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Hiten
04-21-2009, 12:17 AM
Hi there,
I'm new to OpenGL and making an application as Radar Display using OpenGL. Can anyone help me is some links which gives some sample codes or data about Radar Displays in openGL.

Thanks in advance.

Ilian Dinev
04-21-2009, 02:06 AM
Why would anyone have a tutorial or info on such a specific thing, which branches into a specific area, useless for anything else?
Imagine a radar, how it looks, when do bleeps happen. Do some trigonometry maths on paper, and then voila - you'll have the idea.

Hiten
04-21-2009, 04:23 AM
Hi,
Thanks for your reply.
I've developed it upto some level but have some problems.
I've a circle and a pointer which moves along the peripheri of the circle. Its like clock. I have to display all the targets withing the circle and keep the poinetr moving. Since i'm using glClear (GL_COLOR_BUFFER_BIT) and moving the pointer, all the targets which are displayed in the circle also disappeare.

Can you please suggest me something as i'm very new in openGL.

Thanks in advance.

scratt
04-21-2009, 04:29 AM
Draw all the points every time you do glClear, but have a timer or count for each one, which resets to a count (say 10) each time the pointer passes them.

Each time you draw the points decrement their counter and at the same time divide the dots colour by some value which will make it get darker. For example times each colour component by 0.1;

Stop drawing a dot when it's counter is 0.

This is a very basic way to do it.

A more nifty way for the future would be to use shaders and FBOs and draw the points only once when the pointer passes them like a real radar, and feed a copy of the last framebuffer into the next one but processed so that is is faded by a percentage... That method would almost exactly simulate the effect of a real radar... But you'll need to do some reading before you attempt that I suspect. :)
And thinking about it, whilst nice, it's probably a lot of overhead for a few dots!!

Hiten
04-21-2009, 04:37 AM
Hi,
Thank you very much for your valuable reply.
But i've one doubt. As the pointer goes increasing from 0 deg to 359 deg and evry time if i draw all the points wouldn't it be very slow and flickering will occur as these FBO and framebuffer are really new to me so don't know.
If you have any link or code which give some basic of doing this type of application, please forward me.

Thank you very much in advance.

scratt
04-21-2009, 05:04 AM
Google is your friend.. :)

wrt to flickering, you need to look into double buffering.
Again Google is your friend.

Try Nehe's tutorials, or Lighthouse 3D, and for FBOs try googling "Songho FBO".