[Mesa-dev] [PATCH] i965: Map GL_PATCHES to 3DPRIM_PATCHLIST_n.

[Ian Romanick]

On 11/10/2015 01:19 AM, Kenneth Graunke wrote:
> Inspired by a patch by Fabian Bieler.
> 
> Fabian defined a _3DPRIM_PATCHLIST_0 macro (which isn't actually a valid
> topology type); I instead chose to make a macro that takes an argument.
> He also took the number of patch vertices from _mesa_prim (which was set
> to ctx->TessCtrlProgram.patch_vertices) - I chose to use it directly to
> avoid the need for the VBO patch.
> 
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/brw_defines.h | 2 ++
>  src/mesa/drivers/dri/i965/brw_draw.c    | 9 ++++++++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
> index eb91634..6dfaf8f 100644
> --- a/src/mesa/drivers/dri/i965/brw_defines.h
> +++ b/src/mesa/drivers/dri/i965/brw_defines.h
> @@ -78,6 +78,8 @@
>  #define _3DPRIM_LINESTRIP_BF      0x13
>  #define _3DPRIM_LINESTRIP_CONT_BF 0x14
>  #define _3DPRIM_TRIFAN_NOSTIPPLE  0x16
> +#define _3DPRIM_PATCHLIST(n) ({ assert(n > 0 && n <= 32); 0x1F + n; })
> +

Nice assert. :)

The docs list 3DPRIM_PATCHLIST_1 as 0x20.  It may be trivially better to
use 0x20 + (n - 1) so that the value in the code matches the value in
the docs.

>  /* We use this offset to be able to pass native primitive types in struct
>   * _mesa_prim::mode.  Native primitive types are BRW_PRIM_OFFSET +
> diff --git a/src/mesa/drivers/dri/i965/brw_draw.c b/src/mesa/drivers/dri/i965/brw_draw.c
> index 39a26b0..bff484f 100644
> --- a/src/mesa/drivers/dri/i965/brw_draw.c
> +++ b/src/mesa/drivers/dri/i965/brw_draw.c
> @@ -140,9 +140,16 @@ brw_set_prim(struct brw_context *brw, const struct _mesa_prim *prim)
>  static void
>  gen6_set_prim(struct brw_context *brw, const struct _mesa_prim *prim)
>  {
> +   const struct gl_context *ctx = &brw->ctx;
> +   uint32_t hw_prim;
> +
>     DBG("PRIM: %s\n", _mesa_enum_to_string(prim->mode));
>  
> -   const uint32_t hw_prim = get_hw_prim_for_gl_prim(prim->mode);
> +   if (prim->mode == GL_PATCHES)
> +      hw_prim = _3DPRIM_PATCHLIST(ctx->TessCtrlProgram.patch_vertices);
> +   else
> +      hw_prim = get_hw_prim_for_gl_prim(prim->mode);
> +

I'd be tempted to use ?: so that hw_prim could continue to be const, but
it's not a biggie.

With or without either of these changes, this patch is

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

>     if (hw_prim != brw->primitive) {
>        brw->primitive = hw_prim;
>        brw->ctx.NewDriverState |= BRW_NEW_PRIMITIVE;
>