TI99 Environment

CALL_MOTION

Syntax

CALL_MOTION(sprite-number,yspd,xspd)

Description

This function changes the row-velocity, yspd and column-velocity, xspd of sprite sprite-number and sets (or maintains) the sprite in auto-motion in the direction established by the values in yspd and xspd.
sprite-number values range between 1- maxsprites and the sprite must be active. (the Call_Sprite() function can be used to set new sprites in motion).
The row and column velocities (yspd, xspd) may be from -128 to 127. If both the row and column velocities are zero, the sprite is stationary. A positive row velocity (yspd) moves the sprite down and a negative value moves it up. A positive column-velocity (xspd) moves the sprite to the right and a negative value moves it to the left.

Programs that set sprites in auto-motion require a ti_sync() within the program loop instead of the built-in sync or fastsync statement.

Example Code

Example 1:
` Call_Motion test using joystick
speed = 10
CALL_CLEAR()
call_char(33,"7EA5819981BD817E") 
display_at(1,1,"Use joystick to move around",0)
CALL_SPRITE(1,33,5,96,128,0,0)
do
 CALL_JOYST(1,X,Y) : x = joystx : y = joysty
 CALL_MOTION(1,-Y * speed,X * speed)
 ti_sync()
loop

Example 2:
` Bouncing ball - Call_Motion Test
call_char(42,"3c7effffffff7e3c")
call_char(96,"0")
CALL_SPRITE(1,42,5,92,128,0,0)
call_hchar(13,1,96,32)
call_colorchar(96,1,12)
for xvel = -30 to 30 step 2
   for yvel = -50 to 50 step 2
      display_at(1,11,str$(xvel)+"   "+str$(yvel),0)
      CALL_MOTION(1,yvel,xvel)
      ti_sync()
   next yvel
next xvel
CALL_MOTION(1,0,0)
call_char(42,call_charpat(95))
tiwaitkey()
end

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