Merge pull request #57954 from TokageItLab/refactor-cubic-interpolate

Implement `cubic_interpolate()` as MathFunc for refactoring
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Rémi Verschelde 2022-02-13 10:34:13 +01:00 committed by GitHub
commit 7224389468
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GPG key ID: 4AEE18F83AFDEB23
12 changed files with 142 additions and 115 deletions

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@ -235,6 +235,21 @@ public:
static _ALWAYS_INLINE_ double lerp(double p_from, double p_to, double p_weight) { return p_from + (p_to - p_from) * p_weight; }
static _ALWAYS_INLINE_ float lerp(float p_from, float p_to, float p_weight) { return p_from + (p_to - p_from) * p_weight; }
static _ALWAYS_INLINE_ double cubic_interpolate(double p_from, double p_to, double p_pre, double p_post, double p_weight) {
return 0.5 *
((p_from * 2.0) +
(-p_pre + p_to) * p_weight +
(2.0 * p_pre - 5.0 * p_from + 4.0 * p_to - p_post) * (p_weight * p_weight) +
(-p_pre + 3.0 * p_from - 3.0 * p_to + p_post) * (p_weight * p_weight * p_weight));
}
static _ALWAYS_INLINE_ float cubic_interpolate(float p_from, float p_to, float p_pre, float p_post, float p_weight) {
return 0.5f *
((p_from * 2.0f) +
(-p_pre + p_to) * p_weight +
(2.0f * p_pre - 5.0f * p_from + 4.0f * p_to - p_post) * (p_weight * p_weight) +
(-p_pre + 3.0f * p_from - 3.0f * p_to + p_post) * (p_weight * p_weight * p_weight));
}
static _ALWAYS_INLINE_ double lerp_angle(double p_from, double p_to, double p_weight) {
double difference = fmod(p_to - p_from, Math_TAU);
double distance = fmod(2.0 * difference, Math_TAU) - difference;

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@ -153,22 +153,10 @@ Vector2 Vector2::limit_length(const real_t p_len) const {
}
Vector2 Vector2::cubic_interpolate(const Vector2 &p_b, const Vector2 &p_pre_a, const Vector2 &p_post_b, const real_t p_weight) const {
Vector2 p0 = p_pre_a;
Vector2 p1 = *this;
Vector2 p2 = p_b;
Vector2 p3 = p_post_b;
real_t t = p_weight;
real_t t2 = t * t;
real_t t3 = t2 * t;
Vector2 out;
out = 0.5f *
((p1 * 2.0f) +
(-p0 + p2) * t +
(2.0f * p0 - 5.0f * p1 + 4 * p2 - p3) * t2 +
(-p0 + 3.0f * p1 - 3.0f * p2 + p3) * t3);
return out;
Vector2 res = *this;
res.x = Math::cubic_interpolate(res.x, p_b.x, p_pre_a.x, p_post_b.x, p_weight);
res.y = Math::cubic_interpolate(res.y, p_b.y, p_pre_a.y, p_post_b.y, p_weight);
return res;
}
Vector2 Vector2::move_toward(const Vector2 &p_to, const real_t p_delta) const {

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@ -83,22 +83,11 @@ Vector3 Vector3::limit_length(const real_t p_len) const {
}
Vector3 Vector3::cubic_interpolate(const Vector3 &p_b, const Vector3 &p_pre_a, const Vector3 &p_post_b, const real_t p_weight) const {
Vector3 p0 = p_pre_a;
Vector3 p1 = *this;
Vector3 p2 = p_b;
Vector3 p3 = p_post_b;
real_t t = p_weight;
real_t t2 = t * t;
real_t t3 = t2 * t;
Vector3 out;
out = 0.5f *
((p1 * 2.0f) +
(-p0 + p2) * t +
(2.0f * p0 - 5.0f * p1 + 4.0f * p2 - p3) * t2 +
(-p0 + 3.0f * p1 - 3.0f * p2 + p3) * t3);
return out;
Vector3 res = *this;
res.x = Math::cubic_interpolate(res.x, p_b.x, p_pre_a.x, p_post_b.x, p_weight);
res.y = Math::cubic_interpolate(res.y, p_b.y, p_pre_a.y, p_post_b.y, p_weight);
res.z = Math::cubic_interpolate(res.z, p_b.z, p_pre_a.z, p_post_b.z, p_weight);
return res;
}
Vector3 Vector3::move_toward(const Vector3 &p_to, const real_t p_delta) const {

