Merge pull request jnfisher#5 from letatas/fix#3

Using epsilon to prevent numerical imprecision due to floating point comparison to zero.
letatas · May 8, 2015 · 7eeda39 · 7eeda39
2 parents e3d1c0a + fa39ab5
commit 7eeda39
Showing 1 changed file with 18 additions and 16 deletions.
diff --git a/Curve Interpolation/UIBezierPath+Interpolation.m b/Curve Interpolation/UIBezierPath+Interpolation.m
@@ -9,34 +9,36 @@
 #import "UIBezierPath+Interpolation.h"
 #import "CGPointExtension.h"
 
+#define kEPSILON 1.0e-5
+
 @implementation UIBezierPath (Interpolation)
 
 +(UIBezierPath *)interpolateCGPointsWithCatmullRom:(NSArray *)pointsAsNSValues closed:(BOOL)closed alpha:(float)alpha {
     if ([pointsAsNSValues count] < 4)
         return nil;
 
-    int endIndex = (closed ? [pointsAsNSValues count] : [pointsAsNSValues count]-2);
+    NSInteger endIndex = (closed ? [pointsAsNSValues count] : [pointsAsNSValues count]-2);
     NSAssert(alpha >= 0.0 && alpha <= 1.0, @"alpha value is between 0.0 and 1.0, inclusive");
 
     UIBezierPath *path = [UIBezierPath bezierPath];
-    int startIndex = (closed ? 0 : 1);
-    for (int ii=startIndex; ii < endIndex; ++ii) {
+    NSInteger startIndex = (closed ? 0 : 1);
+    for (NSInteger ii=startIndex; ii < endIndex; ++ii) {
         CGPoint p0, p1, p2, p3;
-        int nextii      = (ii+1)%[pointsAsNSValues count];
-        int nextnextii  = (nextii+1)%[pointsAsNSValues count];
-        int previi      = (ii-1 < 0 ? [pointsAsNSValues count]-1 : ii-1);
+        NSInteger nextii      = (ii+1)%[pointsAsNSValues count];
+        NSInteger nextnextii  = (nextii+1)%[pointsAsNSValues count];
+        NSInteger previi      = (ii-1 < 0 ? [pointsAsNSValues count]-1 : ii-1);
 
         [pointsAsNSValues[ii] getValue:&p1];
         [pointsAsNSValues[previi] getValue:&p0];
         [pointsAsNSValues[nextii] getValue:&p2];
         [pointsAsNSValues[nextnextii] getValue:&p3];
 
-        float d1 = ccpLength(ccpSub(p1, p0));
-        float d2 = ccpLength(ccpSub(p2, p1));
-        float d3 = ccpLength(ccpSub(p3, p2));
+        CGFloat d1 = ccpLength(ccpSub(p1, p0));
+        CGFloat d2 = ccpLength(ccpSub(p2, p1));
+        CGFloat d3 = ccpLength(ccpSub(p3, p2));
 
         CGPoint b1, b2;
-        if (d1 == 0) {
+        if (fabs(d1) < kEPSILON) {
             b1 = p1;
         }
         else {
@@ -46,7 +48,7 @@ +(UIBezierPath *)interpolateCGPointsWithCatmullRom:(NSArray *)pointsAsNSValues c
             b1 = ccpMult(b1, 1.0 / (3*powf(d1, alpha)*(powf(d1, alpha)+powf(d2, alpha))));
         }
 
-        if (d3 == 0) {
+        if (fabs(d3) < kEPSILON) {
             b2 = p2;
         }
         else {
@@ -72,25 +74,25 @@ +(UIBezierPath *)interpolateCGPointsWithHermite:(NSArray *)pointsAsNSValues clos
     if ([pointsAsNSValues count] < 2)
         return nil;
 
-    int nCurves = (closed ? [pointsAsNSValues count] : [pointsAsNSValues count]-1);
+    NSInteger nCurves = (closed ? [pointsAsNSValues count] : [pointsAsNSValues count]-1);
 
     UIBezierPath *path = [UIBezierPath bezierPath];
-    for (int ii=0; ii < nCurves; ++ii) {
+    for (NSInteger ii=0; ii < nCurves; ++ii) {
         NSValue *value  = pointsAsNSValues[ii];
 
         CGPoint curPt, prevPt, nextPt, endPt;
         [value getValue:&curPt];
         if (ii==0)
             [path moveToPoint:curPt];
 
-        int nextii = (ii+1)%[pointsAsNSValues count];
-        int previi = (ii-1 < 0 ? [pointsAsNSValues count]-1 : ii-1);
+        NSInteger nextii = (ii+1)%[pointsAsNSValues count];
+        NSInteger previi = (ii-1 < 0 ? [pointsAsNSValues count]-1 : ii-1);
 
         [pointsAsNSValues[previi] getValue:&prevPt];
         [pointsAsNSValues[nextii] getValue:&nextPt];
         endPt = nextPt;
 
-        float mx, my;
+        CGFloat mx, my;
         if (closed || ii > 0) {
             mx = (nextPt.x - curPt.x)*0.5 + (curPt.x - prevPt.x)*0.5;
             my = (nextPt.y - curPt.y)*0.5 + (curPt.y - prevPt.y)*0.5;