curves

math/CMakeLists.txt

@@ -3,6 +3,7 @@ set(SRCS
   lin/vec3.cpp
   lin/quat.cpp
   lin/aabb.cpp
+	curves.cpp
   )
 
 set(SRCS ${SRCS})

math/curves.cpp

@@ -0,0 +1,57 @@
+
+#include <math.h>
+
+#include "math/math_util.h"
+#include "curves.h"
+
+float linearInOut(int t, int fadeInLength, int solidLength, int fadeOutLength) {
+	if (t < 0) return 0;
+	if (t < fadeInLength) {
+		return (float)t / fadeInLength;
+	}
+	t -= fadeInLength;
+	if (t < solidLength) {
+		return 1.0f;
+	}
+	t -= solidLength;
+	if (t < fadeOutLength) {
+		return 1.0f - (float)t / fadeOutLength;
+	}
+	return 0.0f;
+}
+
+float linearIn(int t, int fadeInLength) {
+	if (t < 0) return 0;
+	if (t < fadeInLength) {
+		return (float)t / fadeInLength;
+	}
+	return 1.0f;
+}
+
+float linearOut(int t, int fadeOutLength) {
+	return 1.0f - linearIn(t, fadeOutLength);
+}
+
+float ease(float val) {
+	return ((-cosf(val * PI)) + 1.0f) * 0.5;
+}
+
+float sawtooth(int t, int period) {
+	return (t % period) * (1.0f / (period - 1));
+}
+
+float passWithPause(int t, int fadeInLength, int pauseLength, int fadeOutLength)
+{
+	if (t < fadeInLength) {
+		return -1.0f + (float)t / fadeInLength;
+	}
+	t -= fadeInLength;
+	if (t < pauseLength) {
+		return 0.0f;
+	}
+	t -= pauseLength;
+	if (t < fadeOutLength) {
+		return (float)t / fadeOutLength;
+	}
+	return 1.0f;
+}

math/curves.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <base/basictypes.h>
+
+// Easy curve computation for fades etc.
+
+
+// output range: [0.0, 1.0]
+float linearInOut(int t, int fadeInLength, int solidLength, int fadeOutLength);
+float linearIn(int t, int fadeInLength);
+float linearOut(int t, int fadeInLength);
+
+// smooth operator [0, 1] -> [0, 1]
+float ease(float val);
+
+// need a bouncy ease
+
+// waveforms [0, 1]
+float sawtooth(int t, int period);
+
+// output range: -1.0 to 1.0
+float passWithPause(int t, int fadeInLength, int pauseLength, int fadeOutLength);