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Xerion

Member Since 21 Jan 2009
Offline Last Active Feb 25 2014 07:16 PM

Topics I've Started

Help with Bullet and box selection

27 January 2014 - 06:24 AM

Hello all,

 

I followed the bullet demo for picking object and was able to successfully add it to my pet project.

 

What I am trying to do and failing is to have a rubber band selection in my opengl window.

My though are on this line. A rubber band is pretty much a 2d box so I can easily get the 4 cornes and similalry to the demo for single click picking I can get the near and the far points for each of my corners. Thus I will have 8 points or a frustrum if you wanna call it as such.

 

How can I use bullet to get all my objects that reside in that frustrum ?  

I have been reading that I can do it either via the btPairCachingGhostObject or btGhostObject.

 

Anyone can provide a simple example ?

 

Thanks in advance


Keeping track of torations arround arbitary points

08 February 2009 - 12:43 PM

The titile may be a bit enigmatic but i am in need to know the angles of rotations that are applied when a user moves arround. The user can rotate freely arround any axis or any arbitary point. Things are really easy if you allow rotation only arround x,y,z axis as you can just keep track of the 3 rotation angles... But what happens when we have rotations arround arbitary points ? How can i find the 3 angles that i need to rotate from my origin to get at the same exact view that the user had ? I only talk about rotations cause the translations are really easy to get from the GL_MODELVIEW[16]. I need to do that so i can save the exterior orientation(EO) of the locations that the user selects which actually means knowing the x,y,z and the 3 rotations ω,φ,κ from the origin of the coordinate system. Not allowing the user to move freely arround is not a solution :P Thank you in advance

How can i create gradient circles ?

26 January 2009 - 03:58 PM

Kinda newbie question but here it is ! :) I want to draw lots of circles that are gradient. Can this be done somehow ? or i have to texture map ?

Tile Rendering and wrong colors ?

21 January 2009 - 04:32 PM

Hello i just wanted to save my viewport to higher resolution(for example 4kx4k pixels) and from what i have been reading tile rendering is the way to go or using Framebuffer object and then saving it. Well i tried both but the quality of the image of the FBo was not the best which i really dont know why :) It had some blurness arround the objects i created e.g. 2 white gluDisk. Anyway , for tile rendering i am using this library http://www.mesa3d.org/brianp/TR.html and everything works good apart from the colors being a bit messed. What i mean by that is that colors are saved differently from what they are displayed :) Red becomes Green Green becomes Blue Blue becomed red So RGB is actually saved as GBR.If i could put R in the front everything would be sweet :P I guess its just some messup thingy of how they are being saved but i cant figure it out ... Any help ? :) Thank you in advance ! PS. i used similar code with the one provided in demo2 to save my image.Even in his demo with some changed to not draw random colors what i am saying can be seen.

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