IntyBASIC bats!

[+nanochess]

Hi.

 

Just I worked out this IntyBASIC demo of bats flying and attacking on screen.

 

It uses the new structured programming features (block IF and DO loop) so when you check the source code, there are no labels!

 

Also the SPRITE expr feature available now in IntyBASIC v1.2.3

 

Enjoy it!

	REM
	REM Bats
	REM Demo for IntyBASIC
	REM by Oscar Toledo G. http://nanochess.org/
	REM Sep/01/2015
	REM

	' Note there is no use of labels, thanks to the use of the structured loops

	include "constants.bas"

	DIM x(,y(,f(,dx(

	' Put in random coordinate each bat
        FOR a = 0 TO 7
        x(a) = RANDOM(152) + 8
        y(a) = RANDOM(48) + 24
	f(a) = $2d		' Uses M and W letter ($2d and $37), V for attack ($36)
	dx(a) = 1
	NEXT a

	bats = 8
	
	' Main loop
	DO
		' Show bats
		FOR a = 0 TO 7
			SPRITE a,x(a)+VISIBLE,y(a),f(a)*8+(a AND 1)*3+2
		NEXT a
		WAIT
		' Move bats
		FOR a = 0 TO 7
			IF f(a) = $36 THEN	' Attacking?
				IF y(a) < 104 THEN y(a) = y(a) + 1:IF y(a) > 103 THEN bats = bats - 1
			ELSE
				' Bats goes left to right and back
				x(a) = x(a) + dx(a)
				IF x(a) = 8 OR x(a) = 160 THEN dx(a) = -dx(a)
				' Vertical movement is random (-2 to +2)
				y(a) = y(a) + RANDOM(5) - 2
				IF y(a) < 8 THEN y(a) = 8
				IF y(a) > 80 THEN y(a) = 80
				' Move wings each 4 frames
				IF (FRAME AND 3) = 0 THEN IF f(a) = $2D THEN f(a) = $37 ELSE f(a) = $2d
			END IF
		NEXT a
		IF (FRAME AND 255) = 0 THEN	' Each 256 frames, a bat attacks
			FOR a = 0 TO 7
				IF f(a) <> $36 THEN f(a) = $36:EXIT FOR
			NEXT a
		END IF
	LOOP UNTIL bats = 0

	WAIT

        FOR a = 0 TO 7
		SPRITE a,0
	NEXT a

bats.bas

[artrag]

Lovely !

 

PS

Thanks for the new implementation.

 

Now one can pass from this:

sprite: procedure

on n goto s0,s1,s2,s3,s4,s5,s6,s7

s0: SPRITE 0,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE: return

s1: SPRITE 1,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE: return

s2: SPRITE 2,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE: return

s3: SPRITE 3,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE: return

s4: SPRITE 4,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE: return

s5: SPRITE 5,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE: return

s6: SPRITE 6,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE: return

s7: SPRITE 7,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE: return

end

to this:

SPRITE n,x+VISIBLE,y+ZOOMY2,SPR00+SPR_BLUE

Edited September 2, 2015 by artrag

[JohnPCAE]

Suddenly I had a thought of a port of the Atari 2600 version of Demon Attack...

[Kiwi]

You know what this sample needs? More bats!!!

 

	REM Bats
	REM Demo for IntyBASIC
	REM by Oscar Toledo G. http://nanochess.org/
	REM Sep/01/2015
	REM

	' Note there is no use of labels, thanks to the use of the structured loops

	include "constants.bas"
	FLICKER=0
	Timer=0
	DIM x(16),y(16),f(16),dx(16)

	' Put in random coordinate each bat
        FOR a = 0 TO 15
        x(a) = RANDOM(152) + 8
        y(a) = RANDOM(48) + 24
	f(a) = $2d		' Uses M and W letter ($2d and $37), V for attack ($36)
	dx(a) = 1
	NEXT a

