Merge pull request #105 from a1xd/1.5.x

v1.5

1 files changed, 77 insertions, 0 deletions

diff --git a/common/accel-jump.hpp b/common/accel-jump.hpp
new file mode 100644
index 0000000..95fa461
--- /dev/null
+++ b/common/accel-jump.hpp
@@ -0,0 +1,77 @@
+#pragma once
+
+#include "rawaccel-base.hpp"
+
+namespace rawaccel {
+
+	struct jump_base {
+		static constexpr double smooth_scale = 2 * PI;
+
+		vec2d step;
+		double smooth_rate;
+
+		// requirements: args.smooth in range [0, 1]
+		jump_base(const accel_args& args) :
+			step({ args.offset, args.cap - 1 })
+		{
+			double rate_inverse = args.smooth * step.x;
+
+			if (rate_inverse < 1) {
+				smooth_rate = 0;
+			}
+			else {
+				smooth_rate = smooth_scale / rate_inverse;
+			}
+		}
+
+		bool is_smooth() const
+		{
+			return smooth_rate != 0;
+		}
+
+		double decay(double x) const
+		{
+			return exp(smooth_rate * (step.x - x));
+		}
+
+		double smooth(double x) const
+		{
+			return step.y / (1 + decay(x));
+		}
+
+		double smooth_antideriv(double x) const
+		{
+			return step.y * (x + log(1 + decay(x)) / smooth_rate);
+		}
+	};
+
+	struct jump_legacy : jump_base {
+		using jump_base::jump_base;
+
+		double operator()(double x) const
+		{
+			if (is_smooth()) return smooth(x) + 1;
+			else if (x < step.x) return 1;
+			else return 1 + step.y;
+		}
+	};
+
+	struct jump : jump_base {
+		double C;
+
+		jump(const accel_args& args) :
+			jump_base(args),
+			C(-smooth_antideriv(0)) {}
+
+		double operator()(double x) const
+		{
+			if (x <= 0) return 1;
+
+			if (is_smooth()) return 1 + (smooth_antideriv(x) + C) / x;
+
+			if (x < step.x) return 1;
+			else return 1 + step.y * (x - step.x) / x;
+		}
+	};
+
+}