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Revert "Sin/Cos Opts"

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This reverts commit 1d05f95f746639fdbc4c242d84aa4fcd93d666f4.
This commit is contained in:
Zoe Gidiere 2024-09-23 22:38:45 -06:00
parent 59d943b3ea
commit 6244ffca63
1 changed files with 21 additions and 29 deletions
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50
common/api/src/main/java/com/dfsek/terra/api/util/MathUtil.java
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@ -18,14 +18,22 @@ public final class MathUtil {
* Epsilon for fuzzy floating point comparisons. * Epsilon for fuzzy floating point comparisons.
*/ */
public static final double EPSILON = 1.0E-5; public static final double EPSILON = 1.0E-5;
private static final int lookupBits = 14; private static final int SIN_BITS, SIN_MASK, SIN_COUNT;
private static final double radFull, radToIndex;
private static final double degFull, degToIndex;
private static final double[] sin, cos;
static {
SIN_BITS = 12;
SIN_MASK = ~(-1 << SIN_BITS);
SIN_COUNT = SIN_MASK + 1;
static final int lookupTableSize = 1 << lookupBits; radFull = Math.PI * 2.0;
degFull = 360.0;
radToIndex = SIN_COUNT / radFull;
degToIndex = SIN_COUNT / degFull;
private static final int lookupTableSizeWithMargin = lookupTableSize + 1; sin = new double[SIN_COUNT];
private static final double tauOverLookupSize = TrigonometryConstants.TAU / lookupTableSize; cos = new double[SIN_COUNT];
static final double radianToIndex = (~(-1 << lookupBits) + 1) / TrigonometryConstants.TAU;
private static final long[] sinTable;
static { static {
sinTable = new long[lookupTableSizeWithMargin]; sinTable = new long[lookupTableSizeWithMargin];
@ -33,36 +41,20 @@ public final class MathUtil {
double d = i * tauOverLookupSize; double d = i * tauOverLookupSize;
sinTable[i] = Double.doubleToRawLongBits(StrictMath.sin(d)); sinTable[i] = Double.doubleToRawLongBits(StrictMath.sin(d));
} }
}
static double sinLookup(long index) { // Four cardinal directions (credits: Nate)
// Trigonometric identity: sin(-x) = -sin(x) for(int i = 0; i < 360; i += 90) {
// Given a domain of 0 <= x <= 2*pi, just negate the value if x > pi. sin[(int) (i * degToIndex) & SIN_MASK] = Math.sin(i * Math.PI / 180.0);
// This allows the sin table size to be halved. cos[(int) (i * degToIndex) & SIN_MASK] = Math.cos(i * Math.PI / 180.0);
long neg = (index & 0x8000000000000000L) << 32; }
// All bits set if (pi/2 <= x), none set otherwise
// Extracts the 31st bit from 'half'
long mask = (index << 33) >> 63;
// Trigonometric identity: sin(x) = sin(pi/2 - x)
long pos = (0x8000000000000001L & mask) + (index ^ mask);
// Wrap the position in the table. Moving this down to immediately before the array access
// seems to help the Hotspot compiler optimize the bit math better.
pos &= 0x7fffffffffffffffL;
// Fetch the corresponding value from the LUT and invert the sign bit as needed
// This directly manipulate the sign bit on the double bits to simplify logic
return Double.longBitsToDouble(sinTable[(int) pos] ^ neg);
} }
public static double sin(double rad) { public static double sin(double rad) {
return sinLookup((long) (rad * radianToIndex) & 0xFFFFFFFFL); return sin[(int) (rad * radToIndex) & SIN_MASK];
} }
public static double cos(double rad) { public static double cos(double rad) {
return sinLookup((long) (rad * radianToIndex + lookupTableSize) & 0xFFFFFFFFL); return cos[(int) (rad * radToIndex) & SIN_MASK];
} }
public static double tan(double rad) { public static double tan(double rad) {