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@ -231,6 +231,10 @@ struct VariantUtilityFunctions {
return Math::lerp(from, to, weight);
}
static inline double cubic_interpolate(double from, double to, double pre, double post, double weight) {
return Math::cubic_interpolate(from, to, pre, post, weight);
}
static inline double lerp_angle(double from, double to, double weight) {
return Math::lerp_angle(from, to, weight);
}
@ -1204,6 +1208,7 @@ void Variant::_register_variant_utility_functions() {
FUNCBINDR(snapped, sarray("x", "step"), Variant::UTILITY_FUNC_TYPE_MATH);
FUNCBINDR(lerp, sarray("from", "to", "weight"), Variant::UTILITY_FUNC_TYPE_MATH);
FUNCBINDR(cubic_interpolate, sarray("from", "to", "pre", "post", "weight"), Variant::UTILITY_FUNC_TYPE_MATH);
FUNCBINDR(lerp_angle, sarray("from", "to", "weight"), Variant::UTILITY_FUNC_TYPE_MATH);
FUNCBINDR(inverse_lerp, sarray("from", "to", "weight"), Variant::UTILITY_FUNC_TYPE_MATH);
FUNCBINDR(range_lerp, sarray("value", "istart", "istop", "ostart", "ostop"), Variant::UTILITY_FUNC_TYPE_MATH);

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@ -221,6 +221,17 @@
[/codeblock]
</description>
</method>
<method name="cubic_interpolate">
<return type="float" />
<argument index="0" name="from" type="float" />
<argument index="1" name="to" type="float" />
<argument index="2" name="pre" type="float" />
<argument index="3" name="post" type="float" />
<argument index="4" name="weight" type="float" />
<description>
Cubic interpolates between two values by the factor defined in [code]weight[/code] with pre and post values.
</description>
</method>
<method name="db2linear">
<return type="float" />
<argument index="0" name="db" type="float" />

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@ -179,6 +179,24 @@ namespace Godot
return (real_t)Math.Cosh(s);
}
/// <summary>
/// Cubic interpolates between two values by a normalized value with pre and post values.
/// </summary>
/// <param name="from">The start value for interpolation.</param>
/// <param name="to">The destination value for interpolation.</param>
/// <param name="pre">The value which before "from" value for interpolation.</param>
/// <param name="post">The value which after "to" value for interpolation.</param>
/// <param name="weight">A value on the range of 0.0 to 1.0, representing the amount of interpolation.</param>
/// <returns>The resulting value of the interpolation.</returns>
public static real_t CubicInterpolate(real_t from, real_t to, real_t pre, real_t post, real_t weight)
{
return 0.5f *
((from * 2.0f) +
(-pre + to) * weight +
(2.0f * pre - 5.0f * from + 4.0f * to - post) * (weight * weight) +
(-pre + 3.0f * from - 3.0f * to + post) * (weight * weight * weight));
}
/// <summary>
/// Converts an angle expressed in degrees to radians.
/// </summary>

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@ -204,20 +204,10 @@ namespace Godot
/// <returns>The interpolated vector.</returns>
public Vector2 CubicInterpolate(Vector2 b, Vector2 preA, Vector2 postB, real_t weight)
{
Vector2 p0 = preA;
Vector2 p1 = this;
Vector2 p2 = b;
Vector2 p3 = postB;
real_t t = weight;
real_t t2 = t * t;
real_t t3 = t2 * t;
return 0.5f * (
(p1 * 2.0f) +
((-p0 + p2) * t) +
(((2.0f * p0) - (5.0f * p1) + (4 * p2) - p3) * t2) +
((-p0 + (3.0f * p1) - (3.0f * p2) + p3) * t3)
return new Vector2
(
Mathf.CubicInterpolate(x, b.x, preA.x, postB.x, weight),
Mathf.CubicInterpolate(y, b.y, preA.y, postB.y, weight)
);
}

