[Mesa-dev] [PATCH 02/11] softpipe: Handle adjacency primitives.

[Jose Fonseca]

----- Original Message -----
> On 11/07/2012 08:26 AM, jfonseca at vmware.com wrote:
> > From: José Fonseca<jfonseca at vmware.com>
> >
> > Not fully tested.
> >
> > Based on diagrams from
> > http://msdn.microsoft.com/en-us/library/windows/desktop/bb205124.aspx#Primitive_Adjacency
> > ---
> >   src/gallium/drivers/softpipe/sp_prim_vbuf.c |   46
> >   +++++++++++++++++++++++++++
> >   1 file changed, 46 insertions(+)
> >
> > diff --git a/src/gallium/drivers/softpipe/sp_prim_vbuf.c
> > b/src/gallium/drivers/softpipe/sp_prim_vbuf.c
> > index a142118..593a4fc 100644
> > --- a/src/gallium/drivers/softpipe/sp_prim_vbuf.c
> > +++ b/src/gallium/drivers/softpipe/sp_prim_vbuf.c
> > @@ -380,6 +380,14 @@ sp_vbuf_draw_arrays(struct vbuf_render *vbr,
> > uint start, uint nr)
> >         }
> >         break;
> >
> > +   case PIPE_PRIM_LINES_ADJACENCY:
> > +      for (i = 3; i<  nr; i += 4) {
> > +         sp_setup_line( setup,
> > +                        get_vert(vertex_buffer, i-2, stride),
> > +                        get_vert(vertex_buffer, i-1, stride) );
> > +      }
> > +      break;
> > +
> >      case PIPE_PRIM_LINE_STRIP:
> >         for (i = 1; i<  nr; i ++) {
> >            sp_setup_line( setup,
> > @@ -388,6 +396,14 @@ sp_vbuf_draw_arrays(struct vbuf_render *vbr,
> > uint start, uint nr)
> >         }
> >         break;
> >
> > +   case PIPE_PRIM_LINE_STRIP_ADJACENCY:
> > +      for (i = 3; i<  nr; i++) {
> > +         sp_setup_line( setup,
> > +                     get_vert(vertex_buffer, i-2, stride),
> > +                     get_vert(vertex_buffer, i-1, stride) );
> > +      }
> > +      break;
> > +
> >      case PIPE_PRIM_LINE_LOOP:
> >         for (i = 1; i<  nr; i ++) {
> >            sp_setup_line( setup,
> > @@ -410,6 +426,15 @@ sp_vbuf_draw_arrays(struct vbuf_render *vbr,
> > uint start, uint nr)
> >         }
> >         break;
> >
> > +   case PIPE_PRIM_TRIANGLES_ADJACENCY:
> > +      for (i = 5; i<  nr; i += 6) {
> > +         sp_setup_tri( setup,
> > +                       get_vert(vertex_buffer, i-5, stride),
> > +                       get_vert(vertex_buffer, i-3, stride),
> > +                       get_vert(vertex_buffer, i-1, stride) );
> > +      }
> > +      break;
> > +
> >      case PIPE_PRIM_TRIANGLE_STRIP:
> >         if (flatshade_first) {
> >            for (i = 2; i<  nr; i++) {
> > @@ -431,6 +456,27 @@ sp_vbuf_draw_arrays(struct vbuf_render *vbr,
> > uint start, uint nr)
> >         }
> >         break;
> >
> > +   case PIPE_PRIM_TRIANGLE_STRIP_ADJACENCY:
> > +      if (flatshade_first) {
> > +         for (i = 5; i<  nr; i++) {
> > +            /* emit first triangle vertex as first triangle vertex
> > */
> > +            sp_setup_tri( setup,
> > +                          get_vert(vertex_buffer, i-5, stride),
> > +                          get_vert(vertex_buffer, i+(i&1)-3,
> > stride),
> > +                          get_vert(vertex_buffer, i-(i&1)-1,
> > stride) );
> > +         }
> > +      }
> > +      else {
> > +         for (i = 5; i<  nr; i++) {
> > +            /* emit last triangle vertex as last triangle vertex
> > */
> > +            sp_setup_tri( setup,
> > +                          get_vert(vertex_buffer, i+(i&1)-5,
> > stride),
> > +                          get_vert(vertex_buffer, i-(i&1)-3,
> > stride),
> > +                          get_vert(vertex_buffer, i-1, stride) );
> > +         }
> > +      }
> > +      break;
> > +
> 
> 
> Shouldn't we increment with i+=2 since we emit need to emit a
> triangle
> for every other vertex?

I think you're right. Thanks for the detailed investigation.

Jose

> I wrote a test program to generate and print the indexes for
> adjacency
> triangles based on your arithmetic:
> 
> 
> #include <stdio.h>
> 
> int main(int argc, char *argv[])
> {
>     int i, nr = 14;
>     for (i = 5; i < nr; i++) {
>        int a = i-5;
>        int b = i+(i&1)-3;
>        int c = i-(i&1)-1;
>        printf("%d: %d, %d, %d\n", i, a, b, c);
>     }
>     return 0;
> }
> 
> The output is:
> 
> 5: 0, 3, 3
> 6: 1, 3, 5
> 7: 2, 5, 5
> 8: 3, 5, 7
> 9: 4, 7, 7
> 10: 5, 7, 9
> 11: 6, 9, 9
> 12: 7, 9, 11
> 13: 8, 11, 11
> 
> There's too many triangles and duplicated vertex indexes.
> 
> This seems to work:
> 
> int main(int argc, char *argv[])
> {
>     int i, nr = 14;
>     for (i = 5; i < nr; i+=2) {
>        int a = i-5;
>        int b = (i&2) ? i-1 : i-3;
>        int c = (i&2) ? i-3 : i-1;
>        printf("%d: %d, %d, %d\n", i, a, b, c);
>     }
>     return 0;
> }
> 
> -Brian
>