Select the device which you develop the application for:
The project contains:
- the algorithm of ball movement (considering collisions);
- a character that displays arrows of the movement trajectory;
- character Cat, with animation of eight changing pictures.
Start Game Pilot, select "Prepare demo project", then select the "14 Ball in a labyrinth" project. The project will load to your device into the Documents/Lesson014 folder.
The Lesson014.sc file describes the project scenario:
- - - - - CODE BEGIN - - - - -
Scene Start
Orientation(Landscape)
AutoRotate(0) // Lock screen rotation
Maska = 2 // The number of the current mask
LLetters= 150*TypeDevice // The size of the letters
HLetters= 188*TypeDevice
YLetters= 160*TypeDevice
XLetters= 155*TypeDevice
YLetter = 67*TypeDevice
XLetterC= ScreenCX-XLetters-77*TypeDevice
XLetterA= ScreenCX -77*TypeDevice
XLetterT= ScreenCX+XLetters-77*TypeDevice
Png(Background,,,ScreenX,ScreenY)
// Shaded letters
Png(letter001, ScreenCX-XLetters, YLetters, LLetters, HLetters)
Png(letter002, ScreenCX , YLetters, LLetters, HLetters)
Png(letter003, ScreenCX+XLetters, YLetters, LLetters, HLetters)
Person(way, 1, 0, 0) // The path of the ball
// Person( ball, 1 ) // The way the character causes the character ball
Person(cat, 0) // The Cat Character
// Image for collision detection
PixelMask(ball000, 0, 0)
PixelMask(C, ScreenCX-XLetters- XLetterC, YLetters-YLetter) // С-2
PixelMask(A, ScreenCX - XLetterA, YLetters-YLetter) // A-3
PixelMask(T, ScreenCX+XLetters- XLetterT, YLetters-YLetter) // T-4
- - - - - CODE END - - - - -
Collision control is performed for the images uploaded to the scene with the PixelMask command. For collisions control, an image must not be scaled; so you should make different images for devices with different resolutions: 4x for iPad Retina; -ipad for iPad; -1x for Retina iPhone and -iphone for iPhone.
The algorithm of the ball movement is contained in the ball.stt file:
- - - - - CODE BEGIN - - - - -
// The Character ball
Slot[Time0_ball] = 2 // The position of the ball calculated by the timer
Rest
1: Img=0 Z=20 // Initialization
SpeedX=0 SpeedY=0 // Speed in X and Y
Timer[0]=100 // Interval control the movement of the Ball 100 ms
Rest
2:SpeedX = SpeedX+0.2*TiltX-0.05*SpeedX // Determine the angle of inclination by accelerometer
SpeedY = SpeedY+0.2*TiltY-0.05*SpeedY // And computed components of the velocity vector along the axes
Period = 100 Stop
3:If Period < 10 Rest
Send=MoveBall
LX= SpeedX*Period/100
LY= SpeedY*Period/100
N = Trunc(Max(Abs(LX),Abs(LY)))+1
I = 1 to N if Collision(1,Maska, X+I*LX/N, Y+I*LY/N) {
AngleSpeed= AngleXY (SpeedX, SpeedY) // Determine the angle of the velocity vector
Speed = Distance(SpeedX, SpeedY) // Define the module of the vector speed
A=AngleRange(AngleSpeed-AngleCollision)
B=Abs(A)
if B>90 { // The ball is rolled from the rim