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@ -195,19 +195,11 @@ namespace Godot
/// <returns>The interpolated vector.</returns>
public Vector3 CubicInterpolate(Vector3 b, Vector3 preA, Vector3 postB, real_t weight)
{
Vector3 p0 = preA;
Vector3 p1 = this;
Vector3 p2 = b;
Vector3 p3 = postB;
real_t t = weight;
real_t t2 = t * t;
real_t t3 = t2 * t;
return 0.5f * (
(p1 * 2.0f) + ((-p0 + p2) * t) +
(((2.0f * p0) - (5.0f * p1) + (4f * p2) - p3) * t2) +
((-p0 + (3.0f * p1) - (3.0f * p2) + p3) * t3)
return new Vector3
(
Mathf.CubicInterpolate(x, b.x, preA.x, postB.x, weight),
Mathf.CubicInterpolate(y, b.y, preA.y, postB.y, weight),
Mathf.CubicInterpolate(z, b.z, preA.z, postB.z, weight)
);
}

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@ -96,123 +96,125 @@
<constant name="MATH_LERP" value="26" enum="BuiltinFunc">
Returns a number linearly interpolated between the first two inputs, based on the third input. Uses the formula [code]a + (a - b) * t[/code].
</constant>
<constant name="MATH_INVERSE_LERP" value="27" enum="BuiltinFunc">
<constant name="MATH_CUBIC_INTERPOLATE" value="27" enum="BuiltinFunc">
</constant>
<constant name="MATH_RANGE_LERP" value="28" enum="BuiltinFunc">
<constant name="MATH_INVERSE_LERP" value="28" enum="BuiltinFunc">
</constant>
<constant name="MATH_MOVE_TOWARD" value="29" enum="BuiltinFunc">
<constant name="MATH_RANGE_LERP" value="29" enum="BuiltinFunc">
</constant>
<constant name="MATH_MOVE_TOWARD" value="30" enum="BuiltinFunc">
Moves the number toward a value, based on the third input.
</constant>
<constant name="MATH_RANDOMIZE" value="30" enum="BuiltinFunc">
<constant name="MATH_RANDOMIZE" value="31" enum="BuiltinFunc">
Randomize the seed (or the internal state) of the random number generator. Current implementation reseeds using a number based on time.
</constant>
<constant name="MATH_RANDI" value="31" enum="BuiltinFunc">
<constant name="MATH_RANDI" value="32" enum="BuiltinFunc">
Returns a random 32 bits integer value. To obtain a random value between 0 to N (where N is smaller than 2^32 - 1), you can use it with the remainder function.
</constant>
<constant name="MATH_RANDF" value="32" enum="BuiltinFunc">
<constant name="MATH_RANDF" value="33" enum="BuiltinFunc">
Returns a random floating-point value between 0 and 1. To obtain a random value between 0 to N, you can use it with multiplication.
</constant>
<constant name="MATH_RANDI_RANGE" value="33" enum="BuiltinFunc">
<constant name="MATH_RANDI_RANGE" value="34" enum="BuiltinFunc">
Returns a random 32-bit integer value between the two inputs.
</constant>
<constant name="MATH_RANDF_RANGE" value="34" enum="BuiltinFunc">
<constant name="MATH_RANDF_RANGE" value="35" enum="BuiltinFunc">
Returns a random floating-point value between the two inputs.
</constant>
<constant name="MATH_RANDFN" value="35" enum="BuiltinFunc">
<constant name="MATH_RANDFN" value="36" enum="BuiltinFunc">
Returns a normally-distributed pseudo-random number, using Box-Muller transform with the specified mean and a standard deviation. This is also called Gaussian distribution.
</constant>
<constant name="MATH_SEED" value="36" enum="BuiltinFunc">
<constant name="MATH_SEED" value="37" enum="BuiltinFunc">
Set the seed for the random number generator.
</constant>
<constant name="MATH_RANDSEED" value="37" enum="BuiltinFunc">
<constant name="MATH_RANDSEED" value="38" enum="BuiltinFunc">
Returns a random value from the given seed, along with the new seed.
</constant>
<constant name="MATH_DEG2RAD" value="38" enum="BuiltinFunc">
<constant name="MATH_DEG2RAD" value="39" enum="BuiltinFunc">
Convert the input from degrees to radians.
</constant>
<constant name="MATH_RAD2DEG" value="39" enum="BuiltinFunc">
<constant name="MATH_RAD2DEG" value="40" enum="BuiltinFunc">
Convert the input from radians to degrees.
</constant>
<constant name="MATH_LINEAR2DB" value="40" enum="BuiltinFunc">
<constant name="MATH_LINEAR2DB" value="41" enum="BuiltinFunc">
Convert the input from linear volume to decibel volume.
</constant>
<constant name="MATH_DB2LINEAR" value="41" enum="BuiltinFunc">
<constant name="MATH_DB2LINEAR" value="42" enum="BuiltinFunc">
Convert the input from decibel volume to linear volume.
</constant>
<constant name="MATH_WRAP" value="42" enum="BuiltinFunc">
<constant name="MATH_WRAP" value="43" enum="BuiltinFunc">
</constant>
<constant name="MATH_WRAPF" value="43" enum="BuiltinFunc">
<constant name="MATH_WRAPF" value="44" enum="BuiltinFunc">
</constant>
<constant name="MATH_PINGPONG" value="44" enum="BuiltinFunc">
<constant name="MATH_PINGPONG" value="45" enum="BuiltinFunc">
