Reviewed-by: Juan A. Suarez Romero <jasua...@igalia.com>
On Tue, 2017-01-24 at 15:26 -0800, Francisco Jerez wrote: > --- > src/compiler/glsl/builtin_functions.cpp | 22 +++++++++++++++++++++- > 1 file changed, 21 insertions(+), 1 deletion(-) > > diff --git a/src/compiler/glsl/builtin_functions.cpp > b/src/compiler/glsl/builtin_functions.cpp > index fd59381..9d6ab80 100644 > --- a/src/compiler/glsl/builtin_functions.cpp > +++ b/src/compiler/glsl/builtin_functions.cpp > @@ -3590,11 +3590,31 @@ builtin_builder::_atan2(const glsl_type *type) > body.emit(assign(rcp_scaled_t, rcp(mul(t, scale)))); > ir_expression *s_over_t = mul(mul(s, scale), rcp_scaled_t); > > + /* For |x| = |y| assume tan = 1 even if infinite (i.e. pretend momentarily > + * that ∞/∞ = 1) in order to comply with the rather artificial rules > + * inherited from IEEE 754-2008, namely: > + * > + * "atan2(±∞, −∞) is ±3π/4 > + * atan2(±∞, +∞) is ±π/4" > + * > + * Note that this is inconsistent with the rules for the neighborhood of > + * zero that are based on iterated limits: > + * > + * "atan2(±0, −0) is ±π > + * atan2(±0, +0) is ±0" > + * > + * but GLSL specifically allows implementations to deviate from IEEE rules > + * at (0,0), so we take that license (i.e. pretend that 0/0 = 1 here as > + * well). > + */ > + ir_expression *tan = csel(equal(abs(x), abs(y)), > + imm(1.0f, n), abs(s_over_t)); > + > /* Calculate the arctangent and fix up the result if we had flipped the > * coordinate system. > */ > ir_variable *arc = body.make_temp(type, "arc"); > - do_atan(body, type, arc, abs(s_over_t)); > + do_atan(body, type, arc, tan); > body.emit(assign(arc, add(arc, mul(b2f(flip), imm(M_PI_2f))))); > > /* Rather convoluted calculation of the sign of the result. When x < 0 we _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