Delay = Period*I/N dX=I*LX/N dY=I*LY/N
Delay = 0 Period=Period*(N-I)/N
State = 3
}
if Speed*Cos(AngleCollision-AngleSpeed)>22 { // A heavy blow on the side
// Determine the rebound angle from the side
Rebound = 180 - AngleSpeed + 2*AngleCollision
Speed = 0.5*Speed*(1+Sin(B)) // 0.5 The repayment factor of the rebound speed
SpeedX = Speed*Cos( Rebound)
SpeedY = Speed*Sin(-Rebound)
MP3 = 1
Delay = Period*I/N dX=I*LX/N dY=I*LY/N
Delay = 0 Period=Period*(N-I)/N
If Speed<1 Rest
State = 3
}
// The ball is rolling along the rim
d_X = I*LX/N -Cos(AngleCollision)
d_Y = I*LY/N +Sin(AngleCollision)
Rebound = AngleCollision + Sign(A)*90 // The angle of rebound from the side
Speed = 0.9*Speed*Sin(B) // 0.9 - The braking on the rim
If Speed<3 And i=1 {
dX=d_X dY=d_Y SpeedX=0 SpeedY=0
if Collision(1,Maska, X, Y) { // Push from the second side
dX = -Cos(AngleCollision)
dY = Sin(AngleCollision)
}
Rest }
Delay = Period*I/N dX=d_X dY=d_Y
Delay = 0
Period = Period*(N-I)/N
SpeedX = Speed*Cos( Rebound)
SpeedY = Speed*Sin(-Rebound)
State = 3
}
Delay=Period dX=LX dY=LY Delay=0
Rest
- - - - - CODE END - - - - -
The algorithm of the ball movement is called according to the timer with the 100ms period. The components of the speed vector along the axes of coordinates SpeedX and SpeedY are calculated from the previous value and the angle of inclination by the accelerometer. The speed value determines the line segment for moving the ball, for each 100 ms period. The line segment is divided into N equal parts by intermediate points of movement. For each point of movement in a cycle, we check the collision of the ball with the wall using the function Collision(). If there are no collisions, then the ball can move freely along the line segment, otherwise the value of the collision angle is assigned to the AngleCollision variable. The direction of rebound of the ball from the wall is calculated based on the moving direction and the collision angle.
The ball movement trajectories are contained in the file way.stt:
- - - - - CODE BEGIN - - - - -
// The character way to work with path
Slot[Way]=1
Rest
1: Delay=0
Nomer =10*TypeDevice // The number of path
Index =0
Person[1]=ball State[1]=1 // The character ball
State=Nomer
2: // MoveBall Changing the color of the trajectory when moving the ball
i = Index+1
If Distance(X[1]-X[i], Y[1]-Y[i])<20 Index=i
Color[Index]=ColorGreen
if Index<Count Rest
Slot[MoveBall]
I=2 To Count Color[I]=ColorBlue
Nomer = Nomer + 1
State = Nomer // Moving on to the next path
3: // Initialization of the path
X[1]=X[Index] Y[1]=Y[Index] SpeedX[1]=0 SpeedY[1]=0
// The conclusion of the arrows path at a certain angle
I=Index To Count-1 { Img[i]=0 oX[i]=0 Angle[i]=AngleXY(X[i+1]-X[i],Y[i+1]-Y[i]) }
Img[Count]=0 Angle[Count] =Angle[Count-1] oX[Count]=0
Index=Index-1 Slot [MoveBall]=2