	bats = 16
	
	' Main loop
	DO
		' Show bats
		Timer=Timer+1
		IF flicker=0 then
		FOR a = 0 TO 7
			SPRITE a,x(a)+VISIBLE,y(a),f(a)*8+(a AND 1)*3+2
		NEXT a
		END IF
		if flicker=0 then flicker=1:goto flick
		IF flicker=1 then
		FOR a = 0 TO 7
			SPRITE a,x(a++VISIBLE,y(a+,f(a+*8+(a+8 AND 1)*3+2
		NEXT a
		flicker=0
		END IF
		flick:
		WAIT
		' Move bats
		FOR a = 0 TO 15
			IF f(a) = $36 THEN	' Attacking?
				IF y(a) < 104 THEN y(a) = y(a) + 1:IF y(a) > 103 THEN bats = bats - 1
			ELSE
				' Bats goes left to right and back
				x(a) = x(a) + dx(a)
				IF x(a) = 8 OR x(a) = 160 THEN dx(a) = -dx(a)
				' Vertical movement is random (-2 to +2)
				y(a) = y(a) + RANDOM(5) - 2
				IF y(a) < 8 THEN y(a) = 8
				IF y(a) > 80 THEN y(a) = 80
				' Move wings each 4 frames
				IF (Timer AND 3) = 0 THEN IF f(a) = $2D THEN f(a) = $37 ELSE f(a) = $2d
			END IF
		NEXT a
		IF (Timer AND 255) = 0 THEN	' Each 256 frames, a bat attacks
			FOR a = 0 TO 15
				IF f(a) <> $36 THEN f(a) = $36:EXIT FOR
			NEXT a
		END IF
	LOOP UNTIL bats = 0

	WAIT

        FOR a = 0 TO 7
		SPRITE a,0
	NEXT a

I would have got fired from Mattel for multiplexing sprites and get fired from nanochess for using a label in this sample.

Anyway, I used label to do flickering routine for the Colecovision and decided to use it here since I didn't know a way to do flipflop. I changed FRAME to Timer since FRAME is a 16-bit variable and Timer is 8-bit. So the event of the bats to attack wasn't working properly with 16 bats. This is just a short exercise to test out multiplexing.

[+nanochess]

Hehehe, pretty well done!

 

BTW, as you increase timer in >each< frame, you get same behavior as with FRAME AND 255, besides as Timer is an 8 bits variable the AND 255 is unneeded.

 

Furthermore, you could have created a constant called MAX_BATS = 16, and use it in the FOR loop as MAX_BATS - 1

 

Going further, you can delete the label using the IF block feature:

 

 

IF flicker=0 then
        FOR a = 0 TO 7
            SPRITE a,x(a)+VISIBLE,y(a),f(a)*8+(a AND 1)*3+2
        NEXT a
        flicker = 1
ELSE
        FOR a = 0 TO 7
            SPRITE a,x(a++VISIBLE,y(a+,f(a+*8+(a+8 AND 1)*3+2
        NEXT a
        flicker=0
END IF

[artrag]

While optimizing, you could replace this:

        FOR a = 0 TO 7
            SPRITE a,x(a++VISIBLE,y(a+,f(a+*8+(a+8 AND 1)*3+2
        NEXT a

by the following code, that saves 8*4 = 32 additions at the cost of 8 subtractions

        FOR a = 8 TO 15
            SPRITE a-8,x(a)+VISIBLE,y(a),f(a)*8+(a AND 1)*3+2
        NEXT a

[+nanochess]

 

While optimizing, you could replace this:

        FOR a = 0 TO 7
            SPRITE a,x(a++VISIBLE,y(a+,f(a+*8+(a+8 AND 1)*3+2
        NEXT a

by the following code, that saves 8*4 = 32 additions at the cost of 8 subtractions

        FOR a = 8 TO 15
            SPRITE a-8,x(a)+VISIBLE,y(a),f(a)*8+(a AND 1)*3+2
        NEXT a

In fact thanks to the new IntyBASIC optimizer, both code sequences run at same speed you can write it as you like most

[artrag]

Impressive! Is it already released in the current intybasic or will it appear in the next versions ?

[Kiwi]

Hehehe, pretty well done!

 

BTW, as you increase timer in >each< frame, you get same behavior as with FRAME AND 255, besides as Timer is an 8 bits variable the AND 255 is unneeded.

 

Furthermore, you could have created a constant called MAX_BATS = 16, and use it in the FOR loop as MAX_BATS - 1

 

Going further, you can delete the label using the IF block feature:

IF flicker=0 then
        FOR a = 0 TO 7
            SPRITE a,x(a)+VISIBLE,y(a),f(a)*8+(a AND 1)*3+2
        NEXT a
        flicker = 1
ELSE
        FOR a = 0 TO 7
            SPRITE a,x(a++VISIBLE,y(a+,f(a+*8+(a+8 AND 1)*3+2
        NEXT a
        flicker=0
END IF

 

FRAME variable I believe is increased at every interrupt. So if the game is at half speed, then it won't hit 255 or 3, so I think FRAME is increasing by 2. So the events weren't activating. Currently, I'm trying to figure out how to make it stop multiplexing when the bats are less than 9. Eventually I'll crack the code. And also I'm thinking of making a game based of this sample. Edited September 9, 2015 by Kiwi

[artrag]

I would avoid sprite multiplexing if you plan to run the main loop at 30Hz...

