Scratch

Jens · 2008-02-13 06:04:10

I just tried creating a project which relies on color sensing and noticed that while it does behave correctly in Scratch, it sometimes fails in the online version.

it's an attempt to let a sprite bounce off irregular surfaces:
http://scratch.mit.edu/projects/Jens/98418

It involves rotating a sprite until colored "sensor" dots touch a surface color (black) to approximate the surface's slope. Sometimes the black surface color seems to be sensed by the sprite despite it actually not touching the sensor. I also noticed that this bug appears more frequently the slower the sprite is moved or rotated (Try setting the bouncer's speed to 1).

Looking closely at the sensor dots in the Java player I sometimes seem to make out a dark "mask" around sprites. I wonder if that may be part of the problem.

First I thought it might be related to image compression, so I tried uploading with image compression turned off - no luck. Then I remembered that there is a known bug in version 1.2.1 related to image compression, which cannot be avoided by unchecking image compression:

http://scratch.mit.edu/forums/viewtopic.php?pid=14308#p14308

Hence I did as John suggested in that post and switched to v.1.1 to upload my project. But I'm still encountering the same problem, albeit less often than before.

Any advice?

Paddle2See · 2008-02-13 10:56:46

I have also noticed a dark edge around some sprites when I have uploaded to the web. This is particularly noticable on white sprites (such as the eraser sprite in my Tech Paint project).

tianabannana · 2010-04-04 05:06:07

[blocks} i w\nt to wal kup stairs is it possible

Paddle2See · 2010-04-04 06:18:09

tianabannana wrote:
[blocks} i w\nt to wal kup stairs is it possible

Hi tianabannana - That's an interesting question! But it doesn't seem to have anything to do with the topic that you've posted it on (Color Sensing Issue With The Java Player). In the future, please use the "Post new topic" link in the upper right-hand corner of the main forum page to make your own topic. Also, you probably should post a question like that in the "All About Scratch" forum as "Troubleshooting" is for reporting problems with Scratch or the website smile

Getting to your question about walking up stairs, I'm guessing that you want to do an animation of somebody walking up stairs. Probably the simplest way would be to take a sprite that has a walking cycle in its costumes (like the Scratch Cat) and set up a Forever loop with the Next Costume and a Wait block so that it looks like it's walking, then just change the sprite direction so it is pointing to the top of the stairs and use a Glide block to move it up the stairs. It wouldn't look quite right but it would probably get the idea across.

Another (harder) method would be to build a set of costumes that showed the legs going up stairs and then try to synchronize them with a staircase. I hope that helps...maybe somebody else on the forums has an example they could share smile