if abs is not inserted in the source glsl, that's a wine bug, not a mesa
bug,
Thus I don't think doing this is a good idea.
On 05/06/2016 17:17, Ilia Mirkin wrote:
On Mon, May 30, 2016 at 7:19 PM, Marek Olšák <mar...@gmail.com> wrote:
From: Marek Olšák <marek.ol...@amd.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94627
(against nouveau)
---
src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index aa443a5..0f5ee02 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -1901,13 +1901,15 @@ glsl_to_tgsi_visitor::visit_expression(ir_expression*
ir, st_src_reg *op)
if (have_sqrt) {
emit_scalar(ir, TGSI_OPCODE_SQRT, result_dst, op[0]);
} else {
- /* sqrt(x) = x * rsq(x). */
- emit_scalar(ir, TGSI_OPCODE_RSQ, result_dst, op[0]);
- emit_asm(ir, TGSI_OPCODE_MUL, result_dst, result_src, op[0]);
- /* For incoming channels <= 0, set the result to 0. */
- op[0].negate = ~op[0].negate;
- emit_asm(ir, TGSI_OPCODE_CMP, result_dst,
- op[0], result_src, st_src_reg_for_float(0.0));
+ /* This is the only instruction sequence that makes the game "Risen"
+ * render correctly. ABS is not required for the game, but since GLSL
+ * declares negative values as "undefined", allowing us to do whatever
+ * we want, I choose to use ABS to match DX9 and pre-GLSL RSQ
+ * behavior.
+ */
+ emit_scalar(ir, TGSI_OPCODE_ABS, result_dst, op[0]);
+ emit_scalar(ir, TGSI_OPCODE_RSQ, result_dst, result_src);
+ emit_scalar(ir, TGSI_OPCODE_RCP, result_dst, result_src);
I spent a bunch of time trying to come up with alternatives that still
had the desired behavior for 0 and Infinity (since RCP sucks in terms
of precision). At the end of the day, it depends on what the hw does
with RSQ(0) and RCP(0). For nv50/nvc0, this sequence did have the
desired behavior - perhaps that holds for all hardware?
Either way, I'm fairly ambivalent about this - nv50/nvc0 now claim to
have SQRT support (and perform the lowering in the backend), and I
doubt much of anything would care on nv30. I'd just as soon leave the
abs out of it, but I don't strongly care.
Acked-by: Ilia Mirkin <imir...@alum.mit.edu>
}
break;
case ir_unop_rsq:
--
2.7.4
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