From 4ea281c750c5afcc68f2832bb42d98a1cbce6735 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Konstantin=20Ka=CC=88fer?= <mail@kkaefer.com>
Date: Wed, 16 Jul 2014 18:53:56 -0700
Subject: rename llmr => mbgl

---
 include/mbgl/util/unitbezier.hpp | 121 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 include/mbgl/util/unitbezier.hpp

(limited to 'include/mbgl/util/unitbezier.hpp')

diff --git a/include/mbgl/util/unitbezier.hpp b/include/mbgl/util/unitbezier.hpp
new file mode 100644
index 0000000000..095e15f809
--- /dev/null
+++ b/include/mbgl/util/unitbezier.hpp
@@ -0,0 +1,121 @@
+/*
+ * Copyright (C) 2008 Apple Inc. All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef MBGL_UTIL_UNITBEZIER
+#define MBGL_UTIL_UNITBEZIER
+
+#include <cmath>
+
+namespace mbgl {
+namespace util {
+
+struct UnitBezier {
+    UnitBezier(double p1x, double p1y, double p2x, double p2y) {
+        // Calculate the polynomial coefficients, implicit first and last control points are (0,0) and (1,1).
+        cx = 3.0 * p1x;
+        bx = 3.0 * (p2x - p1x) - cx;
+        ax = 1.0 - cx - bx;
+
+        cy = 3.0 * p1y;
+        by = 3.0 * (p2y - p1y) - cy;
+        ay = 1.0 - cy - by;
+    }
+
+    double sampleCurveX(double t) {
+        // `ax t^3 + bx t^2 + cx t' expanded using Horner's rule.
+        return ((ax * t + bx) * t + cx) * t;
+    }
+
+    double sampleCurveY(double t) {
+        return ((ay * t + by) * t + cy) * t;
+    }
+
+    double sampleCurveDerivativeX(double t) {
+        return (3.0 * ax * t + 2.0 * bx) * t + cx;
+    }
+
+    // Given an x value, find a parametric value it came from.
+    double solveCurveX(double x, double epsilon) {
+        double t0;
+        double t1;
+        double t2;
+        double x2;
+        double d2;
+        int i;
+
+        // First try a few iterations of Newton's method -- normally very fast.
+        for (t2 = x, i = 0; i < 8; ++i) {
+            x2 = sampleCurveX(t2) - x;
+            if (fabs (x2) < epsilon)
+                return t2;
+            d2 = 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 = 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;
+    }
+
+    double solve(double x, double epsilon) {
+        return sampleCurveY(solveCurveX(x, epsilon));
+    }
+
+private:
+    double ax;
+    double bx;
+    double cx;
+
+    double ay;
+    double by;
+    double cy;
+};
+
+}
+}
+
+#endif
-- 
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