rill-core 0.5.0-beta.4

use core::fmt;
use core::ops::*;

/// Base numeric trait for all scalar types.
///
/// Includes arithmetic, min/max/clamp, and abs operations.
/// Implemented for f32, f64 and all integer types (i8/i16/i32/i64, u8/u16/u32/u64).
pub trait Scalar:
    Copy
    + Clone
    + Send
    + Sync
    + 'static
    + Default
    + PartialOrd
    + Add<Output = Self>
    + Sub<Output = Self>
    + Mul<Output = Self>
    + Div<Output = Self>
    + Rem<Output = Self>
    + Neg<Output = Self>
    + AddAssign
    + SubAssign
    + MulAssign
    + DivAssign
    + fmt::Debug
{
    /// Additive identity (zero).
    const ZERO: Self;
    /// Multiplicative identity (one).
    const ONE: Self;
    /// Minimum value typically used in normalized ranges (e.g. -1.0 for floats).
    const MIN: Self;
    /// Maximum value typically used in normalized ranges (e.g. 1.0 for floats).
    const MAX: Self;

    /// Compute the absolute value.
    fn abs(self) -> Self;
    /// Return the smaller of two values.
    fn min(self, other: Self) -> Self;
    /// Return the larger of two values.
    fn max(self, other: Self) -> Self;
    /// Constrain a value to the inclusive range `[min, max]`.
    fn clamp(self, min: Self, max: Self) -> Self;
}

/// Transcendental operations (sin, cos, sqrt, exp, ln).
///
/// Extends `Scalar` with functions available only for floating-point
/// types (f32, f64).
pub trait Transcendental: Scalar {
    /// The constant π (3.14159...).
    const PI: Self;

    /// Convert to f32.
    fn to_f32(self) -> f32;
    /// Create from an f32 value.
    fn from_f32(value: f32) -> Self;

    /// Convert to f64.
    fn to_f64(self) -> f64 {
        self.to_f32() as f64
    }

    /// Create from an f64 value.
    fn from_f64(value: f64) -> Self {
        Self::from_f32(value as f32)
    }

    /// Compute the square root.
    fn sqrt(self) -> Self;
    /// Compute e raised to the power of `self`.
    fn exp(self) -> Self;
    /// Compute the natural logarithm.
    fn ln(self) -> Self;
    /// Compute the sine (input in radians).
    fn sin(self) -> Self;
    /// Compute the cosine (input in radians).
    fn cos(self) -> Self;
    /// Compute the tangent (input in radians).
    fn tan(self) -> Self;

    /// Compute the hyperbolic tangent.
    fn tanh(self) -> Self {
        let e2x = (self + self).exp();
        (e2x - Self::ONE) / (e2x + Self::ONE)
    }

    /// Return the sign of the value: -1, 0, or 1.
    fn signum(self) -> Self;

    /// Generate a random value in the range [-1, 1].
    fn random() -> Self;
}

// -----------------------------------------------------------------------------
// Scalar — f32
// -----------------------------------------------------------------------------

impl Scalar for f32 {
    const ZERO: f32 = 0.0;
    const ONE: f32 = 1.0;
    const MIN: f32 = -1.0;
    const MAX: f32 = 1.0;

    #[inline(always)]
    fn abs(self) -> f32 {
        self.abs()
    }

    #[inline(always)]
    fn min(self, other: f32) -> f32 {
        self.min(other)
    }

    #[inline(always)]
    fn max(self, other: f32) -> f32 {
        self.max(other)
    }

    #[inline(always)]
    fn clamp(self, min: f32, max: f32) -> f32 {
        self.clamp(min, max)
    }
}

impl Transcendental for f32 {
    const PI: f32 = std::f32::consts::PI;

    #[inline(always)]
    fn to_f32(self) -> f32 {
        self
    }

    #[inline(always)]
    fn from_f32(value: f32) -> f32 {
        value
    }

    #[inline(always)]
    fn from_f64(value: f64) -> f32 {
        value as f32
    }

