public void Execute(ArchetypeChunk ac, int ci)
{
if (!ac.DidAddOrChange(lineSegmentType, lastSystemVersion))
{
return;
}
var segs = ac.GetNativeArray(lineSegmentType);
var ltws = ac.GetNativeArray(ltwType);
for (int i = 0; i < segs.Length; i++)
{
var seg = segs[i];
var ltw = ltws[i];
if (seg.from.Equals(seg.to) || seg.from.Equals(cameraPosition))
{
continue;
}
float3 forward = seg.to - seg.from;
//We will use length too so not using normalize here
float lineLength = math.length(forward);
float3 forwardUnit = forward / lineLength;
//billboard rotation
float3 toCamera = math.normalize(cameraPosition - seg.from);
//If forward and toCamera is collinear the cross product is 0
//and it will gives quaternion with tons of NaN
//So we have to check for that and do nothing if that is the case
if (math.cross(forwardUnit, toCamera).Equals(float3.zero))
{
continue;
}
quaternion rotation = quaternion.LookRotation(forwardUnit, toCamera);
var mat = math.mul(
new float4x4(rotation, seg.from),
float4x4.Scale(seg.lineWidth, 1, lineLength));
ltws[i] = new LocalToWorld {
Value = mat
};
}
}