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フラグメントシェーダー 七宝模様
七宝模様です。
DIM ST(2),C(3),T1(2),T2(2)
ASK BITMAP SIZE XSIZE,YSIZE
SET COLOR MODE "NATIVE"
SET POINT STYLE 1
SET WINDOW -XSIZE/MIN(XSIZE,YSIZE),XSIZE/MIN(XSIZE,YSIZE),-YSIZE/MIN(XSIZE,YSIZE),YSIZE/MIN(XSIZE,YSIZE)
CALL VEC2(T1,0,0)
CALL VEC2(T2,1,1)
FOR YY=0 TO YSIZE-1
FOR XX=0 TO XSIZE-1
LET X=(XX*2-XSIZE)/MIN(XSIZE,YSIZE)
LET Y=(YY*2-YSIZE)/MIN(XSIZE,YSIZE)
CALL VEC2(ST,X,Y)
MAT ST=5*ST
FOR I=1 TO 2
LET ST(I)=FRACT(ST(I))
NEXT I
MAT ST=2*ST
LET INDEX=0
LET INDEX=INDEX+STEP(1,MOD(ST(1),2))
LET INDEX=INDEX+STEP(1,MOD(ST(2),2))*2
FOR I=1 TO 2
LET ST(I)=FRACT(ST(I))
NEXT I
IF INDEX=1 OR INDEX=2 THEN
LET ST(1)=1-ST(1)
END IF
IF DISTANCE(ST,T1)<1 AND DISTANCE(ST,T2)<1 THEN
CALL VEC3(C,1,1,0)
ELSE
CALL VEC3(C,1,0,0)
END IF
CALL SETCOLOR(C(1),C(2),C(3))
PLOT POINTS:X,Y
NEXT XX
NEXT YY
END
EXTERNAL SUB SETCOLOR(R,G,B)
SET COLOR COLORINDEX(CLAMP(R,0,1),CLAMP(G,0,1),CLAMP(B,0,1))
END SUB
EXTERNAL FUNCTION DISTANCE(A(),B())
LET DISTANCE=SQR((B(1)-A(1))^2+(B(2)-A(2))^2)
END FUNCTION
EXTERNAL FUNCTION FRACT(X)
LET FRACT=X-INT(X)
END FUNCTION
EXTERNAL FUNCTION STEP(A,X)
IF X0 THEN
LET SIGN=1
ELSE
LET SIGN=0
END IF
END FUNCTION
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