On 14 July 2013 02:39, Chris Forbes <chr...@ijw.co.nz> wrote:
> Adds support for interpolating noperspective varyings linearly in screen
> space when clipping.
>
> Based on Olivier Galibert's patch from last year:
> http://lists.freedesktop.org/archives/mesa-dev/2012-July/024341.html
>
> At this point all -fixed and -vertex interpolation tests work.
>
> [V1-2]: Signed-off-by: Olivier Galibert <galibert at pobox.com>
> Signed-off-by: Chris Forbes <chr...@ijw.co.nz>
> ---
> src/mesa/drivers/dri/i965/brw_clip.c | 8 ++
> src/mesa/drivers/dri/i965/brw_clip.h | 1 +
> src/mesa/drivers/dri/i965/brw_clip_util.c | 120
> +++++++++++++++++++++++++++---
> 3 files changed, 119 insertions(+), 10 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_clip.c
> b/src/mesa/drivers/dri/i965/brw_clip.c
> index 7df4b18..6dd3759 100644
> --- a/src/mesa/drivers/dri/i965/brw_clip.c
> +++ b/src/mesa/drivers/dri/i965/brw_clip.c
> @@ -211,6 +211,14 @@ brw_upload_clip_prog(struct brw_context *brw)
> }
> }
>
> + key.has_noperspective_shading = 0;
> + for (i = 0; i < brw->vue_map_geom_out.num_slots; i++) {
> + if (key.interpolation_mode[i] == INTERP_QUALIFIER_NOPERSPECTIVE) {
> + key.has_noperspective_shading = 1;
> + break;
> + }
> + }
> +
>
As with key.has_flat_shading, I'd prefer to see this moved to
compile_clip_prog() and brw_clip_compile.
> key.pv_first = (ctx->Light.ProvokingVertex ==
> GL_FIRST_VERTEX_CONVENTION);
> /* _NEW_TRANSFORM (also part of VUE map)*/
> key.nr_userclip = _mesa_bitcount_64(ctx->Transform.ClipPlanesEnabled);
> diff --git a/src/mesa/drivers/dri/i965/brw_clip.h
> b/src/mesa/drivers/dri/i965/brw_clip.h
> index 656254b..90e3e33 100644
> --- a/src/mesa/drivers/dri/i965/brw_clip.h
> +++ b/src/mesa/drivers/dri/i965/brw_clip.h
> @@ -47,6 +47,7 @@ struct brw_clip_prog_key {
> GLuint primitive:4;
> GLuint nr_userclip:4;
> GLuint has_flat_shading:1;
> + GLuint has_noperspective_shading:1;
> GLuint pv_first:1;
> GLuint do_unfilled:1;
> GLuint fill_cw:2; /* includes cull information */
> diff --git a/src/mesa/drivers/dri/i965/brw_clip_util.c
> b/src/mesa/drivers/dri/i965/brw_clip_util.c
> index 8a21c1f..56c9ccd 100644
> --- a/src/mesa/drivers/dri/i965/brw_clip_util.c
> +++ b/src/mesa/drivers/dri/i965/brw_clip_util.c
> @@ -128,6 +128,8 @@ static void brw_clip_project_vertex( struct
> brw_clip_compile *c,
>
> /* Interpolate between two vertices and put the result into a0.0.
> * Increment a0.0 accordingly.
> + *
> + * Beware that dest_ptr can be equal to v0_ptr!
> */
> void brw_clip_interp_vertex( struct brw_clip_compile *c,
> struct brw_indirect dest_ptr,
> @@ -137,7 +139,7 @@ void brw_clip_interp_vertex( struct brw_clip_compile
> *c,
> bool force_edgeflag)
> {
> struct brw_compile *p = &c->func;
> - struct brw_reg tmp = get_tmp(c);
> + struct brw_reg t_nopersp, v0_ndc_copy;
> GLuint slot;
>
> /* Just copy the vertex header:
> @@ -148,12 +150,107 @@ void brw_clip_interp_vertex( struct
> brw_clip_compile *c,
> */
> brw_copy_indirect_to_indirect(p, dest_ptr, v0_ptr, 1);
>
> - /* Iterate over each attribute (could be done in pairs?)
> +
> + /* First handle the 3D and NDC interpolation, in case we
> + * need noperspective interpolation. Doing it early has no
> + * performance impact in any case.
