Wierd Deluxe Paint behaviour

[Ral-Clan]

Hi,

I've found some "wierd" behaviour in DeluxePaint when rotating brushes.  The result is a stretched looking brush.  This is something I've never noticed before.  I'm running in emulation under WinUAE and I'm just wondering if anyone can confirm whether or not this also happens with a real hardware Amiga.

The problem occurs when you pick up a brush (like a perfect circle) and rotate it with the "90 degree" option under the BRUSH menu.  The result is no longer a perfect circle, but an elongated egg shape.  Depending on the screen mode used, this could be slight or very, very badly stretched.  Like in 640x200 mode it's really noticeable and unusable.

Here is an example (click on the picture to enlarge it):



The only mode I've found where the rotation works "normally" is PAL 320x256.  That makes sense since it is almost a 1:1 ratio resolution.

This also occurs with the tool that allows you to rotate the brush to any angle.  As the brush approaches an angle 90 degrees from its original orientation it starts to stretch.

So...does this also happen on a real hardware Amiga (just draw a perfect circle or square, pick it up and rotate it to find out)?

[Selles]

Keep in mind that the Amiga is a "video" computer, the PC is not. Also, brushes come natural to the Amiga, but the PC has a very hard time with brushes. In fact, I have never found any PC art program that allows you to cut out an area of graphics, clear the screen or swap to another screen, and stamp that piece of graphic down. We take this operation for granted on the Amiga, but, the PC computers have a very hard time using a piece of graphic as a brush. So, there lies the problem. Even thou you are running Deluxe Paint on an emulated Amiga, it is not a true Amiga computer. You are trying to force PC hardware to do what comes natural to Amiga hardware.
 
Come to think of it, this was one of the features that was missing in the PC version of Deluxe Paint 2, the abilty to cut out a piece of the picture and use it as a brush.

[Ral-Clan]

Keep in mind that the Amiga is a "video" computer, the PC is not.  Also, brushes come natural to the Amiga, but the PC has a very hard time with brushes.  In fact, I have never found any PC art program that allows you to cut out an area of graphics, clear the screen or swap to another screen, and stamp that piece of graphic down.  We take this operation for granted on the Amiga, but, the PC computers have a very hard time using a piece of graphic as a brush.  So, there lies the problem.  Even thou you are running Deluxe Paint on an emulated Amiga, it is not a true Amiga computer.  You are trying to force PC hardware to do what comes natural to Amiga hardware.

Thanks for your reply, but I'm not convinced any of your points are really applicable to the problem stated in the original message.  I'm not trying to run DPAINT directly on a PC, I'm running it inside an emulated Amiga in WinUAE - yes WinUAE runs on a PC, but DPAINT doesn't know that.  Besides, not wanting to veer off the original message, I do know of a few PC programs that allow brushes to be picked up and stamped down on other pictures.

Can anyone confirm whether or not the behaviour mentioned in the first also occurs on a real Amiga?  Thanks.

[Amiduffer]

How bizarre. Yeah, that would never happen with DPaint on regular Ami hardware.

[Selles]

Actually, it does apply. Think about it. A PC does not handle video, and this includes screen modes, the same way the Amiga does. So, what appears one way on an Amiga, can appear differently on a PC.
 
Do you know the names of these PC art programs that can do brushes the same way the Amiga can? I would like to try them.

[Ral-Clan]

Actually, it does apply. Think about it. A PC does not handle video, and this includes screen modes, the same way the Amiga does. So, what appears one way on an Amiga, can appear differently on a PC.
 
Do you know the names of these PC art programs that can do brushes the same way the Amiga can? I would like to try them.

http://cosmigo.com/promotion/index.php?Features
http://pxp.grapefruitopia.com/

Deluxe Paint II for DOS (I just tested in in Windows XP and it works fine - with brushes).
http://www.phatcode.net/downloads.php?id=201

[Merc]

If I remember correctly, DPaint had an option somewhere to tell it to treat your screen as square, ie the same number of vertical and horizontal lines.
It's been a while but I think it was in the preferences somewhere or one of the menus.

I suspect by default it does some scaling to make up for the difference in height vs. width of the screen in pixels and maybe that is coming into play with higher (and more square) resolutions?

There's no reason I can imagine that a PC would have some strange problem rotating a brush, we're emulating an Amiga, so there's no reason it should look any different at all from the real thing unless there's a bug in WinUAE that distorts how bobs are displayed.

@Selles, there's no hardware reason why a PC paint program couldn't behave exactly like DPaint, I think it's just that DPaint was the standard on Amiga so many other programs copied the same sort of functionality, but on the PC it wasn't as common.  I believe the PC version of DPaint 3 (?) has the same brush handling as on the Amiga.

Hope that helps (gonna have to break out UAE now and give old Dpaint a try)

[yakumo9275]

ignore selles ignorant crap

your findings are correct because your seeing a huge difference between the horizontal and vertical aspect ratios. If you drew it sideways correctly and rotated 90 it would be squished in the vertical. You were spot on with your 1:1 guess.

On a real CRT I would expect you to see the same behaviour because your shape still has more vertical lines than horizontal lines.

(ps. cosmigo promotion kicks ass!)

[Ral-Clan]

How bizarre. Yeah, that would never happen with DPaint on regular Ami hardware.

Can someone actually try it on a real Amiga in 680x200 non-interlace mode (or something close) and post the results.  Thanks.

If I use 640x480 (interlace) mode things don't look as bad (obviously because we closer to a 1:1 screen ratio).

The very distorted picture posted at top was done in 640x200 non-interlace mode.

[tone007]

Do you know the names of these PC art programs that can do brushes the same way the Amiga can? I would like to try them.

There was also Paint Shop Pro for DOS back in the 90s that had this feature, I believe.

Good luck finding a copy, though.

[Ral-Clan]

ignore selles ignorant crap

your findings are correct because your seeing a huge difference between the horizontal and vertical aspect ratios. If you drew it sideways correctly and rotated 90 it would be squished in the vertical. You were spot on with your 1:1 guess.

On a real CRT I would expect you to see the same behaviour because your shape still has more vertical lines than horizontal lines.

(ps. cosmigo promotion kicks ass!)

Thanks!  I suspected as much but just needed confirmation that it WASN'T a UAE bug (and it didn't seem to me it would be).

Yes, I think Selles is not understanding what is going on, fundamentally.

[Franko]

It's perfectly normal behaviour when drawing in a mode like 640 x 200. It's nothing to do with the monitor whatsever...

The answer is simple, when you rotate the brush 90 degrees you just use stretch or expand in the horizontal direction to double the width and bob's your uncle the brush is now the correct apsect...