Mercurial > ldforge2 / file diff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/bezier_curve.cpp	Mon Apr 10 14:46:36 2023 +0300
@@ -0,0 +1,47 @@
+#include "bezier_curve.h"
+
+/**
+ * @brief computes the point on a Bezier curve
+ * @param curve
+ * @param t scalar between 0 and 1, with t=0 being P0 and t=1 being P3
+ * @return point on curve
+ */
+glm::vec3 point_on_bezier_curve(const struct bezier_curve &curve, float t)
+{
+	// clamp t as rounding errors might make it slightly out of bounds
+	t = std::clamp(t, 0.0f, 1.0f);
+	const float t_squared = t * t;
+	const float t_cubed = t * t * t;
+	const float coefficients[3] = {
+		-1*t_cubed  +3*t_squared  -3*t  +1,
+		+3*t_cubed  -6*t_squared  +3*t,
+		-3*t_cubed  +3*t_squared,
+	};
+	return coefficients[0] * curve.points[0]
+		+ coefficients[1] * curve.points[1]
+		+ coefficients[2] * curve.points[2]
+		+ t_cubed * curve.points[3];
+}
+
+/**
+ * @brief computes the derivative of a point on a Bezier curve
+ * @param curve
+ * @param t scalar between 0 and 1, with t=0 being P0 and t=1 being P3
+ * @return point on curve
+ */
+glm::vec3 derivate_on_bezier_curve(const struct bezier_curve &curve, float t)
+{
+	// clamp t as rounding errors might make it slightly out of bounds
+	t = std::clamp(t, 0.0f, 1.0f);
+	const float t_cubed = t * t;
+	const float coefficients[4] = {
+		-3*t_cubed + 6*t  -3,
+		+9*t_cubed -12*t  +3,
+		-9*t_cubed + 6*t,
+		+3*t_cubed
+	};
+	return coefficients[0] * curve.points[0]
+		+ coefficients[1] * curve.points[1]
+		+ coefficients[2] * curve.points[2]
+		+ coefficients[3] * curve.points[3];
+}