Code archives/Miscellaneous/Tetris

Framework brl.blitz
Import brl.glmax2d
Import brl.random

Global W[21, 23], F[7, 4, 4, 4], L[7] ;

For S:String = Eachin "ABEF,AEFJEFBC,IEFBABFG,BFJNEFGH,AEFGCBFJEFGKIJFB,EFGCBFJKIEFGABFJ,EFBGBFGJEFGJBEFJ".Split(",") ;
	L[M] = Len(S) / 4 - 1;
	For I = 0 To L[M] ;
		For J = 0 To 3;
			A = S[I * 4 + J] - 65;
			F[M, I, A & 3, A Shr 2] = 1;
		Next;
	Next;
	M:+1;
Next;

Graphics 50, 200;
Y = 19;

Repeat;
	Cls;
	For I = 0 To 20;
		W[1, I] = 1;
		W[12, I] = 1;
		W[I, 20] = 1;
		For J = 1 To 12;
			If W[J, I] Then DrawRect J * 8, I * 8, 8, 8
		Next;
	Next;
	
	For I = 0 To 3;
		For J = 0 To 3;
			If F[N, R, I, J] Then DrawRect(X + I) * 8, (Y + J) * 8, 8, 8
		Next;
	Next;
	
	Flip;
	
	A = X + KeyHit(39) - KeyHit(37) ;
	B = Y + KeyDown(40) ;
	Q = (R + KeyHit(87) - KeyHit(81)) & L[N] ;
	IF C(A, B, N, Q) = 0 Then X = A;
	Y = B;
	R=Q
	M = Millisecs() ;
	If M > T Then
		T = M + 999;
		If C(X, Y + 1, N, R) Then
			If Y = 0 Then End
	
			For I = 0 To 3;
				For J = 0 To 3;
					If F[N, R, I, J] Then W[X + I, Y + J] = 1
				Next;
			Next;
			
			D = 0;
			
			For I = 19 To 0 Step - 1;
				Q = 0;
				For J = 2 To 11;
					If W[J, I] Then Q:+1
					W[J, I + D] = W[J, I] ;
				Next;
				IF Q > 9 Then D:+1
			Next;
			X = 5;
			Y = -1;
			N = Rand(0, 6) ;
		EndIf;
		Y:+1;
	End If;
Until KeyHit(27) ;

Function C(X, Y, N, R) ;
	For I = 0 To 3;
		For J = 0 To 3;
			If F(N, R, I, J) * W[I + X, J + Y] Then Return 1
		Next;
	Next;
EndFunction

SeedRnd Millisecs()

Global World[ 21, 23 ] ' Game field, stretched right for the shorter way to make glass bottom
Global Figure[ 7, 4, 4, 4 ] ' Stored tetris figures ( 7 pieces, 4x4 matrix, up to 4 phases)
Global Phases[ 7 ] ' Quantity of phases for figure ( 1, 2 or 4 )

For S$ = Eachin "ABEF,AEFJEFBC,IEFBABFG,BFJNEFGH,AEFGCBFJEFGKIJFB,EFGCBFJKIEFGABFJ,EFBGBFGJEFGJBEFJ".Split(",")
	' There's all phases of figures stored in the sting, using 4 letters per phase, comma separates figure string chunks
	' Every letter means a quadratic piece of figure in certain position, corresponding to following matrix:
	' ABCD
	' EFGH
	' IJKL
	' MNOP
	
	Phases[ M ] = Len( S ) / 4 - 1 ' ( Quantity of phases - 1 ) can be calculated by dividing string chunk by 4 and subtracting 1
	For I = 0 To Phases[ M ] ' These cycles fills the Figure matrices
		For J = 0 To 3
			A = S[ I * 4 + J ] - 65 ' This number converts symbol to number in range from 0 to 15 
			Figure[ M, I, A & 3, A Shr 2 ] = 1 ' 1 means filled square, 0 (by default) means empty
		Next
	Next
	M :+ 1 ' Incrementing figures counter
Next

Graphics 800, 600
Y = 19 ' current y-coordinate of figure, set to 19 to make initialization of new one

Repeat
	Cls
	For I = 0 To 20
		 ' Making glass boundaries
		World[ 1, I ] = 1 ' left wall (it is shifted from the edge to prevent error 
		' when figure matrix is situated partly outside of the game field)

		World[ 12, I ] = 1 ' right wall
		World[ I, 20 ] = 1 ' bottom
		
		' Drawing game field
		For J = 1 To 12
			If World[ J, I ] Then DrawRect J * 8, I * 8, 8, 8
		Next
	Next
	
	' Drawing current figure
	For I = 0 To 3 
		For J = 0 To 3
			If Figure[ N, R, I, J ] Then DrawRect ( X + I ) * 8, ( Y + J ) * 8, 8, 8
		Next
	Next
	
	Flip
	
	' This is cool controller handing method, that I borrowed from old Speccy magazines
	' If KEY_RIGHT is pressed then new value of X will be less than old by 1
	' If KEY_LEFT is pressed then new value of X will be more than old by 1
	A = X + KeyHit( KEY_RIGHT ) - KeyHit( KEY_LEFT )
	B = Y + KeyDown( KEY_DOWN )
	
	' Phase is "cycling" with (phases quantity - 1) = %0, %1 or %11 - by using logical operator AND
	Q = ( R + KeyHit( KEY_W ) - KeyHit( KEY_Q ) ) & Phases[ N ]
	
	' If new-positioned figure is not colliding with game field then it will be moved
	IF CheckPosition( A, B, N, Q ) = 0 Then
		X = A
		Y = B
		R = Q
	End If
	
	M = Millisecs()
	
	If M > T Then
		T = M + 999 ' figure will be moved down every second
		
		' Checking if figure collides with game field when moved down (if true then "finalize" it)
		If CheckPosition( X, Y + 1, N, R ) Then
			If Y = 0 Then End ' end of game because glass is filled to the top
			
			For I = 0 To 3 ' Transferring figure from its matrix to the game field (by filling corresponding squares)
				For J = 0 To 3
					If Figure[ N, R, I, J ] Then World[ X + I, Y + J ] = 1
				Next
			Next
			
			' This mechanism will check filled rows and also moving down upper stuff if there's any
			D = 0 ' Current steps to shift game field contents by
			For I = 19 To 0 Step -1
				Q = 0
				For J = 2 To 11
					If World[ J, I ] Then Q :+ 1
					World[ J, I + D ] = World[ J, I ]
				Next
				IF Q > 9 Then D :+ 1 ' If there's 10 squares in a row then shift steps will be incremented by 1
			Next
			
			' Initializing new random figure on the top of the glass
			X = 5
			Y =  - 1
			N = Rand( 0, 6 )
		EndIf
		
		Y :+ 1 ' Moving figure down
	End If
Until KeyHit( KEY_ESCAPE )

' This function checks collisions of game field and figure N with phase R in ( X, Y ) coords
Function CheckPosition( X, Y, N, R )
	For I = 0 To 3
		For J = 0 To 3
		 	' Returns 1 if any filled figure square is placed on filled square of game field
			If Figure[ N, R, I, J ] * World[ I + X, J + Y ] Then Return 1
		Next
	Next
	' Returns 0 if there's no collision
EndFunction