Returns the [code]value[/code] wrapped between [code]0[/code] and the [code]length[/code]. If the limit is reached, the next value the function returned is decreased to the [code]0[/code] side or increased to the [code]length[/code] side (like a triangle wave). If [code]length[/code] is less than zero, it becomes positive.
</constant>
<constant name="LOGIC_MAX" value="45" enum="BuiltinFunc">
<constant name="LOGIC_MAX" value="46" enum="BuiltinFunc">
Returns the greater of the two numbers, also known as their maximum.
</constant>
<constant name="LOGIC_MIN" value="46" enum="BuiltinFunc">
<constant name="LOGIC_MIN" value="47" enum="BuiltinFunc">
Returns the lesser of the two numbers, also known as their minimum.
</constant>
<constant name="LOGIC_CLAMP" value="47" enum="BuiltinFunc">
<constant name="LOGIC_CLAMP" value="48" enum="BuiltinFunc">
Returns the input clamped inside the given range, ensuring the result is never outside it. Equivalent to [code]min(max(input, range_low), range_high)[/code].
</constant>
<constant name="LOGIC_NEAREST_PO2" value="48" enum="BuiltinFunc">
<constant name="LOGIC_NEAREST_PO2" value="49" enum="BuiltinFunc">
Returns the nearest power of 2 to the input.
</constant>
<constant name="OBJ_WEAKREF" value="49" enum="BuiltinFunc">
<constant name="OBJ_WEAKREF" value="50" enum="BuiltinFunc">
Create a [WeakRef] from the input.
</constant>
<constant name="TYPE_CONVERT" value="50" enum="BuiltinFunc">
<constant name="TYPE_CONVERT" value="51" enum="BuiltinFunc">
Convert between types.
</constant>
<constant name="TYPE_OF" value="51" enum="BuiltinFunc">
<constant name="TYPE_OF" value="52" enum="BuiltinFunc">
Returns the type of the input as an integer. Check [enum Variant.Type] for the integers that might be returned.
</constant>
<constant name="TYPE_EXISTS" value="52" enum="BuiltinFunc">
<constant name="TYPE_EXISTS" value="53" enum="BuiltinFunc">
Checks if a type is registered in the [ClassDB].
</constant>
<constant name="TEXT_CHAR" value="53" enum="BuiltinFunc">
<constant name="TEXT_CHAR" value="54" enum="BuiltinFunc">
Returns a character with the given ascii value.
</constant>
<constant name="TEXT_STR" value="54" enum="BuiltinFunc">
<constant name="TEXT_STR" value="55" enum="BuiltinFunc">
Convert the input to a string.
</constant>
<constant name="TEXT_PRINT" value="55" enum="BuiltinFunc">
<constant name="TEXT_PRINT" value="56" enum="BuiltinFunc">
Print the given string to the output window.
</constant>
<constant name="TEXT_PRINTERR" value="56" enum="BuiltinFunc">
<constant name="TEXT_PRINTERR" value="57" enum="BuiltinFunc">
Print the given string to the standard error output.
</constant>
<constant name="TEXT_PRINTRAW" value="57" enum="BuiltinFunc">
<constant name="TEXT_PRINTRAW" value="58" enum="BuiltinFunc">
Print the given string to the standard output, without adding a newline.
</constant>
<constant name="TEXT_PRINT_VERBOSE" value="58" enum="BuiltinFunc">
<constant name="TEXT_PRINT_VERBOSE" value="59" enum="BuiltinFunc">
</constant>
<constant name="VAR_TO_STR" value="59" enum="BuiltinFunc">
<constant name="VAR_TO_STR" value="60" enum="BuiltinFunc">
Serialize a [Variant] to a string.
</constant>
<constant name="STR_TO_VAR" value="60" enum="BuiltinFunc">
<constant name="STR_TO_VAR" value="61" enum="BuiltinFunc">
Deserialize a [Variant] from a string serialized using [constant VAR_TO_STR].
</constant>
<constant name="VAR_TO_BYTES" value="61" enum="BuiltinFunc">
<constant name="VAR_TO_BYTES" value="62" enum="BuiltinFunc">
Serialize a [Variant] to a [PackedByteArray].
</constant>
<constant name="BYTES_TO_VAR" value="62" enum="BuiltinFunc">
<constant name="BYTES_TO_VAR" value="63" enum="BuiltinFunc">
Deserialize a [Variant] from a [PackedByteArray] serialized using [constant VAR_TO_BYTES].
</constant>
<constant name="MATH_SMOOTHSTEP" value="63" enum="BuiltinFunc">
<constant name="MATH_SMOOTHSTEP" value="64" enum="BuiltinFunc">
Returns a number smoothly interpolated between the first two inputs, based on the third input. Similar to [constant MATH_LERP], but interpolates faster at the beginning and slower at the end. Using Hermite interpolation formula:
[codeblock]
var t = clamp((weight - from) / (to - from), 0.0, 1.0)
return t * t * (3.0 - 2.0 * t)
[/codeblock]
</constant>
<constant name="MATH_POSMOD" value="64" enum="BuiltinFunc">
<constant name="MATH_POSMOD" value="65" enum="BuiltinFunc">
</constant>
<constant name="MATH_LERP_ANGLE" value="65" enum="BuiltinFunc">
<constant name="MATH_LERP_ANGLE" value="66" enum="BuiltinFunc">
</constant>
<constant name="TEXT_ORD" value="66" enum="BuiltinFunc">
<constant name="TEXT_ORD" value="67" enum="BuiltinFunc">
</constant>
<constant name="FUNC_MAX" value="67" enum="BuiltinFunc">
<constant name="FUNC_MAX" value="68" enum="BuiltinFunc">
Represents the size of the [enum BuiltinFunc] enum.
</constant>
</constants>

