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View Full Version : A lot of doubts about transformation and view.



kaberdock
08-05-2013, 03:06 PM
Hello everyone, first of all thanks to try help me.
Second sorry about my English, I'm brazilian.

I'm trying to model a low-poly hand using basic objects like cyliders and spheres that I will use to represent a hand configuration of brazilian sign language. So in my program I'll enter with a vector of quaternions that will represent the angles of all the joints of the hand. So my problem is:

When I rotate the thumb to be in front of the palm it seems smaller than it should be:

http://imageshack.us/a/img821/7616/e54.th.png (http://imageshack.us/photo/my-images/821/e54.png/)
thumb with right size beside the palm

http://imageshack.us/a/img59/24/rrv5.th.png (http://imageshack.us/photo/my-images/59/rrv5.png/)
thumb in front of the palm that seems smaller.

Other problem that I have is if I change the camera postion to be beside the hand the result is it:

http://imageshack.us/a/img191/1656/uoo0.th.png (http://imageshack.us/photo/my-images/191/uoo0.png/)

so, the first problem I think that can be a problem of projection, but I don't know what and the second problem I really don't know what it can be.

Carmine
08-05-2013, 04:03 PM
When I rotate the thumb to be in front of the palm it seems smaller than it should be ...I can't see your images on my computer, so I'm just guessing below ...

Do you have Z-buffering turned on? Sounds like the thumb might be going behind the hand NOT in front of it. Therefore it would get smaller (assuming you are using a perspective projection). If Z-buffering is not enabled, whatever is drawn last is displayed over stuff that was drawn before it. Z-buffering is turned on as follows: glEnable (GL_DEPTH_TEST);

Also check how you've set up your clipping planes. If that's done incorrectly you can get some funky results.

kaberdock
08-05-2013, 05:39 PM
Yah, it's a stupid error of transformation, the rotation that I do must be with a negative angle (I'm an idiot I know). Thanks a lot.

But the second error that if I put the camera at with Z=0 than then result is a plateau mesh. Other problem that I'm having is that if I change the camera, All my translates change and my hand is separated.

Carmine
08-05-2013, 10:52 PM
I suggest you turn on the Z-Buffering and add some basic lighting to your scene.
It will make your scene easier to understand which will make debugging a lot easier.