Attachment 14065 Details for Bug 13837 – implement gl_FrontFacing for 965

[patch] implement gl_FrontFacing for 965

965-frontfacing.diff (text/plain), 1.96 KB, created by Eric Anholt on 2008-01-31 20:59:24 UTC

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Creator: Eric Anholt

Created: 2008-01-31 20:59:24 UTC

Size: 1.96 KB

patch

obsolete

>commit 7dd18d02750f8f0951c16df3d006e8f0904fe9d9
>Author: Eric Anholt <eric@anholt.net>
>Date:   Mon Jan 28 16:17:59 2008 -0800
>
>    [965] Emit front facing to fogc.y in for glFrontFacing in the fragment shader.
>
>diff --git a/src/mesa/drivers/dri/i965/brw_sf_emit.c b/src/mesa/drivers/dri/i965/brw_sf_emit.c
>index 080a02b..55e927a 100644
>--- a/src/mesa/drivers/dri/i965/brw_sf_emit.c
>+++ b/src/mesa/drivers/dri/i965/brw_sf_emit.c
>@@ -79,6 +79,44 @@ static void copy_bfc( struct brw_sf_compile *c,
>    }
> }
> 
>+/**
>+ * Sets VERT_RESULT_FOGC.Y of the vertices to the front facing flag of the
>+ * primitive.
>+ *
>+ * This is currently executed if the fragment program uses VERT_RESULT_FOGC
>+ * at all, but this could be eliminated with a scan of the FP contents.
>+ */
>+static void
>+set_frontfacing( struct brw_sf_compile *c )
>+{
>+   struct brw_compile *p = &c->func;
>+   GLuint frontface_conditional;
>+   int i;
>+
>+   if (!have_attr(c, VERT_RESULT_FOGC))
>+      return;
>+
>+   if (c->key.frontface_ccw)
>+      frontface_conditional = BRW_CONDITIONAL_G;
>+   else
>+      frontface_conditional = BRW_CONDITIONAL_L;
>+
>+   /* Store the front facing result (1 or 0) in the low bit of the flag reg */
>+   brw_CMP(p, vec4(brw_null_reg()), frontface_conditional, c->det,
>+	   brw_imm_f(0));
>+   brw_set_predicate_control(p, BRW_PREDICATE_NONE);
>+
>+   for (i = 0; i < 3; i++) {
>+      struct brw_reg fogc = get_vert_attr(c, c->vert[i], VERT_RESULT_FOGC);
>+
>+      /* Move the front facing result from the flag reg low bit to the Y
>+       * component of fogcoord for this vertex, where the fragment shader
>+       * would look for it.
>+       */
>+      brw_AND(p, brw_writemask(fogc, WRITEMASK_Y), brw_flag_reg(),
>+	      brw_imm_ud(1));
>+   }
>+}
> 
> static void do_twoside_color( struct brw_sf_compile *c )
> {
>@@ -355,6 +393,7 @@ void brw_emit_tri_setup( struct brw_sf_compile *c, GLboolean allocate)
> 
>    invert_det(c);
>    copy_z_inv_w(c);
>+   set_frontfacing(c);
> 
>    if (c->key.do_twoside_color) 
>       do_twoside_color(c);

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