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Help => Graphics => Topic started by: FRex on December 06, 2012, 04:41:04 am

Title: Order of drawing vertices in vertexarray
Post by: FRex on December 06, 2012, 04:41:04 am

Can there be any assumption about order of drawing primitives in vertexarray? For example 8 vertices, two quads, first one is big rectangle, other is smaller one with it's area completely contained in the area of first one. Will both always show, first in array getting drawn first or is it (implementation /un)defined?

Title: Re: Order of drawing vertices in vertexarray
Post by: cire on December 06, 2012, 05:51:39 am

OpenGL draws them in order and I didn't see any reordering in the source for sf::RenderTarget.  Seems like a safe assumption.

Title: Re: Order of drawing vertices in vertexarray
Post by: Laurent on December 06, 2012, 07:50:41 am

Yes it should be safe, however I don't know if it's explicitely written in the OpenGL spec.

Title: Re: Order of drawing vertices in vertexarray
Post by: cire on December 06, 2012, 08:15:46 am

Quote

When glDrawArrays is called, it uses count sequential elements from each enabled array to construct a sequence of geometric primitives, beginning with element first.

Found here (http://www.opengl.org/sdk/docs/man/xhtml/glDrawArrays.xml).

Title: Re: Order of drawing vertices in vertexarray
Post by: Laurent on December 06, 2012, 08:32:06 am

Thanks :)

Title: Re: Order of drawing vertices in vertexarray
Post by: FRex on December 06, 2012, 11:42:09 pm

Thanks too.
Err... by construct it means render, right?  ;D

Title: Re: Order of drawing vertices in vertexarray
Post by: Laurent on December 07, 2012, 12:00:12 am

Quote

Err... by construct it means render, right?

Of course :P

Title: Re: Order of drawing vertices in vertexarray
Post by: FRex on December 07, 2012, 12:05:21 am

Ah.. obviously it does.. ::)
Thanks. ;)