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@ -65,6 +65,7 @@ const char *VisualScriptBuiltinFunc::func_name[VisualScriptBuiltinFunc::FUNC_MAX
"step_decimals",
"snapped",
"lerp",
"cubic_interpolate",
"inverse_lerp",
"range_lerp",
"move_toward",
@ -212,6 +213,7 @@ int VisualScriptBuiltinFunc::get_func_argument_count(BuiltinFunc p_func) {
case MATH_WRAPF:
case LOGIC_CLAMP:
return 3;
case MATH_CUBIC_INTERPOLATE:
case MATH_RANGE_LERP:
return 5;
case FUNC_MAX: {
@ -329,6 +331,19 @@ PropertyInfo VisualScriptBuiltinFunc::get_input_value_port_info(int p_idx) const
return PropertyInfo(Variant::FLOAT, "weight");
}
} break;
case MATH_CUBIC_INTERPOLATE: {
if (p_idx == 0) {
return PropertyInfo(Variant::FLOAT, "from");
} else if (p_idx == 1) {
return PropertyInfo(Variant::FLOAT, "to");
} else if (p_idx == 2) {
return PropertyInfo(Variant::FLOAT, "pre");
} else if (p_idx == 3) {
return PropertyInfo(Variant::FLOAT, "post");
} else {
return PropertyInfo(Variant::FLOAT, "weight");
}
} break;
case MATH_RANGE_LERP: {
if (p_idx == 0) {
return PropertyInfo(Variant::FLOAT, "value");
@ -525,6 +540,7 @@ PropertyInfo VisualScriptBuiltinFunc::get_output_value_port_info(int p_idx) cons
} break;
case MATH_SNAPPED:
case MATH_LERP:
case MATH_CUBIC_INTERPOLATE:
case MATH_LERP_ANGLE:
case MATH_INVERSE_LERP:
case MATH_RANGE_LERP:
@ -795,6 +811,14 @@ void VisualScriptBuiltinFunc::exec_func(BuiltinFunc p_func, const Variant **p_in
VALIDATE_ARG_NUM(2);
*r_return = Math::lerp((double)*p_inputs[0], (double)*p_inputs[1], (double)*p_inputs[2]);
} break;
case VisualScriptBuiltinFunc::MATH_CUBIC_INTERPOLATE: {
VALIDATE_ARG_NUM(0);
VALIDATE_ARG_NUM(1);
VALIDATE_ARG_NUM(2);
VALIDATE_ARG_NUM(3);
VALIDATE_ARG_NUM(4);
*r_return = Math::cubic_interpolate((double)*p_inputs[0], (double)*p_inputs[1], (double)*p_inputs[2], (double)*p_inputs[3], (double)*p_inputs[4]);
} break;
case VisualScriptBuiltinFunc::MATH_LERP_ANGLE: {
VALIDATE_ARG_NUM(0);
VALIDATE_ARG_NUM(1);
@ -1220,6 +1244,7 @@ void VisualScriptBuiltinFunc::_bind_methods() {
BIND_ENUM_CONSTANT(MATH_STEP_DECIMALS);
BIND_ENUM_CONSTANT(MATH_SNAPPED);
BIND_ENUM_CONSTANT(MATH_LERP);
BIND_ENUM_CONSTANT(MATH_CUBIC_INTERPOLATE);
BIND_ENUM_CONSTANT(MATH_INVERSE_LERP);
BIND_ENUM_CONSTANT(MATH_RANGE_LERP);
BIND_ENUM_CONSTANT(MATH_MOVE_TOWARD);
@ -1309,6 +1334,7 @@ void register_visual_script_builtin_func_node() {
VisualScriptLanguage::singleton->add_register_func("functions/built_in/step_decimals", create_builtin_func_node<VisualScriptBuiltinFunc::MATH_STEP_DECIMALS>);
VisualScriptLanguage::singleton->add_register_func("functions/built_in/snapped", create_builtin_func_node<VisualScriptBuiltinFunc::MATH_SNAPPED>);
VisualScriptLanguage::singleton->add_register_func("functions/built_in/lerp", create_builtin_func_node<VisualScriptBuiltinFunc::MATH_LERP>);
VisualScriptLanguage::singleton->add_register_func("functions/built_in/cubic_interpolate", create_builtin_func_node<VisualScriptBuiltinFunc::MATH_CUBIC_INTERPOLATE>);
VisualScriptLanguage::singleton->add_register_func("functions/built_in/lerp_angle", create_builtin_func_node<VisualScriptBuiltinFunc::MATH_LERP_ANGLE>);
VisualScriptLanguage::singleton->add_register_func("functions/built_in/inverse_lerp", create_builtin_func_node<VisualScriptBuiltinFunc::MATH_INVERSE_LERP>);
VisualScriptLanguage::singleton->add_register_func("functions/built_in/range_lerp", create_builtin_func_node<VisualScriptBuiltinFunc::MATH_RANGE_LERP>);

