As explained by Nicolai, it seems like D3D always compute the absolute value while GLSL says that the result of inversesqrt() is undefined if x <= 0. Using the absolute value looks like safer especially when the game has been ported from D3D to GL.
This gets rid of the NaN values in the "Spec Ops: The Line" game as well as the black squares. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97338 Signed-off-by: Samuel Pitoiset <samuel.pitoi...@gmail.com> --- Nouveau also computes the absolute value before emitting RSQ. src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c b/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c index 1966752cc0..ec6d6b0534 100644 --- a/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c +++ b/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c @@ -754,9 +754,12 @@ static void emit_rsq(const struct lp_build_tgsi_action *action, struct lp_build_tgsi_context *bld_base, struct lp_build_emit_data *emit_data) { - LLVMValueRef sqrt = - lp_build_emit_llvm_unary(bld_base, TGSI_OPCODE_SQRT, - emit_data->args[0]); + LLVMValueRef abs, sqrt; + + abs = lp_build_emit_llvm_unary(bld_base, TGSI_OPCODE_ABS, + emit_data->args[0]); + + sqrt = lp_build_emit_llvm_unary(bld_base, TGSI_OPCODE_SQRT, abs); emit_data->output[emit_data->chan] = lp_build_emit_llvm_binary(bld_base, TGSI_OPCODE_DIV, -- 2.11.0 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
