src/bezier_curve.cpp

Tue, 11 Apr 2023 11:11:28 +0300

author
Teemu Piippo <teemu.s.piippo@gmail.com>
date
Tue, 11 Apr 2023 11:11:28 +0300
changeset 374
75efc3ba5a56
parent 373
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permissions
-rw-r--r--

More refactor and renaming
Added a test function that makes recolors stuff red

373
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1 #include "bezier_curve.h"
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2
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3 /**
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4 * @brief computes the point on a Bezier curve
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5 * @param curve
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6 * @param t scalar between 0 and 1, with t=0 being P0 and t=1 being P3
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7 * @return point on curve
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8 */
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9 glm::vec3 point_on_bezier_curve(const struct bezier_curve &curve, float t)
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10 {
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11 // clamp t as rounding errors might make it slightly out of bounds
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12 t = std::clamp(t, 0.0f, 1.0f);
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13 const float t_squared = t * t;
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14 const float t_cubed = t * t * t;
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15 const float coefficients[3] = {
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16 -1*t_cubed +3*t_squared -3*t +1,
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17 +3*t_cubed -6*t_squared +3*t,
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18 -3*t_cubed +3*t_squared,
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19 };
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20 return coefficients[0] * curve.points[0]
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21 + coefficients[1] * curve.points[1]
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22 + coefficients[2] * curve.points[2]
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23 + t_cubed * curve.points[3];
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24 }
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25
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26 /**
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27 * @brief computes the derivative of a point on a Bezier curve
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28 * @param curve
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29 * @param t scalar between 0 and 1, with t=0 being P0 and t=1 being P3
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30 * @return point on curve
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31 */
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32 glm::vec3 derivate_on_bezier_curve(const struct bezier_curve &curve, float t)
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33 {
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34 // clamp t as rounding errors might make it slightly out of bounds
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35 t = std::clamp(t, 0.0f, 1.0f);
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36 const float t_cubed = t * t;
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37 const float coefficients[4] = {
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38 -3*t_cubed + 6*t -3,
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39 +9*t_cubed -12*t +3,
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40 -9*t_cubed + 6*t,
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41 +3*t_cubed
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42 };
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43 return coefficients[0] * curve.points[0]
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44 + coefficients[1] * curve.points[1]
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45 + coefficients[2] * curve.points[2]
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46 + coefficients[3] * curve.points[3];
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47 }

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