State=2
10: Maska = 2 // The path of the letter C
X = XLetterC Y = YLetter
Parent[ 2]=0 X[ 2]=129 Y[ 2]=158
Parent[ 3]=0 X[ 3]=108 Y[ 3]=166
Parent[ 4]=0 X[ 4]= 86 Y[ 4]=167
Parent[ 5]=0 X[ 5]= 65 Y[ 5]=162
Parent[ 6]=0 X[ 6]= 46 Y[ 6]=152
Parent[ 7]=0 X[ 7]= 31 Y[ 7]=135
Parent[ 8]=0 X[ 8]= 22 Y[ 8]=114
Parent[ 9]=0 X[ 9]= 20 Y[ 9]= 93
Parent[10]=0 X[10]= 22 Y[10]= 71
Parent[11]=0 X[11]= 31 Y[11]= 50
Parent[12]=0 X[12]= 45 Y[12]= 33
Parent[13]=0 X[13]= 64 Y[13]= 22
Parent[14]=0 X[14]= 87 Y[14]= 19
Parent[15]=0 X[15]=111 Y[15]= 20
Parent[16]=0 X[16]=133 Y[16]= 29
Index=2 State=3
11:I=Count Downto 2 Destroy[i] // Remove the path
Maska = 3 // The path of the letter A
X = XLetterA Y = YLetter
Parent[ 2]=0 X[ 2]= 18 Y[ 2]= 12
Parent[ 3]=0 X[ 3]= 23 Y[ 3]= 33
Parent[ 4]=0 X[ 4]= 27 Y[ 4]= 54
Parent[ 5]=0 X[ 5]= 33 Y[ 5]= 73
Parent[ 6]=0 X[ 6]= 38 Y[ 6]= 97
Parent[ 7]=0 X[ 7]= 44 Y[ 7]=118
Parent[ 8]=0 X[ 8]= 51 Y[ 8]=140
Parent[ 9]=0 X[ 9]= 63 Y[ 9]=161
Parent[10]=0 X[10]= 82 Y[10]=161
Parent[11]=0 X[11]= 94 Y[11]=142
Parent[12]=0 X[12]=103 Y[12]=120
Parent[13]=0 X[13]=110 Y[13]= 99
Parent[14]=0 X[14]=116 Y[14]= 75
Parent[15]=0 X[15]=121 Y[15]= 55
Parent[16]=0 X[16]=126 Y[16]= 35
Parent[17]=0 X[17]=129 Y[17]= 17
Index=2 State=3
12: // Horizontal stick letters A
Parent[18]=0 X[18]= 50 Y[18]= 84
Parent[19]=0 X[19]= 75 Y[19]= 84
Parent[20]=0 X[20]=100 Y[20]= 84
Index=18 State=3
13: I=Count Downto 2 Destroy[i]
Maska = 4 // The path of the letter T
X = XLetterT Y = YLetter
Parent[ 2]=0 X[ 2]= 72 Y[ 2]=153
Parent[ 3]=0 X[ 3]= 72 Y[ 3]=132
Parent[ 4]=0 X[ 4]= 72 Y[ 4]=109
Parent[ 5]=0 X[ 5]= 72 Y[ 5]= 84
Parent[ 6]=0 X[ 6]= 72 Y[ 6]= 60
Parent[ 7]=0 X[ 7]= 72 Y[ 7]= 38
Parent[ 8]=0 X[ 8]= 72 Y[ 8]= 14
Index=2 State=3
14: // Horizontal stick letters T
Parent[ 9]=0 X[ 9]= 11 Y[ 9]=162
Parent[10]=0 X[10]= 35 Y[10]=162
Parent[11]=0 X[11]= 57 Y[11]=162
Parent[12]=0 X[12]= 81 Y[12]=162
Parent[13]=0 X[13]=105 Y[13]=162
Parent[14]=0 X[14]=128 Y[14]=162
Index=9 State=3
15:I=Count Downto 1 Destroy[i] // Remove the path
Send=CatMove
Rest
20: Maska = 2 // The path of the letter C in iPad (*2)
X = XLetterC Y = YLetter
Parent[ 2]=0 X[ 2]=258 Y[ 2]=316
Parent[ 3]=0 X[ 3]=216 Y[ 3]=332
Parent[ 4]=0 X[ 4]=172 Y[ 4]=334
Parent[ 5]=0 X[ 5]=130 Y[ 5]=324
Parent[ 6]=0 X[ 6]= 92 Y[ 6]=304
Parent[ 7]=0 X[ 7]= 62 Y[ 7]=270
Parent[ 8]=0 X[ 8]= 44 Y[ 8]=228
Parent[ 9]=0 X[ 9]= 40 Y[ 9]=186
Parent[10]=0 X[10]= 44 Y[10]=142
Parent[11]=0 X[11]= 62 Y[11]=100
Parent[12]=0 X[12]= 90 Y[12]= 66
Parent[13]=0 X[13]=128 Y[13]= 44
Parent[14]=0 X[14]=174 Y[14]= 38
Parent[15]=0 X[15]=222 Y[15]= 40
Parent[16]=0 X[16]=266 Y[16]= 58
Index=2 State=3
21:I=Count Downto 2 Destroy[i] // Remove the path
Maska = 3 // The path of the letter A in iPad
X = XLetterA Y = YLetter
Parent[ 2]=0 X[ 2]= 36 Y[ 2]= 24
Parent[ 3]=0 X[ 3]= 46 Y[ 3]= 66
