if white_x > (maxx - (20 + ballradius)) then white_x := maxx - (20 + ballradius) white_xsp := - (white_xsp) end if if white_y < (20 + ballradius) + lowbar then white_y := (20 + ballradius) + lowbar white_ysp := - (white_ysp) end if if white_y > (maxy - (20 + ballradius)) then white_y := maxy - (20 + ballradius) white_ysp := - (white_ysp) end if % decays the ball if white_xsp > 0 then white_xsp := white_xsp - (white_xsp / decay) end if if white_ysp > 0 then white_ysp := white_ysp - (white_ysp / decay) end if if white_xsp < 0 then white_xsp := white_xsp + (- (white_xsp / decay)) end if if white_ysp < 0 then white_ysp := white_ysp + (- (white_ysp / decay)) end if % makes the ball stop if white_ysp > - (lowestspeed) and white_ysp < (lowestspeed) then white_ysp := 0 end if if white_xsp > - (lowestspeed) and white_xsp < (lowestspeed) then white_xsp := 0 end if drawfilloval (round (white_x), round (white_y), ballradius, ballradius, white) drawoval (round (white_x), round (white_y), ballradius, ballradius, black) end whiteball_mov proc poolcue if (x > white_x - 5) and x < (white_x + ballradius) and (y > white_y - ballradius) and y < (white_y + ballradius) and but = 1 then white_xsp := 0 white_ysp := 0 loop drawfield Mouse.Where (x, y, but) %gets exit when but = 0 drawfilloval (round (white_x), round (white_y), ballradius, ballradius, white) drawoval (round (white_x), round (white_y), ballradius, ballradius, black) balls_mov Draw.Line (round (white_x), round (white_y), x, y, cuecolor) delay (10)% take this away if the game runs too slowly, my computer is a 2.6 Ghz so doesnt amtters to me :) View.Update cls end loop white_xsp := (white_x - x) / 15 % gets the power from cue for the shot white_ysp := (white_y - y) / 15 if white_xsp > highestspeed then % sees if the power is according to the highest speed e.t.c white_xsp := highestspeed elsif white_xsp < -highestspeed then white_xsp := -highestspeed end if if white_ysp > highestspeed then white_ysp := highestspeed elsif white_ysp < -highestspeed then white_ysp := -highestspeed end if end if end poolcue % main loop, i always like procedure, very easy to add rules and stuff to the game, my final isp just uses a single procedure for all rules loop drawfield white_collide balls_collide whiteball_mov balls_mov if but = 1 then poolcue end if View.Update cls end loop i hope u liked it, if you did let me know by replying ----------------------------------- TheXploder Fri Jan 23, 2004 8:25 pm ----------------------------------- wow, amazing!! :D I think it speeds up a bit too fast, and slows almost abruptly, I think it should roll a bit more. But hey +10 bits good job, maybe some mods can give you more, hint, hint, :wink: , :wink:... ----------------------------------- thoughtful Fri Jan 23, 2004 8:29 pm ----------------------------------- thanks a lot, though as i said i left some error in their..otherwise it wont be any fun..all the guys would have the same pool game...so you can improve this and put in rules e.t.c, the version i made actually jsut had a procedure for everything and was very easy to add/ remove stuff(specially rules for 8-ball,9-ball,e.t.c). The slowing down and speed you can adjust with the constants. ----------------------------------- AsianSensation Fri Jan 23, 2004 8:31 pm ----------------------------------- very very nice. This is a great program. It also has that kinda of polished look to it. Here, have some bits, you deserve it. +50 bits ----------------------------------- Tony Fri Jan 23, 2004 8:58 pm ----------------------------------- awesome 8) I'm going to link to this from my old tutorial +50Bits ----------------------------------- Cervantes Fri Jan 23, 2004 9:06 pm ----------------------------------- wow thats amazing!! GREAT work!!! ----------------------------------- Cervantes Sat Jan 24, 2004 1:32 pm ----------------------------------- hmmm.. I wonder if there's a way to use this kind of collision style in Slime Volleyball :) ballspx and ballspy is so much easier than ballangle and velocity and weight and all :? ----------------------------------- thoughtful Sat Jan 24, 2004 5:13 pm ----------------------------------- yes..you can, jsut use a decay for the y speed, so tht it goes downwards if you thinking off a side view volley ball. If its top view ti should be rpetty simple ----------------------------------- Cervantes Sat Jan 24, 2004 5:54 pm ----------------------------------- hhmmm.. I shall try to impliment that... I'm almost done making a game like the space game that turing comes with.. will post it here in a bit. ----------------------------------- Kuntzy Mon Jan 26, 2004 7:27 pm ----------------------------------- Great tutorial! +bits, it helped me out a lot, I get your code, only when I run the pool oi made base off of yours, my veloities seem to ammplify when balls collide with eachother. :cry: ----------------------------------- jonos Mon Jan 26, 2004 7:54 pm ----------------------------------- where do all you guys learn this. do you get the basics from compsci class then just learn it on your own. im trying to learn on my own cause my compsci grade 10 class was useless, but ahhhhhhh it takes so long. ----------------------------------- Tony Mon Jan 26, 2004 8:40 pm ----------------------------------- yeah, preaty much. Just pick up syntax from compsci class and pick a challange for yourself. You'll learn a great deal while trying to achieve it. btw - pool involves trig and physics, so that might be a bit above gr10 level :? ----------------------------------- jonos Mon Jan 26, 2004 8:42 pm ----------------------------------- ok, should i take trig and physics in grade 11 and stuff like that or will i learn that in compsci 11 and 12 ----------------------------------- Tony Mon Jan 26, 2004 8:45 pm ----------------------------------- you learn trig in grade10/11 math. And you should defenatly take physics 11 if you're into making games. You dont learn that in CS... heck, you dont learn