Thanks, I'll have a look.
I modified your LCD line procedure (this works on my glcd as well),
but why do you use sword to draw a line? I assume that you can only
start and end a line within LCD_X_RES 0 to 84, and LCD_Y_RES 0 to 48.
It is good practice to use small variables if possible. In your case,
byte variables may be enough. The same may be true for ellipse/circle
-- draw line procedure
procedure lcd_line_2(byte in x0,byte in y0, byte in x1, byte in y1)
is
var sword dx = sword(x1) - sword(x0)
var sword dy = sword(y1) - sword(y0)
var sword twoDx = dx + dx
var sword twoDy = dy + dy
var sword currentX = sword(x0), currentY = sword(y0)
var sword xinc = 1, yinc = 1
var sword twoDx_accumulated_error, twoDy_accumulated_error
if dx < 0 then
xinc = -1
dx = -dx
twoDx = -twoDx
end if
if dy < 0 then
yinc = -1
dy = -dy
twoDy = -twoDy
end if
lcd_write_pixel(x0,y0,LCD_PEN_COLOR) -- first point is special case
if (dx != 0) | (dy != 0) then -- are there other points on the line?
if dy <= dx then -- is the slope <= 1 ?
twoDx_accumulated_error = 0 -- initialize error
while currentX != x1 loop
currentX = currentX + xinc -- consider x's from x0 to x1
twoDx_accumulated_error = twoDx_accumulated_error + twoDy
if twoDx_accumulated_error > dx then
currentY = currentY + yinc
twoDx_accumulated_error = twoDx_accumulated_error - twoDx
end if
lcd_write_pixel(byte(currentX), byte(currentY), LCD_PEN_COLOR)
end loop
else -- the slope is large: reverse roles of X & Y
twoDy_accumulated_error = 0 -- initialize error
while currentY != y1 loop
currentY = currentY + yinc -- consider y's from y0 to y1
twoDy_accumulated_error = twoDy_accumulated_error + twoDx
if twoDy_accumulated_error > dy then
currentX = currentX + xinc
twoDy_accumulated_error = twoDy_accumulated_error - twoDy
end if
lcd_write_pixel(byte(currentX), byte(currentY), LCD_PEN_COLOR)
end loop
end if
end if
end procedure
Matt.
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