/**
- * Helper to compute the mirror function for the PIPE_WRAP_MIRROR modes.
+ * Helper to compute the mirror function for the PIPE_WRAP_MIRROR_REPEAT mode.
+ * (Note that with pot sizes could do this much more easily post-scale
+ * with some bit arithmetic.)
*/
static LLVMValueRef
lp_build_coord_mirror(struct lp_build_sample_context *bld,
- LLVMValueRef coord)
+ LLVMValueRef coord, boolean posOnly)
{
struct lp_build_context *coord_bld = &bld->coord_bld;
- struct lp_build_context *int_coord_bld = &bld->int_coord_bld;
- LLVMValueRef fract, flr, isOdd;
-
- lp_build_ifloor_fract(coord_bld, coord, &flr, &fract);
- /* kill off NaNs */
- /* XXX: not safe without arch rounding, fract can be anything. */
- fract = lp_build_max_ext(coord_bld, fract, coord_bld->zero,
- GALLIVM_NAN_RETURN_OTHER_SECOND_NONNAN);
-
- /* isOdd = flr & 1 */
- isOdd = LLVMBuildAnd(bld->gallivm->builder, flr, int_coord_bld->one, "");
+ LLVMValueRef fract;
+ LLVMValueRef half = lp_build_const_vec(bld->gallivm, coord_bld->type, 0.5);
- /* make coord positive or negative depending on isOdd */
- /* XXX slight overkill masking out sign bit is unnecessary */
- coord = lp_build_set_sign(coord_bld, fract, isOdd);
+ /*
+ * We can just use 2*(x - round(0.5*x)) to do all the mirroring,
+ * it all works out. (The result is in range [-1, 1.0], negative if
+ * the coord is in the "odd" section, otherwise positive.)
+ */
- /* convert isOdd to float */
- isOdd = lp_build_int_to_float(coord_bld, isOdd);
+ coord = lp_build_mul(coord_bld, coord, half);
+ fract = lp_build_round(coord_bld, coord);
+ fract = lp_build_sub(coord_bld, coord, fract);
+ coord = lp_build_add(coord_bld, fract, fract);
- /* add isOdd to coord */
- coord = lp_build_add(coord_bld, coord, isOdd);
+ if (posOnly) {
+ /*
+ * Theoretically it's not quite 100% accurate because the spec says
+ * that ultimately a scaled coord of -x.0 should map to int coord
+ * -x + 1 with mirroring, not -x (this does not matter for bilinear
+ * filtering).
+ */
+ coord = lp_build_abs(coord_bld, coord);
+ /* kill off NaNs */
+ /* XXX: not safe without arch rounding, fract can be anything. */
+ coord = lp_build_max_ext(coord_bld, coord, coord_bld->zero,
+ GALLIVM_NAN_RETURN_OTHER_SECOND_NONNAN);
+ }
return coord;
}
coord = lp_build_add(coord_bld, coord, offset);
}
- /* clamp to [0, length] */
+ /*
+ * clamp to [0, length]
+ *
+ * Unlike some other wrap modes, this should be correct for gather
+ * too. GL_CLAMP explicitly does this clamp on the coord prior to
+ * actual wrapping (which is per sample).
+ */
coord = lp_build_clamp(coord_bld, coord, coord_bld->zero, length_f);
coord = lp_build_sub(coord_bld, coord, half);
offset = lp_build_int_to_float(coord_bld, offset);
coord = lp_build_add(coord_bld, coord, offset);
}
- /* was: clamp to [-0.5, length + 0.5], then sub 0.5 */
- /* can skip clamp (though might not work for very large coord values) */
+ /*
+ * We don't need any clamp. Technically, for very large (pos or neg)
+ * (or infinite) values, clamp against [-length, length] would be
+ * correct, but we don't need to guarantee any specific
+ * result for such coords (the ifloor will be undefined, but for modes
+ * requiring border all resulting coords are safe).
+ */
coord = lp_build_sub(coord_bld, coord, half);
/* convert to int, compute lerp weight */
lp_build_ifloor_fract(coord_bld, coord, &coord0, &weight);
offset = lp_build_div(coord_bld, offset, length_f);
coord = lp_build_add(coord_bld, coord, offset);
}
- /* compute mirror function */
- /*
- * XXX: This looks incorrect wrt gather. Due to wrap specification,
- * it is possible the first coord ends up larger than the second one.
- * However, with our simplifications the coordinates will be swapped
- * in this case. (Albeit some other api tests don't like it even
- * with this fixed...)