Parent[ 4]=0 X[ 4]= 54 Y[ 4]=108
Parent[ 5]=0 X[ 5]= 66 Y[ 5]=146
Parent[ 6]=0 X[ 6]= 76 Y[ 6]=194
Parent[ 7]=0 X[ 7]= 88 Y[ 7]=236
Parent[ 8]=0 X[ 8]=102 Y[ 8]=280
Parent[ 9]=0 X[ 9]=126 Y[ 9]=322
Parent[10]=0 X[10]=164 Y[10]=322
Parent[11]=0 X[11]=188 Y[11]=284
Parent[12]=0 X[12]=206 Y[12]=240
Parent[13]=0 X[13]=220 Y[13]=198
Parent[14]=0 X[14]=232 Y[14]=150
Parent[15]=0 X[15]=242 Y[15]=110
Parent[16]=0 X[16]=252 Y[16]= 70
Parent[17]=0 X[17]=258 Y[17]= 34
Index=2 State=3
22: // Horizontal stick letters А
Parent[18]=0 X[18]=100 Y[18]=168
Parent[19]=0 X[19]=150 Y[19]=168
Parent[20]=0 X[20]=200 Y[20]=168
Index=18 State=3
23: I=Count Downto 2 Destroy[i]
Maska = 4 // The path of the letter T in iPad
X = XLetterT Y = YLetter
Parent[ 2]=0 X[ 2]=144 Y[ 2]=306
Parent[ 3]=0 X[ 3]=144 Y[ 3]=264
Parent[ 4]=0 X[ 4]=144 Y[ 4]=218
Parent[ 5]=0 X[ 5]=144 Y[ 5]=168
Parent[ 6]=0 X[ 6]=144 Y[ 6]=120
Parent[ 7]=0 X[ 7]=144 Y[ 7]= 76
Parent[ 8]=0 X[ 8]=144 Y[ 8]= 28
Index=2 State=3
24: // Horizontal stick letters T
Parent[ 9]=0 X[ 9]= 22 Y[ 9]=324
Parent[10]=0 X[10]= 70 Y[10]=324
Parent[11]=0 X[11]=114 Y[11]=324
Parent[12]=0 X[12]=162 Y[12]=324
Parent[13]=0 X[13]=210 Y[13]=324
Parent[14]=0 X[14]=256 Y[14]=324
Index=9 State=3
25:I=Count Downto 1 Destroy[i] // Remove the path
Send=CatMove
Rest
- - - - - CODE END - - - - -
Character way creates subordinate character ball as well as several child sprites with the arrow image for showing the path. The rotation angle of each arrow of the path is determined by the function AngleXY() so that the arrow points to the next sprite.
The number of the current path arrow is stored in the Index variable.
As the ball moves, the distance from it to the current arrow is determined by the Distance() function. If the ball is next to the current arrow, then the color of the arrow changes from white to green.
After the ball moved successfully through the maze, the child sprites and the subordinate character ball are be deleted, and the CatMove message is sent.
File cat.stt contains the description of character cat:
- - - - - CODE BEGIN - - - - -
// The Character Cat
Scale = 50
Slot[CatMove]=2
Rest
// The cat went
2: X=ScreenX Y=100 Opacity=100
Step = 1
// The gait of the cat is formed by the change of pictures 1..8
3: Img=Step Delay=200 dX=-15
Delay=0 Step=Step+1 if Step>8 Step=1
If X>0 State=3
// The cat has gone
Opacity=0
Send =Way
Rest
- - - - - CODE END - - - - -
The CatMove message calls state 2 and the movement begins. For animation of the Cat character, eight pictures are used. Each picture shows different position of the legs: cat001.png .. cat008.png. In state 3, the pictures changing order is set up, and the character moves smoothly to the left.
When the character reaches the left screen border, it disappears and sends the Way message for "Ball in a labyrinth" algorithm.
