Sine/Cosine
BlitzPlus Forums/BlitzPlus Beginners Area/Sine/Cosine
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| Apparently math class last year wasn't all useless... however, if I had known that at the time, maybe I would have paid attention. I'm trying my hand at a 2D space shooter (yes, you can groan) - as if this world didn't have enough of them. My problem is the max speed of the ship. It messes everything up. Sometimes it doesn't allow the ship to move in a specific direction, and it is definitely messed up. For example, when facing right, the ship's y movement should be zero, no? I've been stuck for a while, and any help would be much appreciated. Thanks! Here's the full code: Graphics 800, 600 TFormFilter 0;Gets rid of that rascally man, Mr. T-form SeedRnd MilliSecs() Const leftkey = 203, rightkey = 205, upkey = 200, downkey = 208 Const spacebar = 57 Global globaltimer Type ship;sets up the type for the player Field x, y Field dx, dy Field rotations Field image Field frame Field direction Field totalframehunks;total rotations of ship in image Field framehunk;current one (see above) Field shootingframehunk;the framehunk that it needs to have to shoot Field turnspeed;different ships turn at different rates Field turntimer;how much time has elapsed since the last turn... Field shootspeed;see turnspeed Field shoottimer;see turntimer Field chargeupshooter;if it is a charge-up shooter or not. 1 is yes, 0 is no. Field chargeup;if it's a charge-up shooter, then this becomes 1 if it is in the chargeup sequence. End Type Global ship.ship = New ship;actually creates the ship that the player uses ship\x = 0 ship\y = 0 ship\dx = 0 ship\dy = 0 ship\rotations = 32 ship\totalframehunks = 4 ship\shootingframehunk = 4 ship\image = LoadAnimImage("TotalShip.bmp", 175, 175, 0, ship\rotations * ship\totalframehunks) MaskImage ship\image, 255, 0, 0 ship\direction = 0 ship\framehunk = 1 ship\frame = 0 ship\turnspeed = 50 ship\turntimer = MilliSecs() ship\shootspeed = 1000 ship\shoottimer = MilliSecs() ship\chargeupshooter = 1 ship\chargeup = 0 Dim xtopspeedtable#(ship\rotations) Dim ytopspeedtable#(ship\rotations) ;gets the sine and cosine tables ;Run through the full rotation cycle, and use Sin and Cos at increments. ;This helps to speed up the game because the compy doesn't have ; to compute the Sine or Cosine in Real-Time. Poor ol' compy. multiplyer = 360/ship\rotations Dim xSinTable#(ship\rotations) Dim yCosTable#(ship\rotations) For angle = 0 To ship\rotations - 1;through each and every one. xSinTable#(angle) = Sin(angle*multiplyer) yCosTable#(angle) = -Cos(angle*multiplyer);negates the Cosine so the ship doesn't spin oddly. Next precomputetopspeedtables(2);THIS IS THE PROBLEMATIC CODE THING!! HELP!! SetBuffer BackBuffer();Makes it work Global startingtime = MilliSecs() Global timepassed While Not KeyDown(1);Let's begin! globaltimer = MilliSecs() If globaltimer > startingtime timepassed = globaltimer - startingtime Cls testkeys() moveship() draw() Flip startingtime = globaltimer Delay 15 EndIf Wend Function draw();draws all images DrawImage ship\image, ship\x, ship\y, ship\frame Text 400, 0, "Ship\dx: " + ship\dx Text 400, 10, "Ship\dy: " + ship\dy Text 400, 400, "X-Top Speed: " + xtopspeedtable#((ship\frame / ship\framehunk)) Text 400, 410, "Ship X-movement: " + ship\x + (ship\dy * timepassed) Text 400, 420, "Time passed: " + timepassed Text 400, 430, "Y-Top Speed: " + ytopspeedtable#((ship\frame / ship\framehunk)) End Function Function moveship() If ship\dx > xtopspeedtable#((ship\frame / ship\framehunk)) ship\dx = xtopspeedtable#((ship\frame / ship\framehunk)) EndIf If ship\dy > ytopspeedtable#((ship\frame / ship\framehunk)) ship\dy = ytopspeedtable#((ship\frame / ship\framehunk)) EndIf ship\x = ship\x + (ship\dx * timepassed) ship\y = ship\y + (ship\dy * timepassed);move in realtime End Function Function testkeys();tests all key presses ;SIDE-TO-SIDE MOVEMENT If globaltimer > ship\turntimer + ship\turnspeed;if it's been long enough for ;the ship to turn again If KeyDown(rightkey);rotates ship clockwise ship\frame = ship\frame + 1 If ship\frame > (ship\rotations * ship\framehunk) - 1;nifty code for getting ;the frames right ship\frame = (ship\rotations * ship\framehunk) - ship\rotations EndIf EndIf If KeyDown(leftkey);rotates ship counter-clockwise ship\frame = ship\frame - 1 If ship\frame < (ship\rotations * ship\framehunk) - ship\rotations;gets the frames right ship\frame = (ship\rotations * ship\framehunk) - 1 EndIf EndIf ship\turntimer = globaltimer;resets the turning timer, so the ship