Bug#405803: [Mesa3d-dev] Blender extrusion makes X SIGSEGV

[Brian Paul]

Cyril Brulebois wrote:
> Hi again,
> 
> I built xorg-server 1.2.0 on top of mesa 6.5.2 (instead of 1.1.1 on top
> of mesa 6.5.1) and this problem looks like vanished. I'm currently
> trying to see whether a backport of the fix is easy, which would be good
> news for the next (one can hope) Debian stable release.

There was a line-clipping fix that went into 6.5.2:

diff Mesa-6.5.1/src/mesa/tnl/t_vb_cliptmp.h 
Mesa-6.5.2/src/mesa/tnl/t_vb_cliptmp.h
3c3
<  * Version:  6.5.1
---
 >  * Version:  6.5.2
127a128
 >    const GLuint v0_orig = v0;
156c157
<    else
---
 >    else {
157a159
 >    }
158a161,164
 >    /* Note: we need to use vertex v0_orig when computing the new
 >     * interpolated/clipped vertex position, not the current v0 which
 >     * may have got set when we clipped the other end of the line!
 >     */
160,161c166,167
<       INTERP_4F( t1, coord[newvert], coord[v1], coord[v0] );
<       interp( ctx, t1, newvert, v1, v0, GL_FALSE );
---
 >       INTERP_4F( t1, coord[newvert], coord[v1], coord[v0_orig] );
 >       interp( ctx, t1, newvert, v1, v0_orig, GL_FALSE );
170c176
<    else
---
 >    else {
171a178
 >    }

That may be it.  I've been unable to reproduce the Blender crash.

-Brian