Finite loop in VBezier::tAtLength()

mymedia2 · hermet · commit 625bc4c48a2d · 2021-08-05T10:13:14.000+09:00
diff --git a/src/vector/vbezier.cpp b/src/vector/vbezier.cpp
@@ -81,12 +81,12 @@ float VBezier::tAtLength(float l, float totalLength) const
     t *= 0.5;
 
     float lastBigger = 1.0;
-    while (1) {
+    for (int num = 0; num < 100500; num++) {
         VBezier right = *this;
         VBezier left;
         right.parameterSplitLeft(t, &left);
         float lLen = left.length();
-        if (fabs(lLen - l) < error) break;
+        if (fabs(lLen - l) < error) return t;
 
         if (lLen < l) {
             t += (lastBigger - t) * 0.5f;
@@ -95,6 +95,7 @@ float VBezier::tAtLength(float l, float totalLength) const
             t -= t * 0.5f;
         }
     }
+    vWarning << "no convergence";
     return t;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -81,12 +81,12 @@ float VBezier::tAtLength(float l, float totalLength) const`
`81`	`81`	`t *= 0.5;`
`82`	`82`
`83`	`83`	`float lastBigger = 1.0;`
`84`		`- while (1) {`
	`84`	`+ for (int num = 0; num < 100500; num++) {`
`85`	`85`	`VBezier right = *this;`
`86`	`86`	`VBezier left;`
`87`	`87`	`right.parameterSplitLeft(t, &left);`
`88`	`88`	`float lLen = left.length();`
`89`		`- if (fabs(lLen - l) < error) break;`
	`89`	`+ if (fabs(lLen - l) < error) return t;`
`90`	`90`
`91`	`91`	`if (lLen < l) {`
`92`	`92`	`t += (lastBigger - t) * 0.5f;`
`@@ -95,6 +95,7 @@ float VBezier::tAtLength(float l, float totalLength) const`
`95`	`95`	`t -= t * 0.5f;`
`96`	`96`	`}`
`97`	`97`	`}`
	`98`	`+ vWarning << "no convergence";`
`98`	`99`	`return t;`
`99`	`100`	`}`
`100`	`101`