private void Update(EvaluationContext context)
{
if (!(SourcePoints.GetValue(context) is StructuredList <Point> sourcePoints))
{
return;
}
if (sourcePoints.NumElements == 0)
{
sourcePoints.SetLength(0);
ResultList.Value = sourcePoints;
return;
}
var spread = Spread.GetValue(context);
var spreadMode = (SpreadModes)SpreadMode.GetValue(context);
var indexWithinSegment = 0;
var lineSegmentLength = 0f;
var totalLength = 0f;
var maxLength = float.NegativeInfinity;
var randomizeStart = RandomizeStart.GetValue(context);
var randomizeDuration = RandomizeDuration.GetValue(context);
// Measure...
segments.Clear();
for (var pointIndex = 0; pointIndex < sourcePoints.NumElements; pointIndex++)
{
if (float.IsNaN(sourcePoints.TypedElements[pointIndex].W))
{
var hasAtLeastTwoPoints = indexWithinSegment > 1;
if (hasAtLeastTwoPoints)
{
if (lineSegmentLength > maxLength)
{
maxLength = lineSegmentLength;
}
totalLength += lineSegmentLength;
segments.Add(new Segment
{
PointIndex = pointIndex - indexWithinSegment,
PointCount = indexWithinSegment,
AccumulatedLength = totalLength,
SegmentLength = lineSegmentLength
});
}
lineSegmentLength = 0;
indexWithinSegment = 0;
}
else
{
if (indexWithinSegment > 0)
{
lineSegmentLength += Vector3.Distance(sourcePoints.TypedElements[pointIndex - 1].Position,
sourcePoints.TypedElements[pointIndex].Position);
}
indexWithinSegment++;
}
}
if (totalLength < 0.0001f || segments.Count < 2)
{
Log.Warning("Stroke animation requires at least two segments with of some length");
return;
}
// Write offsets...
float dist = maxLength / (segments.Count - 1);
_random = new Random(42);
for (var segmentIndex = 0; segmentIndex < segments.Count; segmentIndex++)
{
var segmentOffset = ComputeOverlappingProgress(0, segmentIndex, segments.Count, spread);
var lengthProgressWithingSegment = 0f;
var segment = segments[segmentIndex];
// see https://www.figma.com/file/V5k13NMMIsnAnbWH651clI/Untitled?node-id=205%3A96
var stackedRange = TimeRange.FromStartAndDuration(segment.AccumulatedLength - segment.SegmentLength, segment.SegmentLength) * (1 / totalLength);
var anchor = segmentIndex * segment.SegmentLength / (segments.Count - 1);
var pGrid = segmentIndex * dist;
var packedRange = TimeRange.FromStartAndDuration(pGrid - anchor, segment.SegmentLength) * (1 / maxLength);
var range = TimeRange.Lerp(packedRange, stackedRange, spread);
if (Math.Abs(randomizeStart) > 0.0001f)
{
var randomStart = (float)_random.NextDouble() * (1 - range.Duration);
range.Start = MathUtils.Lerp(range.Start, randomStart, randomizeStart);
}
if (Math.Abs(randomizeDuration) > 0.0001f)
{
var randomDuration = (float)_random.NextDouble() * (1 - range.Start);
range.Duration = MathUtils.Lerp(range.Duration, randomDuration, randomizeDuration);
}
for (var pointIndexInSegment = 0; pointIndexInSegment < segment.PointCount; pointIndexInSegment++)
{
var pi = segment.PointIndex + pointIndexInSegment;
if (pointIndexInSegment > 0)
{
lengthProgressWithingSegment += Vector3.Distance(sourcePoints.TypedElements[pi - 1].Position,
sourcePoints.TypedElements[pi].Position);
}
var normalizedSegmentPosition = pointIndexInSegment / (segment.PointCount - 1);
float w = 0;
switch (spreadMode)
{
case SpreadModes.IgnoreStrokeLengths:
var f = lengthProgressWithingSegment / segment.SegmentLength.Clamp(0.001f, 999999f);
w = (f - segmentOffset) / (segments.Count + 1);
break;
case SpreadModes.UseStrokeLength:
w = MathUtils.Lerp(range.Start, range.End, normalizedSegmentPosition);
break;
case SpreadModes.Weird:
w = segmentOffset * 0.2f + pointIndexInSegment / segment.PointCount / 2;
break;
}
sourcePoints.TypedElements[pi].W = w;
}
}
StrokeCount.Value = segments.Count;
ResultList.Value = sourcePoints;
StrokeCount.DirtyFlag.Clear();
ResultList.DirtyFlag.Clear();
}