    #[inline(always)]
    fn sqrt(self) -> f32 {
        self.sqrt()
    }

    #[inline(always)]
    fn exp(self) -> f32 {
        self.exp()
    }

    #[inline(always)]
    fn ln(self) -> f32 {
        self.ln()
    }

    #[inline(always)]
    fn sin(self) -> f32 {
        self.sin()
    }

    #[inline(always)]
    fn cos(self) -> f32 {
        self.cos()
    }

    #[inline(always)]
    fn tan(self) -> f32 {
        f32::tan(self)
    }

    #[inline(always)]
    fn tanh(self) -> f32 {
        f32::tanh(self)
    }

    #[inline(always)]
    fn signum(self) -> f32 {
        f32::signum(self)
    }

    #[inline(always)]
    fn random() -> f32 {
        rand::random::<f32>() * 2.0 - 1.0
    }
}

// -----------------------------------------------------------------------------
// Scalar + Transcendental — f64
// -----------------------------------------------------------------------------

impl Scalar for f64 {
    const ZERO: f64 = 0.0;
    const ONE: f64 = 1.0;
    const MIN: f64 = -1.0;
    const MAX: f64 = 1.0;

    #[inline(always)]
    fn abs(self) -> f64 {
        self.abs()
    }

    #[inline(always)]
    fn min(self, other: f64) -> f64 {
        self.min(other)
    }

    #[inline(always)]
    fn max(self, other: f64) -> f64 {
        self.max(other)
    }

    #[inline(always)]
    fn clamp(self, min: f64, max: f64) -> f64 {
        self.clamp(min, max)
    }
}

impl Transcendental for f64 {
    const PI: f64 = std::f64::consts::PI;

    #[inline(always)]
    fn to_f32(self) -> f32 {
        self as f32
    }

    #[inline(always)]
    fn from_f32(value: f32) -> f64 {
        value as f64
    }

    #[inline(always)]
    fn from_f64(value: f64) -> f64 {
        value
    }

    #[inline(always)]
    fn sqrt(self) -> f64 {
        self.sqrt()
    }

    #[inline(always)]
    fn exp(self) -> f64 {
        self.exp()
    }

    #[inline(always)]
    fn ln(self) -> f64 {
        self.ln()
    }

    #[inline(always)]
    fn sin(self) -> f64 {
        self.sin()
    }

    #[inline(always)]
    fn cos(self) -> f64 {
        self.cos()
    }

    #[inline(always)]
    fn tan(self) -> f64 {
        self.tan()
    }

    #[inline(always)]
    fn tanh(self) -> f64 {
        self.tanh()
    }

    #[inline(always)]
    fn signum(self) -> f64 {
        self.signum()
    }

    #[inline(always)]
    fn random() -> f64 {
        rand::random::<f64>() * 2.0 - 1.0
    }
}

// -----------------------------------------------------------------------------
// Scalar — integer types
// -----------------------------------------------------------------------------

macro_rules! impl_scalar_int {
    ($ty:ty, $zero:expr, $one:expr, $min:expr, $max:expr) => {
        impl Scalar for $ty {
            const ZERO: $ty = $zero;
            const ONE: $ty = $one;
            const MIN: $ty = $min;
            const MAX: $ty = $max;

            #[inline(always)]
            fn abs(self) -> $ty {
                if self >= 0 {
                    self
                } else {
                    -self
                }
            }

            #[inline(always)]
            fn min(self, other: $ty) -> $ty {
                core::cmp::Ord::min(self, other)
            }

            #[inline(always)]
            fn max(self, other: $ty) -> $ty {
                core::cmp::Ord::max(self, other)
            }

            #[inline(always)]
            fn clamp(self, lo: $ty, hi: $ty) -> $ty {
                core::cmp::Ord::clamp(self, lo, hi)
            }
        }
    };
}

impl_scalar_int!(i8, 0, 1, i8::MIN, i8::MAX);
impl_scalar_int!(i16, 0, 1, i16::MIN, i16::MAX);
impl_scalar_int!(i32, 0, 1, i32::MIN, i32::MAX);
impl_scalar_int!(i64, 0, 1, i64::MIN, i64::MAX);