diff options
Diffstat (limited to 'src/compiler/glsl/builtin_functions.cpp')
| -rw-r--r-- | src/compiler/glsl/builtin_functions.cpp | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/src/compiler/glsl/builtin_functions.cpp b/src/compiler/glsl/builtin_functions.cpp index 3e4bcbb..3dead1a 100644 --- a/src/compiler/glsl/builtin_functions.cpp +++ b/src/compiler/glsl/builtin_functions.cpp @@ -3563,9 +3563,17 @@ builtin_builder::_tanh(const glsl_type *type) ir_variable *x = in_var(type, "x"); MAKE_SIG(type, v130, 1, x); + /* Clamp x to [-10, +10] to avoid precision problems. + * When x > 10, e^(-x) is so small relative to e^x that it gets flushed to + * zero in the computation e^x + e^(-x). The same happens in the other + * direction when x < -10. + */ + ir_variable *t = body.make_temp(type, "tmp"); + body.emit(assign(t, min2(max2(x, imm(-10.0f)), imm(10.0f)))); + /* (e^x - e^(-x)) / (e^x + e^(-x)) */ - body.emit(ret(div(sub(exp(x), exp(neg(x))), - add(exp(x), exp(neg(x)))))); + body.emit(ret(div(sub(exp(t), exp(neg(t))), + add(exp(t), exp(neg(t)))))); return sig; } |