The point I was making is simply that your x and y should always fit into a byte. sword, word, etc are all too large. sbyte is not good to use either since someone with more then 127 x_pixels or y_pixels can't use byte.
If all your swords are changed to byte, you will save 7 bytes ram, and some program memory. It takes longer to process larger variables. You don't have to change it, I'm just suggesting. Matt. On Dec 14, 4:23 pm, pdhaene <[email protected]> wrote: > I used sword because: > > x0 = 50 > x1 = 3 > > will make dx < 0 > > Paul > > On 14 Dec., 21:27, mattschinkel <[email protected]> wrote: > > > > > 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.- Hide quoted text - > > - Show quoted text - -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
