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Tommato

Member Since 25 Oct 2010
Offline Last Active Aug 21 2014 02:13 AM

Topics I've Started

Wireframe Overlay - glPolygonOffset

07 August 2014 - 04:02 AM

Hi All

 

I need to draw wireframe over solid object. As I've understood from google, glPolygonOffset is a standard solution for this - but I can't get it to work. With first argument negative it has effect - wireframe disappears. But my wireframe still "blinks" with any view change, no matter what values are passed to glPolygonOffset. I've also tried different draw order and wireframe drawn as lines - no luck. What am I doing wrong?

 

Thanks

 

Tommato


Picking a set of vertices

02 August 2014 - 06:22 AM

Hi All

 

I'm looking for standard/convenient solution for picking a set of vertices (see attach). Questions:

 

- is glFeedbackBuffer a way to go?

- if so how can I detect vertex indices and (more important) vertex visibility (e.g. it's overlapped by polygon(s)). Solutions based on culling/normals aren't perfect, for example no vertices could be selected on plane turned back. In other hand it looks too expensive to write a raytracer for this task.

 

Thanks

 

Tom

 

Attached File  Vertices.png   52.47KB   1 downloads


Blocked SwapBuffers

06 February 2014 - 07:17 AM

Hi All

In some cases aglSwapBuffers doesn't update screen. However when mouse pressed in window, it's updated without any re-render.
No luck with caatch update moment/call in debugger. For example if stop on breakpoint - screen is already updated, but if go step by step - not updated yet. In past a bit similar prob was solved with set AGL_SWAP_INTERVAL = 1, but now it has no effect.

I realize agl framework is totally obsolete but we need a refactoring to get rid of it, that is what I'm doing now.

Any idea?

Thx

 

Tommato


Just Hilite cell with Quartz

27 January 2014 - 12:01 PM

Hi All,
 
I'm porting old app and replacing old QuickDraw drawing with Quartz one. There are a lot of "hilites" in old code that typically replaces background color with selection color inside cell/rectangle. How to make same with Quartz?
 
What I tried is:
 
1) Use cache CGBitmapContextRef. It works but now app took ~300Mb of RAM (vs 50 before). From what I read I've figured out - it's conceptual mistake, triple-buffer.
 
2) Ok, so I've switched to Quatz "blend modes". There are a lot of them, but no one does what I need. If I change background, so text's and other colors are changed too.
I can't find a way to replace a color selectively.
 
Any suggestion is very appreciated.
 
Thx
 
Tommato

Sphere/Cylinder mapping with OpenGL

29 March 2013 - 05:27 AM

Hi All
 
I need spherical/cylindrical map for arbitrary objects (not a reflection mapping). Actually I'm calculating UV manually. If a polygon crosses UV seam or pole, then I split it into several new polygons. It works but it's a big piece of code that makes app much slower. Are there better ways with OpenGL?
 
Thanks
Tom

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