anything in CS. Just "if" statements :lol: ----------------------------------- Cervantes Tue Jan 27, 2004 11:18 am ----------------------------------- long live the if statements!! :) we learn trig (or start learning it) in gr 10 math, (im only in gr 10 now, and have math next semester) you also learn some physics in gr10 science, but not enough to do much in turing... for compsci it just helps you understand the physics in other ppls games :) ----------------------------------- Tendulkar Wed Feb 04, 2004 4:23 pm ----------------------------------- this is great! excellent work thoughtful ----------------------------------- gamer Thu Apr 08, 2004 2:39 pm ----------------------------------- helo thoughtful btw GREAT JOB on this pool program, u see im kind of new to program so my question is, do you think u can explain to me how the collision part of the program works?? i understand the fact that u applied trig but how exactly did you do it? ----------------------------------- gamer Sat Apr 10, 2004 6:21 pm ----------------------------------- heloo?? thoughtful can ya reply? or anyone else who knows please tell me, i reli gota understand thnx ----------------------------------- gamer Mon Apr 12, 2004 3:52 pm ----------------------------------- still no reply??? omg ----------------------------------- Paul Mon Apr 12, 2004 3:55 pm ----------------------------------- Thoughtful is not on Compsci very often, and don't triple post lol, Asian Sensation would be angry at you. Im sure whenever he gets on, he'll try and reply. You could always send him a PM. ----------------------------------- Tony Mon Apr 12, 2004 3:59 pm ----------------------------------- you find the angle you break it up into vector components (x and y) you find total energy transfer from the collision you use vector components as ratios to redestribute the energy after collision. ----------------------------------- gamer Mon Apr 12, 2004 4:14 pm ----------------------------------- thnx ----------------------------------- evildaddy911 Sun Oct 16, 2011 1:35 pm RE:Tutorial: Basic POOL and realistic collision ----------------------------------- i dont have gr11 math till next semester, can you explain what you mean by vector components? ----------------------------------- Raknarg Wed Oct 19, 2011 3:33 pm RE:Tutorial: Basic POOL and realistic collision ----------------------------------- It's actually physics... lets say you have a line. This line goes up by 3 and across by 4. Those woule be the x and y vector components: The change in x and the change in y. Correect me if I'm wrong. ----------------------------------- evildaddy911 Wed Oct 19, 2011 3:47 pm RE:Tutorial: Basic POOL and realistic collision ----------------------------------- so its like finding slope, but not actually finding the slope, cuz slope is change in y divided by change in x, but you dont do the dividing ----------------------------------- Raknarg Wed Oct 19, 2011 3:53 pm RE:Tutorial: Basic POOL and realistic collision ----------------------------------- Its basically trigonometry. Usually when you're working with vectors, you are given a bunch of distances with directions (ex. 35m[E25oS], or 25 meters, East 25 degrees to the South) and from that you calculate the overall displacement and the overall angle (compared from your starting point to your finishing point). Of course, this is a really bad explaination. You should look it up: http://zonalandeducation.com/mstm/physics/mechanics/vectors/introduction/introductionVectors.html That seems promising. ----------------------------------- evildaddy911 Thu Oct 20, 2011 3:29 pm Re: Tutorial: Basic POOL and realistic collision ----------------------------------- okay, so the vectors are really just horizontal/vertical distances.... and i puzzled out a quick screensaver-like program... im not sure what you mean by displacement, but i think i could figure out the angle... anyways, voila: var x, y, xv, yv : int var change_time : int := 10000 var last_change : int := -change_time x := Rand.Int (10, maxx - 10) y := Rand.Int (10, maxy - 10) xv := Rand.Int ((-5), 5) yv := Rand.Int ((-5), 5) loop var now := Time.Elapsed if now - last_change >= change_time then xv := Rand.Int ((-5), 5) yv := Rand.Int ((-5), 5) last_change := now end if drawfilloval (x, y, 10, 10, white) x := xv + x y := y + yv if x = maxx - 10 then xv := xv * (-1) end if if y >= maxy - 10 or y yPos then t := 270 elsif x < xPos and y = yPos then t := 0 elsif x = xPos and y < yPos then t := 90 elsif x > xPos and y = yPos then t := 180 elsif x = xPos and y = yPos then t := 0 elsif x > xPos then t := arctand ((y - yPos) / (x - xPos)) + 180 else t := arctand ((y - yPos) / (x - xPos)) end if % This thing here calculates your angle. It'll make sense if you've ever done vectors before. It uses the function tan-1. The ones before it are for mathematical correctness; you cannot divide anything by zero. if b = 1 and bltd = true then % Only shoots when the bullet is dead and the button is clicked. bltd := false bltx := xPos - (40 * cosd (t)) % setting the position of the bullet blty := yPos - (40 * sind (t)) % same bltvx := -5 * cosd (t) % setting the change in x bltvy := -5 * sind (t) % setting the change in y end if Draw.FillOval (xPos, yPos, 20, 20, blue) Draw.ThickLine (xPos, yPos, xPos - round (40 * cosd (t)), yPos - round (40 * sind (t)), 4, 7) % This is important for drawing shapes according to an angle. You add onto the original postion. In the case of x, its the radius * cos(angle). For y it's radius * sin (angle) if bltd = false then Draw.FillOval (round (bltx), round (blty), 4, 4, brightred) Draw.FillOval (round (bltx), round (blty), 2, 2, 7) bltx += bltvx % Changes the bullet x position relative to the change in x blty += bltvy % Changes the bullet y position relative to the change in y if bltx > maxx or bltx < 0 or blty > maxy or blty < 0 then % If the bullet hits the edge, it dies bltd := true end if end if View.Update cls end loop