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; + } + } + 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); + } + + /* 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
