X-Git-Url: http://git.mutantstargoat.com?p=faros-demo;a=blobdiff_plain;f=src%2Ftrack.cc;fp=src%2Ftrack.cc;h=bc775baed0ba6a16b39f25e77fd89970b9d20c97;hp=0000000000000000000000000000000000000000;hb=d60954c471d6f446523bad8c4c4860aa2138da1e;hpb=6917510e2aff5fa6599065c684a344a24e42123d

diff --git a/src/track.cc b/src/track.cc
new file mode 100644
index 0000000..bc775ba
--- /dev/null
+++ b/src/track.cc
@@ -0,0 +1,146 @@
+#include <assert.h>
+#include <algorithm>
+#include "track.h"
+
+static long remap_time(ExtrapMode mode, long t, long t0, long t1);
+static float smoothstep(float a, float b, float x);
+
+Track::Track()
+{
+	interp = INTERP_SIGMOID;
+	extrap = EXTRAP_CLAMP;
+	keys_sorted = true;
+	defval = 0.0f;
+}
+
+void Track::clear()
+{
+	keys.clear();
+}
+
+void Track::set_key(long tm, float val)
+{
+	int idx = find_key(tm);
+	if(idx >= 0) {
+		keys[idx].value = val;
+		return;
+	}
+
+	TrackKey key = {tm, val};
+	keys.push_back(key);
+	keys_sorted = false;
+}
+
+float Track::get_key(long tm) const
+{
+	int idx = find_key(tm);
+	if(idx == -1) return 0.0f;
+	return keys[idx].value;
+}
+
+int Track::find_key(long tm) const
+{
+	int sz = (int)keys.size();
+	for(int i=0; i<sz; i++) {
+		if(keys[i].time == tm) return i;
+	}
+	return -1;
+}
+
+static bool keycmp(const TrackKey &a, const TrackKey &b)
+{
+	return a.time < b.time;
+}
+
+float Track::operator ()(long tm) const
+{
+	if(keys.empty()) {
+		return defval;
+	}
+
+	int nkeys = keys.size();
+	if(nkeys == 1) {
+		return keys[0].value;
+	}
+	if(!keys_sorted) {
+		Track *track = (Track*)this;
+		std::sort(track->keys.begin(), track->keys.end(), keycmp);
+		keys_sorted = true;
+	}
+
+	long tstart = keys[0].time;
+	long tend = keys[nkeys - 1].time;
+
+	tm = remap_time(extrap, tm, tstart, tend);
+
+	int idx0 = get_interval(tm);
+	assert(idx0 >= 0 && idx0 < nkeys);
+	int idx1 = idx0 + 1;
+
+	if(idx0 == nkeys - 1) {
+		return keys[idx0].value;
+	}
+
+	float dt = (float)(keys[idx1].time - keys[idx0].time);
+	float t = (float)(tm - keys[idx0].time) / dt;
+
+	switch(interp) {
+	case INTERP_STEP:
+		return keys[idx0].value;
+
+	case INTERP_SIGMOID:
+		t = smoothstep(0, 1, t);
+	case INTERP_LINEAR:
+		return keys[idx0].value + (keys[idx1].value - keys[idx0].value) * t;
+
+	default:
+		break;
+	}
+	return 0.0f;
+}
+
+int Track::get_interval(long tm) const
+{
+	int nkeys = (int)keys.size();
+
+	for(int i=0; i<nkeys-1; i++) {
+		if(tm < keys[i + 1].time) {
+			return i;
+		}
+	}
+	return nkeys - 1;
+}
+
+static long remap_time(ExtrapMode mode, long t, long t0, long t1)
+{
+	long interval = t1 - t0;
+
+	switch(mode) {
+	case EXTRAP_CLAMP:
+		if(interval <= 0) return t0;
+		return t < t0 ? t0 : (t >= t1 ? t1 : t);
+
+	case EXTRAP_REPEAT:
+		if(interval > 0) {
+			long x = (t - t0) % interval;
+			if(x < 0) x += interval;
+			return x + t0;
+		}
+		return t0;
+
+	default:
+		break;
+	}
+
+	assert(!"unreachable");
+	return t;
+}
+
+static float smoothstep(float a, float b, float x)
+{
+	if(x < a) return 0.0f;
+	if(x >= b) return 1.0f;
+
+	x = (x - a) / (b - a);
+	return x * x * (3.0f - 2.0f * x);
+}