| /* |
| * Copyright 2023 Google LLC |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| #ifndef SkCubics_DEFINED |
| #define SkCubics_DEFINED |
| |
| /** |
| * Utilities for dealing with cubic formulas with one variable: |
| * f(t) = A*t^3 + B*t^2 + C*t + d |
| */ |
| class SkCubics { |
| public: |
| /** |
| * Puts up to 3 real solutions to the equation |
| * A*t^3 + B*t^2 + C*t + d = 0 |
| * in the provided array. |
| */ |
| static int RootsReal(double A, double B, double C, double D, |
| double solution[3]); |
| |
| /** |
| * Puts up to 3 real solutions to the equation |
| * A*t^3 + B*t^2 + C*t + D = 0 |
| * in the provided array, with the constraint that t is in the range [0.0, 1.0]. |
| */ |
| static int RootsValidT(double A, double B, double C, double D, |
| double solution[3]); |
| |
| |
| /** |
| * Evaluates the cubic function with the 4 provided coefficients and the |
| * provided variable. |
| */ |
| static double EvalAt(double A, double B, double C, double D, double t) { |
| return A * t * t * t + |
| B * t * t + |
| C * t + |
| D; |
| } |
| |
| static double EvalAt(double coefficients[4], double t) { |
| return EvalAt(coefficients[0], coefficients[1], coefficients[2], coefficients[3], t); |
| } |
| }; |
| |
| #endif |