- */
- coord = lp_build_coord_mirror(bld, coord);
+ if (!is_gather) {
+ /* compute mirror function */
+ coord = lp_build_coord_mirror(bld, coord, TRUE);
- /* scale coord to length */
- coord = lp_build_mul(coord_bld, coord, length_f);
- coord = lp_build_sub(coord_bld, coord, half);
+ /* scale coord to length */
+ coord = lp_build_mul(coord_bld, coord, length_f);
+ coord = lp_build_sub(coord_bld, coord, half);
- /* convert to int, compute lerp weight */
- lp_build_ifloor_fract(coord_bld, coord, &coord0, &weight);
- coord1 = lp_build_add(int_coord_bld, coord0, int_coord_bld->one);
+ /* convert to int, compute lerp weight */
+ lp_build_ifloor_fract(coord_bld, coord, &coord0, &weight);
+ coord1 = lp_build_add(int_coord_bld, coord0, int_coord_bld->one);
+
+ /* coord0 = max(coord0, 0) */
+ coord0 = lp_build_max(int_coord_bld, coord0, int_coord_bld->zero);
+ /* coord1 = min(coord1, length-1) */
+ coord1 = lp_build_min(int_coord_bld, coord1, length_minus_one);
+ } else {
+ /*
+ * This is pretty reasonable in the end, all what the tests care
+ * about is nasty edge cases (scaled coords x.5, so the individual
+ * coords are actually integers, which is REALLY tricky to get right
+ * due to this working differently both for negative numbers as well
+ * as for even/odd cases). But with enough magic it's not too complex
+ * after all.
+ * Maybe should try a bit arithmetic one though for POT textures...
+ */
+ LLVMValueRef isNeg;
+ /*
+ * Wrapping just once still works, even though it means we can
+ * get "wrong" sign due to performing mirror in the middle of the
+ * two coords (because this can only happen very near the odd/even
+ * edges, so both coords will actually end up as 0 or length - 1
+ * in the end).
+ * For GL4 gather with per-sample offsets we'd need to the mirroring
+ * per coord too.
+ */
+ coord = lp_build_coord_mirror(bld, coord, FALSE);
+ coord = lp_build_mul(coord_bld, coord, length_f);
+
+ /*
+ * NaNs should be safe here, we'll do away with them with
+ * the ones' complement plus min.
+ */
+ coord0 = lp_build_sub(coord_bld, coord, half);
+ coord0 = lp_build_ifloor(coord_bld, coord0);
+ coord1 = lp_build_add(int_coord_bld, coord0, int_coord_bld->one);
+ /* ones complement for neg numbers (mirror(negX) = X - 1) */
+ isNeg = lp_build_cmp(int_coord_bld, PIPE_FUNC_LESS,
+ coord0, int_coord_bld->zero);
+ coord0 = lp_build_xor(int_coord_bld, coord0, isNeg);
+ isNeg = lp_build_cmp(int_coord_bld, PIPE_FUNC_LESS,
+ coord1, int_coord_bld->zero);
+ coord1 = lp_build_xor(int_coord_bld, coord1, isNeg);
+ coord0 = lp_build_min(int_coord_bld, coord0, length_minus_one);
+ coord1 = lp_build_min(int_coord_bld, coord1, length_minus_one);
- /* coord0 = max(coord0, 0) */
- coord0 = lp_build_max(int_coord_bld, coord0, int_coord_bld->zero);
- /* coord1 = min(coord1, length-1) */
- coord1 = lp_build_min(int_coord_bld, coord1, length_minus_one);
+ weight = coord_bld->undef;
+ }
break;
case PIPE_TEX_WRAP_MIRROR_CLAMP:
offset = lp_build_int_to_float(coord_bld, offset);
coord = lp_build_add(coord_bld, coord, offset);
}
+ /*
+ * XXX: probably not correct for gather, albeit I'm not
+ * entirely sure as it's poorly specified. The wrapping looks
+ * correct according to the spec which is against gl 1.2.1,
+ * however negative values will be swapped - gl re-specified
+ * wrapping with newer versions (no more pre-clamp except with
+ * GL_CLAMP).
+ */
coord = lp_build_abs(coord_bld, coord);
/* clamp to [0, length] */
- coord = lp_build_min(coord_bld, coord, length_f);
+ coord = lp_build_min_ext(coord_bld, coord, length_f,
+ GALLIVM_NAN_RETURN_OTHER_SECOND_NONNAN);
coord = lp_build_sub(coord_bld, coord, half);
offset = lp_build_int_to_float(coord_bld, offset);
coord = lp_build_add(coord_bld, coord, offset);
}
- /*
- * XXX: This looks incorrect wrt gather. Due to wrap specification,
- * the first and second texel actually end up with "different order"
- * for negative coords. For example, if the scaled coord would
- * be -0.6, then the first coord should end up as 1
- * (floor(-0.6 - 0.5) == -2, mirror makes that 1), the second as 0
- * (floor(-0.6 - 0.5) + 1 == -1, mirror makes that 0).
- * But with our simplifications the second coord will always be the
- * larger one. The other two mirror_clamp modes have the same problem.