has to wait ;the "ship\turnspeed" in milliseconds EndIf ;FORWARD MOVEMENT If KeyDown(upkey) ship\dx = ship\dx + (xSinTable#((ship\frame / ship\framehunk))) ship\dy = ship\dy + (yCosTable#((ship\frame / ship\framehunk))) EndIf ;SHOOTING MOVEMENT If globaltimer > ship\shoottimer + ship\shootspeed;if it's been long enough for ;the ship to shoot again If ship\chargeupshooter = 1;if the ship charges up to shoot If KeyDown(spacebar);enters shooting chargeup or shifts to next phase of shooting ship\frame = ship\frame + ship\rotations;moves forward one "framehunk" ship\framehunk = ship\framehunk + 1 If ship\framehunk > ship\shootingframehunk;if the frame is bigger than ;the total frames in the image ship\frame = ship\frame - ship\rotations;reset the frame! ship\framehunk = ship\shootingframehunk EndIf EndIf EndIf ship\shoottimer = globaltimer EndIf If Not KeyDown(spacebar);if they're not pressing spacebar... If ship\framehunk = ship\shootingframehunk;if they let go of spacebar when gun is charged... shoot() EndIf ship\frame = ship\frame - (ship\rotations * (ship\framehunk - 1));resets the frame ship\framehunk = 1 EndIf End Function Function shoot() Text 400, 300, "S H O O T !", True, False End Function Function precomputetopspeedtables(speedtouse#) Local speedcontrol# Local xmaxrange = ship\rotations Local xangle = xmaxrange Local yangle = 0 ; setup our speed modifier speedmodifier# = (speedtouse# / ship\rotations) ; save our Top Speed speedcontrol# = speedtouse# For angle = 0 To ship\rotations ; get that absolute value of our current speed control ; minus the speed modifier speedcontrol# = Abs(speedcontrol# - speedmodifier#) ; if it's below a certain level, just set it to zero If speedcontrol# < .0001 Then speedcontrol# = .000000 EndIf ; assign the speed control per x,y angle xtopspeedtable#(xangle) = speedcontrol# ytopspeedtable#(yangle) = speedcontrol# ; make sure that arrays are being loaded ; in opposite directions xangle = xangle - 1 yangle = yangle + 1 Next End Function End;Closinnng Tiiiime.... EDIT: I really don't understand some of the max speed stuff... I kind of took it from krylar's book without fully understanding it, and tweaked it (a bad idea). Also, can someone tell me how to make that blue code box on the forums? |
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| <code> </code> but preferred for large chunks o' code: <codebox> </codebox> replace <> with [] |
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| one thing I see after a quick look over is when you use cos and sin,you need to make your ships dx and dy a float.In fact you need to make everything that has to do with your movement floats.I've ran into a similar problems a few weeks back. Reason is,if your dx is an int,and you do float math ,it will round it to the nearest whole number. Hope this helps, mudcat |
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Here's something to paste and run.Graphics 800,600 SetBuffer BackBuffer() x#=GraphicsWidth()/2 y#=GraphicsHeight()/2 While Not KeyDown(1) Cls Line x-100,y,x+100,y Line x,y-100,x,y+100 Line x,y,MouseX(),MouseY() a#=ATan2(MouseY()-y,MouseX()-x) Text 100,100,"angle= "+a Text x-100,y,"-100",1 Text x+100,y,"+100",1 Text x,y-100-FontHeight(),"-100",1 Text x,y+100,"+100",1 Flip Wend |
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| mudcat- Thanks, but it doesn't help. I still can't move the ship directly to the right. By the way, do all <b>html</b> tags work in here? EDIT: I guess not |
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| By the way, do all <b>html</b> tags work in here? html I gues they do you have to use [] not <> |
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| Ahh... Thanks, but I'd still like to get back to my main problem... [marquee]Sweet![/marquee] |
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| You guys, I'm desparate! Help!! Gaaaaaaaaaaaaaaaaah! |
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| I took out the top speed completely, and something is wrong with my angles. At 180 degrees, the dx value should be zero, yet it isn't. I think I can fix it though. |
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| It's fixed! Hallelujah! |
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| btw I did some test of putting sin in an array to read instead of calling Sin realtime and it really was only fractionally faster. In the old days it would have been a lot faster. |
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| Wow. Things have gotten fast. |
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