Quaternion to Euler very imprecise Hi everybody, I was always amazed in the bad way how Quaternion to Euler gives so much imprecise result. Here he code I use: void Quaternion::FromEulerAngles(const float X, const float Y, const float Z) { const float HP = 0.5f * X; const float HY = 0.5f * Y; const float HR = 0.5f * Z; const float SinHP = CMath::Sin(HP); const float SinHY = CMath::Sin(HY); const float SinHR = CMath::Sin(HR); const float CosHP = CMath::Cos(HP); const float CosHY = CMath::Cos(HY); const float CosHR = CMath::Cos(HR); x = CosHY * SinHP * CosHR + SinHY * CosHP * SinHR; y = SinHY * CosHP * CosHR - CosHY * SinHP * SinHR; z = CosHY * CosHP * SinHR - SinHY * SinHP * CosHR; w = CosHY * CosHP * CosHR + SinHY * SinHP * SinHR; } void Quaternion::ToEulerAngles(float* X, float* Y, float* Z) const { const float SingularityTest = (x * y) + (z * w); if (SingularityTest > 0.4999995f) { *Y = 2.0f * std::atan2(x, w); *Z = Math::HALF_PI; *X = 0.0f; } else if (SingularityTest < -0.4999995f) { *Y = -2.0f * std::atan2(x, w); *Z = -Math::HALF_PI; *X = 0.0f; } else { const float zz = z * z; *Y = std::atan2(2.0f * ((y * w) - (x * z)), 1.0f - 2.0f * ((y * y) + zz)); *Z = std::asin(2.0f * SingularityTest); *X = std::atan2(2.0f * ((x * w) - (y * z)), 1.0f - 2.0f * ((x * x) + zz)); } } It's not just a little imprecision but really the result is noticeable because the difference is large when you create the quaternion after the conversion and see the result on a mesh. Is it normal and no way to have better result exists? Thanks https://ift.tt/eA8V8J

Hi everybody, I was always amazed in the bad way how Quaternion to Euler gives so much imprecise result. Here he code I use: void Quaternion::FromEulerAngles(const float X, const float Y, const float Z) { const float HP = 0.5f * X; const float HY = 0.5f * Y; const float HR = 0.5f * Z; const float SinHP = CMath::Sin(HP); const float SinHY = CMath::Sin(HY); const float SinHR = CMath::Sin(HR); const float CosHP = CMath::Cos(HP); const float CosHY = CMath::Cos(HY); const float CosHR = CMath::Cos(HR); x = CosHY * SinHP * CosHR + SinHY * CosHP * SinHR; y = SinHY * CosHP * CosHR - CosHY * SinHP * SinHR; z = CosHY * CosHP * SinHR - SinHY * SinHP * CosHR; w = CosHY * CosHP * CosHR + SinHY * SinHP * SinHR; } void Quaternion::ToEulerAngles(float* X, float* Y, float* Z) const { const float SingularityTest = (x * y) + (z * w); if (SingularityTest > 0.4999995f) { *Y = 2.0f * std::atan2(x, w); *Z = Math::HALF_PI; *X = 0.0f; } else if (SingularityTest < -0.4999995f) { *Y = -2.0f * std::atan2(x, w); *Z = -Math::HALF_PI; *X = 0.0f; } else { const float zz = z * z; *Y = std::atan2(2.0f * ((y * w) - (x * z)), 1.0f - 2.0f * ((y * y) + zz)); *Z = std::asin(2.0f * SingularityTest); *X = std::atan2(2.0f * ((x * w) - (y * z)), 1.0f - 2.0f * ((x * x) + zz)); } } It's not just a little imprecision but really the result is noticeable because the difference is large when you create the quaternion after the conversion and see the result on a mesh. Is it normal and no way to have better result exists? Thanks

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