> + */
> +
> + /* Take a copy of the v0 NDC coordinates, in case dest == v0. */
> + if (c->key.has_noperspective_shading) {
> + GLuint offset = brw_varying_to_offset(&c->vue_map,
> + BRW_VARYING_SLOT_NDC);
> + v0_ndc_copy = get_tmp(c);
> + brw_MOV(p, v0_ndc_copy, deref_4f(v0_ptr, offset));
> + }
> +
> + /* Compute the new 3D position
> + *
> + * dest_hpos = v0_hpos * (1 - t0) + v1_hpos * t0
> + */
> + {
> + GLuint delta = brw_varying_to_offset(&c->vue_map, VARYING_SLOT_POS);
> + struct brw_reg tmp = get_tmp(c);
> + brw_MUL(p, vec4(brw_null_reg()), deref_4f(v1_ptr, delta), t0);
> + brw_MAC(p, tmp, negate(deref_4f(v0_ptr, delta)), t0);
> + brw_ADD(p, deref_4f(dest_ptr, delta), deref_4f(v0_ptr, delta), tmp);
> + release_tmp(c, tmp);
> + }
> +
> + /* Recreate the projected (NDC) coordinate in the new vertex header */
> + brw_clip_project_vertex(c, dest_ptr);
> +
> + /* If we have noperspective attributes,
> + * we need to compute the screen-space t
> + */
> + if (c->key.has_noperspective_shading) {
> + GLuint delta = brw_varying_to_offset(&c->vue_map,
> + BRW_VARYING_SLOT_NDC);
> + struct brw_reg tmp = get_tmp(c);
> + t_nopersp = get_tmp(c);
> +
> + /* t_nopersp = vec4(v1.xy, dest.xy) */
> + brw_MOV(p, t_nopersp, deref_4f(v1_ptr, delta));
> + brw_MOV(p, tmp, deref_4f(dest_ptr, delta));
> + brw_set_access_mode(p, BRW_ALIGN_16);
> + brw_MOV(p,
> + brw_writemask(t_nopersp, WRITEMASK_ZW),
> + brw_swizzle(tmp, 0, 1, 0, 1));
> +
> + /* t_nopersp = vec4(v1.xy, dest.xy) - v0.xyxy */
> + brw_ADD(p, t_nopersp, t_nopersp,
> + negate(brw_swizzle(v0_ndc_copy, 0, 1, 0, 1)));
> +
> + /* Add the absolute values of the X and Y deltas so that if
> + * the points aren't in the same place on the screen we get
> + * nonzero values to divide.
> + *
> + * After that, we have vert1 - vert0 in t_nopersp.x and
> + * vertnew - vert0 in t_nopersp.y
> + *
> + * t_nopersp = vec2(|v1.x -v0.x| + |v1.y -v0.y|,
> + * |dest.x-v0.x| + |dest.y-v0.y|)
> + */
> + brw_ADD(p,
> + brw_writemask(t_nopersp, WRITEMASK_XY),
> + brw_abs(brw_swizzle(t_nopersp, 0, 2, 0, 0)),
> + brw_abs(brw_swizzle(t_nopersp, 1, 3, 0, 0)));
> + brw_set_access_mode(p, BRW_ALIGN_1);
> +
> + /* If the points are in the same place, just substitute a
> + * value to avoid divide-by-zero
> + */
> + brw_CMP(p, vec1(brw_null_reg()), BRW_CONDITIONAL_EQ,
> + vec1(t_nopersp),
> + brw_imm_f(0));
> + brw_IF(p, BRW_EXECUTE_1);
> + brw_MOV(p, t_nopersp, brw_imm_vf4(VF_ONE, VF_ZERO, VF_ZERO,
> VF_ZERO));
> + brw_ENDIF(p);
> +
> + /* Now compute t_nopersp = t_nopersp.y/t_nopersp.x and broadcast
> it. */
> + brw_math_invert(p, get_element(t_nopersp, 0),
> get_element(t_nopersp, 0));
> + brw_MUL(p, vec1(t_nopersp), vec1(t_nopersp),
> + vec1(suboffset(t_nopersp, 1)));
> + brw_set_access_mode(p, BRW_ALIGN_16);
> + brw_MOV(p, t_nopersp, brw_swizzle(t_nopersp, 0, 0, 0, 0));
> + brw_set_access_mode(p, BRW_ALIGN_1);
> +
> + release_tmp(c, tmp);
> + release_tmp(c, v0_ndc_copy);
> + }
>
I haven't had a chance to work through all the math above, but I trust that
the piglit tests are adequate, so for this I'm just going to say
Acked-by: Paul Berry <stereotype...@gmail.com>
> +
> + /* Now we can iterate over each attribute
> + * (could be done in pairs?)
> */
> for (slot = 0; slot < c->vue_map.num_slots; slot++) {
> int varying = c->vue_map.slot_to_varying[slot];
> GLuint delta = brw_vue_slot_to_offset(slot);
>
> + /* HPOS is already handled above */
> + if (varying == VARYING_SLOT_POS)
> + continue;
> +
> +
> if (varying == VARYING_SLOT_EDGE) {
> if (force_edgeflag)
> brw_MOV(p, deref_4f(dest_ptr, delta), brw_imm_f(1));
> @@ -173,20 +270,27 @@ void brw_clip_interp_vertex( struct brw_clip_compile
> *c,
> *
> * New = attr0 + t*attr1 - t*attr0
> */
> + struct brw_reg tmp = get_tmp(c);
> + struct brw_reg t =
> + c->key.interpolation_mode[slot] ==
> INTERP_QUALIFIER_NOPERSPECTIVE ?
> + t_nopersp : t0;
> +
> brw_MUL(p,
> vec4(brw_null_reg()),
> deref_4f(v1_ptr, delta),
> - t0);
> + t);
>
> brw_MAC(p,
> tmp,
> negate(deref_4f(v0_ptr, delta)),
> - t0);
> + t);
>
> brw_ADD(p,
> deref_4f(dest_ptr, delta),
> deref_4f(v0_ptr, delta),
> tmp);
> +
> + release_tmp(c, tmp);
> }
> }
>
> @@ -196,12 +300,8 @@ void brw_clip_interp_vertex( struct brw_clip_compile
> *c,
> brw_MOV(p, deref_4f(dest_ptr, delta), brw_imm_f(0));
> }
>
> - release_tmp(c, tmp);
> -
> - /* Recreate the projected (NDC) coordinate in the new vertex
> - * header:
> - */
> - brw_clip_project_vertex(c, dest_ptr );
> + if (c->key.has_noperspective_shading)
> + release_tmp(c, t_nopersp);
> }
>
> void brw_clip_emit_vue(struct brw_clip_compile *c,
> --
> 1.8.3.2
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
