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Merge "Adds lerpInv, saturate, lerpInvSat and constrainedMap to MathUtils."

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Zak Cohen
2019-02-13 00:26:04 +00:00
committed by Android (Google) Code Review
parent 2b5eef9eef c730de9118
commit dfe4c235fd
1 changed files with 46 additions and 0 deletions
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46
core/java/android/util/MathUtils.java
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@@ -165,6 +165,26 @@ public final class MathUtils {
return start + (stop - start) * amount;
}
/**
* Returns the interpolation scalar (s) that satisfies the equation: {@code value = }{@link
* #lerp}{@code (a, b, s)}
*
* <p>If {@code a == b}, then this function will return 0.
*/
public static float lerpInv(float a, float b, float value) {
return a != b ? ((value - a) / (b - a)) : 0.0f;
}
/** Returns the single argument constrained between [0.0, 1.0]. */
public static float saturate(float value) {
return constrain(value, 0.0f, 1.0f);
}
/** Returns the saturated (constrained between [0, 1]) result of {@link #lerpInv}. */
public static float lerpInvSat(float a, float b, float value) {
return saturate(lerpInv(a, b, value));
}
/**
* Returns an interpolated angle in degrees between a set of start and end
* angles.
@@ -194,6 +214,32 @@ public final class MathUtils {
return maxStart + (maxStop - maxStart) * ((value - minStart) / (minStop - minStart));
}
/**
* Calculates a value in [rangeMin, rangeMax] that maps value in [valueMin, valueMax] to
* returnVal in [rangeMin, rangeMax].
* <p>
* Always returns a constrained value in the range [rangeMin, rangeMax], even if value is
* outside [valueMin, valueMax].
* <p>
* Eg:
* constrainedMap(0f, 100f, 0f, 1f, 0.5f) = 50f
* constrainedMap(20f, 200f, 10f, 20f, 20f) = 200f
* constrainedMap(20f, 200f, 10f, 20f, 50f) = 200f
* constrainedMap(10f, 50f, 10f, 20f, 5f) = 10f
*
* @param rangeMin minimum of the range that should be returned.
* @param rangeMax maximum of the range that should be returned.
* @param valueMin minimum of range to map {@code value} to.
* @param valueMax maximum of range to map {@code value} to.
* @param value to map to the range [{@code valueMin}, {@code valueMax}]. Note, can be outside
* this range, resulting in a clamped value.
* @return the mapped value, constrained to [{@code rangeMin}, {@code rangeMax}.
*/
public static float constrainedMap(
float rangeMin, float rangeMax, float valueMin, float valueMax, float value) {
return lerp(rangeMin, rangeMax, lerpInvSat(valueMin, valueMax, value));
}
/**
* Perform Hermite interpolation between two values.
* Eg: