[Bug 89634] New: dEQP-GLES3: sin, cos, tan do not have enough precision

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=89634

            Bug ID: 89634
           Summary: dEQP-GLES3: sin, cos, tan do not have enough precision
           Product: Mesa
           Version: git
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/DRI/i965
          Assignee: idr at freedesktop.org
          Reporter: itoral at igalia.com
        QA Contact: intel-3d-bugs at lists.freedesktop.org

List of affected tests:

dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.mediump_vertex.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.mediump_vertex.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.mediump_vertex.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.mediump_vertex.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.mediump_fragment.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.mediump_fragment.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.mediump_fragment.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.mediump_fragment.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.highp_vertex.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.highp_vertex.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.highp_vertex.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.highp_vertex.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.highp_fragment.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.highp_fragment.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.highp_fragment.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.sin.highp_fragment.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.mediump_vertex.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.mediump_vertex.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.mediump_vertex.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.mediump_vertex.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.mediump_fragment.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.mediump_fragment.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.mediump_fragment.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.mediump_fragment.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.highp_vertex.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.highp_vertex.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.highp_vertex.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.highp_vertex.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.highp_fragment.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.highp_fragment.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.highp_fragment.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.cos.highp_fragment.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.tan.mediump_vertex.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.tan.mediump_vertex.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.tan.mediump_vertex.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.tan.mediump_vertex.vec4
dEQP-GLES3.functional.shaders.builtin_functions.precision.tan.mediump_fragment.scalar
dEQP-GLES3.functional.shaders.builtin_functions.precision.tan.mediump_fragment.vec2
dEQP-GLES3.functional.shaders.builtin_functions.precision.tan.mediump_fragment.vec3
dEQP-GLES3.functional.shaders.builtin_functions.precision.tan.mediump_fragment.vec4

The GLES3 specs say that trigonometric functions do not have a defined
precision, so I wonder if these tests are valid at all. However, it is true
that for large enough angles the results have so much error that they are
completely bogus. This can probably be fixed in software by rounding input
angles to 0..2PI for example, but I woder if we want to take the cost of that
considering that the precision error only becomes big enough for very large
values of the input angle.

There was a brief discussion on the mailing list about this topic:
http://lists.freedesktop.org/archives/mesa-dev/2014-December/072429.html

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