mesa3d-dev

[Mesa3d-dev] polygon stipple fix(?)

[relnev <re...@ma...>]

Here is a patch for Mesa 3.3 src/polygon.c. I think this is the correct
fix.

gl_unpack_polygon_stipple was never called, so GL_UNPACK_LSB_FIRST never
did anything.  Both pack and unpack swap the bytes around for each row,
why is this? 

How does GL_UNPACK_SWAP_BYTES affect the stipple pattern? The pattern is
defined as an array of bytes, and swapping doesn't make sense for bytes 
(at least the way I understand it).

If you set both GL_UNPACK_LSB_FIRST and GL_PACK_LSB_FIRST to the same
value (TRUE/FALSE), should you get your original stipple back when you
call glPolygonStipple then glGetPolygonStipple?


Steven Fuller

[Mesa3d-dev] Re: polygon stipple fix(?)

[relnev <re...@ma...>]

> gl_unpack_polygon_stipple was never called, so GL_UNPACK_LSB_FIRST never
> did anything.  Both pack and unpack swap the bytes around for each row,
> why is this? 

Actually, the swaps are needed for rendering on GL_BACK, but not on
GL_FRONT (which I had been testing with..)

Not sure where to look for this, my guess its something with the X code.

Steven Fuller

Re: [Mesa3d-dev] Re: polygon stipple fix(?)

[Brian P. <br...@pr...>]

relnev wrote:
> 
> > gl_unpack_polygon_stipple was never called, so GL_UNPACK_LSB_FIRST never
> > did anything.  Both pack and unpack swap the bytes around for each row,
> > why is this?
> 
> Actually, the swaps are needed for rendering on GL_BACK, but not on
> GL_FRONT (which I had been testing with..)
> 
> Not sure where to look for this, my guess its something with the X code.

GL_FRONT/GL_BACK shouldn't effect the polygon stipple.  I've checked
it out with a test program.

-Brian

Re: [Mesa3d-dev] polygon stipple fix(?)

[Brian P. <br...@pr...>]

relnev wrote:
> 
> Here is a patch for Mesa 3.3 src/polygon.c. I think this is the correct
> fix.
> 
> gl_unpack_polygon_stipple was never called, so GL_UNPACK_LSB_FIRST never
> did anything.  Both pack and unpack swap the bytes around for each row,
> why is this?
> 
> How does GL_UNPACK_SWAP_BYTES affect the stipple pattern? The pattern is
> defined as an array of bytes, and swapping doesn't make sense for bytes
> (at least the way I understand it).
> 
> If you set both GL_UNPACK_LSB_FIRST and GL_PACK_LSB_FIRST to the same
> value (TRUE/FALSE), should you get your original stipple back when you
> call glPolygonStipple then glGetPolygonStipple?

Yes.

During the move to the new dispatch mechanism the code to unpack polygon
stipples was lost.  I've restored it now and done some work on
glGetPolygonStipple() to match.

You're right that SWAP_BYTES has no effect on polygon stipples.

-Brian