104 lines
2.3 KiB
Mathematica
104 lines
2.3 KiB
Mathematica
|
#include <tgmath.h>
|
||
|
|
|
||
|
|
#import "REABezierNode.h"
|
||
|
|
#import "REAUtils.h"
|
||
|
|
#import "REANodesManager.h"
|
||
|
|
#import <React/RCTConvert.h>
|
||
|
|
#import <React/RCTLog.h>
|
||
|
|
|
||
|
|
#define EPS 1e-5
|
||
|
|
|
||
|
|
@implementation REABezierNode {
|
||
|
|
CGFloat ax, bx, cx, ay, by, cy;
|
||
|
|
NSNumber *_inputNodeID;
|
||
|
|
}
|
||
|
|
|
||
|
|
- (instancetype)initWithID:(REANodeID)nodeID config:(NSDictionary<NSString *,id> *)config
|
||
|
|
{
|
||
|
|
if ((self = [super initWithID:nodeID config:config])) {
|
||
|
|
_inputNodeID = [RCTConvert NSNumber:config[@"input"]];
|
||
|
|
REA_LOG_ERROR_IF_NIL(_inputNodeID, @"Reanimated: First argument passed to bezier node is either of wrong type or is missing.");
|
||
|
|
|
||
|
|
CGFloat mX1 = [config[@"mX1"] doubleValue];
|
||
|
|
CGFloat mY1 = [config[@"mY1"] doubleValue];
|
||
|
|
CGFloat mX2 = [config[@"mX2"] doubleValue];
|
||
|
|
CGFloat mY2 = [config[@"mY2"] doubleValue];
|
||
|
|
|
||
|
|
// Calculate the polynomial coefficients, implicit first and last control points are (0,0) and (1,1).
|
||
|
|
cx = 3.0 * mX1;
|
||
|
|
bx = 3.0 * (mX2 - mX1) - cx;
|
||
|
|
ax = 1.0 - cx -bx;
|
||
|
|
|
||
|
|
cy = 3.0 * mY1;
|
||
|
|
by = 3.0 * (mY2 - mY1) - cy;
|
||
|
|
ay = 1.0 - cy - by;
|
||
|
|
}
|
||
|
|
return self;
|
||
|
|
}
|
||
|
|
|
||
|
|
- (CGFloat)sampleCurveX:(CGFloat)t
|
||
|
|
{
|
||
|
|
// `ax t^3 + bx t^2 + cx t' expanded using Horner's rule.
|
||
|
|
return ((ax * t + bx) * t + cx) * t;
|
||
|
|
}
|
||
|
|
|
||
|
|
- (CGFloat)sampleCurveY:(CGFloat)t
|
||
|
|
{
|
||
|
|
return ((ay * t + by) * t + cy) * t;
|
||
|
|
}
|
||
|
|
|
||
|
|
- (CGFloat)sampleCurveDerivativeX:(CGFloat)t
|
||
|
|
{
|
||
|
|
return (3.0 * ax * t + 2.0 * bx) * t + cx;
|
||
|
|
}
|
||
|
|
|
||
|
|
- (CGFloat)solveCurveX:(CGFloat)x withEpsilon:(CGFloat)epsilon
|
||
|
|
{
|
||
|
|
CGFloat t0, t1, t2, x2, d2;
|
||
|
|
NSUInteger i;
|
||
|
|
|
||
|
|
// First try a few iterations of Newton's method -- normally very fast.
|
||
|
|
for (t2 = x, i = 0; i < 8; i++) {
|
||
|
|
x2 = [self sampleCurveX:t2] - x;
|
||
|
|
if (fabs (x2) < epsilon)
|
||
|
|
return t2;
|
||
|
|
d2 = [self sampleCurveDerivativeX:t2];
|
||
|
|
if (fabs(d2) < 1e-6)
|
||
|
|
break;
|
||
|
|
t2 = t2 - x2 / d2;
|
||
|
|
}
|
||
|
|
|
||
|
|
// Fall back to the bisection method for reliability.
|
||
|
|
t0 = 0.0;
|
||
|
|
t1 = 1.0;
|
||
|
|
t2 = x;
|
||
|
|
|
||
|
|
if (t2 < t0)
|
||
|
|
return t0;
|
||
|
|
if (t2 > t1)
|
||
|
|
return t1;
|
||
|
|
|
||
|
|
while (t0 < t1) {
|
||
|
|
x2 = [self sampleCurveX:t2];
|
||
|
|
if (fabs(x2 - x) < epsilon)
|
||
|
|
return t2;
|
||
|
|
if (x > x2)
|
||
|
|
t0 = t2;
|
||
|
|
else
|
||
|
|
t1 = t2;
|
||
|
|
t2 = (t1 - t0) * .5 + t0;
|
||
|
|
}
|
||
|
|
|
||
|
|
// Failure.
|
||
|
|
return t2;
|
||
|
|
}
|
||
|
|
|
||
|
|
- (id)evaluate
|
||
|
|
{
|
||
|
|
CGFloat x = [[[self.nodesManager findNodeByID:_inputNodeID] value] doubleValue];
|
||
|
|
CGFloat y = [self sampleCurveY:[self solveCurveX:x withEpsilon:EPS]];
|
||
|
|
return @(y);
|
||
|
|
}
|
||
|
|
|
||
|
|
@end
|