- * Moreover, for coords close to zero we should end up with both
- * coords being 0, but we will end up with coord1 being 1 instead
- * (with bilinear filtering this is ok as the weight is 0.0) (this
- * problem is specific to mirror_clamp_to_edge).
- */
- coord = lp_build_abs(coord_bld, coord);
+ if (!is_gather) {
+ coord = lp_build_abs(coord_bld, coord);
- /* clamp to length max */
- coord = lp_build_min_ext(coord_bld, coord, length_f,
- GALLIVM_NAN_RETURN_OTHER_SECOND_NONNAN);
- /* subtract 0.5 */
- coord = lp_build_sub(coord_bld, coord, half);
- /* clamp to [0, length - 0.5] */
- coord = lp_build_max(coord_bld, coord, coord_bld->zero);
+ /* clamp to length max */
+ coord = lp_build_min_ext(coord_bld, coord, length_f,
+ GALLIVM_NAN_RETURN_OTHER_SECOND_NONNAN);
+ /* subtract 0.5 */
+ coord = lp_build_sub(coord_bld, coord, half);
+ /* clamp to [0, length - 0.5] */
+ coord = lp_build_max(coord_bld, coord, coord_bld->zero);
- /* convert to int, compute lerp weight */
- lp_build_ifloor_fract(&abs_coord_bld, coord, &coord0, &weight);
- coord1 = lp_build_add(int_coord_bld, coord0, int_coord_bld->one);
- /* coord1 = min(coord1, length-1) */
- coord1 = lp_build_min(int_coord_bld, coord1, length_minus_one);
+ /* convert to int, compute lerp weight */
+ lp_build_ifloor_fract(&abs_coord_bld, coord, &coord0, &weight);
+ coord1 = lp_build_add(int_coord_bld, coord0, int_coord_bld->one);
+ /* coord1 = min(coord1, length-1) */
+ coord1 = lp_build_min(int_coord_bld, coord1, length_minus_one);
+ } else {
+ /*
+ * The non-gather path will swap coord0/1 if coord was negative,
+ * which is ok for filtering since the filter weight matches
+ * accordingly. Also, if coord is close to zero, coord0/1 will
+ * be 0 and 1, instead of 0 and 0 (again ok due to filter
+ * weight being 0.0). Both issues need to be fixed for gather.
+ */
+ LLVMValueRef isNeg;
+
+ /*
+ * Actually wanted to cheat here and use:
+ * coord1 = lp_build_iround(coord_bld, coord);
+ * but it's not good enough for some tests (even piglit
+ * textureGather is set up in a way so the coords area always
+ * .5, that is right at the crossover points).
+ * So do ordinary sub/floor, then do ones' complement
+ * for negative numbers.
+ * (Note can't just do sub|add/abs/itrunc per coord neither -
+ * because the spec demands that mirror(3.0) = 3 but
+ * mirror(-3.0) = 2.)
+ */
+ coord = lp_build_sub(coord_bld, coord, half);
+ coord0 = lp_build_ifloor(coord_bld, coord);
+ coord1 = lp_build_add(int_coord_bld, coord0, int_coord_bld->one);
+ isNeg = lp_build_cmp(int_coord_bld, PIPE_FUNC_LESS, coord0,
+ int_coord_bld->zero);
+ coord0 = lp_build_xor(int_coord_bld, isNeg, coord0);
+ coord0 = lp_build_min(int_coord_bld, coord0, length_minus_one);
+
+ isNeg = lp_build_cmp(int_coord_bld, PIPE_FUNC_LESS, coord1,
+ int_coord_bld->zero);
+ coord1 = lp_build_xor(int_coord_bld, isNeg, coord1);
+ coord1 = lp_build_min(int_coord_bld, coord1, length_minus_one);
+
+ weight = coord_bld->undef;
+ }
}
break;
offset = lp_build_int_to_float(coord_bld, offset);
coord = lp_build_add(coord_bld, coord, offset);
}
+ /*
+ * XXX: probably not correct for gather due to swapped
+ * order if coord is negative (same rationale as for
+ * MIRROR_CLAMP).
+ */
coord = lp_build_abs(coord_bld, coord);
- /* was: clamp to [-0.5, length + 0.5] then sub 0.5 */
- /* skip clamp - always positive, and other side
- only potentially matters for very large coords */
+ /*
+ * We don't need any clamp. Technically, for very large
+ * (or infinite) values, clamp against length would be
+ * correct, but we don't need to guarantee any specific
+ * result for such coords (the ifloor will be undefined, but
+ * for modes requiring border all resulting coords are safe).
+ */
coord = lp_build_sub(coord_bld, coord, half);
/* convert to int, compute lerp weight */
coord = lp_build_add(coord_bld, coord, offset);
}
/* compute mirror function */
- coord = lp_build_coord_mirror(bld, coord);
+ coord = lp_build_coord_mirror(bld, coord, TRUE);
/* scale coord to length */
assert(bld->static_sampler_state->normalized_coords);
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