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@ -65,6 +65,7 @@ public:
MATH_STEP_DECIMALS,
MATH_SNAPPED,
MATH_LERP,
MATH_CUBIC_INTERPOLATE,
MATH_INVERSE_LERP,
MATH_RANGE_LERP,
MATH_MOVE_TOWARD,

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@ -2320,22 +2320,12 @@ Variant Animation::_cubic_interpolate(const Variant &p_pre_a, const Variant &p_a
if (vformat == ((1 << Variant::INT) | (1 << Variant::FLOAT)) || vformat == (1 << Variant::FLOAT)) {
//mix of real and int
real_t a = p_a;
real_t b = p_b;
real_t pa = p_pre_a;
real_t pb = p_post_b;
real_t p0 = p_pre_a;
real_t p1 = p_a;
real_t p2 = p_b;
real_t p3 = p_post_b;
real_t t = p_c;
real_t t2 = t * t;
real_t t3 = t2 * t;
return 0.5f *
((p1 * 2.0f) +
(-p0 + p2) * t +
(2.0f * p0 - 5.0f * p1 + 4 * p2 - p3) * t2 +
(-p0 + 3.0f * p1 - 3.0f * p2 + p3) * t3);
return Math::cubic_interpolate(a, b, pa, pb, p_c);
} else if ((vformat & (vformat - 1))) {
return p_a; //can't interpolate, mix of types
}