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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:generate go run gen.go -output table.go
// Package f32 implements some linear algebra and GL helpers for float32s.
//
// Types defined in this package have methods implementing common
// mathematical operations. The common form for these functions is
//
// func (dst *T) Op(lhs, rhs *T)
//
// which reads in traditional mathematical notation as
//
// dst = lhs op rhs.
//
// It is safe to use the destination address as the left-hand side,
// that is, dst *= rhs is dst.Mul(dst, rhs).
//
// # WARNING
//
// The interface to this package is not stable. It will change considerably.
// Only use functions that provide package documentation. Semantics are
// non-obvious. Be prepared for the package name to change.
package f32
import (
"encoding/binary"
"fmt"
"math"
)
type Radian float32
func Cos(x float32) float32 {
const n = sinTableLen
i := uint32(int32(x * (n / math.Pi)))
i += n / 2
i &= 2*n - 1
if i >= n {
return -sinTable[i&(n-1)]
}
return sinTable[i&(n-1)]
}
func Sin(x float32) float32 {
const n = sinTableLen
i := uint32(int32(x * (n / math.Pi)))
i &= 2*n - 1
if i >= n {
return -sinTable[i&(n-1)]
}
return sinTable[i&(n-1)]
}
func Sqrt(x float32) float32 {
return float32(math.Sqrt(float64(x))) // TODO(crawshaw): implement
}
func Tan(x float32) float32 {
return float32(math.Tan(float64(x))) // TODO(crawshaw): fast version
}
// Bytes returns the byte representation of float32 values in the given byte
// order. byteOrder must be either binary.BigEndian or binary.LittleEndian.
func Bytes(byteOrder binary.ByteOrder, values ...float32) []byte {
le := false
switch byteOrder {
case binary.BigEndian:
case binary.LittleEndian:
le = true
default:
panic(fmt.Sprintf("invalid byte order %v", byteOrder))
}
b := make([]byte, 4*len(values))
for i, v := range values {
u := math.Float32bits(v)
if le {
b[4*i+0] = byte(u >> 0)
b[4*i+1] = byte(u >> 8)
b[4*i+2] = byte(u >> 16)
b[4*i+3] = byte(u >> 24)
} else {
b[4*i+0] = byte(u >> 24)
b[4*i+1] = byte(u >> 16)
b[4*i+2] = byte(u >> 8)
b[4*i+3] = byte(u >> 0)
}
}
return b
}
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