Flickering would be too high.

 

Btw

There is also on frame gosub...

It could be used to multiplex sprites independently of the main loop timings.

Edited September 9, 2015 by artrag

[+nanochess]

Impressive! Is it already released in the current intybasic or will it appear in the next versions ?

 

Already supported since v1.2

 

FRAME variable I believe is increased at every interrupt. So if the game is at half speed, then it won't hit 255 or 3, so I think FRAME is increasing by 2. So the events weren't activating. Currently, I'm trying to figure out how to make it stop multiplexing when the bats are less than 9. Eventually I'll crack the code. And also I'm thinking of making a game based of this sample.

 

Yes, but you were updating the variable in each frame or maybe simply the program went slow and you were losing frames.

 

You can use the 'bats' variable as reference counter as the bats are deleted in sequence.

[intvnut]

Currently, I'm trying to figure out how to make it stop multiplexing when the bats are less than 9. Eventually I'll crack the code. And also I'm thinking of making a game based of this sample.

 

The trick I use is to keep track of the "first not displayed" sprite when scanning the list of active sprites, and display the first 8 active sprites after that. Then I update the "first not displayed" variable, so the next frame picks up where I left off. This results in gradual multiplexing as the scene gets busier.

 

I whipped up a really crude demo just now to demonstrate. Buttons 0..7 on the two controllers will toggle 16 different sprites on/off. Once 9 go active, it starts multiplexing, but only one sprite gets left off of each screen, and the unlucky sprite rotates through the whole list.

.

' Multiplexing demo with up to 16 sprites
' An inactive sprite sets x(i) = 0
'
' Demo by J. Zbiciak
' Hereby placed in public domain

DIM x(16), y(16), #a(16)

first_not_displayed = 0

CLS

' Initially all sprites are off
FOR i = 0 TO 15 
    x(i) = 0
NEXT i


WHILE 1
    WAIT

    ' Keys 0 .. 7 on each controller toggle which sprites are active

    IF bounce_counter = 0 THEN
        IF CONT1.KEY < 8 THEN snum =     CONT1.KEY : GOSUB ToggleSprite
        IF CONT2.KEY < 8 THEN snum = 8 + CONT2.KEY : GOSUB ToggleSprite
    ELSE
        IF CONT.KEY = 12 THEN bounce_counter = bounce_counter - 1
    END IF

    ' Multiplex loop:  Scan starting at 'first not displayed' until up to
    ' 8 active sprites are found

    active = 0
    FOR i = 0 to 15
        ii = (i + first_not_displayed) AND 15

        IF x(ii) <> 0 THEN
            SPRITE active, x(ii) + $200, y(ii) + $100, #a(ii)
            active = active + 1
            IF active = 8 THEN
                first_not_displayed = (ii + 1) AND 15
                EXIT FOR
            END IF
        END IF
    NEXT i

WEND



ToggleSprite:   PROCEDURE 
    bounce_counter = 5

    IF x(snum) > 0 THEN
        x(snum) = 0
        RETURN
    END IF

    x (snum) = 9 * snum + 9 
    y (snum) = 6 * snum + 6
    #a(snum) = ($41 + snum) * 8 + 7

    RETURN
END

Edited September 9, 2015 by intvnut

[+DZ-Jay]

That's neat, intvnut. Do you mind if we add it to the SDK "Examples" folder?

[intvnut]

That's neat, intvnut. Do you mind if we add it to the SDK "Examples" folder?

 

Certainly! Be my guest!

 

I'll leave it as an "exercise for the reader" to fold this approach into the Bats program that started the thread.

 

[+DZ-Jay]

 

Certainly! Be my guest!

 

I'll leave it as an "exercise for the reader" to fold this approach into the Bats program that started the thread.

 

Cool, thanks.

[Rev]

How about a mode where we can shoot the bats?

[+nanochess]

How about a mode where we can shoot the bats?

Possible. It would look a lot like Galaxian

[carlsson]

Indeed! The demo reminds me a bit of the second level in Arcadia by Imagine Software, for the ZX Spectrum, VIC-20, C64 and Dragon 32. The game is said to borrow from both Galaxian and Gorf.

 

https://en.wikipedia.org/wiki/Arcadia_(video_game)